,illustration3 ,compare the unfavorable 
artificial environment of a crowded city
 with the more favorable environment of 
the country4                      ,a    
,,civic ,,biology                       
,presented in ,problems                 
,,by              ,,george ,,william    
,,hunter1 ,a4,m4    ,,head ,,of ,,the   
,,department ,,of ,,biology1 ,,de ,,witt
 ,,clinton           ,,high ,,school1   
,,city ,,of ,,new ,,york4      ,,author 
,,of ,,elements ,,of ,,biology1         
,,essentials ,,of                       
,,biology1 ,,etc4                       
,illustration3  ,printer's ,logo        
,,american ,,book ,,company    ,,new    
,,york         ,,cincinnati             
,,chicago                               
,,copyright1 #aiad1 ,,by                
,,george ,,william ,,hunter4            
,,copyright1 #aiad1 ,,in ,,great        
,,britain4              99     99     99
     99     99                ,,hunter1 
,,civic ,,biology4                      
,w4 ,p4 #c                              

,dedicated                       ,,to   
,,my                  ,,fellow          
,,teachers           ,,of ,,the         
,,department ,,of ,,biology        ,,in 
,,the ,,de ,,witt ,,clinton ,,high      
,,school         ,,whose ,,capable1     
,,earnest1 ,,unselfish            ,,and 
,,inspiring ,,aid ,,has ,,made          
,,this ,,book ,,possible                
,,foreword ,,to ,,teachers   ,a course  
in biology given to beginners in the    
secondary school should have certain    
aims4 ,these aims must be determined to 
a degree1 first1 by the capabilities of 
the pupils1 second1 by their native     
interests1 and1 third1 by the           
environment of the pupils4  ,the boy or 
girl of average ability upon admission  
to the secondary school is not a        
thinking individual4 ,the training given
 up to this time1 with but rare         
exceptions1 has been in the forming of  
simple concepts4 ,these concepts have   
been reached didactically and           
empirically4 ,drill and memory work have

 been the pedagogic vehicles4 ,even the 
elementary science work given has       
resulted at the best in an              
interpretation of some of the common    
factors in the pupil's environment1 and 
a widening of the meaning of some of his
 concepts4 ,therefore1 the first science
 of the secondary school1 elementary    
biology1 should be primarily the vehicle
 by which the child is taught to solve  
problems and to think straight in so    
doing4 ,no other subject is more capable
 of logical development4 ,no subject is 
more vital because of its relation to   
the vital things in the life of the     
child4 ,a series of experiments and     
demonstrations1 discussed and applied as
 definite concrete problems which have  
arisen within the child's horizon1 will 
develop power in thinking more surely   
than any other subject in the first year
 of the secondary school4  ,but in our  
eagerness to develop the power of       
logical thinking we must not lose sight 
of the previous training of our pupil4  

,up to this time the method of          
induction1 that handmaiden of logical   
thought1 has been almost unknown4       
,concepts have been formed deductively  
by a series of comparisons4 ,all        
concepts have been handed down by the   
authority of the teacher or the text2   
the inductive search for the unknown is 
as yet a closed book4 ,it is unwise1    
then1 to directly introduce the pupil to
 the method of induction with a series  
of printed directions which1 though     
definite in the mind of the teacher     
because of his wider horizon1 mean      
little or nothing as a definite problem 
to the pupil4 ,the child must be brought
 to the appreciation of the problem     
through the deductive method1 by a      
comparison of the future problem with   
some definite concrete experience within
 his own field of vision4 ,then by the  
inductive experiment1 still led by a    
series of oral questions1 he comes to   
the real end of the experiment1 the     
conclusion1 with the true spirit of the 

investigator4 ,the result is tested in  
the light of past experiment and a      
generalization is formed which means    
something to the pupil4  ,for the above 
reason the laboratory problems1 which   
naturally precede the textbook work1    
should be separated from the subject    
matter of the text4 ,a textbook in      
biology should serve to verify the      
student's observations made in the      
laboratory1 it should round out his     
concept or generalization by adding such
 material as he cannot readily observe  
and it should give the student directly 
such information as he cannot be        
expected to gain directly or indirectly 
through his laboratory experience4 ,for 
these reasons the laboratory manual has 
been separated from the text4       ,the
 laboratory method was such an          
emancipation from the      old-time     
bookish slavery of pre-laboratory days  
that we may      have been inclined to  
overdo it and to subject ourselves to   
a new slavery4 ,it should never be      

forgotten that the      laboratory is   
simply a means to the end2 that the     
dominant      thing should be a         
consistent chain of ideas which the     
laboratory may serve to elucidate4      
,when1 however1 the      laboratory     
assumes the first place and other phases
 of the      course are made explanatory
 to it1 we have taken1 in my      mind1 
an attitude fundamentally wrong4 ,the   
question is1 not      what types may be 
taken up in the laboratory to be fitted 
into the general scheme afterwards1 but 
what ideas are      most worth while to 
be worked out and developed in the      
laboratory1 if that happens to be the   
best way of doing it1      or if not1   
some other way to be adopted with       
perfect      freedom4 ,too often our    
course of study of an animal or plant   
takes the easiest rather than the most  
illuminating path4      ,what is easier1
 for instance1 particularly with large  
classes of restless pupils who          
apparently need to be kept in      a    

condition of uniform occupation1 than to
 kill a supply of      animals1         
preferably as near alike as possible1   
and set the      pupils to work drawing 
the dead remains8 ,this method is       
usually supplemented by a series of     
questions concerning the      remains   
which are sure to keep the pupils busy a
 while      longer1 perhaps until the   
bell strikes1 and which usually      are
 so planned as to anticipate any ideas  
that might      naturally crop up in the
 pupil's mind during the drawing        
exercise4       ,such an abuse of the   
laboratory idea is all wrong and        
should be avoided4 ,the ideal laboratory
 ought to be a      retreat for rainy   
days2 a substitute for out of doors2 a  
clearing house of ideas brought in from 
the outside4 ,any      course in biology
 which can be confined within four      
walls1      even if these walls be of a 
modern1 well-equipped      laboratory1  
is in some measure a failure4 ,living   
things1 to      be appreciated and      

correctly interpreted1 must be seen and 
studied in the open where they will be  
encountered      throughout life4 ,the  
place where an animal or plant is       
found is just as important a            
characteristic as its shape or          
function4 ,impossible field excursions  
with large classes      within school   
hours1 which only bring confusion to    
inflexible school programs1 are not     
necessary to      accomplish this       
result4 ,properly administered1 it is   
without      doubt one of our most      
efficient devices for developing        
biological ideas1 but the laboratory    
should be kept in its      proper       
relation to the other means at our      
disposal and never      be allowed to   
degenerate either into a place for      
vacuous      drawing exercises or a     
biological morgue where dead remains    
are viewed4--,dr4 ,h4 ,e4 ,walter4  ,for
 the sake of the pupil the number of    
technical and scientific terms has been 
reduced to a minimum4 ,the language has 

been made as simple as possible and the 
problems made to hinge upon material    
already known1 by hearsay at least1 to  
the pupil4 ,so far as consistent with a 
well-rounded course in the essentials of
 biological science1 the interests of   
the children have been kept in the      
foreground4 ,in a recent questionnaire  
sent out by the author and answered by  
over three thousand children studying   
biology in the secondary schools of     
,connecticut1 ,massachusetts1 ,new      
,jersey1 and ,new ,york by far the      
greatest number gave as the most        
interesting topics those relating to the
 care and functions of the human body   
and the control and betterment of the   
environment4 ,as would be expected1 boys
 have different biological interests    
from girls1 and children in rural       
schools wish to study different topics  
from those in congested districts in    
large communities4 ,the time has come   
when we must frankly recognize these    
interests and adapt the content of our  

courses in biology to interpret the     
immediate world of the pupil4  ,with    
this end in view the following pages    
have been written4 ,this book shows boys
 and girls living in an urban community 
how they may best live within their own 
environment and how they may cooperate  
with the civic authorities for the      
betterment of their environment4 ,a     
logical course is built up around the   
topics which appeal to the average      
normal boy or girl1 topics given in a   
logical sequence so as to work out the  
solution of problems bearing on the     
ultimate problem of the entire course1  
that of preparation for citizenship in  
the largest sense4  ,seasonal use of    
materials has been kept in mind in      
outlining this course4 ,field trips1    
when properly organized and later used  
as a basis for discussion in the        
classroom1 make a firm foundation on    
which to build the superstructure of a  
course in biology4 ,the normal          
environment1 its relation to the        

artificial environment of the city1 the 
relations of mutual give and take       
existing between plants and animals1 are
 better shown by means of field trips   
than in any other way4 ,field and museum
 trips are enjoyed by the pupils as     
well4 ,these result in interest and in  
better work4 ,the course is worked up   
around certain great biological         
principles2 hence insects may be studied
 when abundant in the fall in connection
 with their relations to green plants   
and especially in their relation to     
flowers4 ,in the winter months material 
available for the laboratory is used4   
,saprophytic and parasitic organisms1   
wild plants in the household1 are       
studied in their relations to mankind1  
both as destroyers of food1 property and
 life and as man's invaluable friends4  
,the economic phase of biology may well 
be taken up during the winter months1   
thus gaining variety in subject matter  
and in method of treatment4 ,the        
apparent emphasis placed upon economic  

material in the following pages is not  
real4 ,it has been found that material  
so given makes for variety1 as it may be
 assigned as a topical reading lesson or
 simply used as reference when needed4  
,cyclic work in the study of life       
phenomena and of the needs of organisms 
for oxygen1 food1 and reproduction      
culminates1 as it rightly should1 in the
 study of life-processes of man and     
man's relation to his environment4  ,in 
a course in biology the difficulty comes
 not so much in knowing what to teach as
 in knowing what not to teach4 ,the     
author believes that he has made a      
selection of the topics most vital in a 
well-rounded course in elementary       
biology directed toward civic           
betterment4 ,the physiological functions
 of plants and animals1 the hygiene of  
the individual within the community1    
conservation and the betterment of      
existing plant and animal products1 the 
big underlying biological concepts on   
which society is built1 have all been   

used to the end that the pupil will     
become a better1 stronger and more      
unselfish citizen4 ,the spiral or cyclic
 method of treatment has been used      
throughout1 the purpose being to        
ultimately build up a number of         
well-rounded concepts by constant       
repetition but with constantly varied   
viewpoint4  ,the sincere thanks of the  
author is extended to all who have      
helped make this book possible1 and     
especially to the members of the        
,department of ,biology in the ,de ,witt
 ,clinton ,high ,school4 ,most of the   
men there have directly or indirectly   
contributed their time and ideas to help
 make this book worth more to teachers  
and pupils4 ,the following have read the
 manuscript in its entirety and have    
offered much valuable constructive      
criticism3 ,dr4 ,herbert ,e4 ,walter1   
,professor of ,zoology in ,brown        
,university2 ,miss ,elsie ,kupfer1 ,head
 of the ,department of ,biology in      
,wadleigh ,high ,school2 ,george ,c4    

,wood1 of the ,department of ,biology in
 the ,boys' ,high ,school1 ,brooklyn2   
,edgar ,a4 ,bedford1 ,head of           
,department of ,biology in the          
,stuyvesant ,high ,school2 ,george ,e4  
,hewitt1 ,george ,t4 ,hastings1 ,john   
,d4 ,mc,carthy1 and ,frank ,m4 ,wheat1  
all of the ,department of ,biology in   
the ,de ,witt ,clinton ,high ,school4   
,thanks are due1 also1 to ,professor ,e4
 ,b4 ,wilson1 ,professor ,g4 ,n4        
,calkins1 ,mr4 ,william ,c4 ,barbour1   
,dr4 ,john ,a4 ,sampson1 ,w4 ,c4        
,stevens1 and ,c4 ,w4 ,beebe1 ,dr4      
,alvin ,davison1 and ,dr4 ,frank        
,overton2 to the ,united ,states        
,department of ,agriculture2 the ,new   
,york ,aquarium2 the ,charity           
,organization ,society2 and the         
,american ,museum of ,natural ,history1 
for permission to copy and use certain  
photographs and cuts which have been    
found useful in teaching4 ,dr4 ,charles 
,h4 ,morse and ,dr4 ,lucius ,j4 ,mason1 
of the ,de ,witt ,clinton ,high ,school1

 prepared the hygiene outline in the    
appendix4 ,frank ,m4 ,wheat and my      
former pupil1 ,john ,w4 ,teitz1 now a   
teacher in the school1 made many of the 
line drawings and took several of the   
photographs of experiments prepared for 
this book4 ,to them especially ,i wish  
to express my thanks4  ,at the end of   
each of the following chapters is a list
 of books which have proved their use   
either as reference reading for students
 or as aids to the teacher4 ,most of the
 books mentioned are within the means of
 the small school4 ,two sets are        
expensive3 one1 ,the ,natural ,history  
of ,plants1 by ,kerner1 translated by   
,oliver1 published by ,henry ,holt and  
,company1 in two volumes1 at #aa2 the   
other1 ,plant ,geography upon a         
,physiological ,basis1 by ,schimper1    
published by the ,clarendon ,press1 #ab2
 but both works are invaluable for      
reference4  ,for a general introduction 
to physiological biology1 ,parker1      
,elementary ,biology1 ,the ,macmillan   

,company2 ,sedgwick and ,wilson1        
,general ,biology1 ,henry ,holt and     
,company2 ,verworn1 ,general            
,physiology1 ,the ,macmillan ,company2  
and ,needham1 ,general ,biology1        
,comstock ,publishing ,company1 are most
 useful and inspiring books4  ,two books
 stand out from the pedagogical         
standpoint as by far the most helpful of
 their kind on the market4 ,no teacher  
of botany or zoology can afford to be   
without them4 ,they are3 ,lloyd and     
,bigelow1 ,the ,teaching of ,biology1   
,longmans1 ,green1 and ,company1 and ,c4
 ,f4 ,hodge1 ,nature ,study and ,life1  
,ginn and ,company4 ,other books of     
value from the teacher's standpoint are3
 ,ganong1 ,the ,teaching ,botanist1 ,the
 ,macmillan ,company2 ,l4 ,h4 ,bailey1  
,the ,nature ,study ,idea1 ,doubleday1  
,page1 and ,company2 and ,mc,murry's    
,how to ,study1 ,houghton ,mifflin      
,company4                               
,,contents     ,,chapter                
,,page           ,,foreword ,,to        

,,teachers                              
#g        ,i4 ,,some ,,reasons ,,for    
,,the ,,study ,,of ,,biology            
#ae       ,,ii4 ,,the ,,environment ,,of
 ,,plants ,,and ,,animals               
#ai      ,,iii4 ,,the ,,interrelations  
,,of ,,plants ,,and ,,animals           
#bh       ,,iv4 ,,the ,,functions ,,and 
,,composition ,,of ,,living ,,things    
#dg        ,v4 ,,plant ,,growth ,,and   
,,nutrition--,,the ,,causes ,,of        
,,growth       #eh       ,,vi4 ,,the    
,,organs ,,of ,,nutrition ,,in          
,,plants--,,the ,,soil ,,and            
,,its ,,relation ,,to ,,roots           
#ga      ,,vii4 ,,plant ,,growth ,,and  
,,nutrition--,,plants ,,make ,,food     
#hd     ,,viii4 ,,plant ,,growth ,,and  
,,nutrition--,,the ,,circulation ,,and  
,,final ,,uses ,,of ,,food ,,by ,,plants
                           #ig          
,,ix4 ,,our ,,forests1 ,,their ,,uses   
,,and ,,the ,,necessity ,,of ,,their    
,,protection                            
#aje        ,x4 ,,the ,,economic        

,,relation ,,of ,,green ,,plants ,,to   
,,man          #aag       ,,xi4 ,,plants
 ,,without ,,chlorophyll ,,in ,,their   
,,relation ,,to          ,,man          
#acj      ,,xii4 ,,the ,,relations ,,of 
,,plants ,,to ,,animals                 
#aei     ,,xiii4 ,,single-,,celled      
,,animals ,,considered ,,as ,,organisms 
#aff      ,,xiv4 ,,division ,,of        
,,labor1 ,,the ,,various ,,forms ,,of   
,,plants ,,and          ,,animals       
#agc       ,,xv4 ,,the ,,economic       
,,importance ,,of ,,animals             
#aig      ,,xvi4 ,,an ,,introductory    
,,study ,,of ,,vertebrates              
#bcb     ,,xvii4 ,,heredity1            
,,variation1 ,,plant ,,and ,,animal     
,,breeding        #bdi    ,,xviii4 ,,the
 ,,human ,,machine ,,and ,,its ,,needs  
#bff      ,,xix4 ,,foods ,,and          
,,dietaries                             
#bgb       ,,xx4 ,,digestion ,,and      
,,absorption                            
#bif      ,,xxi4 ,,the ,,blood ,,and    
,,its ,,circulation                     

#cac     ,,xxii4 ,,respiration ,,and    
,,excretion                             
#cbi    ,,xxiii4 ,,body ,,control ,,and 
,,habit ,,formation                     
#cdh     ,,xxiv4 ,,man',s ,,improvement 
,,of ,,his ,,environment                
#cgc      ,,xxv4 ,,some ,,great ,,names 
,,in ,,biology                          
#cih    ,,appendix                      
#djg           ,,suggested ,,course     
,,with ,,time ,,allotment ,,and         
,,sequence            ,,of ,,topics     
,,for ,,course ,,beginning ,,in ,,fall  
#djg           ,,suggested ,,syllabus   
,,for ,,course ,,in ,,biology           
,,beginning            ,,in ,,february  
,,and ,,ending ,,the ,,next ,,january   
#daa           ,,hygiene ,,outline      
#dae           ,,weights1 ,,measures1   
,,and ,,temperatures                    
#dag           ,,suggestions ,,for      
,,laboratory ,,equipment                
#dah    ,,index                         
#dai                      ,a ,,civic    
,,biology     ,i4 ,,the ,,general       

,,problem--,,some ,,reasons ,,for ,,the 
,,study ,,of ,,biology   ,what is       
,biology8--,biology is the study of     
living beings1 both plant and animal4   
,inasmuch as man is an animal1 the study
 of biology includes the study of man in
 his relations to the plants and the    
animals which surround him4 ,most       
important of all is that branch of      
biology which treats of the mechanism we
 call the human body1--of its parts and 
their uses1 and its repair4 ,this       
subject we call human physiology4  ,why 
study ,biology8--,although biology is a 
very modern science1 it has found its   
way into most high schools2 and an      
increasingly large number of girls and  
boys are yearly engaged in its study4   
,these questions might well be asked by 
any of the students3 ,why do ,i take up 
the study of biology8 ,of what practical
 value is it to me8 ,besides the        
discipline it gives me1 is there        
anything that ,i can take away which    
will help me in my future life8  ,human 

,physiology4--,the answer to this       
question is plain4 ,if the study of     
biology will give us a better           
understanding of our own bodies and     
their care1 then it certainly is of use 
to us4 ,that phase of biology known as  
physiology deals with the uses of the   
parts of a plant or animal2 human       
physiology and hygiene deal with the    
uses and care of the parts of the human 
animal4 ,the prevention of sickness is  
due in a large part to the study of     
hygiene4 ,it is estimated that over     
twenty-five per cent of the deaths that 
occur yearly in this country could be   
averted if all people lived in a        
hygienic manner4 ,in its application to 
the lives of each of us1 as a member of 
our family1 as a member of the school we
 attend1 and as a future citizen1 a     
knowledge of hygiene is of the greatest 
importance4  ,relations of ,plants to   
,animals4--,but there are other reasons 
why an educated person should know      
something about biology4 ,we do not     

always realize that if it were not for  
the green plants1 there would be no     
animals on the earth4 ,green plants     
furnish food to animals4 ,even the      
meat-eating animals feed upon those that
 feed upon plants4 ,how the plants      
manufacture this food and the relation  
they bear to animals will be discussed  
in later chapters4 ,plants furnish man  
with the greater part of his food in the
 form of grains and cereals1 fruits and 
nuts1 edible roots and leaves2 they     
provide his domesticated animals with   
food2 they give him timber for his      
houses and wood and coal for his fires2 
they provide him with pulp wood1 from   
which he makes his paper1 and oak galls1
 from which he may make ink4 ,much of   
man's clothing and the thread with which
 it is sewed together come from         
fiber-producing plants4 ,most medicines1
 beverages1 flavoring extracts1 and     
spices are plant products1 while plants 
are made use of in hundreds of ways in  
the useful arts and trades1 producing   

varnishes1 dyestuffs1 rubber1 and other 
products4  ,bacteria in their ,relation 
to ,man4--,in still another way1 certain
 plants vitally affect mankind4 ,tiny   
plants1 called bacteria1 so small that  
millions can exist in a single drop of  
fluid1 exist almost everywhere about    
us1--in water1 soil1 food1 and the air4 
,they play a tremendous part in shaping 
the destiny of man on the earth4 ,they  
help him in that they act as scavengers1
 causing things to decay2 thus they     
remove the dead bodies of plants and    
animals from the surface of the earth1  
and turn this material back to the      
ground2 they assist the tanner2 they    
help make cheese and butter2 they       
improve the soil for crop growing2 so   
the farmer cannot do without them4 ,but 
they likewise sometimes spoil our meat  
and fish1 and our vegetables and fruits2
 they sour our milk1 and may make our   
canned goods spoil4 ,worst of all1 they 
cause diseases1 among others            
tuberculosis1 a disease so harmful as to

 be called the white plague4 ,fully one 
half of all yearly deaths are caused by 
these plants4 ,so important are the     
bacteria that a sub-division of biology1
 called bacteriology1 has been named    
after them1 and hundreds of scientists  
are devoting their lives to the study of
 bacteria and their control4 ,the       
greatest of all bacteriologists1 ,louis 
,pasteur1 once said1 ,it is within the  
power of man to cause all parasitic     
diseases 7diseases mostly caused by     
bacteria7 to disappear from the world4  
,his prophecy is gradually being        
fulfilled1 and it may be the lot of some
 boys or girls who read this book to do 
their share in helping to bring this    
condition of affairs about4  ,the       
,relation of ,animals to ,man4--,animals
 also play an important part in the     
world in causing and carrying disease4  
,animals that cause disease are usually 
tiny1 and live in other animals as      
parasites2 that is1 they get their      
living from their hosts on which they   

feed4 ,among the diseases caused by     
parasitic animals are malaria1 yellow   
fever1 the sleeping sickness1 and the   
hookworm disease4 ,animals also carry   
disease1 especially the flies and       
mosquitoes2 rats and other animals are  
also well known as spreaders of disease4
  ,from a money standpoint1 animals     
called insects do much harm4 ,it is     
estimated that in this country alone    
they are annually responsible for       
#hjj1jjj1jjj worth of damage by eating  
crops1 forest trees1 stored food1 and   
other material wealth4  ,the ,uses of   
,animals to ,man4--,we all know the uses
 man has made of the domesticated       
animals for food and as beasts of       
burden4 ,but many other uses are found  
for animal products1 and materials made 
from animals4 ,wool1 furs1 leather1     
hides1 feathers1 and silk are examples4 
,the arts make use of ivory1 tortoise   
shell1 corals1 and mother-of-pearl2 from
 animals come perfumes and oils1 glue1  
lard1 and butter2 animals produce honey1

 wax1 milk1 eggs1 and various other     
commodities4  ,the ,conservation of our 
,natural ,resources4--,still another    
reason why we should study biology is   
that we may work understandingly for the
 conservation of our natural resources1 
especially of our forests4 ,the forest1 
aside from its beauty and its           
health-giving properties1 holds water in
 the earth4 ,it keeps the water from    
drying out of the earth on hot days and 
from running off on rainy days4 ,thus a 
more even supply of water is given to   
our rivers1 and thus freshets are       
prevented4 ,countries that have been    
deforested1 such as ,china1 ,italy1 and 
parts of ,france1 are now subject to    
floods1 and are in many places barren4  
,on the forests depend our supply of    
timber1 our future water power1 and the 
future commercial importance of cities  
which1 like ,new ,york1 are located at  
the mouths of our navigable rivers4     
,plants and ,animals mutually           
,helpful4--,most plants and animals     

stand in an attitude of mutual          
helpfulness to one another1 plants      
providing food and shelter for animals2 
animals giving off waste materials      
useful to plants in the making of food4 
,we also learn that plants and animals  
need the same conditions in their       
surroundings in order to live3 water1   
air1 food1 a favorable temperature1 and 
usually light4 ,the life processes of   
both plants and animals are essentially 
the same1 and the living matter of a    
tree is as much alive as is the living  
matter in a fish1 a dog1 or a man4      
,biology in its ,relation to            
,society4--,again1 the study of biology 
should be part of the education of every
 boy and girl1 because society itself is
 founded upon the principles which      
biology teaches4 ,plants and animals are
 living things1 taking what they can    
from their surroundings2 they enter into
 competition with one another1 and those
 which are the best fitted for life     
outstrip the others4 ,animals and plants

 tend to vary each from its nearest     
relative in all details of structure4   
,the strong may thus hand down to their 
offspring the characteristics which make
 them the winners4 ,health and strength 
of body and mind are factors which tell 
in winning4  ,man has made use of this  
message of nature1 and has developed    
improved breeds of horses1 cattle1 and  
other domestic animals4 ,plant breeders 
have likewise selected the plants or    
seeds that have varied toward better    
plants1 and thus have stocked the earth 
with hardier and more fruitful          
domesticated plants4 ,man's dominion    
over the living things of the earth is  
tremendous4 ,this is due to his         
understanding the principles which      
underlie the science of biology4        
,finally the study of biology ought to  
make us better men and women by teaching
 us that unselfishness exists in the    
natural world as well as among the      
highest members of society4 ,animals1   
lowly and complex1 sacrifice their      

comfort and their very lives for their  
young4 ,in the insect communities the   
welfare of the individual is given up   
for the best interests of the community4
 ,the law of mutual give and take1 of   
sacrifice for the common good1 is seen  
everywhere4 ,this should teach us1 as we
 come to take our places in society1 to 
be willing to give up our individual    
pleasure or selfish gain for the good of
 the community in which we live4 ,thus  
the application of biological principles
 will benefit society4     ,,ii4 ,,the  
,,environment ,,of ,,plants ,,and       
,,animals  ,problem4--,to discover some 
of the factors of the environment of    
plants and            animals4          
7a7 ,environment of a plant4            
7b7 ,environment of an animal4          
7c7 ,home environment of a girl or boy4 
,,laboratory ,,suggestions              
,laboratory demonstrations4--,factors of
 the environment of        a living     
plant or animal in the vivarium4        
,home exercise4--,the study of the      

factors making up my own                
environment and how ,i can aid in their 
control4   ,environment4--,each one of  
us1 no matter where he lives1 comes in  
contact with certain surroundings4 ,air 
is everywhere around us2 light is       
necessary to us1 so much so that we use 
artificial light at night4 ,the city    
street1 with its dirty and hard paving  
stones1 has come to take the place of   
the soil of the village or farm4 ,water 
and food are a necessary part of our    
surroundings4 ,our clothing1 useful to  
maintain a certain temperature1 must    
also be included4 ,all these            
things--air1 light1 heat1 water1        
food--together make up our environment4 
,illustration3 ,an unfavorable city     
environment4  ,all other animals1 and   
all plants as well1 are surrounded by   
and use practically the same things from
 their environment as we do4 ,the potted
 plant in the window1 the goldfish in   
the aquarium1 your pet dog at home1 all 
use1 as we will later prove1 the factors

 of their environment in the same       
manner4 ,air1 water1 light1 a certain   
amount of heat1 soil to live in or on1  
and food form parts of the surroundings 
of every living thing4  ,illustration3  
,an experiment that shows the air       
contains about four fifths nitrogen4    
,illustration3 ,apparatus for separating
 water by means of an electric current  
into the two elements1 hydrogen and     
oxygen4  ,the ,same ,elements found in  
,plants and ,animals as in their        
,environment4--,it has been found by    
chemists that the plants and animals as 
well as their environment may be reduced
 to about eighty very simple substances 
known as chemical elements4 ,for        
example1 the air is made up largely of  
two elements1 oxygen and nitrogen4      
,water1 by means of an electric current1
 may be broken up into two elements1    
oxygen and hydrogen4 ,the elements in   
water are combined to make a chemical   
compound4 ,the oxygen and nitrogen of   
the air are not so united1 but exist as 

separate gases4 ,if we were to study the
 chemistry of the bodies of plants and  
animals and of their foods1 we would    
find them to be made up of certain      
chemical elements combined in various   
complex compounds4 ,these elements are  
principally carbon1 hydrogen1 oxygen1   
nitrogen1 and perhaps a dozen others in 
very minute proportions4 ,but the same  
elements present in the living things   
might also be found in the environment1 
for example1 water1 food1 the air1 and  
the soil4 ,it is logical to believe that
 living things use the chemical elements
 in their surroundings and in some      
wonderful manner build up their own     
bodies from the materials found in their
 environment4 ,how this is done we will 
learn in later chapters4  ,illustration3
 ,chart to show the percentage of       
chemical elements in the human body4    
,what ,plants and ,animals take from    
their ,environment4 ,air4--,it is a     
self-evident fact that animals need air4
 ,even those living in the water use the

 air dissolved in the water4 ,a fish    
placed in an air-tight jar will soon    
die4 ,it will be proven later that      
plants also need air in order to live4  
,illustration3 ,the effect of water upon
 the growth of trees4 ,these trees were 
all planted at the same time in soil    
that is sandy and uniform4 ,they are    
watered by a small stream which runs    
from left to right in the picture4 ,most
 of the water soaks into the ground     
before reaching the last trees4         
,water4--,we all know that water must   
form part of the environment of plants  
and animals4 ,it is a matter of common  
knowledge that pets need water to drink2
 so do other animals4 ,every one knows  
we must water a potted plant if we      
expect it to grow4 ,water is of so much 
importance to man that from the time of 
the ,caesars until now he has spent     
enormous sums of money to bring pure    
water to his cities4 ,the ,united       
,states government is spending millions 
of dollars at the present time to bring 

by irrigation the water needed to       
support life in the western desert      
lands4  ,illustration3 ,the effect of   
light upon a growing plant4  ,light as  
,condition of the ,environment4--,light 
is another important factor of the      
environment4 ,a study of the leaves on  
any green plant growing near a window   
will convince one that such plants grow 
toward the light4 ,all green plants are 
thus influenced by the sun4 ,other      
plants which are not green seem either  
indifferent or are negatively influenced
 7move away from7 the source of light4  
,animals may or may not be attracted by 
light4 ,a moth1 for example1 will fly   
toward a flame1 an earthworm will move  
away from light4 ,some animals prefer a 
moderate or weak intensity of light and 
live in shady forests or jungles1       
prowling about at night4 ,others seem to
 need much and strong light4 ,and man   
himself enjoys only moderate intensity  
of light and heat4 ,look at the shady   
side of a city street on any hot day to 

prove this statement4  ,heat4--,animals 
and plants are both affected by heat or 
the absence of it4 ,in cold weather     
green plants either die or their life   
activities are temporarily              
suspended1--the plant becomes dormant4  
,likewise small animals1 such as        
insects1 may be killed by cold or they  
may hibernate under stones or boards4   
,their life activities are stilled until
 the coming of warm weather4 ,bears and 
other large animals go to sleep during  
the winter and awake thin and active at 
the approach of warm weather4 ,animals  
or plants used to certain temperatures  
are killed if removed from those        
temperatures4 ,even man1 the most       
adaptable of all animals1 cannot stand  
great changes without discomfort and    
sometimes death4 ,he heats his houses in
 winter and cools them in summer so as  
to have the amount of heat most         
acceptable to him1 i4e4 about #gj deg4  
,fahrenheit4  ,illustration3 ,vegetation
 in ,northern ,russia4 ,the trees in    

this picture are nearly one hundred     
years old4 ,they live under conditions  
of extreme cold most of the year4  ,the 
,environment determines the ,kind of    
,animals and ,plants within ,it4--,in   
our study of geography we learned that  
certain luxuriant growths of trees and  
climbing plants were characteristic of  
the tropics with its moist1 warm        
climate4 ,no one would expect to find   
living there the hardy stunted plants of
 the arctic region4 ,nor would we expect
 to find the same kinds of animal life  
in warm regions as in cold4 ,the        
surroundings determine the kind of      
living things there4 ,plants or animals 
fitted to live in a given locality will 
probably be found there if they have had
 an opportunity to reach that locality4 
,if1 for example1 temperate forms of    
life were introduced by man into the    
tropics1 they would either die or they  
would gradually change so as to become  
fitted to live in their new environment4
 ,sheep with long wool fitted to live in

 ,england1 when removed to ,cuba1 where 
conditions of greater heat exist1 soon  
died because they were not fitted or    
adapted to live in their changed        
environment4  ,illustration3 ,plant life
 in a moist tropical forest4 ,notice the
 air plants to the left and the         
resurrection ferns on the tree trunk4   
,adaptations4--,plants and animals are  
not only fitted to live under certain   
conditions1 but each part of the body   
may be fitted to do certain work4 ,i    
notice that as ,i write these words the 
fingers of my right hand grasp the pen  
firmly and the hand and arm execute some
 very complicated movements4 ,this they 
are able to do because of the free      
movement given through the arrangement  
of the delicate bones of the wrist and  
fingers1 their attachment to the bones  
of the arm1 a wonderful complex of      
muscles which move the bones1 and a     
directing nervous system which plans the
 work4 ,because of the peculiar fitness 
in the structure of the hand for this   

work we say it is adapted to its        
function of grasping objects4 ,each part
 of a plant or animal is usually fitted 
for some particular work4 ,the root of a
 green plant1 for example1 is fitted to 
take in water by having tiny absorbing  
organs growing from it1 the stems have  
pipes or tubes to convey liquids up and 
down and are strong enough to support   
the leafy part of the plant4 ,each part 
of a plant does work1 and is fitted1 by 
means of certain structures1 to do that 
work4 ,it is because of these           
adaptations that living things are able 
to do their work within their particular
 environment4  ,plants and ,animals and 
their ,natural ,environment4--,those of 
us who have tried to keep potted plants 
in the schoolroom know how difficult it 
is to keep them healthy4 ,dust1 foreign 
gases in the air1 lack of moisture1 and 
other causes make the artificial        
environment in which they are placed    
unsuitable for them4  ,a goldfish placed
 in a small glass jar with no food or no

 green water plants soon seeks the      
surface of the water1 and if the water  
is not changed frequently so as to      
supply air the fish will die4 ,again the
 artificial environment lacks something 
that the fish needs4 ,each plant and    
animal is limited to a certain          
environment because of certain          
individual needs which make the         
surroundings fit for it to live in4     
,illustration3 ,a natural barrier on a  
stream4 ,no trout would be found above  
this fall4 ,why not8  ,changes in       
,environment4--,most plants and animals 
do not change their environment4 ,trees1
 green plants of all kinds1 and some    
animals remain fixed in one spot        
practically all their lives4 ,certain   
tiny plants and most animals move from  
place to place1 either in air1 water1 on
 the earth or in the earth1 but they    
maintain relatively the same conditions 
in environment4 ,birds are perhaps the  
most striking exception1 for some may   
fly thousands of miles from their summer

 homes to winter in the south4 ,other   
animals1 too1 migrate from place to     
place1 but not usually where there are  
great changes in the surroundings4 ,a   
high mountain chain with intense cold at
 the upper altitudes would be a barrier 
over which1 for example1 a bear1 a deer1
 or a snail could not travel4 ,fish like
 trout will migrate up a stream until   
they come to a fall too high for them to
 jump4 ,there they must stop because    
their environment limits them4          
,illustration3 ,a new apartment house1  
with out-of-door sleeping porch4  ,man  
in his ,environment4--,man1 while he is 
like other animals in requiring heat1   
light1 water1 and food1 differs from    
them in that he has come to live in a   
more or less artificial environment4    
,men who lived on the earth thousands of
 year ago did not wear clothes or have  
elaborate homes of wood or brick or     
stone4 ,they did not use fire1 nor did  
they eat cooked foods4 ,in short1 by    
slow degrees1 civilized man has come to 

live in a changed environment from that 
of other animals4 ,the living together  
of men in communities has caused certain
 needs to develop4 ,many things can be  
supplied in common1 as water1 milk1     
foods4 ,wastes of all kinds have to be  
disposed of in a town or city4 ,houses  
have come to be placed close together1  
or piled on top of each other1 as in the
 modern apartment4 ,fields and trees1   
all outdoor life1 has practically       
disappeared4 ,man has come to live in an
 artificial environment4  ,care and     
,improvement of ,one's                  
,environment4--,man can modify or change
 his surroundings by making this        
artificial environment favorable to live
 in4 ,he may heat his dwellings in      
winter and cool them in summer so as to 
maintain a moderate and nearly constant 
temperature4 ,he may see that his       
dwellings have windows so as to let     
light and air pass in and out4 ,he may  
have light at night and shade by day    
from intense light4 ,he may have a      

system of pure water supply and may see 
that drains or sewers carry away his    
wastes4 ,he may see to it that people   
ill with catching or infectious diseases
 are isolated or quarantined from       
others4 ,this care of the artificial    
environment is known as sanitation1     
while the care of the individual for    
himself within the environment is known 
as hygiene4 ,it will be the chief end of
 this book to show girls and boys how   
they may become good citizens through   
the proper control of personal hygiene  
and sanitation4                         
,,reference ,,books                     
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,hough and         
,sedgwick1 ,elements of ,hygiene and    
,sanitation4        ,ginn and ,company4 
,jordan and ,kellogg1 ,animal ,life4    
,appleton4      ,sharpe1 ,a ,laboratory 
,manual for the ,solution of ,problems  
in        ,biology1 p4 #ie4 ,american   
,book ,company4      ,tolman1 ,hygiene  

for the ,worker4 ,american ,book        
,company4                               
,,advanced       ,allen1 ,civics and    
,health4 ,ginn and ,company4     ,,iii4 
,,the ,,interrelations ,,of ,,plants    
,,and ,,animals  ,problem4--,to discover
 the general interrelations of green    
plants and            animals4          
7a7 ,plants as homes for insects4       
7b7 ,plants as food for insects4        
7c7 ,insects as pollinating agents4     
,,laboratory ,,suggestions       ,a     
field trip3--,object3 to collect common 
insects and study        their general  
characteristics2 to study the food and  
shelter        relation of plant and    
insects4 ,the pollination of flowers    
should also be carefully studied so as  
to give the pupil a        general      
viewpoint as an introduction to the     
study of        biology4                
,laboratory exercise4--,examination of  
simple insect1        identification of 
parts--drawing4 ,examination and        
identification of some orders of        

insects4      ,laboratory               
demonstration4--,life history of monarch
 and        some other butterflies or   
moths4      ,laboratory                 
exercise4--,study of simple             
flower--emphasis on        work of      
essential organs1 drawing4              
,laboratory exercise4--,study of mutual 
adaptations in a        given insect and
 a given flower1 e4g4 butter and eggs   
and        bumble bee4                  
,demonstration of examples of insect    
pollination4   ,the ,object of a ,field 
,trip4--,many of us live in the city1   
where the crowded streets1 the closely  
packed apartments1 and the city         
playgrounds form our environment4 ,it is
 very artificial at best4 ,to understand
 better the normal environment of plants
 or animals we should go into the       
country4 ,failing in this1 an overgrown 
city lot or a park will give us much    
more closely the environment as it      
touches some animals lower than man4 ,we
 must then remember that in learning    

something of the natural environment of 
other living creatures we may better    
understand our own environment and our  
relation to it4  ,on any bright warm day
 in the fall we will find insects       
swarming everywhere in any vacant lot or
 the less cultivated parts of a city    
park4 ,grasshoppers1 butterflies        
alighting now and then on the flowers1  
brightly marked hornets1 bees busily    
working over the purple asters or golden
 rod1 and many other forms hidden away  
on the leaves or stems of plants may be 
seen4 ,if we were to select for         
observation some partially decayed tree1
 we would find it also inhabited4       
,beetles would be found boring through  
its bark and wood1 while caterpillars   
7the young stages of butterflies or     
moths7 are feeding on its leaves or     
building homes in its branches4         
,everywhere above1 on1 and under ground 
may be noticed small forms of life1 many
 of them insects4 ,let us first see how 
we would go to work to identify some of 

the common forms we would be likely to  
find on plants4 ,then a little later we 
will find out what they are doing on    
these plants4  ,illustration3 ,an insect
 viewed from the side4 ,notice the head1
 thorax1 and abdomen4 ,what other       
characters do you find8  ,how to tell an
 ,insect4--,a bee is a good example of  
the group of animals we call insects4   
,if we examine its body carefully1 we   
notice that it has three regions1 a     
front part or head1 a middle part called
 the thorax1 and a hind portion1 jointed
 and hairy1 the abdomen4 ,we cannot     
escape noting the fact that this insect 
has wings with which it flies and that  
it also has legs4 ,the three pairs of   
legs1 which are jointed and provided    
with tiny hooks at the end1 are attached
 to the thorax4 ,two pairs of delicate  
wings are attached to the upper or      
dorsal side of the thorax4 ,the thorax  
and indeed the entire body1 is covered  
with a hard shell of material similar to
 a cow's horn1 there being no skeleton  

inside for the attachment of muscles4   
,if we carefully watch the abdomen of a 
living bee1 we notice it move up and    
down quite regularly4 ,the animal is    
breathing through tiny breathing holes  
called spiracles1 placed along the side 
of the thorax and abdomen4 ,bees also   
have compound eyes4 ,wings are not found
 on all insects1 but all the other      
characters just given are marks of the  
great group of animals we call insects4 
,illustration3 ,part of the compound eye
 of an insect 7highly magnified74       
,forms to be looked for on a ,field     
,trip4--,inasmuch as there are over     
#cfj1jjj different species or kinds of  
insects1 it is evident that it would be 
a hopeless task for us even to think of 
recognizing all of them4 ,but we can    
learn to recognize a few examples of the
 common forms that might be met on a    
field trip4 ,in the fields1 on grass1 or
 on flowering plants we may count on    
finding members from six groups or      
orders of insects4 ,these may be known  

by the following characters4  ,the order
 ,hymenoptera 7membrane wing7 to which  
the bees1 wasps1 and ants belong is the 
only insect group the members of which  
are provided with true stings4 ,this    
sting is placed in a sheath at the      
extreme hind end of the abdomen4 ,other 
characteristics1 which show them to be  
insects1 have been given above4         
,butterflies or moths will be found     
hovering over flowers4 ,they belong to  
the order ,lepidoptera 7scale wings74   
,this name is given to them because     
their wings are covered with tiny       
scales1 which fit into little sockets on
 the wing much as shingles are placed on
 a roof4 ,the dust which comes off on   
the fingers when one catches a butterfly
 is composed of these scales4 ,the wings
 are always large and usually brightly  
colored1 the legs small1 and one pair is
 often inconspicuous4 ,these insects may
 be seen to take liquid food through a  
long tubelike organ1 called the         
proboscis1 which they keep rolled up    

under the head when not in use4 ,the    
young of the butterfly or moth are known
 as caterpillars and feed on plants by  
means of a pair of hard jaws4           
,grasshoppers1 found almost everywhere1 
and crickets1 black grasshopper-like    
insects often found under stones1 belong
 to the order ,orthoptera 7straight     
wings74 ,members of this group may      
usually be distinguished by their       
strong1 jumping hind legs1 by their     
chewing or biting mouth parts1 and by   
the fact that the hind wings are folded 
up under the somewhat stiffer front     
wings4  ,illustration3 ,forms of life to
 be met on a field trip4 ,a1 ,the       
red-legged locust1 one of the           
,orthoptera2 o1 the egg-layer1 about    
natural size4 ,b1 the honey bee1 one of 
the ,hymenoptera1 about natural size4   
,c1 a bug1 one of the ,hemiptera1 about 
natural size4 ,d1 a butterfly1 an       
example of the ,lepidoptera1 slightly   
reduced4 ,e1 a house fly1 an example of 
the ,diptera1 about twice natural size4 

,f1 an orb-weaving spider1 about half   
natural size4 7,this is not an insect1  
note the number of legs47 ,g1 a beetle1 
slightly reduced1 one of the            
,coleoptera4  ,another group of insects 
sometimes found on flowers in the fall  
are flies4 ,they belong to the order    
,diptera 7two wings74 ,these insects are
 usually rather small and have a single 
pair of gauzy wings4 ,flies are of much 
importance to man because certain of    
their number are disease carriers4      
,bugs1 members of the order ,hemiptera  
7half wings71 have a jointed proboscis  
which points backward between the front 
legs4 ,they are usually small and may or
 may not have wings4  ,the beetles or   
,coleoptera 7sheath wings71 often       
mistaken for bugs by the uneducated1    
have the first pair of hardened wings   
meeting in a straight line in the middle
 of the back1 the second pair of wings  
being covered by them4 ,beetles are     
frequently found on goldenrod blossoms  
in the fall4  ,other forms of life1     

especially spiders1 which have four     
pairs of walking legs1 centipedes and   
millepedes1 both of which are wormlike  
and have many pairs of legs1 may be     
found4  ,try to discover members of the 
six different orders named above4       
,collect specimens and bring them to the
 laboratory for identification4  ,why do
 ,insects live on ,plants8--,we have    
found insect life abundant on living    
green plants1 some visiting flowers1    
others hidden away on the stalks or     
leaves of the plants4 ,let us next try  
to find out why insects live among and  
upon flowering green plants4  ,the ,life
 ,history of the ,milkweed              
,butterfly4--,if it is possible to find 
on our trip some growing milkweed1 we   
are quite likely to find hovering near1 
a golden brown and black butterfly1 the 
monarch or milkweed butterfly 7,anosia  
plexippus74 ,its body1 as in all        
insects1 is composed of three regions4  
,the monarch frequents the milkweed in  
order to lay eggs there4 ,this she may  

be found doing at almost any time from  
,june until ,september4  ,egg and       
,larva4--,the eggs1 tiny hat-shaped dots
 a twentieth of an inch in length1 are  
fastened singly to the underside of     
milkweed leaves4 ,some wonderful        
instinct leads the animal to deposit the
 eggs on the milkweed1 for the young    
feed upon no other plant4 ,the eggs     
hatch out in four or five days into     
rapid-growing wormlike caterpillars1    
each of which will shed its skin several
 times before it becomes full size4     
,these caterpillars possess1 in addition
 to the three pairs of true legs1       
additional pairs of prolegs or          
caterpillar legs4 ,the animal at this   
stage is known as a larva4  ,formation  
of ,pupa4--,after a life of a few weeks 
at most1 the caterpillar stops eating   
and begins to spin a tiny mat of silk   
upon a leaf or stem4 ,it attaches itself
 to this web by the last pair of        
prolegs1 and there hangs in the dormant 
stage known as the chrysalis or pupa4   

,this is a resting stage during which   
the body changes from a caterpillar to a
 butterfly4  ,illustration3 ,monarch    
butterfly3 adults1 larvae1 and pupa on  
their food plant1 the milkweed4 7,from a
 photograph loaned by the ,american     
,museum of ,natural ,history47  ,the    
,adult4--,after a week or more of       
inactivity in the pupa state1 the outer 
skin is split along the back1 and the   
adult butterfly emerges4 ,at first the  
wings are soft and much smaller than in 
the adult4 ,within fifteen minutes to   
half an hour after the butterfly        
emerges1 however1 the wings are         
full-sized1 having been pumped full of  
blood and air1 and the little insect is 
ready after her wedding flight to follow
 her instinct to deposit her eggs on a  
milkweed plant4  ,plants furnish        
,insects with ,food4--,food is the most 
important factor of any animal's        
environment4 ,the insects which we have 
seen on our field trip feed on the green
 plants among which they live4 ,each    

insect has its own particular favorite  
food plant or plants1 and in many cases 
the eggs of the insect are laid on the  
food plant so that the young may have   
food close at hand4 ,some insects prefer
 the rotted wood of trees4 ,an ,american
 zoologist1 ,packard1 has estimated that
 over #dej kinds of insects live upon   
oak trees alone4 ,everywhere animals are
 engaged in taking their nourishment    
from plants1 and millions of dollars of 
damage is done every year to gardens1   
fruits1 and cereal crops by insects4    
,illustration3 ,damage done by insects4 
,these trees have been killed by boring 
insects4  ,all ,animals depend on ,green
 ,plants4--,but insects in their turn   
are the food of birds2 cats and dogs may
 kill birds2 lions or tigers live on    
still larger defenseless animals as deer
 or cattle4 ,and finally comes man1 who 
eats the bodies of both plants and      
animals4 ,but if we reduce this search  
after food to its final limit1 we see   
that green plants provide all the food  

for animals4 ,for the lion or tiger eats
 the deer which feeds upon grass or     
green shoots of young trees1 or the cat 
eats the bird that lives on weed seeds4 
,green plants supply the food of the    
world4 ,later by experiment we will     
prove this4  ,homes and                 
,shelter4--,after a field trip no one   
can escape the knowledge that plants    
often give animals a home4 ,the grass   
shelters millions of grasshoppers and   
countless hordes of other small insects 
which can be obtained by sweeping       
through the grass with an insect net4   
,some insects build their homes in the  
trees or bushes on which they feed1     
while others tunnel through the wood1   
making homes there4 ,spiders build webs 
on plants1 often using the leaves for   
shelter4 ,birds nest in trees1 and many 
other wild animals use the forest as    
their home4 ,man has come to use all    
kinds of plant products to aid him in   
making his home1 wood and various fibers
 being the most important of these4     

,what do ,animals do for ,plants8--,so  
far it has seemed that green plants     
benefit animals and receive nothing in  
return4 ,we will later see that plants  
and animals together form a balance of  
life on the earth and that one is       
necessary for the other4 ,certain       
substances found in the body wastes from
 animals are necessary to the life of a 
green plant4  ,insects and              
,flowers4--,certain other problems can  
be worked out in the fall of the year4  
,one of these is the biological         
interrelations between insects and      
flowers4 ,it is easy on a field trip to 
find insects lighting upon flowers4     
,they evidently have a reason for doing 
this4 ,to find out why they go there and
 what they do when there1 it will be    
first necessary for us to study flowers 
with the idea of finding out what the   
insects get from them1 and what the     
flowers get from the insects4           
,illustration3 ,a section of a flower1  
cut lengthwise4 ,in the center find the 

pistil with the ovary containing a      
number of ovules4 ,around this organ    
notice a circle of stalked structures1  
the stamens2 the knobs at the end       
contain pollen4 ,the outer circles of   
parts are called the petals and sepals1 
as we go from the inside outward4  ,the 
,use and ,structure of a ,flower4--,it  
is a matter of common knowledge that    
flowers form fruits and that fruits     
contain seeds4 ,they are1 then1 very    
important parts of certain plants4 ,our 
field trip shows us that flowers are of 
various shapes1 colors1 and sizes4 ,it  
will now be our problem first to learn  
to know the parts of a flower1 and then 
find out how they are fitted to attract 
and receive insect visitors4  ,the      
,floral ,envelope4--,in a flower the    
expanded portion of the flower stalk1   
which holds the parts of the flower1 is 
called the receptacle4 ,the green       
leaflike parts covering the unopened    
flower are called the sepals4 ,together 
they form the calyx4  ,the more brightly

 colored structures are the petals4     
,together they form the corolla4 ,the   
corolla is of importance1 as we shall   
see later1 in making the flower         
conspicuous4 ,frequently the petals or  
corolla have bright marks or dots which 
lead down to the base of the cup of the 
flower1 where a sweet fluid called      
nectar is made and secreted4 ,it is     
principally this food substance1 later  
made into honey by bees1 that makes     
flowers attractive to insects4  ,the    
,essential ,organs4--,a flower1 however1
 could live without sepals or petals and
 still do the work for which it exists4 
,certain essential organs of the flower 
are within the so-called floral         
envelope4 ,they consist of the stamens  
and pistil1 the latter being in the     
center of the flower4 ,the structures   
with the knobbed ends are called        
stamens4 ,in a single stamen the boxlike
 part at the end is the anther2 the     
stalk which holds the anther is called  
the filament4 ,the anther is in reality 

a hollow box which produces a large     
number of little grains called pollen4  
,each pistil is composed of a rather    
stout base called the ovary1 and a more 
or less lengthened portion rising from  
the ovary called the style4 ,the upper  
end of the style1 which in some cases is
 somewhat broadened1 is called the      
stigma4 ,the free end of the stigma     
usually secretes a sweet fluid in which 
grains of pollen from flowers of the    
same kind can grow4  ,insects as        
,pollinating ,agents4--,insects often   
visit flowers to obtain pollen as well  
as nectar4 ,in so doing they may        
transfer some of the pollen from one    
flower to another of the same kind4     
,this transfer of pollen1 called        
pollination1 is of the greatest use to  
the plant1 as we will later prove4 ,no  
one who sees a hive of bees with their  
wonderful communal life can fail to see 
that these insects play a great part in 
the life of the flowers near the hive4  
,a famous observer named ,sir ,john     

,lubbock tested bees and wasps to see   
how many trips they made daily from     
their homes to the flowers1 and found   
that the wasp went out on #aaf visits   
during a working day of #af hours1 while
 the bee made but a few less visits1 and
 worked only a little less time than the
 wasp worked4 ,it is evident that in the
 course of so many trips to the fields a
 bee must light on hundreds of flowers4 
,illustration3 ,bumblebees4 a1 queen2 b1
 worker2 c1 drone4  ,adaptations in a   
,bee4--,if we look closely at the bee1  
we find the body and legs more or less  
covered with tiny hairs2 especially are 
these hairs found on the legs4 ,when a  
plant or animal structure is fitted to  
do a certain kind of work1 we say it is 
adapted to do that work4 ,the joints in 
the leg of the bee adapt it for         
complicated movements2 the arrangement  
of stiff hairs along the edge of a      
concavity in one of the joints of the   
leg forms a structure well adapted to   
hold pollen4 ,in this way pollen is     

collected by the bee and taken to the   
hive to be used as food4 ,but while     
gathering pollen for itself1 the dust is
 caught on the hairs and other          
projections on the body or legs and is  
thus carried from flower to flower4 ,the
 value of this to a flower we will see  
later4  ,field ,work4--,is ,color or    
,odor in a ,flower an ,attraction to an 
,insect8--,sir ,john ,lubbock tried an  
experiment which it would pay a number  
of careful pupils to repeat4 ,he placed 
a few drops of honey on glass slips and 
placed them over papers of various      
colors4 ,in this way he found that the  
honeybee1 for example1 could evidently  
distinguish different colors4 ,bees     
seemed to prefer blue to any other      
color4 ,flowers of a yellow or flesh    
color were preferred by flies4 ,it would
 be of considerable interest for some   
student to work out this problem with   
our native bees and with other insects  
by using paper flowers and honey or     
sirup4 ,test the keenness of sight in   

insects by placing a white object 7a    
white golf ball will do7 in the grass   
and see how many insects will alight on 
it4 ,try to work out some method by     
which you can decide whether a given    
insect is attracted to a flower by odor 
alone4  ,the ,sight of the              
,bumblebee4--,the large eyes located on 
the sides of the head are made up of a  
large number of little units1 each of   
which is considered to be a very simple 
eye4 ,the large eyes are therefore      
called the compound eyes4 ,all insects  
are provided with compound eyes1 with   
simple eyes1 or in most cases with both4
 ,the simple eyes of the bee may be     
found by a careful observer between and 
above the compound eyes4  ,insects can1 
as we have already learned1 distinguish 
differences in color at some distance2  
they can see moving objects1 but they do
 not seem to be able to make out form   
well4 ,to make up for this1 they appear 
to have an extremely well-developed     
sense of smell4 ,insects can distinguish

 at a great distance odors which to the 
human nose are indistinguishable4       
,night-flying insects1 especially1 find 
the flowers by the odor rather than by  
color4  ,illustration3 ,the head of a   
bee4 ,a1 antennae or feelers2 ,e1       
compound eye2 ,s1 simple eye2 ,m1 mouth 
parts2 ,t1 tongue4  ,mouth ,parts of the
 ,bee4--,the mouth of the bee is adapted
 to take in the foods we have mentioned1
 and is used for the purposes for which 
man would use the hands and fingers4    
,the honeybee laps or sucks nectar from 
flowers1 it chews the pollen1 and it    
uses part of the mouth as a trowel in   
making the honeycomb4 ,the uses of the  
mouth parts may be made out by watching 
a bee on a well-opened flower4          
,suggestions for ,field ,work4--,in any 
locality where flowers are abundant1 try
 to answer the following questions3 ,how
 many bees visit the locality in ten    
minutes8 ,how many other insects alight 
on the flowers8 ,do bees visit flowers  
of the same kinds in succession1 or fly 

from one flower on a given plant to     
another on a plant of a different kind8 
,if the bee lights on a flower cluster1 
does it visit more than one flower in   
the same cluster8 ,how does a bee       
alight8 ,exactly what does the bee do   
when it alights8  ,illustration3 ,flower
 cluster of butter and eggs4  ,butter   
and ,eggs 7,linaria vulgaris74--,from   
,july to ,october this very abundant    
weed may be found especially along      
roadsides and in sunny fields4 ,the     
flower cluster forms a tall and         
conspicuous cluster of orange and yellow
 flowers4  ,the corolla projects into a 
spur on the lower side2 an upper        
two-parted lip shuts down upon a lower  
three-parted lip4 ,the four stamens are 
in pairs1 two long and two short4       
,illustration3 ,diagram to show how the 
bee pollinates butter and eggs4 ,the    
bumblebee1 upon entering the flower1    
rubs its head against the long pair of  
anthers 7a71 then continuing to press   
into the flower so as to reach the      

nectar at 7,n7 it brushes against the   
stigma 7,s71 thus pollinating the       
flower4 ,inasmuch as bees visit other   
flowers in the same cluster1            
cross-pollination would also be likely4 
,why8  ,certain parts of the corolla are
 more brightly colored than the rest of 
the flower4 ,this color is a guide to   
insects4 ,butter and eggs is visited    
most by bumblebees1 which are guided by 
the orange lip to alight just where they
 can push their way into the flower4    
,the bee1 seeking the nectar secreted in
 the spur1 brushes his head and         
shoulders against the stamens4 ,he may  
then1 as he pushes down after nectar1   
leave some pollen upon the pistil1 thus 
assisting in self-pollination4 ,visiting
 another flower of the cluster1 it would
 be an easy matter accidentally to      
transfer this pollen to the stigma of   
another flower4 ,in this way pollen is  
carried by the insect to another flower 
of the same kind4 ,this is known as     
cross-pollination4 ,by pollination we   

mean the transfer of pollen from an     
anther to the stigma of a flower4       
,self-pollination is the transfer of    
pollen from the anther to the stigma of 
the same flower2 cross-pollination is   
the transfer of pollen from the anthers 
of one flower to the stigma of another  
flower on the same or another plant of  
the same kind4  ,illustration3 ,a wild  
orchid1 a flower of the type from which 
,charles ,darwin worked out his theory  
of cross-pollination by insects4        
,history of the ,discoveries regarding  
,pollination of ,flowers4--,although the
 ancient ,greek and ,roman naturalists  
had some vague ideas on the subject of  
pollination1 it was not until the first 
part of the nineteenth century that a   
book appeared in which a ,german named  
,conrad ,sprengel worked out the facts  
that the structure of certain flowers   
seemed to be adapted to the visits of   
insects4 ,certain facilities were       
offered to an insect in the way of easy 
foothold1 sweet odor1 and especially    

food in the shape of pollen and nectar1 
the latter a sweet-tasting substance    
manufactured by certain parts of the    
flower known as the nectar glands4      
,sprengel further discovered the fact   
that pollen could be and was carried by 
the insect visitors from the anthers of 
the flower to its stigma4 ,it was not   
until the middle of the nineteenth      
century1 however1 that an ,englishman1  
,charles ,darwin1 applied ,sprengel's   
discoveries on the relation of insects  
to flowers by his investigations upon   
cross-pollination4 ,the growth of the   
pollen on the stigma of the flower      
results eventually in the production of 
seeds1 and thus new plants4 ,many       
species of flowers are self-pollinated  
and do not do so well in seed production
 if cross-pollinated1 but ,charles      
,darwin found that some flowers which   
were self-pollinated did not produce so 
many seeds1 and that the plants which   
grew from their seeds were smaller and  
weaker than plants from seeds produced  

by cross-pollinated flowers of the same 
kind4 ,he also found that plants grown  
from cross-pollinated seeds tended to   
vary more than those grown from         
self-pollinated seed4 ,this has an      
important bearing1 as we shall see      
later1 in the production of new         
varieties of plants4 ,microscopic       
examination of the stigma at the time of
 pollination also shows that the pollen 
from another flower usually germinates  
before the pollen which has fallen from 
the anthers of the same flower4 ,this   
latter fact alone in most cases renders 
it unlikely for a flower to produce     
seeds by its own pollen4 ,darwin worked 
for years on the pollination of many    
insect-visited flowers1 and discovered  
in almost every case that showy1        
sweet-scented1 or otherwise attractive  
flowers were adapted or fitted to be    
cross-pollinated by insects4 ,he also   
found that1 in the case of flowers that 
were inconspicuous in appearance1 often 
a compensation appeared in the odor     

which rendered them attractive to       
certain insects4 ,the so-called carrion 
flowers1 pollinated by flies1 are       
examples1 the odor in this case being   
like decayed flesh4 ,other flowers open 
at night1 are white1 and provided with a
 powerful scent4 ,thus they attract     
night-flying moths and other insects4   
,other ,examples of ,mutual ,aid between
 ,flowers and ,insects4--,many other    
examples of adaptations to secure       
cross-pollination by means of the visits
 of insects might be given4 ,the        
mountain laurel1 which makes our        
hillsides so beautiful in late spring1  
shows a remarkable adaptation in having 
the anthers of the stamens caught in    
little pockets of the corolla4 ,the     
weight of the visiting insect on the    
corolla releases the anther from the    
pocket in which it rests so that it     
springs up1 dusting the body of the     
visitor with pollen4  ,illustration3    
,the condition of stamens and pistils on
 the spiked loosestrife 7,lythrum       

salicaria74  ,in some flowers1 as shown 
by the primroses or primula of our      
hothouses1 the stamens and pistils are  
of different lengths in different       
flowers4 ,short styles and long or      
high-placed filaments are found in one  
flower1 and long styles with short or   
low-placed filaments in the other4      
,pollination will be effected only when 
some of the pollen from a low-placed    
anther reaches the stigma of a          
short-styled flower1 or when the pollen 
from a high anther is placed upon a     
long-styled pistil4 ,there are1 as in   
the case of the loosestrife1 flowers    
having pistils and stamens of three     
lengths4 ,pollen only grows on pistils  
of the same length as the stamens from  
which it came4  ,the milkweed or        
butterfly weed already mentioned is     
another example of a flower adapted to  
insect pollination4#a       ,footnote   
#a3 ,for an excellent account of        
cross-pollination of this      flower1  
the reader is referred to ,w4 ,c4       

,stevens1 ,introduction to      ,botany4
 ,orchids are well known to botanists as
 showing some very      wonderful       
adaptations4 ,a classic easily read is  
,darwin1 ,on the      ,fertilization of 
,orchids4  ,illustration3 ,the pronuba  
moth within the yucca flower4  ,a very  
remarkable instance of insect help is   
found in the pollination of the yucca1 a
 semitropical lily which lives in       
deserts 7to be seen in most botanic     
gardens74 ,in this flower the stigmatic 
surface is above the anther1 and the    
pollen is sticky and cannot be          
transferred except by insect aid4 ,this 
is accomplished in a remarkable manner4 
,a little moth1 called the pronuba1     
after gathering pollen from an anther1  
deposits an egg in the ovary of the     
pistil1 and then rubs its load of pollen
 over the stigma of the flower4 ,the    
young hatch out and feed on the young   
seeds which have grown because of the   
pollen placed on the stigma by the      
mother4 ,the baby caterpillars eat some 

of the developing seeds and later bore  
out of the seed pod and escape to the   
ground1 leaving the plant to develop the
 remaining seeds without further        
molestation4  ,illustration3 ,the       
pronuba pollinating the pistil of the   
yucca4  ,the fig insect 7,blastophaga   
grossorum7 is another member of the     
insect tribe that is of considerable    
economic importance4 ,it is only in     
recent years that the fruit growers of  
,california have discovered that the    
fertilization of the female flowers is  
brought about by a gallfly which bores  
into the young fruit4 ,by importing the 
gallflies it has been possible to grow  
figs where for many years it was        
believed that the climate prevented figs
 from ripening4  ,illustration3 ,pod of 
yucca showing where the young pronubas  
escaped4  ,other ,flower                
,visitors4--,other insects besides those
 already mentioned are pollen carriers  
for flowers4 ,among the most useful are 
moths and butterflies4 ,projecting from 

each side of the head of a butterfly is 
a fluffy structure1 the palp4 ,this     
collects and carries a large amount of  
pollen1 which is deposited upon the     
stigmas of other flowers when the       
butterfly pushes its head down into the 
flower tube after nectar4 ,the scales   
and hairs on the wings1 legs1 and body  
also carry pollen4  ,illustration3 ,a   
humming bird about to cross-pollinate a 
lily4  ,flies and some other insects are
 agents in cross-pollination4 ,humming  
birds are also active agents in some    
flowers4 ,snails are said in rare       
instances to carry pollen4 ,man and the 
domesticated animals undoubtedly        
frequently pollinate flowers by brushing
 past them through the fields4          
,illustration3 ,a cornfield showing     
staminate and pistillate flowers1 the   
latter having become grains of corn4 ,an
 ear of corn is a bunch of ripened      
fruits4  ,pollination by the            
,wind4--,not all flowers are dependent  
upon insects or other animals for       

cross-pollination4 ,many of the earliest
 of spring flowers appear almost before 
the insects do4 ,such flowers are       
dependent upon the wind for carrying    
pollen from the stamens of one flower to
 the pistil of another4 ,most of our    
common trees1 oak1 poplar1 maple1 and   
others1 are cross-pollinated almost     
entirely by the wind4  ,flowers         
pollinated by the wind are generally    
inconspicuous and often lack a corolla4 
,the anthers are exposed to the wind and
 provided with much pollen1 while the   
surface of the stigma may be long and   
feathery4 ,such flowers may also lack   
odor1 nectar1 and bright color4 ,can you
 tell why8  ,imperfect ,flowers4--,some 
flowers1 the wind-pollinated ones in    
particular1 are imperfect2 that is1 they
 lack either stamens or pistils4 ,again1
 in some cases1 imperfect flowers having
 stamens only are alone found on one    
plant1 while those flowers having       
pistils only are found on another plant 
of the same kind4 ,in such flowers1     

cross-pollination must of necessity     
follow4 ,many of our common trees are   
examples4  ,illustration3 ,the flower of
 ,lady ,washington geranium1 in which   
stamens and pistil ripen at different   
times1 thus insuring cross-pollination4 
,a1 flower with ripe stamens2 ,b1 flower
 with stamens withered and ripe pistil4 
,other ,cases4--,the stamens and pistil 
ripen at different times in some        
flowers4 ,the ,lady ,washington         
geranium1 a common house plant1 shows   
this condition4 ,here also              
cross-pollination must take place if    
seeds are to be formed4  ,summary4--,if 
we now collect our observations upon    
flowers with a view to making a summary 
of the different devices flowers have   
assumed to prevent self-pollination and 
to secure cross-pollination1 we find    
that they are as follows3--  7#a7 ,the  
stamens and pistils may be found in     
separate flowers1 either on the same or 
on different plants4  7#b7 ,the stamens 
may produce pollen before the pistil is 

ready to receive it1 or vice versa4     
7#c7 ,the stamens and pistils may be so 
placed with reference to each other that
 pollination can be brought about only  
by outside assistance4  ,artificial     
,cross-pollination and its ,practical   
,benefits to ,man4--,artificial         
cross-pollination is practiced by plant 
breeders and can easily be tried in the 
laboratory or at home4 ,first the       
anthers must be carefully removed from  
the bud of the flower so as to eliminate
 all possibility of self-pollination4   
,the flower must then be covered so as  
to prevent access of pollen from        
without2 when the ovary is sufficiently 
developed1 pollen from another flower1  
having the characters desired1 is placed
 on the stigma and the flower again     
covered to prevent any other pollen     
reaching the flower4 ,the seeds from    
this flower when planted may give rise  
to plants with the best characters of   
each of the plants which contributed to 
the making of the seeds4                

,,reference ,,books                     
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,andrews1 ,a       
,practical ,course in ,botany1 pages    
#bad-bdi4        ,american ,book        
,company4      ,atkinson1 ,first        
,studies of ,plant ,life1 ,chaps4       
,,xxv-,,xxvi4        ,ginn and ,company4
      ,coulter1 ,plant ,life and ,plant 
,uses1 pages #cja-cbb4        ,american 
,book ,company4      ,dana1 ,plants and 
their ,children1 pages #ahg-bee4        
,american        ,book ,company4        
,lubbock1 ,flowers1 ,fruits1 and        
,leaves1 ,part ,i4 ,the                 
,macmillan ,company4      ,needham1     
,general ,biology1 pages #a-ej4 ,the    
,comstalk        ,publishing ,company4  
,newell1 ,a ,reader in ,botany1 ,part   
,,ii1 pages #a-if4 ,ginn and            
,company4      ,sharpe1 ,a ,laboratory  
,manual in ,biology1 pages #dc-dh4      
,american ,book ,company4               
,,advanced       ,bailey1 ,plant        

,breeding4 ,the ,macmillan ,company4    
,campbell1 ,lectures on the ,evolution  
of ,plants4 ,the        ,macmillan      
,company4      ,coulter1 ,barnes1 and   
,cowles1 ,a ,textbook of ,botany1 ,part 
,,ii4 ,american ,book ,company4         
,darwin1 ,different ,forms of ,flowers  
on ,plants of the ,same        ,species1
 ,d4 ,appleton and ,company4            
,darwin1 ,fertilization in the          
,vegetable ,kingdom1 ,chaps4 ,i         
and ,,ii4 ,d4 ,appleton and ,company4   
,darwin1 ,orchids ,fertilized by        
,insects1 ,d4 ,appleton and             
,company4      ,lubbock1 ,british ,wild 
,flowers4 ,the ,macmillan ,company4     
,mueller1 ,the ,fertilization of        
,flowers4 ,the ,macmillan               
,company4     ,,iv4 ,,the ,,functions   
,,and ,,composition ,,of ,,living       
,,things  ,problems4--,to discover the  
functions of living matter4             
7a7 ,in a living plant4           7b7   
,in a living animal4                    
,,laboratory ,,suggestions              

,laboratory study of a living           
plant4--,any whole plant may        be  
used2 a weed is preferable4             
,laboratory demonstration or home       
study4--,the functions of        a      
living animal4                          
,demonstration4--,the growth of pollen  
tubes4      ,laboratory exercise4--,the 
growth of the mature ovary into         
the fruit1 e4g4 bean or pea pod4   ,a   
,living ,plant and a ,living ,animal    
,compared4--,a walk into the fields or  
any vacant lot on a day in the early    
fall will give us first-hand            
acquaintance with many common plants    
which1 because of their ability to grow 
under somewhat unfavorable conditions1  
are called weeds4 ,such plants--the     
dandelion1 butter and eggs1 the         
shepherd's purse--are particularly well 
fitted by nature to produce many of     
their kind1 and by this means drive out 
other plants which cannot do this so    
well4 ,on these or other plants we find 
feeding several kinds of animals1       

usually insects4  ,if we attempt to     
compare1 for example1 a grasshopper with
 the plant on which it feeds1 we see    
several points of likeness and          
difference at once4 ,both plant and     
insect are made up of parts1 each of    
which1 as the stem of the plant or the  
leg of the insect1 appears to be        
distinct1 but which is a part of the    
whole living plant or animal4 ,each part
 of the living plant or animal which has
 a separate work to do is called an     
organ4 ,thus plants and animals are     
spoken of as living organisms4          
,illustration3 ,a weed--notice the      
unfavorable environment4  ,functions of 
the ,parts of a ,plant4--,we are all    
familiar with the parts of a plant1--the
 root1 stem1 leaves1 flowers1 and fruit4
 ,but we may not know so much about     
their uses to the plant4 ,each of these 
structures differs from every other     
part1 and each has a separate work or   
function to perform for the plant4 ,the 
root holds the plant firmly in the      

ground and takes in water and mineral   
matter from the soil2 the stem holds the
 leaves up to the light and acts as a   
pathway for fluids between the root and 
leaves2 the leaves1 under certain       
conditions1 manufacture food for the    
plant and breathe2 the flowers form the 
fruits2 the fruits hold the seeds1 which
 in turn hold young plants which are    
capable of reproducing adult plants of  
the same kind4  ,the ,functions of an   
,animal4--,as we have already seen1 the 
grasshopper has a head1 a jointed body  
composed of a middle and a hind part1   
three pairs of jointed legs1 and two    
pairs of wings4 ,obviously1 the wings   
and legs are used for movement2 a       
careful watching of the hind part of the
 animal shows us that breathing         
movements are taking place2 a bit of    
grass placed before it may be eaten1 the
 tiny black jaws biting little pieces   
out of the grass4 ,if disturbed1 the    
insect hops away1 and if we try to get  
it1 it jumps or flies away1 evidently   

seeing us before we can grasp it4       
,hundreds of little grasshoppers on the 
grass indicate that the grasshopper can 
reproduce its own kind1 but in other    
respects the animal seems quite unlike  
the plant4 ,the animal moves1 breathes1 
feeds1 and has sensation1 while         
apparently the plant does none of these4
 ,it will be the purpose of later       
chapters to prove that the functions of 
plants and animals are in many respects 
similar and that both plants and animals
 breathe1 feed1 and reproduce4          
,illustration3 ,section through the     
blade of a leaf4 e1 cells of the upper  
surface2 d1 cells of the lower surface2 
i1 air spaces in the leaf2 v1 vein in   
cross sections2 p1 green cells4         
,organs4--,if we look carefully at the  
organ of a plant called a leaf1 we find 
that the materials of which it is       
composed do not appear to be everywhere 
the same4 ,the leaf is much thinner and 
more delicate in some parts than in     
others4 ,holding the flat1 expanded     

blade away from the branch is a little  
stalk1 which extends into the blade of  
the leaf4 ,here it splits up into a     
network of tiny veins which evidently   
form a framework for the flat blade     
somewhat as the sticks of a kite hold   
the paper in place4 ,if we examine under
 the compound microscope a thin section 
cut across the leaf1 we shall find that 
the veins as well as the other parts are
 made up of many tiny boxlike units of  
various sizes and shapes4 ,these        
smallest units of building material of  
the plant or animal disclosed by the    
compound microscope are called cells4   
,the organs of a plant or animal are    
built of these tiny structures4         
,illustration3 ,several cells of        
,elodea1 a water plant4 chl41           
chlorophyll bodies2 c4s41 cell sap2     
c4w41 cell wall2 n41 nucleus2 p41       
protoplasm4 ,the arrows show the        
direction of the protoplasmic movement4 
,tissues4#b--,the cells which form      
certain parts of the veins1 the flat    

blade1 or other portions of the plant1  
are often found in groups or            
collections1 the cells of which are more
 or less alike in size and shape4 ,such 
a collection of cells is called a       
tissue4 ,examples of tissues are the    
cells covering the outside of the human 
body1 the muscle cells1 which           
collectively allow of movement1 bony    
tissues which form the framework to     
which the muscles are attached1 and many
 others4       ,footnote #b3 ,to the    
,teacher4--,any simple plant or animal  
tissue can be used to demonstrate the   
cell4 ,epidermal cells      may be      
stripped from the body of the frog or   
obtained by      scraping the inside of 
one's mouth4 ,the thin skin from an     
onion stained with tincture of iodine   
shows well1 as do thin      sections of 
a young stem1 as the bean or pea4 ,one  
of the      best places to study a      
tissue and the cells of which it is     
composed is in the leaf of a green water
 plant1 ,elodea4 ,in      this plant the

 cells are large1 and not only their    
outline1      but the movement of the   
living matter within the cells1 may     
easily be seen1 and the parts described 
in the next      paragraph can be       
demonstrated4  ,illustration3 ,a cell4  
ch41 chromosomes2 c4w41 cell wall2 n41  
nucleus2 p41 protoplasm4  ,cells4--,a   
cell may be defined as a tiny mass of   
living matter containing a nucleus1     
either living alone or forming a unit of
 the building material of a living      
thing4 ,the living matter of which all  
cells are formed is known as protoplasm 
7formed from two ,greek words meaning   
first form74 ,if we examine under a     
compound microscope a small bit of the  
water plant ,elodea1 we see a number of 
structures resembling bricks in a wall4 
,each brick1 however1 is really a plant 
cell bounded by a thin wall4 ,if we look
 carefully1 we can see that the material
 inside of this wall is slowly moving   
and is carrying around in its substance 
a number of little green bodies4 ,this  

moving substance is living matter1 the  
protoplasm of the cell4 ,the green      
bodies 7the chlorophyll bodies7 we shall
 learn more about later2 they are found 
only in plant cells4 ,all plant and     
animal cells appear to be alike in the  
fact that every living cell possesses a 
structure known as the nucleus 7pl4     
nuclei71 which is found within the body 
of the cell4 ,this nucleus is not easy  
to find in the cells of ,elodea4 ,within
 the nucleus of all cells are found     
certain bodies called chromosomes4      
,these chromosomes in a given plant or  
animal are always constant in number4   
,these chromosomes are supposed to be   
the bearers of the qualities which we   
believe can be handed down from plant to
 plant and from animal to animal1 in    
other words1 the inheritable qualities  
which make the offspring like its       
parents4  ,how ,cells form              
,others4--,cells grow to a certain size 
and then split into two new cells4 ,in  
this process1 which is of very great    

importance in the growth of both plants 
and animals1 the nucleus divides first4 
,the chromosomes also divide1 each      
splitting lengthwise and the parts going
 in equal numbers to each of the two    
cells formed from the old cell4 ,in this
 way the matter in the chromosomes is   
divided equally between the two new     
cells4 ,then the rest of the protoplasm 
separates1 and two new cells are formed4
 ,this process is known as fission4 ,it 
is the usual method of growth found in  
the tissues of plants and animals4      
,illustration3 ,stages in the division  
of one cell to form two4 ,which part of 
the cell divides first8 ,what seems to  
become of the chromosomes8  ,cells of   
,various ,sizes and ,shapes4--,plant    
cells and animal cells are of very      
diverse shapes and sizes4 ,there are    
cells so large that they can easily be  
seen with the unaided eye2 for example1 
the root hairs of plants and eggs of    
some animals4 ,on the other hand1 cells 
may be so minute1 as in the case of the 

plant cells named bacteria1 that several
 million might be present in a few drops
 of milk4 ,the forms of cells may be    
extremely varied in different tissues2  
they may assume the form of cubes1      
columns1 spheres1 flat plates1 or may be
 extremely irregular in shape4 ,one kind
 of tissue cell1 found in man1 has a    
body so small as to be quite invisible  
to the naked eye1 although it has a     
prolongation several feet in length4    
,such are some of the cells of the      
nervous system of man and other large   
animals1 as the ox1 elephant1 and whale4
  ,varying ,sizes of ,living            
,things4--,plant cells and animal cells 
may live alone1 or they may form        
collections of cells4 ,some plants are  
so simple in structure as to be formed  
of only one kind of cells4 ,usually     
living organisms are composed of several
 groups of different kinds of cells4 ,it
 is only necessary to call attention to 
the fact that such collections of cells 
may form organisms so tiny as to be     

barely visible to the eye2 as1 for      
instance1 some of the small flowerless  
plants or many of the tiny animals      
living in fresh water or salt water4 ,on
 the other hand1 among animals1 the bulk
 of the elephant and whale1 and among   
plants the big trees of ,california1    
stand out as notable examples4 ,the     
large plants and animals are made up of 
more1 not necessarily larger1 cells4    
,what ,protoplasm can ,do4--,it responds
 to influences or stimulation from      
without its own substance4 ,both plants 
and animals are sensitive to touch or   
stimulation by light1 heat or cold1     
certain chemical substances1 gravity1   
and electricity4 ,green plants turn     
toward the source of light4 ,some       
animals are attracted to light and      
others repelled by it2 the earthworm is 
an example of the latter4 ,protoplasm is
 thus said to be irritable4  ,protoplasm
 has the power to contract and to move4 
,muscular movement is a familiar        
instance of this power4 ,movement may   

also take place in plants4 ,some plants 
fold up their leaves at night2 others1  
like the sensitive plant1 fold their    
leaflets when touched4  ,protoplasm can 
form new living matter out of food4 ,to 
do this1 food materials must be absorbed
 into the cells of the living organism4 
,to make protoplasm1 it is evident that 
the same chemical elements must enter   
into the composition of the food        
substances as are found in living       
matter4 ,the simplest plants and animals
 have this wonderful power as certainly 
developed as the most complex forms of  
life4  ,protoplasm1 be it in plant or   
animal1 breathes and throws off waste   
materials4 ,when a living thing does    
work oxygen unites with food in the     
body2 the food is burned or oxidized and
 work is done by means of the energy    
released from the food4 ,the waste      
materials are excreted or passed out4   
,plants and animals alike pass off the  
carbon dioxide which results from the   
oxidation of food and of parts of their 

own bodies4 ,animals eliminate wastes   
containing nitrogen through the skin and
 the kidneys4  ,protoplasm can          
reproduce1 that is1 form other matter   
like itself4 ,new plants are constantly 
appearing to take the places of those   
that die4 ,the supply of living things  
upon the earth is not decreasing2       
reproduction is constantly taking place4
 ,in a general way it is possible to say
 that plants and animals reproduce in a 
very similar manner4  ,the ,importance  
of ,reproduction4--,reproduction is the 
final process that plants and animals   
are called upon to perform4 ,without the
 formation of new living things no      
progress would be possible on the earth4
 ,we have found that insects help       
flowering plants in this process4 ,let  
us now see exactly what happens when    
pollen is placed by the bee on the      
stigma of another flower of the same    
kind4 ,to understand this process of    
reproduction in flowers1 we must first  
study carefully pollen grains from the  

anther of some growing flower4          
,illustration3 ,pollen grains of        
different shapes and sizes4             
,pollen4--,pollen grains of various     
flowers1 when seen under the microscope1
 differ greatly in form and appearance4 
,some are relatively large1 some small1 
some rough1 others smooth1 some         
spherical1 and others angular4 ,they all
 agree1 however1 in having a thick wall1
 with a thin membrane under it1 the     
whole inclosing a mass of protoplasm4   
,at an early stage the pollen grain     
contains but a single cell4 ,a little   
later1 however1 two nuclei may be found 
in the protoplasm4 ,hence we know that  
at least two cells exist there1 one of  
which is called the sperm cell2 its     
nucleus is the sperm nucleus4           
,illustration3 ,a pollen grain greatly  
magnified4 ,two nuclei are found 7n1 n'7
 at this stage of its growth4           
,illustration3 ,three stages in the     
germination of the pollen grain4 ,the   
nuclei in the tube in 7#c7 are the sperm

 nuclei4 ,drawn under the compound      
microscope4  ,growth of ,pollen         
,grains4--,under certain conditions a   
pollen grain will grow or germinate4    
,this growth can be artificially        
produced in the laboratory by sprinkling
 pollen from well-opened flowers of     
sweet pea or nasturtium on a solution of
 #ae parts of sugar to #ajj of water4   
,left for a few hours in a warm and     
moist place and then examined under the 
microscope1 the grains of pollen will be
 found to have germinated1 a long1      
threadlike mass of protoplasm growing   
from it into the sugar solution4 ,the   
presence of this sugar solution was     
sufficient to induce growth4 ,when the  
pollen grain germinates1 the nuclei     
enter the threadlike growth 7this growth
 is called the pollen tube2 see         
,figure74 ,one of the nuclei which grows
 into the pollen tube is known as the   
sperm nucleus4  ,illustration3          
,fertilization of the ovule4 ,a flower  
cut down lengthwise 7only one side      

shown74 ,the pollen tube is seen        
entering the ovule4 a1 anther2 f1       
filament2 pg1 pollen grain2 s1 stigmatic
 surface2 pt1 pollen tube2 st1 style2 o1
 ovary2 m1 micropyle2 sp1 space within  
ovary2 e1 egg cell2 ,p1 petal2 ,s1      
sepal4  ,fertilization of the           
,flower4--,if we cut the pistil of a    
large flower 7as a lily7 lengthwise1 we 
notice that the style appears to be     
composed of rather spongy material in   
the interior2 the ovary is hollow and is
 seen to contain a number of rounded    
structures which appear to grow out from
 the wall of the ovary4 ,these are the  
ovules4 ,the ovules1 under certain      
conditions1 will become seeds4 ,an      
explanation of these conditions may be  
had if we examine1 under the microscope1
 a very thin section of a pistil1 on    
which pollen has begun to germinate4    
,the central part of the style is found 
to be either hollow or composed of a    
soft tissue through which the pollen    
tube can easily grow4  ,upon            

germination1 the pollen tube grows      
downward through the spongy center of   
the style1 follows the path of least    
resistance to the space within the      
ovary1 and there enters the ovule4  ,it 
is believed that some chemical influence
 thus attracts the pollen tube4 ,when it
 reaches the ovary1 the sperm cell      
penetrates an ovule by making its way   
through a little hole called the        
micropyle4 ,it then grows toward a clear
 bit of protoplasm known as the embryo  
sac4 ,the embryo sac is an ovoid space1 
microscopic in size1 filled with        
semifluid protoplasm containing several 
nuclei4 7,see ,figure47 ,one of the     
nuclei1 with the protoplasm immediately 
surrounding it1 is called the egg cell4 
,it is this cell that the sperm nucleus 
of the pollen tube grows toward2        
ultimately the sperm nucleus reaches the
 egg nucleus and unites with it4 ,the   
two nuclei1 after coming together1 unite
 to form a single cell4 ,this process is
 known as fertilization4 ,this single   

cell formed by the union of the pollen  
tube cell or sperm and the egg cell is  
now called a fertilized egg4            
,development of ,ovule into ,seed4--,the
 primary reason for the existence of a  
flower is that it may produce seeds from
 which future plants will grow4 ,after  
fertilization the ovule grows into a    
seed4 ,the first beginning of the growth
 of the seed takes place at the moment  
of fertilization4 ,from that time on    
there is a growth of the fertilized egg 
within the ovule which makes a baby     
plant called the embryo4 ,the embryo    
will give rise to the adult plant4      
,illustration3 ,the fruit of the locust1
 a bean-like fruit4 p1 the attachment to
 the placenta2 s1 the stigma4  ,a       
,typical ,fruit1--the ,pea or ,bean     
,pod4--,if a withered flower of any one 
of the pea or bean family is examined   
carefully1 it will be found that the    
pistil of the flower continues to grow  
after the rest of the flower withers4   
,if we remove the pistil from such a    

flower and examine it carefully1 we find
 that it is the ovary that has enlarged4
 ,the space within the ovary has become 
nearly filled with a number of nearly   
ovoid bodies1 attached along one edge of
 the inner wall4 ,these we recognize as 
the young seeds4  ,the pod of a bean1   
pea1 or locust illustrates well the     
growth from the flower4 ,the pod1 which 
is in reality a ripened ovary with other
 parts of the pistil attached to it1 is 
considered as a fruit4 ,by definition1 a
 fruit is a ripened ovary and its       
contents together with any parts of the 
flower that may be attached to it4 ,the 
chief use of the fruit to the flower is 
to hold and to protect the seeds2 it may
 ultimately distribute them where they  
can reproduce young plants4             
,illustration3 ,the development of an   
apple4 ,notice that in this fruit       
additional parts besides the ovary 7o7  
become part of the fruit4 ,certain outer
 parts of the flower1 the sepals 7s7 and
 receptacle1 become the fleshy part of  

the fruit1 while the ovary becomes the  
core4 ,stages numbered #a to #g are in  
the order of development4  ,the         
,necessity of ,fruit and ,seed          
,dispersal to a ,plant4--,we have seen  
that the chief reason for flowers1 from 
the plant's standpoint1 is to produce   
fruits which contain seeds4             
,reproduction and the ultimate          
scattering of fruits and seeds are      
absolutely necessary in order that      
colonies of plants may reach new        
localities4 ,it is evident that plants  
best fitted to scatter their seeds1 or  
place fruits containing the seeds some  
little distance from the parent plants1 
are the ones which will spread most     
rapidly4 ,a plant1 if it is to advance  
into new territory1 must get its seeds  
there first4 ,plants which are best     
fitted to do this are the most widely   
distributed on the earth4  ,how ,seeds  
and ,fruits are ,scattered4--,seed      
dispersal is accomplished in many       
different ways4 ,some plants produce    

enormous numbers of seeds which may or  
may not have special devices to aid in  
their scattering4 ,most weeds are thus  
started in pastures new4 ,some prolific 
plants1 like the milkweed1 have seeds   
with a little tuft of hairlike down     
which allows them to be carried by the  
wind4 ,others1 as the omnipresent       
dandelion1 have their fruits provided   
with a similar structure1 the pappus4   
,some plants1 as the burdock and        
clotbur1 have fruits provided with tiny 
hooks which stick to the hair of        
animals1 thus proving a means of        
transportation4 ,most fleshy fruits     
contain indigestible seeds1 so that when
 the fruits are eaten by animals the    
seeds are passed off from the body      
unharmed and may1 if favorably placed1  
grow4 ,nuts of various kinds are often  
carried off by animals1 buried1 and     
forgotten1 to grow later4 ,such are a   
few of the ways in which seeds are      
scattered4 ,all other things being      
equal1 the plants best equipped to      

scatter seeds or fruits are those which 
will drive out other plants in a given  
locality4 ,because of their adaptations 
they are likely to be very numerous1 and
 when unfavorable conditions come1 for  
that reason1 if for no other1 are likely
 to survive4 ,such plants are best      
exemplified in the weeds of the         
grassplots and gardens4                 
,,reference ,,books                     
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,andrews1 ,a       
,practical ,course in ,botany1 pages    
#bej-bgj4        ,american ,book        
,company4      ,atkinson1 ,first        
,studies of ,plant ,life1 ,chaps4       
,,xxv-,,xxvi4        ,ginn and ,company4
      ,bailey1 ,lessons with ,plants1   
,part ,,iii1 pages #aca-bej4 ,the       
,macmillan ,company4      ,coulter1     
,plant ,life and ,plant ,uses4 ,american
 ,book ,company4      ,dana1 ,plants and
 their ,children1 pages #ahg-bee4       
,american        ,book ,company4        

,lubbock1 ,flowers1 ,fruit1 and ,leaves1
 ,part ,i4 ,the ,macmillan              
,company4      ,newell1 ,a ,reader in   
,botany1 ,part ,,ii1 pages #a-if4 ,ginn 
and        ,company4                    
,,advanced       ,bailey1 ,plant        
,breeding4 ,the ,macmillan ,company4    
,campbell1 ,lectures on the ,evolution  
of ,plants4 ,the        ,macmillan      
,company4      ,coulter1 ,barnes1 and   
,cowles1 ,a ,textbook of ,botany1 ,part 
,,ii4 ,american ,book ,company4         
,darwin1 ,different ,forms of ,flowers  
on ,plants of the ,same        ,species4
 ,appleton4      ,darwin1 ,fertilization
 in the ,vegetable ,kingdom1 ,chaps4 ,i 
and ,,ii4 ,appleton4      ,darwin1      
,orchids ,fertilized by ,insects4 ,d4   
,appleton and        ,company4          
,mueller1 ,the ,fertilization of        
,flowers4 ,the ,macmillan               
,company4     ,v4 ,,plant ,,growth ,,and
 ,,nutrition4 ,,causes ,,of ,,growth    
,problem4--,what causes a young plant to
 grow8          7a7 ,the relation of the

 young plant to its food supply4        
7b7 ,the outside conditions necessary   
for germination4          7c7 ,what the 
young plant does with its food supply4  
7d7 ,how a plant or animal is able to   
use its food supply4          7e7 ,how a
 plant or animal prepares food to use in
 various parts               of the     
body4                                   
,,laboratory ,,suggestions              
,laboratory exercise4--,examination of  
bean in pod4        ,examination and    
identification of parts of bean seed4   
,laboratory demonstration4--,tests for  
the nutrients3        starch1 fats or   
oils1 protein4      ,laboratory         
demonstration4--,proof that such foods  
exist in        bean4      ,home        
work4--,test of various common foods for
 nutrients4        ,tabulate results4   
,extra home work by selected            
pupils4--,factors necessary for         
germination of bean4 ,demonstration of  
experiments to class4                   
,demonstration4--,oxidation of candle in

 closed jar4 ,test        with lime     
water for products of oxidation4        
,demonstration4--,proof that materials  
are oxidized within        the human    
body4      ,demonstration4--,oxidation  
takes place in growing seeds4           
,test for oxidation products4 ,oxygen   
necessary for        germination4       
,laboratory exercise4--,examination of  
corn on cob1 the corn        grain1     
longitudinal sections of corn grain     
stained with        iodine to show that 
embryo is distinct from food supply4    
,demonstration4--,test for grape sugar4 
,demonstration4--,grape sugar present in
 growing corn grain4                    
,demonstration4--,the action of diastase
 on starch4        ,conditions necessary
 for action of diastase4   ,what makes a
 ,seed ,grow4--,the general problem of  
the pages that follow will be to explain
 how the baby plant1 or embryo1 formed  
in the seed as the result of the        
fertilization of the egg cell1 is able  
to grow into an adult plant4 ,two sets  

of factors are necessary for its growth3
 first1 the presence of food to give the
 young plant a start2 second1 certain   
stimulating factors outside the young   
plant1 such as water and heat4          
,illustration3 ,three views of a kidney 
bean1 the lower one having one cotyledon
 removed to show the hypocotyl and      
plumule4  ,if we open a bean pod1 we    
find the seeds lying along one edge of  
the pod1 each attached by a little stalk
 to the inner wall of the ovary4 ,if we 
pull a single bean from its attachment1 
we find that the stalk leaves a scar on 
the coat of the bean2 this scar is      
called the hilum4 ,the tiny hole near   
the hilum is called the micropyle4 ,turn
 back to the figure 7page #ed7 showing  
the ovule in the ovary4 ,find there the 
little hole through which the pollen    
tube reached the embryo sac4 ,this hole 
is identical with the micropyle in the  
seed4 ,the thick outer coat 7the testa7 
is easily removed from a soaked bean1   
the delicate coat under it easily       

escaping notice4 ,the seed separates    
into two parts2 these are called the    
cotyledons4 ,if you pull apart the      
cotyledons very carefully1 you find     
certain other structures between them4  
,the rodlike part is called the         
hypocotyl 7meaning under the            
cotyledons74 ,this will later form the  
root 7and part of the stem7 of the young
 bean plant4 ,the first true leaves1    
very tiny structures1 are folded        
together between the cotyledons4 ,that  
part of the plant above the cotyledons  
is known as the plumule or epicotyl     
7meaning above the cotyledons74 ,all the
 parts of the seed within the seed coats
 together form the embryo or young      
plant4 ,a bean seed contains1 then1 a   
tiny plant protected by a tough coat4   
,food in the ,cotyledons4--,the problem 
now before us is to find out how the    
embryo of the bean is adapted to grow   
into an adult plant4 ,up to this stage  
of its existence it has had the         
advantage of food and protection from   

the parent plant4 ,now it must begin the
 battle of life alone4 ,we shall find in
 all our work with plants and animals   
that the problem of food supply is      
always the most important problem to be 
solved by the growing organism4 ,let us 
see if the embryo is able to get a start
 in life 7which many animals get in the 
egg7 from food provided for it within   
its own body4  ,organic                 
,nutrients4--,organic foods 7those which
 come from living sources7 are made up  
of two kinds of substances1 the         
nutrients or food substances and wastes 
or refuse4 ,an egg1 for example1        
contains the white and the yolk1        
composed of nutrients1 and the shell1   
which is waste4 ,the organic nutrients  
are classed in three groups4            
,carbohydrates1 foods which contain     
carbon1 hydrogen1 and oxygen in a       
certain fixed proportion 7,c#f;,h#aj,o#e
 is an example74 ,they are the simplest 
of these very complex chemical compounds
 we call organic nutrients4 ,starch and 

sugar are common examples of            
carbohydrates4  ,fats and ,oils4--,these
 foods are also composed of carbon1     
hydrogen1 and oxygen in a proportion    
which enables them to unite readily with
 oxygen4  ,proteins4--,a third group of 
organic foods1 proteins1 are the most   
complex of all in their composition1 and
 have1 besides carbon1 oxygen1 and      
hydrogen1 the element nitrogen and      
minute quantities of other elements4    
,illustration3 ,starch grains in the    
cells of a potato tuber4  ,test for     
,starch4--,if we boil water with a piece
 of laundry starch in a test tube1 then 
cool it and add to the mixture two or   
three drops of iodine solution1#c we    
find that the mixture in the test tube  
turns purple or deep blue4 ,it has been 
discovered by experiment that starch1   
and no other known substance1 will be   
turned purple or dark blue by iodine4   
,therefore1 iodine solution has come to 
be used as a test for the presence of   
starch4       ,footnote #c3 ,iodine     

solution is made by simply adding a few 
crystals of the element iodine to #ie   
per cent alcohol2 or1      better1 take 
by weight #a gram of iodine crystals1   
#b_/c gram      of iodide of potassium1 
and dilute to a dark brown color in     
weak alcohol 7#ce per cent7 or distilled
 water4  ,illustration3 ,test for       
,starch4  ,starch in the ,bean4--,if we 
mash up a little piece of a bean        
cotyledon which has been previously     
soaked in water1 and test for starch    
with iodine solution1 the characteristic
 blue-black color appears1 showing the  
presence of the starch4 ,if a little of 
the stained material is mounted in water
 on a glass slide under the compound    
microscope1 you will find that the      
starch is in the form of little ovoid   
bodies called starch grains4 ,the starch
 grains and other food products are made
 use of by the growing plant4  ,test for
 ,oils4--,if the substance believed to  
contain oil is rubbed on brown paper or 
is placed on paper and then heated in an

 oven1 the presence of oil will be known
 by a translucent spot on the paper4    
,illustration3 ,test for protein4       
,protein in the ,bean4--,another        
nutrient present in the bean cotyledon  
is protein4 ,several tests are used to  
detect the presence of this nutrient4   
,the following is one of the best       
known3--  ,place in a test tube the     
substance to be tested2 for example1 a  
bit of hard-boiled egg4 ,pour over it a 
little strong 7#fj per cent7 nitric acid
 and heat gently4 ,note the color that  
appears--a lemon yellow4 ,if the egg is 
washed in water and a little ammonium   
hydrate added1 the color changes to a   
deep orange1 showing that a protein is  
present4  ,if the protein is in a liquid
 state1 its presence may be proved by   
heating1 for when it coagulates or      
thickens1 as does the white of an egg   
when boiled1 protein in the form of an  
albumin is present4  ,another           
characteristic protein test easily made 
at home is burning the substance4 ,if it

 burns with the odor of burning feathers
 or leather1 then protein forms part of 
its composition4#d       ,footnote #d3  
,other tests somewhat more reliable1 but
 much      more delicate1 are the biuret
 test and test with ,millon's           
reagent4  ,a test of the cotyledon of a 
bean for protein food with nitric acid  
and ammonium hydrate shows us the       
presence of this food4 ,beans are found 
by actual test to contain about #bc per 
cent of protein1 #ei per cent of        
carbohydrates1 and about #b per cent    
oils4 ,the young plant within a pea or  
bean is thus shown to be well supplied  
with nourishment until it is able to    
take care of itself4 ,in this respect it
 is somewhat like a young animal within 
the egg1 a bird or fish1 for example4   
,beans and ,peas as ,food for ,man4--,so
 much food is stored in legumes 7as     
beans and peas7 that man has come to    
consider them a very valuable and cheap 
source of food4 ,study carefully the    
following table3--         ,,nutrients  

,,furnished ,,for ,,ten ,,cents ,,in    
,,beans ,,and ,,peas ,,at               
,,certain ,,prices ,,per ,,pound        
,,ten ,,cents ,,will ,,pay ,,for        
,,prices                                
----------------------------------------
--   ,,food ,,materials         ,,per   
,,total                       ,,as      
,,purchased         ,,pound    ,,food   
,,protein   ,,fat   ,,carbohydrates     
,,material                              
----------------------------------------
----------------------------            
,cents ,pounds ,pounds,pounds  ,pounds  
,kidney beans1 dried     #e       #b4jj 
#j4de    #j4jd      #a4ai   ,lima beans1
 fresh1                                 
shelled                #h       #a4be   
4#jd     --        4#ab   ,lima beans1  
dried       #f       #a4fg      4#cj    
4#jc      #a4aj   ,string beans1 fresh1 
#cj cents per peck      #c       #c4cc  
4#jg     4#ja       4#bc   ,beans1      
baked1 canned    #e       #b4jj         
4#ad     4#je       4#ci   ,lentils1    

dried         #aj       #a4jj      4#bf 
4#ja       4#ei   ,peas1 green1 in pod1 
#cj cents per peck      #c       #c4cc  
4#ab     4#ja       4#cc   ,peas1 dried 
#d       #b4ej      4#fb     4#jc       
#a4ee     ,illustration3 ,a series of   
early stages in the germination of the  
kidney bean4  ,germination of the       
,bean4--,if dry seeds are planted in    
sawdust or earth1 they will not grow4 ,a
 moderate supply of water must be given 
to them4 ,if seeds were to be kept in a 
freezing temperature or at a very high  
temperature1 no growth would take place4
 ,a moderate temperature and a moderate 
water supply are most favorable for     
their development4  ,illustration3 ,bean
 seedlings4 ,the older seedlings at the 
left have used up all of the food supply
 in the cotyledons4  ,if some beans were
 planted so that we might make a record 
of their growth1 we would find the first
 signs of germination to be the breaking
 of the testa and the pushing outward of
 the hypocotyl to form the first root4  

,a little later the hypocotyl begins to 
curve downward4 ,a later stage shows the
 hypocotyl lifting the cotyledon upward4
 ,in consequence the hypocotyl forms an 
arch1 dragging after it the bulky       
cotyledons4 ,the stem1 as soon as it is 
released from the ground1 straightens   
out4 ,from between the cotyledons the   
budlike plumule or epicotyl grows       
upward1 forming the first true leaves   
and all of the stem above the           
cotyledons4 ,as growth continues1 we    
notice that the cotyledons become       
smaller and smaller1 until their food   
contents are completely absorbed into   
the young plant4 ,the young plant is now
 able to care for itself and may be said
 to have passed through the stages of   
germination4  ,what makes an ,engine    
,go4--,if we examine the sawdust or soil
 in which the seeds are growing1 we find
 it forced up by the growing seed4      
,evidently work was done2 in other      
words1 energy was released by the seeds4
 ,a familiar example of release of      

energy is seen in an engine4 ,coal is   
placed in the firebox and lighted1 the  
lower door of the furnace is then opened
 so as to make a draft of air which will
 reach the coal4 ,you know the result4  
,the coal burns1 heat is given off1     
causing the water in the boiler to make 
steam1 the engine wheels to turn1 and   
work to be done4 ,let us see what       
happens from the chemical standpoint4   
,coal1 ,organic ,matter4--,coal is made 
largely from dead plants1 long since    
pressed into its present hard form4 ,it 
contains a large amount of a chemical   
element called carbon1 the presence of  
which is characteristic of all organic  
material4  ,illustration3 ,the limewater
 test4 ,the tube at the right shows the 
effect of the carbon dioxide4           
,oxidation1 its ,results4--,when things 
containing carbon are lighted1 they     
burn4 ,if we place a lighted candle     
which contains carbon in a closed glass 
jar1 the candle soon goes out4 ,if we   
then carefully test the air in the jar  

with a substance known as limewater1#e  
the latter1 when shaken up with the air 
in the jar1 turns milky4 ,this test     
proves the presence in the jar of a gas1
 known as carbon dioxide4 ,this gas is  
formed by the carbon of the candle      
uniting with the oxygen in the air4     
,when the oxygen of the air in the jar  
was used up1 the flame went out1 showing
 that oxygen is necessary to make a     
thing burn4 ,this uniting of oxygen with
 some other substance is called         
oxidation4       ,footnote #e3          
,limewater can be made by shaking up a  
piece of      quicklime the size of your
 fist in about two quarts of      water4
 ,filter or strain the limewater into   
bottles and it is      ready for use4   
,illustration3 ,diagram to show that    
when a piece of wood is burned it forms 
water and carbon dioxide4  ,oxidation   
possible without a ,flame4--,but a flame
 is not necessary for oxidation4 ,iron1 
if left in a damp place1 becomes rusty4 
,a union between the oxygen in the water

 or air and the iron makes what is known
 as iron oxide or rust4 ,this is an     
example of slow oxidation4  ,oxidation  
in our ,bodies4--,if we expel the air   
from our lungs through a tube into a    
bottle of limewater1 we notice the      
limewater becomes milky4 ,evidently     
carbon dioxide is formed in our own     
bodies and oxidation takes place there4 
,is it fair to believe that the heat of 
our body 7for example1 #ih4f deg4       
,fahrenheit under the tongue7 is due to 
oxidation within the body1 and that the 
work we do results from this chemical   
process4 ,if so1 what is oxidized8      
,energy comes from ,foods4--,from the   
foregoing experiment it is evident that 
food is oxidized within the human body  
to release energy for our daily work4   
,is it not logical to suppose that all  
living things1 both plant and animal1   
release energy as the result of         
oxidation of foods within their cells8  
,let us see if this is true in the case 
of the pea4  ,food oxidized in          

,germinating ,seeds4--,if we take equal 
numbers of soaked peas1 placed in two   
bottles1 one tightly stoppered1 the     
other having no stopper1 both bottles   
being exposed to identical conditions of
 light1 temperature1 and moisture1 we   
find that the seeds in both bottles     
start to germinate1 but that those in   
the closed bottle soon stop1 while those
 in the open jar continue to grow almost
 as well as similar seeds placed in an  
open dish would4  ,illustration3        
,experiment that shows the necessity for
 air in germination4  ,why did not the  
seeds in the covered jar germinate8 ,to 
answer this question1 let us carefully  
remove the stopper from the stoppered   
jar and insert a lighted candle4 ,the   
candle goes out at once4 ,the surer test
 of limewater shows the presence of     
carbon dioxide in the jar4 ,the carbon  
of the foodstuffs of the pea united with
 the oxygen of the air1 forming carbon  
dioxide4 ,growth stopped as soon as the 
oxygen was exhausted4 ,the presence of  

carbon dioxide in the jar is an         
indication that a very important process
 which we associate with animals rather 
than plants1 that of respiration1 is    
taking place4 ,the seed1 in order to    
release the energy locked up in its food
 supply1 must have oxygen1 so that the  
oxidation of the food may take place4   
,hence a constant supply of fresh air is
 an important factor in germination4 ,it
 is important that air should penetrate 
between the grains of soil around a     
seed4 ,the frequent stirring of the soil
 enables the air to reach the seed4 ,air
 also acts upon some materials in the   
soil and puts them in a form that the   
germinating seed can use4 ,this         
necessity for oxygen shows us at least  
one reason why the farmer plows and     
harrows a field and one important use of
 the earthworm4 ,explain4               
,illustration3 ,a grain of corn cut     
lengthwise4 ,c1 cotyledon2 ,e1          
endosperm2 ,h1 hypocotyl2 ,p1 plumule4  
,structure of a ,grain of               

,corn4--,examination of a well-soaked   
grain of corn discloses a difference in 
the two flat sides of the grain4 ,a     
light-colored area found on one surface 
marks the position of the embryo2 the   
rest of the grain contains the food     
supply4 ,the interesting thing to       
remember here is that the food supply is
 outside of the embryo4  ,a grain cut   
lengthwise perpendicular to the flat    
side and then dipped in weak iodine     
shows two distinct parts1 an area       
containing considerable starch1 the     
endosperm1 and the embryo or young      
plant4 ,careful inspection shows the    
hypocotyl and plumule 7the latter       
pointing toward the free end of the     
grain7 and a part surrounding them1 the 
single cotyledon 7see ,figure74 ,here   
again we have an example of a fitting   
for future needs1 for in this fruit the 
one seed has at hand all the food       
material necessary for rapid growth1    
although the food is here outside the   
embryo4  ,illustration3 ,longitudinal   

section of young ear of corn4 ,o1 the   
fruits2 ,s1 the stigmas2 ,,sh1 the      
sheath-like leaves2 ,,st1 the flower    
stalk4 7,after ,sargent47  ,endosperm   
the ,food ,supply of ,corn4--,we find   
that the one cotyledon of the corn grain
 does not serve the same purpose to the 
young plant as do the two cotyledons of 
the bean4 ,although we find a little    
starch in the corn cotyledon1 still it  
is evident from our tests that the      
endosperm is the chief source of food   
supply4 ,the study of a thin section of 
the corn grain under the compound       
microscope shows us that the starch     
grains in the endosperm are large and   
regular in size4 ,when the grain has    
begun to grow1 examination shows that   
the starch grains near the edge of the  
cotyledon are much smaller and quite    
irregular1 having large holes in them4  
,we know that the germinating grain has 
a much sweeter taste than that which is 
not growing4 ,this is noticed in        
sprouting barley or malt4 ,we shall     

later find that1 in order to make use of
 starchy food1 a plant or animal must in
 some manner change it over to sugar4   
,this change is necessary1 because      
starch will not dissolve in water1 while
 sugar will2 in this form substances can
 pass from cell to cell in the plant and
 thus distribute the food where it is   
needed4  ,illustration3 ,test for grape 
sugar4  ,a ,test for ,grape             
,sugar4--,place in a test tube the      
substance to be tested and heat it in a 
little water so as to dissolve the      
sugar4 ,add to the fluid twice its bulk 
of ,fehling's solution1#f which has been
 previously prepared4 ,heat the mixture1
 which should now have a blue color1 in 
the test tube4 ,if grape sugar is       
present in considerable quantity1 the   
contents of the tube will turn first a  
greenish1 then yellow1 and finally a    
brick-red color4 ,smaller amounts will  
show less decided red4 ,no other        
substance than sugar will give this     
reaction4 ,if ,benedict's test#g is     

used1 a colored precipitate will appear 
in the test tube after boiling4         
,footnotes #f and #g3 ,directions for   
making these solutions      will be     
found in ,hunter's ,laboratory ,problems
 in ,civic      ,biology4  ,starch      
changed to ,grape ,sugar in the         
,corn4--,that starch is being changed to
 grape sugar in the germinating corn    
grain can easily be shown if we cut     
lengthwise through the embryos of half a
 dozen grains of corn that have just    
begun to germinate1 place them in a test
 tube with some ,fehling's solution1 and
 heat almost to the boiling point4 ,they
 will be found to give a reaction       
showing the presence of sugar along the 
edge of the cotyledon and between it and
 the endosperm4  ,digestion4--,this     
change of starch to grape sugar in the  
corn is a process of digestion4 ,if you 
chew a bit of unsweetened cracker in the
 mouth for a little time1 it will begin 
to taste sweet1 and if the chewed       
cracker1 which we know contains starch1 

is tested with ,fehling's solution1 some
 of the starch will be found to have    
changed to grape sugar4 ,here1 again1 a 
process of digestion has taken place4   
,in both the corn and in the mouth1 the 
change is brought about by the action of
 peculiar substances known as digestive 
ferments1 or enzymes4 ,such substances  
have the power under certain conditions 
to change insoluble foods--solids--into 
soluble substances--liquids4 ,the result
 is that substances which before        
digestion would not dissolve in water   
now will dissolve4  ,illustration3 ,a   
germinating corn grain4 ,c1 cotyledon2  
,h1 growing root 7hypocotyl72 ,p1       
growing stem 7plumule72 ,s1 endosperm2  
d4s41 digested starch2 p4r41 primary    
root2 s4r41 secondary root2 r4h41 root  
hairs4  ,the ,action of ,diastase on    
,starch4--,the enzyme found in the      
cotyledon of the corn1 which changes    
starch to grape sugar1 is called        
diastase4 ,it may be separated from the 
cotyledon and used in the form of a     

powder4  ,to a little starch in half a  
cup of water we add a very little 7#a   
gram7 of diastase and put the vessel    
containing the mixture in a warm place1 
where the temperature will remain nearly
 constant at about #ih deg4 ,fahrenheit4
 ,on testing part of the contents at the
 end of half an hour1 and the remainder 
the next morning1 for starch and for    
grape sugar1 we find from the morning   
test that the starch has been almost    
completely changed to grape sugar4      
,starch and warm water alone under      
similar conditions will not react to the
 test for grape sugar4  ,digestion has  
the ,same ,purpose in ,plants and       
,animals4--,in our own bodies we know   
that solid foods taken into the mouth   
are broken up by the teeth and moistened
 by saliva4 ,if we could follow that    
food1 we would find that eventually it  
became part of the blood4 ,it was made  
soluble by digestion1 and in a liquid   
form was able to reach the blood4 ,once 
a part of the body1 the food is used    

either to release energy or to build up 
the body4  ,summary4--,we have seen3    
#a4 ,that seeds1 in order to grow1 must 
possess a food supply either in or      
around their bodies4  #b4 ,that this    
food supply must be oxidized before     
energy is released4  #c4 ,that in cases 
where the food is not stored at the     
point where it is to be oxidized the    
food must be digested so that it may be 
transported from one part to another in 
the same plant4  ,the life processes of 
plants and animals1 so far1 may be      
considered as alike2 they both feed1    
breathe 7oxidize their food71 do work1  
and grow4                               
,,reference ,,books                     
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,andrews1 ,a       
,practical ,course in ,botany1 pages    
#a-ba4        ,american ,book ,company4 
,atkinson1 ,first ,studies of ,plant    
,life1 ,chap4 ,,xxx4 ,ginn and          
,company4      ,bailey1 ,botany1 ,chaps4

 ,,xx1 ,,xxx4 ,the ,macmillan ,company4 
,beal1 ,seed ,dispersal4 ,ginn and      
,company4      ,bergen and ,davis1      
,principles of ,botany1 ,chaps4 ,,xx1   
,,xxx4        ,ginn and ,company4       
,coulter1 ,plant ,life and ,plant ,uses4
 ,american ,book ,company4      ,dana1  
,plants and their ,children4 ,american  
,book ,company4      ,mayne and ,hatch1 
,high ,school ,agriculture4 ,american   
,book        ,company4      ,lubbock1   
,flowers1 ,fruits1 and ,leaves4 ,the    
,macmillan        ,company4             
,newell1 ,reader in ,botany1 pages      
#bd-di4 ,ginn and ,company4             
,sharpe1 ,a ,laboratory ,manual in      
,biology1 pages #ee-fe4        ,american
 ,book ,company4                        
,,advanced       ,bailey1 ,the          
,evolution of our ,native ,fruits4 ,the 
,macmillan        ,company4             
,bailey1 ,plant ,breeding4 ,the         
,macmillan ,company4      ,coulter1     
,barnes1 and ,cowles1 ,a ,textbook of   
,botany1 ,vol4 ,i4        ,american     

,book ,company4      ,de ,candolle1     
,origin of ,cultivated ,plants4 ,d4     
,appleton and        ,company4          
,duggar1 ,plant ,physiology4 ,the       
,macmillan ,company4      ,farmers'     
,bulletins1 ,nos4 #gh1 #hf1 #bbe1 #cdd4 
,u4 ,s4 ,department        of           
,agriculture4      ,hodge1 ,nature      
,study and ,life1 ,chaps4 ,x1 ,,xx4     
,ginn and ,company4      ,kerner        
7translated by ,oliver71 ,natural       
,history of ,plants4        ,henry ,holt
 and ,company1 #d vols4 ,vol4 ,,ii1     
,part #b4      ,sargent1 ,corn ,plants4 
,houghton1 ,mifflin1 and ,company4      
,,vi4 ,,the ,,organs ,,of ,,nutrition   
,,in ,,plants--,,the ,,soil ,,and ,,its 
,,relation ,,to ,,the ,,roots           
,problem4--,what a plant takes from the 
soil and how it gets it4          7a7   
,what determines the direction of growth
 of roots8          7b7 ,how is the root
 built8          7d7 ,what is in the    
soil that a root might take out8        
7e7 ,why is nitrogen necessary1 and how 

is it obtained8                         
,,laboratory ,,suggestions              
,demonstration4--,roots of bean or pea4 
,demonstration or home                  
experiment4--,response of root to       
gravity and to water4 ,what part of root
 is most responsive8      ,laboratory   
work4--,root hairs1 radish or corn1     
position on        root1 gross structure
 only4 ,drawing4                        
,demonstration4--,root hair under       
compound microscope4                    
,demonstration4--,apparatus illustrating
 osmosis4      ,demonstration or a home 
experiment4--,organic matter            
present in soil4                        
,demonstration4--,root tubercles of     
legume4      ,demonstration4--,nutrients
 present in some roots4   ,uses of the  
,root4--,if one of the seedlings of the 
bean spoken of in the last chapter is   
allowed to grow in sawdust and is given 
light1 air1 and water1 sooner or later  
it will die4 ,soil is part of its       
natural environment1 and the roots which

 come in contact with the soil are very 
important4 ,it is the purpose of this   
chapter to find out just how the young  
plant is fitted to get what it needs    
from this part of its environment2      
namely1 the soil4  ,the development of a
 bean seedling has shown us that the    
root grows first4 ,one of the most      
important functions of the root to a    
young seed plant is that of a holdfast1 
an anchor to fasten it in the place     
where it is to develop4 ,it has many    
other uses1 as the taking in of water   
with the mineral and organic matter     
dissolved therein1 the storage of food1 
climbing1 etc4 ,all functions other than
 the first one stated arise after the   
young plant has begun to develop4       
,illustration3 ,a root system1 showing  
primary and secondary roots4  ,root     
,system4--,if you dig up a young bean   
seedling and carefully wash the dirt    
from the roots1 you will see that a long
 root is developed as a continuation of 
the hypocotyl4 ,this root is called the 

primary root4 ,other smaller roots which
 grow from the primary root are called  
secondary1 or tertiary1 depending on    
their relation to the first root        
developed4  ,downward ,growth of ,root4 
,influence of ,gravity4--,most of the   
roots examined take a more or less      
downward direction4 ,we are all familiar
 with the fact that the force we call   
gravity influences life upon this earth 
to a great degree4 ,does gravity act on 
the growing root8 ,this question may be 
answered by a simple experiment4        
,illustration3 ,revolve this figure in  
the direction of the arrows to see if   
the roots of the radish respond to      
gravity4  ,plant mustard or radish seeds
 in a pocket garden1 place it on one    
edge and allow the seeds to germinate   
until the root has grown to a length of 
about half an inch4 ,then turn it at    
right angles to the first position and  
allow it to remain for one day          
undisturbed4 ,the roots now will be     
found to have turned in response to the 

change in position1 that part of the    
root near the growing point being the   
most sensitive to the change4 ,this     
experiment seems to indicate that the   
roots are influenced to grow downward by
 the force of gravity4  ,experiments to 
determine the ,influence of ,moisture on
 a ,growing ,root4--,the objection might
 well be interposed that possibly the   
roots in the pocket garden#h grew       
downward after water4 ,that moisture has
 an influence on the growing root is    
easily proved4       ,footnote #h3 ,the 
,pocket ,garden4--,a very convenient    
form of      pocket germinator may be   
made as follows4 ,obtain two cleaned    
four by five negatives 7window glass    
will do72 place one      flat on the    
table and place on this half a dozen    
pieces of      colored blotting paper   
cut to a size a little less than the    
glass4 ,now cut four thin strips of wood
 to fit on the glass      just outside  
of the paper4  ,next moisten the        
blotter1 place      on it some          

well-soaked radish1 mustard seeds or    
barley      grains1 and cover with the  
other glass4 ,the whole box thus        
made should be bound together with      
bicycle tape4 ,seeds will      germinate
 in this box and with care may live for 
two weeks      or more4  ,plant bird    
seed1 mustard or radish seed in the     
underside of a sponge1 which should be  
kept wet1 and may be suspended by a     
string under a bell jar in the          
schoolroom window4 ,note whether the    
roots leave the sponge to grow downward1
 or if the moisture in the sponge is    
sufficient to counterbalance the force  
of gravity4  ,water a ,factor which     
determines the ,course taken by         
,roots4--,water1 as well as the force of
 gravity1 has much to do with the       
direction taken by roots4 ,water is     
always found below the surface of the   
ground1 but sometimes at a great depth4 
,most trees1 and all grasses1 have a    
greater area of surface exposed by the  
roots than by the branches4 ,the roots  

of alfalfa1 a cloverlike plant used for 
hay in the ,western states1 often       
penetrate the soil after water for a    
distance of ten to twenty feet below the
 surface of the ground4  ,fine          
,structure of a ,root4#i--,when we      
examine a delicate root in thin         
longitudinal section under the compound 
microscope1 we find the entire root to  
be made up of cells1 the walls of which 
are uniformly rather thin4 ,over the    
lower end of the root is found a        
collection of cells1 most of which are  
dead1 loosely arranged so as to form a  
cap over the growing tip4 ,this is      
evidently an adaptation which protects  
the young and actively growing cells    
just under the root cap4 ,in the body of
 the root a central cylinder can easily 
be distinguished from the surrounding   
cells4 ,in a longitudinal section a     
series of tubelike structures may be    
found within the central cylinder4      
,these structures are cells which have  
grown together at the small end1 the    

long axis of the cells running the      
length of the main root4 ,in their      
development the cells mentioned have    
grown together in such a manner as to   
lose their small ends1 and now form     
continuous hollow tubes with rather     
strong walls4 ,other cells have come to 
develop greatly thickened walls2 these  
cells give mechanical support to the    
tubelike cells4 ,collections of such    
tubes and supporting woody cells        
together make up what are known as      
fibrovascular bundles4       ,footnote  
#i3 ,sections of tradescantia roots are 
excellent for      demonstration of     
these structures4  ,illustration3 ,cross
 section of a young taproot2 a1 a1 root 
hairs2 b1 outer layer of bark2 c1 inner 
layer of bark2 d1 wood or central       
cylinder4  ,root ,hairs4--,careful      
examination of the root of one of the   
seedlings of mustard1 radish1 or barley 
grown in the pocket germinator shows a  
covering of tiny fuzzy structures4      
,these structures are very minute1 at   

most #c to #d millimeters in length4    
,they vary in length according to their 
position on the root1 the most and the  
longest root hairs being found near the 
point marked ,r4 ,h4 in the figure4     
,these structures are outgrowths of the 
outer layer of the root 7the epidermis71
 and are of very great importance to the
 living plant4  ,illustration3 ,young   
embryo of corn1 showing root hairs 7,r4 
,h47 and growing stem 7,p474  ,structure
 of a ,root ,hair4--,a single root hair 
examined under a compound microscope    
will be found to be a long1 round       
structure1 almost colorless in          
appearance4 ,the wall1 which is very    
flexible and thin1 is made up of        
cellulose1 a substance somewhat like    
wood in chemical composition1 through   
which fluids may easily pass4 ,clinging 
close to the cell wall is the protoplasm
 of the cell4 ,the interior of the root 
hair is more or less filled with a fluid
 called cell sap4 ,forming a part of the
 living protoplasm of the root hair1    

sometimes in the hairlike prolongation  
and sometimes in that part of the cell  
which forms the epidermis1 is found a   
nucleus4 ,the protoplasm and nucleus are
 alive2 the cell wall formed by the     
living matter in the cell is dead4 ,the 
root hair is a living plant cell with a 
wall so delicate that water and mineral 
substances from the soil can pass       
through it into the interior of the     
root4  ,illustration3 ,diagram of a root
 hair2 ,,cs1 cell sap2 ,,cw1 cell wall2 
,p1 protoplasm2 ,n1 nucleus2 ,s1        
particles of soil4  ,how the ,root      
absorbs ,water4--,the process by which  
the root hair takes up soil water can   
better be understood if we make an      
artificial root hair large enough to be 
easily seen4 ,an egg with part of the   
outer shell removed so as to expose the 
soft skinlike membrane underneath is an 
example4 ,better1 an artificial root    
hair may be made in the following way4  
,pour some soft celloidin into a test   
tube2 carefully revolve the test tube so

 that an even film of celloidin dries on
 the inside4 ,this membrane is removed1 
filled with white of egg1 and tied over 
the end of a rubber cork in which a     
glass tube has previously been inserted4
 ,when placed in water1 it gives a very 
accurate picture of the root hair at    
work4 ,after a short time water begins  
to rise in the tube1 having passed      
through the film of celloidin4 ,if grape
 sugar1 salt1 or some other substance   
which will dissolve in water were placed
 in the water outside the artificial    
root hair1 it could soon be proved by   
test to pass through the wall and into  
the liquid inside4  ,osmosis4--,to      
explain this process we must remember   
that gases and liquids of different     
densities1 when separated by a membrane1
 tend to flow toward each other and     
mingle1 the greater flow always being in
 the direction of the denser medium4    
,the process by which two gases or      
fluids1 separated by a membrane1 tend to
 pass through the membrane and mingle   

with each other1 is called osmosis4 ,the
 method by which the root hairs take up 
soil water is exactly the same process4 
,it is by osmosis4 ,the white of the egg
 is the best possible substitute for    
living matter2 the celloidin membrane   
separating the egg from the water is    
much like the delicate membrane-like    
wall which separates the protoplasm of  
the root hair from the water in the soil
 surrounding it4 ,the fluid in the root 
hair is denser than the soil water2     
hence the greater flow is toward the    
interior of the root hair4#aj           
,footnote #aj3 ,for an excellent        
elementary discussion of      osmosis   
see ,moore1 ,physiology of ,man and     
,other ,animals4      ,henry ,holt and  
,company4  ,illustration3 ,the soil     
particles are each surrounded with a    
delicate film of water4 ,how might the  
root hairs take up this water8  ,passage
 of ,soil ,water within the ,root4--,we 
have already seen that in an exchange of
 fluids by osmosis the greater flow is  

always toward the denser fluid4 ,thus it
 is that the root hairs take in more    
fluid than they give up4 ,the cell sap1 
which partly fills the interior of the  
root hair1 is a fluid of greater density
 than the water outside in the soil4    
,when the root hairs become filled with 
water1 the density of the cell sap is   
lessened1 and the cells of the epidermis
 are thus in a position to pass along   
their supply of water to the cells next 
to them and nearer to the center of the 
root4 ,these cells1 in turn1 become less
 dense than their inside neighbors1 and 
so the transfer of water goes on until  
the water at last reaches the central   
cylinder4 ,here it is passed over to the
 tubes of the woody bundles and started 
up the stem4 ,the pressure created by   
this process of osmosis is sufficient to
 send water up the stem to a distance1  
in some plants1 of #be to #cj feet4     
,cases are on record of water having    
been raised in the birch a distance of  
#he feet4  ,physiological ,importance of

 ,osmosis4--,it is not an exaggeration  
to say that osmosis is a process not    
only of great importance to a plant1 but
 to an animal as well4 ,foods are       
digested in the food tube of an animal2 
that is1 they are changed into a soluble
 form so that they may pass through the 
walls of the food tube and become part  
of the blood4 ,the inner lining of part 
of the food tube is thrown into millions
 of little fingerlike projections which 
look somewhat1 in size at least1 like   
root hairs4 ,these fingerlike processes 
are 7unlike a root hair7 made up of many
 cells4 ,but they serve the same purpose
 as the root hairs1 for they absorb     
liquid food into the blood4 ,this       
process of absorption is largely by     
osmosis4 ,without the process of osmosis
 we should be unable to use much of the 
food we eat4  ,composition of           
,soil4--,if we examine a mass of        
ordinary loam carefully1 we find that it
 is composed of numerous particles of   
varying size and weight4 ,between these 

particles1 if the soil is not caked and 
hard packed1 we can find tiny spaces4   
,in well-tilled soil these spaces are   
constantly being formed and enlarged4   
,they allow air and water to penetrate  
the soil4 ,if we examine soil under the 
microscope1 we find considerable water  
clinging to the soil particles and      
forming a delicate film around each     
particle4 ,in this manner most of the   
water is held in the soil4              
,illustration3 ,inorganic soil is being 
formed by weathering4  ,how ,water is   
held in ,soil4--,to understand what     
comes in with the soil water1 it will be
 necessary to find out a little more    
about soil4 ,scientists who have made   
the subject of the composition of the   
earth a study1 tell us that once upon a 
time at least a part of the earth was   
molten4 ,later1 it cooled into solid    
rock4 ,soil making began when the ice   
and frost1 working alternately with the 
heat1 chipped off pieces of rock4 ,these
 pieces in time became ground into      

fragments by action of ice1 glaciers1   
running water1 or the atmosphere4 ,this 
process is called weathering4           
,weathering is aided by oxidation4 ,a   
glance at almost any crumbling stones   
will convince you of this1 because of   
the yellow oxide of iron 7rust7         
disclosed4 ,so by slow degrees this     
earth became covered with a coating of  
what we call inorganic soil4 ,later1    
generation after generation of tiny     
plants and animals which lived in the   
soil died1 and their remains formed the 
first organic materials of the soil4    
,illustration3 ,this picture shows how  
the forests help to cover the inorganic 
soil with an organic coating4 ,explain  
how4  ,you are all familiar with the    
difference between the so-called rich   
soil and poor soil4 ,the dark soil      
contains more dead plant and animal     
matter1 which forms the portion called  
humus4  ,illustration3 ,apparatus for   
testing the capacity of soils to take in
 and retain moisture4  ,humus contains  

,organic ,matter4--,it is an easy matter
 to prove that black soil contains      
organic matter1 for if an equal weight  
of carefully dried humus and soil from a
 sandy road is heated red-hot for some  
time and then reweighed1 the humus will 
be found to have lost considerably in   
weight1 and the sandy soil to have lost 
very little4  ,the material left after  
heating is inorganic material1 the      
organic matter having been burned out4  
,soil containing organic materials holds
 water much more readily than inorganic 
soil1 as a glance at the accompanying   
figure shows4 ,if we fill each of the   
vessels with a given weight 7say #ajj   
grams each7 of gravel1 sand1 barren     
soil1 rich loam1 leaf mold1 and #be     
grams of dry1 pulverized leaves1 then   
pour equal amounts of water 7#ajj c4c47 
on each and measure all that runs       
through1 the water that has been        
retained will represent the water supply
 that plants could draw on from such    
soil4  ,illustration3 ,soil particles   

cling to root hairs4 ,why8  ,the ,root  
,hairs take more than ,water out of the 
,soil4--,if a root containing a fringe  
of root hairs is washed carefully1 it   
will be found to have little particles  
of soil still clinging to it4 ,examined 
under the microscope1 these particles of
 soil seem to be cemented to the sticky 
surface of the root hair4 ,the soil     
contains1 besides a number of chemical  
compounds of various mineral            
substances1--lime1 potash1 iron1 silica1
 and many others1--a considerable amount
 of organic material4 ,acids of various 
kinds are present in the soil4 ,these   
acids so act upon certain of the mineral
 substances that they become dissolved  
in the water which is absorbed by the   
root hairs4 ,root hairs also give off   
small amounts of acid4 ,an interesting  
experiment may be shown 7see ,figure on 
page #hj7 to prove this4 ,a solution of 
phenolphthalein loses its color when an 
acid is added to it4 ,if a growing pea  
be placed in a tube containing some of  

this solution the latter will quickly   
change from a rose pink to a colorless  
solution4  ,a ,plant needs ,mineral     
,matter to ,make ,living                
,matter4--,living matter 7protoplasm71  
besides containing the chemical elements
 carbon1 hydrogen1 oxygen1 and nitrogen1
 contains a very minute proportion of   
various elements which make up the basis
 of certain minerals4 ,these are calcium
 7lime71 sulphur1 iron1 potassium1      
magnesium1 phosphorus1 sodium1 and      
chlorine4  ,that plants will not grow   
well without certain of these mineral   
substances can be proved by the growth  
of seedlings in a so-called nutrient    
solution4#aa ,such a solution contains  
all the mineral matter that a plant uses
 for food4 ,if certain ingredients are  
left out of this solution1 the plants   
placed in it will not live4             
,footnote #aa3 ,see ,hunter's           
,laboratory ,problems in ,civic         
,biology for list of ingredients4       
,illustration3 ,effect of root hairs on 

phenolphthalein solution4 ,the change of
 color indicates the presence of acid4  
,nitrogen in a ,usable ,form necessary  
for ,growth of ,plants4--,a chemical    
element needed by the plant to make     
protoplasm is nitrogen4 ,the air can be 
proven by experiment to be made up of   
about four fifths nitrogen1 but this    
element cannot be taken from either     
soil1 water1 or air in a pure state1 but
 is usually obtained from the organic   
matter in the soil1 where it exists with
 other substances in the form of        
nitrates4 ,ammonia and other organic    
compounds which contain nitrogen are    
changed by two groups of little plants  
called bacteria1 first into nitrites and
 then nitrates4#ab       ,footnote #ab3 
,it has recently been discovered that   
under some      conditions these        
bacteria are preyed upon by tiny        
one-celled      animals 7protozoa7      
living in the soil and are so reduced   
in numbers that they cannot do their    
work effectively4 ,if1      then1 the   

soil is heated artificially or treated  
with      antiseptics so as to kill the 
protozoa1 the bacteria which      escape
 multiply so rapidly as to make the land
 much richer      than before4          
,illustration3 ,diagram to show how the 
nitrogen-fixing bacteria prepare        
nitrogen for use by plants2 t1          
tubercles4  ,relation of ,bacteria to   
,free ,nitrogen4--,it has been known    
since the time of the ,romans that the  
growth of clover1 peas1 beans1 and other
 legumes in soil causes it to become    
more favorable for growth of other      
plants4 ,the reason for this has been   
discovered in late years4 ,on the roots 
of the plants mentioned are found little
 swellings or nodules2 in the nodules   
exist millions of bacteria1 which take  
nitrogen from the atmosphere and fix it 
so that it can be used by the plant2    
that is1 they assist in forming nitrates
 for the plants to use4 ,only these     
bacteria1 of all the living plants1 have
 the power to take the free nitrogen    

from the air and make it over into a    
form that can be used by the roots4 ,as 
all the compounds of nitrogen are used  
over and over again1 first by plants1   
then as food for animals1 eventually    
returning to the soil again1 or in part 
being turned into free nitrogen1 it is  
evident that any new supply of usable   
nitrogen must come by means of these    
nitrogen-fixing bacteria4  ,rotation of 
,crops4--,the facts mentioned above are 
made use of by careful farmers who wish 
to make as much as possible from a given
 area of ground in a given time4 ,such  
plants as are hosts for the             
nitrogen-fixing bacteria are planted    
early in the season4 ,later these plants
 are plowed in and a second crop is     
planted4 ,the latter grows quickly and  
luxuriantly because of the nitrates left
 in the soil by the bacteria which lived
 with the first crop4 ,for this reason1 
clover is often grown on land in which  
it is proposed to plant corn1 the       
nitrogen left in the soil thus giving   

nourishment to the young corn plants4   
,in scientifically managed farms1       
different crops are planted in a given  
field on different years so that one    
crop may replace some of the elements   
taken from the soil by the previous     
crop4 ,this is known as rotation of     
crops4#ac ,the annual yield of the      
average farm may thus be greatly        
increased4       ,footnote #ac3 ,that   
crop rotation is not primarily a process
      to conserve the fertility of the  
soil1 but is a sanitary      measure to 
prevent infection of the soil1 is the   
latest      belief of the scientist4    
,illustration3 ,nitrogen in the soil is 
necessary for plants4 ,explain from this
 diagram how nitrogen is put into the   
soil by some plants and taken out by    
others4  ,five of the elements necessary
 to the life of the plant which may be  
taken out of the soil by constant use   
are calcium1 nitrogen1 phosphorus1      
potassium1 and sulphur4 ,several methods
 are used by the farmer to prevent the  

exhaustion of these and other raw food  
materials from the soil4 ,one method    
known as fallowing is to allow the soil 
to remain idle until bacteria and       
oxidation have renewed the chemical     
materials used by the plants4 ,this is  
an expensive method1 if land is dear4   
,the most common method of enriching    
soil is by means of fertilizing material
 rich in plant food4 ,manure is most    
frequently used1 but many artificial    
fertilizers1 most of which contain      
nitrogen in the form of some nitrate1   
are used1 because they can be more      
easily transported and sold4 ,such are  
ground bone1 guano 7bird manure71       
nitrate of soda1 and many others4 ,these
 also contain other important raw food  
materials for plants1 especially potash 
and phosphoric acid4 ,both of these     
substances are made soluble so as to be 
taken into the roots by the action of   
the carbon dioxide in the soil4  ,the   
,indirect ,relation of this to the ,city
 ,dweller4--,all of us living in the    

city are aware of the importance of     
fresh vegetables1 brought in from the   
neighboring market gardens4 ,but we     
sometimes forget that our great staple  
crops1 wheat and other cereals1         
potatoes1 fruits of all kinds1 our      
cotton crop1 and all plants we make use 
of grow directly in proportion to the   
amount of raw food materials they take  
in through the roots4 ,when we also     
remember that many industries within the
 cities1 as mills1 bakeries1 and the    
like1 as well as the earnings of our    
railways and steamship lines1 are       
largely dependent on the abundance of   
the crops1 we may recognize the         
importance of what we have read in this 
chapter4  ,food ,storage in ,roots of   
,commercial ,importance4--,some plants1 
as the parsnip1 carrot1 and radish1     
produce no seed until the second year1  
storing food in the roots the first year
 and using it to get an early start the 
following spring1 so as to be better    
able to produce seeds when the time     

comes4 ,this food storage in roots is of
 much practical value to mankind4 ,many 
of our commonest garden vegetables1 as  
those mentioned above1 and the beet1    
turnip1 oyster plant1 sweet potato and  
many others1 are of value because of the
 food stored4 ,the sugar beet has1 in   
,europe especially1 become the basis of 
a great industry4                       
,,reference ,,books                     
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,bigelow1 ,applied 
,biology4 ,the ,macmillan ,company4     
,coulter1 ,plant ,life and ,plant ,uses1
 ,chaps4 ,,iii1 ,,iv4        ,american  
,book ,company4      ,mayne and ,hatch1 
,high ,school ,agriculture4 ,american   
,book        ,company4      ,moore1 ,the
 ,physiology of ,man and ,other         
,animals4 ,henry ,holt        and       
,company4      ,sharpe1 ,laboratory     
,manual in ,biology1 pp4 #gc-hg4        
,american        ,book ,company4        
,,advanced       ,coulter1 ,barnes1 and 

,cowles1 ,a ,textbook of ,botany1 ,part 
,,ii4 ,amer4 ,book ,co4      ,duggar1   
,plant ,physiology4 ,the ,macmillan     
,company4      ,goodale1 ,physiological 
,botany4 ,american ,book ,company4      
,green1 ,vegetable ,physiology1 ,chaps4 
,v1 ,,vi4 ,j4 and ,a4        ,churchill4
      ,kerner-,oliver1 ,natural ,history
 of ,plants4 ,henry ,holt and           
,company4      ,mac,dougal1 ,plant      
,physiology4 ,longmans1 ,green1 and     
,company4     ,,vii4 ,,plant ,,growth   
,,and ,,nutrition--,,plants ,,make      
,,food  ,problem4--,where1 when1 and how
 do green plants make food8          7a7
 ,how and why is moisture given off from
 leaves8          7b7 ,what is the      
reaction of leaves to light8            
7c7 ,what is made in green leaves in the
 sunlight8          7d7 ,what           
by-products are given off in the above  
process8          7e7 ,other functions  
of leaves4                              
,,laboratory ,,suggestions              
,demonstration4--,water given off by    

plant in sunlight4 ,loss        of      
weight due to transpiration measured4   
,laboratory exercise4--        7a7      
,gross structure of a leaf4        7b7  
,study of stoma and lower epidermis     
under microscope4        7c7 ,study of  
cross section to show cells and air     
spaces4      ,demonstration4--,reaction 
of leaves to light4                     
,demonstration4--,light necessary to    
starch making4                          
,demonstration4--,air necessary to      
starch making4                          
,demonstration4--,oxygen a by-product of
 starch making4   ,what becomes of the  
,water taken in by the ,roots8--,we have
 seen that more than pure water has been
 absorbed through the root hairs into   
the roots4 ,what becomes of this water  
and the other substances that have been 
absorbed8 ,this question may be partly  
answered by the following experiments4  
,illustration3 ,apple twigs split to    
show the course of colored water up the 
stem4  ,passage of ,fluids up the       

,stem4--,if any young growing shoots    
7young seedlings of corn or pea1 or the 
older stems of garden balsam1           
touch-me-not1 or sunflower7 are placed  
in red ink 7eosin71 and left in the sun 
for a few hours1 the red ink will be    
found to have passed up the stem4 ,if   
such stems were examined carefully1 it  
would be seen that the colored fluid is 
confined to collections of woody tubes  
immediately under the inner bark4 ,water
 evidently rises in that part of the    
stem we call the wood4  ,illustration3  
,experiment to prove that water is given
 off through the leaves of a green      
plant4  ,water given off by ,evaporation
 from ,leaves4--,take some well-watered 
potted green plant1 as a geranium or    
hydrangea1 cover the pot with sheet     
rubber1 fastening the rubber close to   
the stem of the plant4 ,next weigh the  
plant with the pot4 ,then cover it with 
a tall bell jar and place the apparatus 
in the sun4 ,in a few minutes drops of  
moisture are seen to gather on the      

inside of the jar4 ,if we now weigh the 
potted plant1 we find it weighs less    
than before4 ,obviously the loss comes  
from the water lost1 and evidently this 
water escapes as vapor from either the  
stem or leaves4  ,illustration3 ,the    
skeleton of a leaf4 ,m4,r41 the midrib2 
,p41 the leafstalk2 ,v41 the veins4     
,the ,structure of a ,leaf4--,in the    
experiment with the red ink mentioned   
above we will find that the fluid has   
gone out into the skeleton or framework 
of the leaf4 ,let us now examine a leaf 
more carefully4 ,it shows usually 7#a7 a
 flat1 broad blade1 which may take      
almost any conceivable shape2 7#b7 a    
stem which spreads out in the blade 7#c7
 in a number of veins4  ,illustration3  
,section through the blade of a leaf as 
seen under the compound microscope4 ,s1 
air spaces1 which communicate with the  
outside air2 ,v1 vein in cross section2 
,s4,t41 breathing hole 7stoma72 ,e1     
outer layer of cells2 ,p1 green cells4  
,the ,cell ,structure of a ,leaf4--,the 

under surface of a leaf seen under the  
microscope usually shows numbers of tiny
 oval openings4 ,these are called       
stomata 7singular stoma74 ,two cells1   
usually kidney-shaped1 are found1 one on
 each side of the opening4 ,these are   
the guard cells4 ,by change in shape of 
these cells the opening of the stoma is 
made larger or smaller4 ,larger         
irregular cells form the epidermis1 or  
outer covering of the leaf4 ,study of   
the leaf in cross section shows that    
these stomata open directly into air    
chambers which penetrate between and    
around the loosely arranged cells       
composing the underpart of the leaf4    
,the upper surface of leaves sometimes  
contains stomata1 but more often they   
are lacking4 ,the under surface of an   
oak leaf of ordinary size contains about
 #b1jjj1jjj stomata4 ,under the upper   
epidermis is a layer of green cells     
closely packed together 7called         
collectively the palisade layer74 ,these
 cells are more or less columnar in     

shape4 ,under these are several rows of 
rather loosely placed cells just        
mentioned4 ,these are called            
collectively the spongy tissue4 ,if we  
happen to have a section cut through a  
vein1 we find this composed of a number 
of tubes made up of1 and strengthened   
by1 thick-walled cells4 ,the veins are  
evidently a continuation of the tubes of
 the stem out into the blade of the     
leaf4  ,evaporation of ,water4--,during 
the day an enormous amount of water is  
taken up by the roots and passed out    
through the leaves4 ,so great is this   
excess at times that a small grass plant
 on a summer's day evaporates more than 
its own weight in water4 ,this would    
make nearly half a ton of water         
delivered to the air during twenty-four 
hours by a grass plot twenty-five by one
 hundred feet1 the size of the average  
city lot4 ,according to ,ward1 an oak   
tree may pass off two hundred and       
twenty-six times its own weight in water
 during the season from ,june to        

,october4  ,from which ,surface of the  
,leaf is ,water ,lost8--,in order to    
find out whether water is passed out    
from any particular part of the leaf1 we
 may remove two leaves of the same size 
and weight from some large-leaved       
plant#ad--;a mullein was used for the   
illustrations given below--and cover the
 upper surface of one leaf and the lower
 surface of the other with vaseline4    
,the leaf stalks of each should be      
covered with wax or vaseline1 and the   
two leaves exactly balanced on the pans 
of a balance which has previously been  
placed in a warm and sunny place4       
,within an hour the leaf which has the  
upper surface covered with vaseline will
 show a loss of weight4 ,examination of 
the surface of a mullein leaf shows us  
that the lower surface of the leaf is   
provided with stomata4 ,it is through   
these organs1 then1 that water is passed
 out from the tissues of the leaf4      
,footnote #ad3 ,the rubber plant leaf is
 an easily obtainable      and excellent

 demonstration4  ,illustration3         
,experiment to show through which       
surface of a leaf water passes off4     
,factors in ,transpiration4--,the amount
 of water lost from a plant varies      
greatly under different conditions4 ,the
 humidity of the air1 its temperature1  
and the temperature of the plant all    
affect the rate of transpiration4 ,the  
stomata also tend to close under some   
conditions1 thus helping to prevent     
evaporation4 ,but there seems to be no  
certain regulation of this water loss4  
,consequently plants droop or wilt on   
hot dry days because they cannot obtain 
water rapidly enough from the soil to   
make up for the loss through the leaves4
  ,illustration3 ,diagrams of a stoma4  
a1 surface view of a closed stoma2 b1   
the same stoma opened4 7,after ,hanson47
 c1 diagrams of a transverse section    
through a stoma1 dotted lines indicate  
the closed position of the guard cells1 
the heavy lines the open condition4     
7,after ,schwendener47  ,green ,plants  

,food ,makers4--,we have previously     
stated that green plants are the great  
food makers for themselves and for      
animals4 ,we are now ready to attack the
 problem of how green plants make food4 
,the ,sun a ,source of ,energy4--,we all
 know the sun is a source of most of the
 energy that is released on this earth  
in the form of heat or light4 ,every boy
 knows the power of a burning glass4    
,solar engines have not come into any   
great use as yet1 because fuel is       
cheaper1 but some day we undoubtedly    
will directly harness the energy of the 
sun in everyday work4 ,actual           
experiments have shown that vast amounts
 of energy are given to the earth4 ,when
 the sun is highest in the sky1 energy  
equivalent to one hundred horse power is
 received by a plot of land twenty-five 
by one hundred feet1 the size of a city 
lot4 ,plants receive and use much of    
this energy by means of their leaves4   
,effect of ,light on ,plants4--,in young
 plants which have been grown in total  

darkness1 no green color is found in    
either stems or leaves1 the latter often
 being reduced to mere scales4 ,the     
stems are long and more or less         
reclining4 ,we can explain the changed  
condition of the seedling grown in the  
dark only by assuming that light has    
some effect on the protoplasm of the    
seedling and induces the growth of the  
green part of the plant4 ,if seedlings  
have been growing on a window sill1 or  
where the light comes in from one side1 
you have doubtless noticed that the stem
 and leaves of the seedlings incline in 
the direction from which the light      
comes4 ,the experiment pictured shows   
this effect of light very plainly4 ,a   
hole was cut in one end of a cigar box  
and barriers were erected in the        
interior of the box so that the seeds   
planted in the sawdust received their   
light by an indirect course4 ,the young 
seedling in this case responded to the  
influence of the stimulus of light so as
 to grow out finally through the hole in

 the box into the open air4 ,this growth
 of the stem to the light is of very    
great importance to a growing plant1    
because1 as we shall see later1 food    
making depends largely on the amount of 
sunlight the leaves receive4            
,illustration3 ,two stages in an        
experiment to show that green plants    
grow toward the light4  ,effect of      
,light on ,leaf ,arrangement4--,it is a 
matter of common knowledge that green   
leaves turn toward the light4 ,place    
growing pea seedlings1 oxalis1 or any   
other plants of rapid growth near a     
window which receives full sunlight4    
,within a short time the leaves are     
found to be in positions to receive the 
most sunlight possible4 ,careful        
observation of any plant growing        
outdoors shows us that in almost every  
case the leaves are so disposed as to   
get much sunlight4 ,the ivy climbing up 
the wall1 the morning-glory1 the        
dandelion1 and the burdock all show     
different arrangements of leaves1 each  

presenting a large surface to the light4
 ,leaves are often definitely arranged1 
fitting in between one another so as to 
present their upper surface to the sun4 
,such an arrangement is known as a leaf 
mosaic4 ,in the case of the dandelion1 a
 rosette or whorled cluster of leaves is
 found4 ,in the horse-chestnut1 where   
the leaves come out opposite each other1
 the older leaves have longer petioles  
than the young ones4 ,in the mullein the
 entire plant forms a cone4 ,the old    
leaves near the bottom have long stalks1
 and the little ones near the apex come 
out close to the main stalk4 ,in every  
case each leaf receives a large amount  
of light4 ,other modifications of these 
forms may easily be found on any field  
trip4  ,illustration3 ,a lily1 showing  
long narrow leaves4  ,illustration3 ,the
 dandelion1 showing a whorled           
arrangement of long irregular leaves4   
,starch made by a ,green ,leaf4--,if we 
examine the palisade layer of the leaf1 
we find cells which are almost          

cylindrical in form4 ,in the protoplasm 
of such cells are found a number of     
little green-colored bodies1 which are  
known as chloroplasts or chlorophyll    
bodies4 ,if we place the leaf in wood   
alcohol1 we find that the bodies still  
remain1 but that the color is extracted1
 going into the alcohol and giving to it
 a beautiful green color4 ,the          
chloroplasts are1 indeed1 simply part of
 the protoplasm of the cell colored     
green4 ,these bodies are of the greatest
 importance directly to plants and      
indirectly to animals4 ,the             
chloroplasts1 by means of the energy    
received from the sun1 manufacture      
starch out of certain raw materials4    
,these raw materials are soil water1    
which is passed up through the bundles  
of tubes into the veins of the leaf from
 the roots1 and carbon dioxide1 which is
 taken in through the stomata or pores1 
which dot the under surface of the leaf4
 ,a plant with variegated leaves1 as the
 coleus1 makes starch only in the green 

part of the leaf1 even though these raw 
materials reach all parts of the leaf4  
,illustration3 ,an experiment to show   
the effect of excluding light 7but not  
air7 from the leaves of a green plant4  
,the result of this experiment is seen  
in the next picture4 7,experiment       
performed by ,c4 ,dobbins and ,a4       
,schwartz47  ,illustration3 ,starchless 
area in a leaf caused by excluding      
sunlight by means of a strip of black   
cloth4  ,light and ,air necessary for   
,starch ,making4--,if we pin strips of  
black cloth1 such as alpaca1 over some  
of the leaves of a growing hydrangea    
which has previously been placed in a   
dark room for a few hours1 and then put 
the plant in direct sunlight for an hour
 or two1 we are ready to test for       
starch4 ,we then remove some of the     
covered leaves and extract the          
chlorophyll with wood alcohol 7because  
the green color of the chlorophyll      
interferes with the blue color of the   
starch test74 ,a test then shows that   

starch is present only in the portions  
of the leaves exposed to sunlight4 ,from
 this experiment we infer that the sun  
has something to do with starch making  
in a leaf4 ,the necessity of a part of  
the air 7carbon dioxide7 for starch     
making may also easily be proved1 for   
the parts of leaves covered with        
vaseline will be found to contain no    
starch1 while parts of the leaf without 
vaseline1 but exposed to the sun and    
air1 do contain starch4  ,illustration3 
,diagram to show starch making4 ,read   
the text carefully and then explain this
 diagram4  ,air is necessary for the    
process of starch making in a leaf1 not 
only because carbon dioxide gas is      
absorbed 7there are from three to four  
parts in ten thousand present in the    
atmosphere71 but also because the leaf  
is alive and must have oxygen in order  
to do work4 ,this oxygen it takes from  
the air around it4  ,illustration3      
,diagram to illustrate the formation of 
starch in a leaf4  ,comparison of       

,starch ,making and ,milling4--,the     
manufacture of starch by the green leaf 
is not easily understood4 ,the process  
has been compared to the milling of     
grain4 ,in this case the mill is the    
green part of the leaf4 ,the sun        
furnishes the motive power1 the         
chloroplasts constitute the machinery1  
and soil water and carbon dioxide are   
the raw products taken into the mill4   
,the manufactured product is starch1 and
 a certain by-product 7corresponding to 
the waste in a mill7 is also given out4 
,this by-product is oxygen4 ,to         
understand the process fully1 we must   
refer to a small portion of the leaf    
shown below4 ,here we find that the     
cells of the green layer of the leaf1   
under the upper epidermis1 perform most 
of the work4 ,the carbon dioxide is     
taken in through the stomata and reaches
 the green cells by way of the          
intercellular spaces and by osmosis from
 cell to cell4 ,water reaches the green 
cells through the veins4 ,it then passes

 into the cells by osmosis1 and there   
becomes part of the cell sap4 ,the light
 of the sun easily penetrates to the    
cells of the palisade layer1 giving the 
energy needed to make the starch4 ,this 
whole process is a very delicate one1   
and will take place only when external  
conditions are favorable4 ,for example1 
too much heat or too little heat stops  
starch making in the leaf4 ,this        
building up of food and the release of  
oxygen by the plant in the presence of  
sunlight is called photosynthesis4      
,illustration3 ,diagram 7after ,stevens7
 to illustrate the processes of         
breathing and food making in the cells  
of a green leaf in the sunlight4        
,manufacture of ,fats4--,inasmuch as    
tiny droplets of oil are found inside   
the chlorophyll bodies in the leaf1 we  
believe that fats1 too1 are made there1 
probably by a transformation of the     
starch already manufactured4  ,protein  
,making and its ,relation to the ,making
 of ,living ,matter4--,protein material 

is a food which is necessary to form    
protoplasm4 ,protein food is present in 
the leaf1 and is found in the stem or   
root as well4 ,proteins can apparently  
be manufactured in any of the cells of  
green plants1 the presence of light not 
seeming to be a necessary factor4 ,how  
it is manufactured is a matter of       
conjecture4 ,the minerals brought up in 
the soil water form part of its         
composition1 and starch or grape sugar  
give three elements 7,c1 ,h1 and ,o74   
,the element nitrogen is taken up by the
 roots as a nitrate 7nitrogen in        
combination with lime or potash74       
,proteins are probably not made directly
 into protoplasm in the leaf1 but are   
stored by the cells of the plant and    
used when needed1 either to form new    
cells in growth or to repair waste4     
,while plants and animals obtain their  
food in different ways1 they probably   
make it into living substance           
7assimilate it7 in exactly the same     
manner4  ,illustration3 ,an example of  

how a tree may exert energy4 ,this rock 
has been split by the growing tree4     
,foods serve exactly the same purposes  
in plants and in animals2 they either   
build living matter or they are burned  
7oxidized7 to furnish energy 7power to  
do work74 ,if you doubt that a plant    
exerts energy1 note how the roots of a  
tree bore their way through the hardest 
soil1 and how stems or roots of trees   
often split open the hardest rocks1 as  
illustrated in the figure above4        
,starch-,making and its ,relation to    
,human ,welfare4--,leaves which have    
been in darkness show starch to be      
present soon after exposure to light4 ,a
 corn plant sends #aj to #ae grams of   
reserve material into the ears in a     
single day4 ,the formation of fruit1 and
 especially the growth of the grain     
fields1 show the economic importance of 
this fact4 ,not only do plants make     
their own food and store it away1 but   
they make food for animals as well4 ,and
 the food is stored in such a stable    

form that it may be sent to all parts of
 the world in the form of grain or other
 fruits4 ,animals1 herbivorous and      
flesh-eating1 man himself1 all are      
dependent upon the starch-making        
processes of the green plant for the    
ultimate source of their food4 ,when we 
remember that in #aiac in the ,united   
,states the total value of all farm     
crops was over #f1jjj1jjj1jjj1 and when 
we realize that these products came from
 the air and soil through the energy of 
the sun1 we may begin to realize why as 
city boys and girls the study of plant  
biology is of importance to us4         
,illustration3 ,experiment to show that 
oxygen is given off by green plants in  
the sunlight4  ,green ,plants give off  
,oxygen in ,sunlight4--,in still another
 way green plants are of direct use to  
us in the city4 ,during this process of 
starch-making oxygen is given off as a  
by-product4 ,this may easily be proven  
by the following experiment4#ae ,place  
any green water plant in a battery jar  

partly filled with water1 cover the     
plants with a glass funnel and mount a  
test tube full of water over the mouth  
of the funnel4 ,then place the apparatus
 in a warm sunny window4 ,bubbles of gas
 are seen to rise from the plant4 ,after
 two or three hours of hot sun1 enough  
of the gas can be obtained by           
displacement of the water to make the   
oxygen test4       ,footnote #ae3       
,immediate success with this experiment 
will be      obtained if the water has  
been previously charged with      carbon
 dioxide4  ,that oxygen is given off as 
a by-product by green plants is a fact  
of far-reaching importance4 ,city parks 
are true breathing spaces4 ,the green   
covering of the earth is giving to      
animals an element that they must have1 
while the animals in their turn are     
supplying to the plants carbon dioxide1 
a compound used in food-making4 ,thus a 
widespread relation of mutual           
helpfulness exists between plants and   
animals4  ,respiration by ,leaves4--,all

 living things require oxygen4 ,it is by
 means of the oxidation of food         
materials within the plant's body that  
the energy used in growth and movement  
is released4 ,a plant takes in oxygen   
largely through the stomata of the      
leaves1 to a less extent through the    
lenticels or breathing holes in the     
stem1 and through the roots4 ,thus      
rapidly growing tissues receive the     
oxygen necessary for them to perform    
their work4 ,the products of oxidation  
in the form of carbon dioxide are also  
passed off through these same organs4   
,it can be shown by experiment that a   
plant uses up oxygen in the darkness2 in
 the light the amount of oxygen given   
off as a by-product in the process of   
starch-making is1 of course1 much       
greater than the amount used by the     
plant4  ,summary4--,from the above      
paragraphs it is seen that a leaf       
performs the following functions3 7#a7  
breathing1 or the taking in of oxygen   
and passing off of carbon dioxide2 7#b7 

starch-making1 with the incidental      
passing out of oxygen2 7#c7 formation of
 proteins1 with their digestion and     
assimilation to form new tissues2 and   
7#d7 the transpiration of water4        
,,reference ,,books                     
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,andrews1 ,a       
,practical ,course in ,botany1 pages    
#afj-agg4        ,american ,book        
,company4      ,coulter1 ,a ,textbook of
 ,botany1 pages #e-dj4 ,d4 ,appleton and
        ,company4      ,coulter1 ,plant 
,life and ,plant ,uses4 ,american ,book 
,company4      ,dana1 ,plants and their 
,children1 pages #ace-ahe4 ,american    
,book ,company4      ,sharpe1 ,a        
,laboratory ,manual in ,biology1 pages  
#ij-ajb4        ,american ,book         
,company4      ,stevens1 ,introduction  
to ,botany1 pages #ha-ii4 ,d4 ,c4 ,heath
        and ,company4                   
,,advanced       ,clement1 ,plant       
,physiology and ,ecology4 ,henry ,holt  

and        ,company4      ,coulter1     
,barnes1 and ,cowles1 ,a ,textbook of   
,botany1 ,part        ,,ii1 and ,vol4   
,,ii4 ,american ,book ,company4         
,darwin1 ,insectivorous ,plants4 ,d4    
,appleton and ,company4      ,duggar1   
,plant ,physiology4 ,the ,macmillan     
,company4      ,goodale1 ,physiological 
,botany1 pages #ccg-cec and #dji-dbd4   
,american ,book ,company4      ,green1  
,vegetable ,physiology4 ,j4 and ,a4     
,churchill4      ,lubbock1 ,flowers1    
,fruits1 and ,leaves1 last part4 ,the   
,macmillan ,company4      ,mac,dougal1  
,practical ,textbook of ,plant          
,physiology4        ,longmans1 ,green1  
and ,company4      ,report of the       
,division of ,forestry1 ,u4,s4          
,department of        ,agriculture1     
#ahii4      ,ward1 ,the ,oak4 ,d4       
,appleton and ,company4     ,,viii4     
,,plant ,,growth ,,and                  
,,nutrition--,,the ,,circulation ,,and  
,,final ,,uses ,,of ,,food ,,by ,,plants
  ,problem4--,how green plants store and

 use the food they make4          7a7   
,what are the organs of circulation8    
7b7 ,how and where does food circulate8 
7c7 ,how does the plant assimilate its  
food8                                   
,,laboratory ,,suggestions              
,laboratory exercise4--,the structure   
7cross section7 of a        woody stem4 
,demonstration4--,to show that food     
passes downward in the        bark4     
,demonstration4--,to show the condition 
of food passing        through the stem4
      ,demonstration4--,plants with     
special digestive organs4   ,the        
,circulation and ,final ,uses of ,foods 
in ,green ,plants4--,we have seen that  
cells of green plants make food and that
 such cells are mostly in the leaves4   
,but all parts of the bodies of plants  
grow4 ,roots1 stems1 leaves1 flowers1   
and fruits grow4 ,seeds are storehouses 
of food4 ,we must now examine the stem  
of some plant in order to see how food  
is distributed1 stored1 and finally used
 in the various parts of the plant4     

,the ,structure of a ,woody ,stem4--,if 
we cut a cross section through a young  
willow or apple stem1 we find it shows  
three distinct regions4 ,the center is  
occupied by the spongy1 soft pith2      
surrounding this is found the rather    
tough wood1 while the outermost area is 
bark4 ,more careful study of the bark   
reveals the presence of three layers--an
 outer layer1 a middle green layer1 and 
an inner fibrous layer1 the latter      
usually brown in color4 ,this layer is  
made up largely of tough fiberlike cells
 known as bast fibers4 ,the most        
important parts of this inner bark1 so  
far as the plant is concerned1 are many 
tubelike structures known as sieve      
tubes4 ,these are long rows of living   
cells1 having perforated sievelike ends4
 ,through these cells food materials    
pass downward from the upper part of the
 plant1 where they are manufactured4    
,illustration3 ,section of a twig of box
 elder three years old1 showing three   
annual growth rings4 ,the radiating     

lines 7m7 which cross the wood 7w7      
represent the pith rays1 the principal  
ones extending from the pith in the     
center to the cortex or bark4 7,from    
,coulter's ,plant ,relations47  ,in the 
wood will be noticed 7see ,figure7 a    
number of lines radiating outward from  
the pith toward the bark4 ,these are    
thin plates of pith which separate the  
wood into a number of wedge-shaped      
masses4 ,these masses of wood are       
composed of many elongated cells1 which1
 placed end to end1 form thousands of   
little tubes connecting the leaves with 
the roots4 ,in addition to these are    
many thick-walled cells1 which give     
strength to the mass of wood4 ,the      
bundles of tubes with their surrounding 
hard walled cells are the continuation  
of the bundles of tubes which are found 
in the root4 ,in sections of wood which 
have taken several years to grow1 we    
find so-called annual rings4 ,the       
distance between one ring and the next  
7see ,figure7 usually represents the    

amount of growth in one year4 ,growth   
takes place from an actively dividing   
layer of cells1 known as the cambium    
layer4 ,this layer forms wood cells from
 its inner surface and bark from its    
outer surface4 ,thus new wood is formed 
as a distinct ring around the old wood4 
,use of the ,outer ,bark4--,the outer   
bark of a tree is protective4 ,the cells
 are dead1 the heavy woody skeletons    
serving to keep out cold and dryness1 as
 well as prevent the evaporation of     
fluids from within4 ,the bark also      
protects the tree from attack of other  
plants or animals which might harm it4  
,most trees are provided with a layer of
 corky cells4 ,this layer in the cork   
oak is thick enough to be of commercial 
importance4 ,the function of the corky  
layer in preventing evaporation is well 
seen in the case of the potato1 which is
 a true stem1 though found underground4 
,if two potatoes of equal weight are    
balanced on the scales1 the skin having 
been peeled from one1 the peeled potato 

will be found to lose weight rapidly4   
,this is due to loss of water1 which is 
held in by the skin of the unpeeled     
potato 7see right hand figure below74   
,there are also small breathing holes   
known as lenticels scattered through the
 surface of the bark4 ,these can easily 
be seen in a young woody stem of apple1 
beech1 or horse-chestnut4               
,illustration3 ,experiment to show that 
the skin of the potato 7a stem7 retards 
evaporation4  ,proof that ,food passes  
down the ,stem4--,if freshly cut willow 
twigs are placed in water1 roots soon   
begin to develop from that part of the  
stem which is under water4 ,if now the  
stem is girdled by removing the bark in 
a ring just above where the roots are   
growing1 the latter will eventually die1
 and new roots will appear above the    
girdled area4 ,the food material        
necessary for the outgrowth of roots    
evidently comes from above1 and the     
passage of food materials takes place in
 a downward direction just outside the  

wood in the layer of bark which contains
 the bast fibers and sieve tubes4 ,this 
experiment with the willow explains why 
it is that trees die when girdled so as 
to cut the sieve tubes of the inner     
bark4 ,the food supply is cut off from  
the protoplasm of the cells in the part 
of the tree below the cut area4 ,many of
 the canoe birches of our ,adirondack   
forest are thus killed1 girdled by      
thoughtless visitors4 ,in the same      
manner mice and other gnawing animals   
kill fruit trees4 ,food substances are  
also conducted to a much less extent in 
the wood itself1 and food passes from   
the inner bark to the center of the tree
 by way of the pith plates4 ,this can be
 proved by testing for starch in the    
pith plates of young stems4 ,it is found
 that much starch is stored in this part
 of the tree trunk4  ,illustration3     
,experiment to show that food material  
passes down in the inner bark4  ,in what
 ,form does ,food pass through the      
,stem8--,we have already seen that      

materials in solution 7those substances 
which will dissolve in the water7 will  
pass from cell to cell by the process of
 osmosis4 ,this is shown in the         
experiment illustrated in the figure4   
,two thistle tubes are partly filled1   
one with starch and water1 the other    
with sugar and water1 and a piece of    
parchment paper is tied over the end of 
each4 ,the lower ends of both tubes are 
placed in a glass dish under water4     
,after twenty-four hours1 the water in  
the dish is tested for starch1 and then 
for sugar4 ,we find that only the sugar1
 which has been dissolved by the water1 
can pass through the membrane4          
,illustration3 ,experiment to show      
osmosis of sugar 7right hand tube7 and  
non-osmosis of starch 7left hand tube74 
,digestion4--,much of the food made in  
the leaves is stored in the form of     
starch4 ,but starch1 being insoluble1   
cannot be passed from cell to cell in a 
plant4 ,it must be changed to a soluble 
form1 for otherwise it could not pass   

through the delicate cell membranes4    
,this is accomplished by the process of 
digestion4 ,we have already seen that   
starch is changed to grape sugar in the 
corn by the action of a substance 7an   
enzyme7 called diastase4 ,this process  
of digestion seemingly may take place in
 all living parts of the plant1 although
 most of it is done in the leaves4 ,in  
the bodies of all animals1 including    
man1 starchy foods are changed in a     
similar manner1 but by other enzymes1   
into soluble grape sugar4  ,the food    
material may be passed in a soluble form
 until it comes to a place where food   
storage is to take place1 then it can be
 transformed to an insoluble form       
7starch1 for example72 later1 when      
needed by the plant in growth1 it may   
again be transformed and sent in a      
soluble form through the stem to the    
place where it will be used4  ,in a     
similar manner1 protein seems to be     
changed and transferred to various parts
 of the plant4 ,some forms of protein   

substance are soluble and others        
insoluble in water4 ,white of egg1 for  
example1 is slightly soluble1 but can be
 rendered insoluble by heating it so    
that it coagulates4 ,insoluble proteins 
are digested within the plant2 how and  
where is but slightly understood4 ,in a 
plant1 soluble proteins pass down the   
sieve tubes in the bast and then may be 
stored in the bast or medullary rays of 
the wood in an insoluble form1 or they  
may pass into the fruit or seeds of a   
plant1 and be stored there4             
,illustration3 ,diagram to show the     
areas in a plant through which the raw  
food materials pass up the stem and food
 materials pass down4  ,what forces     
,water up the ,stem4--,we have seen that
 the process of osmosis is responsible  
for taking in soil water1 and that the  
enormous absorbing surface exposed by   
the root hairs makes possible the       
absorption of a large amount of water4  
,frequently this is more than the weight
 of the plant in every twenty-four      

hours4  ,experiments have been made     
which show that at certain times in the 
year this water is in some way forced up
 the tiny tubes of the stem4 ,during the
 spring season1 in young and rapidly    
growing trees1 water has been proved to 
rise to a height of nearly ninety feet4 
,the force that causes this rise of     
water in stems is known as root         
pressure4  ,the greatest factor1        
however1 is transpiration of water from 
leaves4 ,this evaporation of water in   
the form of vapor seems to result in a  
kind of suction on the column of water  
in the stem4 ,in the fall1 after the    
leaves have gone1 much less water is    
taken in by roots1 showing that an      
intimate relation exists between the    
leaves and the root4  ,summary of the   
,functions of ,green ,plants4--,the     
processes which we have just described  
7with the exception of food making7 are 
those which occur in the lives of any   
plant or animal4 ,all plants and animals
 breathe1 they oxidize their foods to   

release energy1 carbon dioxide being    
given off as the result of the union of 
the carbon in the foods with the oxygen 
of the air4 ,both plants and animals    
digest their food2 plants may do this in
 the cells of the root1 stem1 and leaf4 
,digestion must always occur so that    
food can be moved in a soluble condition
 from cell to cell in the plant's body4 
,illustration3 ,leaf of sundew closing  
over a captured insect4  ,illustration3 
,the ,venus fly trap1 showing open and  
closed leaves4  ,plants with ,special   
,digestive ,organs4--,some plants have  
special organs of digestion4 ,one of    
these1 the sundew1 has leaves which are 
covered on one side with tiny glandular 
hairs4 ,these attract insects and later 
serve to catch and digest the           
nitrogenous matter of these insects by  
means of enzymes poured out by the same 
hairs4 ,another plant1 the ,venus fly   
trap1 catches insects in a sensitive    
leaf which folds up and holds the insect
 fast until enzymes poured out by the   

leaf slowly digest it4 ,still others1   
called pitcher plants1 use as food the  
decayed bodies of insects which fall    
into their cuplike leaves and die there4
 ,in this respect plants are like those 
animals which have certain organs in the
 body set apart for the digestion of    
food4  ,assimilation4--,the assimilation
 of foods1 or making of foods into      
living matter1 is a process we know very
 little about4 ,we know it takes place  
in the living cells of plants and       
animals4 ,but how foods are changed into
 living matter is one of the mysteries  
of life which we have not yet solved4   
,excretion4--,the waste and repair of   
living matter seems to take place in    
both plants and animals4 ,when living   
plants breathe1 they give off carbon    
dioxide4 ,in the process of             
starch-making1 oxygen might be          
considered the waste product4 ,water is 
evaporated from leaves and stems4 ,the  
leaves fall and carry away waste mineral
 substances which they contain4         

,illustration3 ,the embryos of 7a7 the  
morning glory1 7b7 the barberry1 7c7 the
 potato1 7d7 the four o'clock1 showing  
the position of their food supply4      
7,after ,gray47                         
,reproduction4--,finally1 both plants   
and animals have organs of reproduction4
 ,we have seen that the flower gives    
rise1 after pollination1 to a fruit     
which holds the seeds4 ,these seeds hold
 the embryo4 ,thus the young plant is   
doubly protected for a time and is      
finally thrown off in the seed with     
enough food to give it a start in life4 
,in much the same way we will find that 
animals reproduce1 either by laying eggs
 which contain an embryo and food to    
start it in life or1 as in the higher   
animals1 by holding and protecting the  
embryo within the body of the mother    
until it is born1 a helpless little     
creature1 to be tenderly nourished by   
the mother until able to care for       
itself4  ,the ,life ,cycle4--,ultimately
 both plants and animals grow old and   

die4 ,some plants1 for example the pea  
or bean1 live but a season2 others1 such
 as the big trees of ,california1 live  
for hundreds of years4 ,some insects    
exist as adults but a day1 while the    
elephant is said to live almost two     
hundred years4 ,the span of life from   
the time the plant or animal begins to  
grow until it dies is known as the life 
cycle4                                  
,,reference ,,books                     
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,andrews1 ,a       
,practical ,course in ,botany1 pages    
#aab-abg4        ,american ,book        
,company4      ,atkinson1 ,first        
,studies of ,plant ,life1 ,chaps4 ,,iv1 
,v1 ,,vi1        ,,viii1 ,,xxi4 ,ginn4  
,coulter1 ,plant ,life and ,plant ,uses1
 ,chap4 ,v4 ,american ,book             
,company4      ,dana1 ,plants and their 
,children1 pages #ii-abi4 ,american     
,book ,company4      ,mayne and ,hatch1 
,high ,school ,agriculture4 ,american   

,book        ,company4      ,hodge1     
,nature ,study and ,life1 ,chaps4 ,,ix1 
,x1 ,,xi4 ,ginn and        ,company4    
,mac,dougal1 ,the ,nature and ,work of  
,plants4 ,the ,macmillan                
,company4                               
,,advanced       ,apgar1 ,trees of the  
,united ,states1 ,chaps4 ,,ii1 ,v1 ,,vi4
        ,american ,book ,company4       
,coulter1 ,barnes1 and ,cowles1 ,a      
,textbook of ,botany1 ,vol4 ,i4         
,american ,book ,company4      ,duggar1 
,plant ,physiology4 ,the ,macmillan     
,company4      ,ganong1 ,the ,teaching  
,botanist4 ,the ,macmillan ,company4    
,goebel1 ,organography of ,plants1 ,part
 ,v4 ,clarendon ,press4      ,goodale1  
,physiological ,botany4 ,american ,book 
,company4      ,gray1 ,structural       
,botany1 ,chap4 ,v4 ,american ,book     
,company4      ,kerner-,oliver1 ,natural
 ,history of ,plants4 ,henry ,holt and  
,company4      ,strasburger1 ,noll1     
,schenck1 and ,karston1 ,a ,textbook of 
,botany4 ,the ,macmillan ,company4      

,ward1 ,the ,oak4 ,d4 ,appleton and     
,company4      ,yearbook1 ,u4 ,s4       
,department of ,agriculture1 #ahid1     
#ahie1        #ahih-aiaj4     ,,ix4     
,,our ,,forests1 ,,their ,,uses ,,and   
,,the ,,necessity ,,for ,,their         
,,protection  ,problem4--,man's         
relations to forests4          7a7 ,what
 is the value of forests to man8        
7b7 ,what can man do to prevent forest  
destruction8                            
,,laboratory ,,suggestions              
,demonstration of some uses of wood4    
,optional exercise on        structure  
of wood4 ,method of cutting determined  
by        examination4 ,home work on    
study of furniture trim1 etc4           
,visit to ,museum to study some economic
 uses of wood4      ,visit to ,museum or
 field trip to learn some common trees4 
,illustration3 ,a forest in ,north      
,carolina4 7,u4 ,s4 ,g4 ,s47  ,the      
,economic ,value of ,trees4 ,protection 
and ,regulation of ,water               
,supply4--,trees form a protective      

covering for parts of the earth's       
surface4 ,they prevent soil from being  
washed away1 and they hold moisture in  
the ground4 ,the devastation of immense 
areas in ,china and considerable damage 
by floods in parts of ,switzerland1     
,france1 and in ,pennsylvania has       
resulted where the forest covering has  
been removed4 ,no one who has tramped   
through our ,adirondack forest can      
escape noticing the differences in the  
condition of streams surrounded by      
forest and those which flow through     
areas from which trees have been cut4   
,the latter streams often dry up        
entirely in hot weather1 while the      
forest-shaded stream has a never failing
 supply of crystal water4               
,illustration3 ,working to prevent      
erosion after the removal of the forest 
in the ,french ,alps4  ,illustration3   
,erosion at ,sayre1 ,pennsylvania1 by   
the ,chemung ,river4 7,photograph by ,w4
 ,c4 ,barbour47  ,the city of ,new ,york
 owes much of its importance to its     

position at the mouth of a great river  
with a harbor large enough to float the 
navies of the world4 ,this river is     
supplied with water largely from the    
,adirondack and ,catskill forests4      
,should these forests be destroyed1 it  
is not impossible that the frequent     
freshets which would follow would so    
fill the ,hudson ,river with silt and   
debris that the ship channels in the    
bay1 already costing the government     
hundreds of thousands of dollars a year 
to keep dredged1 would become too       
shallow for ships4 ,if this should      
occur1 the greatest city in this country
 would soon lose its place and become of
 second-rate importance4  ,the story of 
how this very thing happened to the old 
,greek city of ,poseidonia is           
graphically told in the following       
lines3--       ,it was such a strange1  
tremendous story1 that of the ,greek    
,poseidonia1 later the ,roman ,paestum4 
,long ago those      adventuring        
mariners from ,greece had seized the    

fertile      plain1 which at that time  
was covered with forests of great       
oak and watered by two clear and shining
 rivers4 ,they drove      the ,italian  
natives back into the distant hills1 for
 the      white man's burden even then  
included the taking of all the          
desirable things that were being wasted 
by incompetent      natives1 and they   
brought over colonists--whom the        
philosophers and moralists at home      
maligned1 no doubt1 in      the same    
pleasant fashion of our own day4 ,and   
the colonists      cut down the oaks1   
and plowed the land1 and built cities1  
and made harbors1 and finally dusted    
their busy hands and      busy souls of 
the grime of labor and wrought splendid 
temples in honor of the benign gods who 
had given them the      possessions of  
the ,italians and filled them with power
 and      fatness4       ,every once in 
so often the natives looked lustfully   
down      from the hills upon this      
fatness1 made an armed snatch at        

it1 were driven back with bloody        
contumely1 and the heaping      of      
riches upon riches went on4 ,and more   
and more the oaks      were cut         
down--mark that6 for the stories of     
nations are so      inextricably bound  
up with the stories of trees--until all 
the plain was cleared and tilled2 and   
then the foothills      were denuded1   
and the wave of destruction crept up the
      mountain sides1 and they1 too1    
were left naked to the sun      and the 
rains4       ,at first these rains1     
sweeping down torrentially1             
unhindered by the lost forests1 only    
enriched the plain with      the        
long-hoarded sweetness of the trees2 but
 by and by the      living rivers grew  
heavy and thick1 vomiting mud into the  
ever shallowing harbors1 and the land   
soured with the      undrained stagnant 
water4 ,commerce turned more and more to
      deeper ports1 and mosquitoes began
 to breed in the brackish      soil that
 was making fast between the city and   

the sea4       ,who of all those        
powerful landowners and rich merchants  
could ever have dreamed that little     
buzzing insects could      sting a great
 city to death8 ,but they did4 ,fevers  
grew more      and more prevalent4 ,the 
malaria haunted population went more    
and more languidly about their business4
 ,the natives1 hardy      and vigorous  
in the hills1 were but feebly repulsed4 
,carthage demanded tribute1 and ,rome   
took it1 and changed the      city's    
name from ,poseidonia to ,paestum4      
,after ,rome grew weak1      ,saracen   
corsairs came in by sea and grasped the 
slackly      defended riches1 and the   
little winged poisoners of the          
night struck again and again1 until     
grass grew in the      streets1 and the 
wharves crumbled where they stood4      
,finally1      the wretched remnant of a
 great people wandered away into        
the more wholesome hills1 the marshes   
rotted in the heat and      grew up in  
coarse reeds where corn and vine had    

flourished1      and the city melted    
back into the wasted earth4#af          
,footnote #af3 ,elizabeth ,bisland and  
,anne ,hoyt1 ,seekers in      ,sicily4  
,john ,lane ,company4  ,illustration3   
,result of deforestation in ,china4     
,this land has been ruined by erosion4  
7,carnegie ,institution ,research in    
,china47  ,prevention of ,erosion by    
,covering of ,organic ,soil4--,we have  
shown how ungoverned streams might dig  
out soil and carry it far from its      
original source4 ,examples of what      
streams have done may be seen in the    
deltas formed at the mouths of great    
rivers4 ,the forest prevents this by    
holding the water supply and letting it 
out gradually4 ,this it does by covering
 the inorganic soil with humus or       
decayed organic material4 ,in this way  
the forest floor becomes like a sponge1 
holding water through long periods of   
drought4 ,the roots of the trees1 too1  
help hold the soil in place4 ,the       
gradual evaporation of water through the

 stomata of the leaves cools the        
atmosphere1 and this tends to           
precipitate the moisture in the air4    
,eventually the dead bodies of the trees
 themselves are added to the organic    
covering1 and new trees take their      
place4  ,illustration3 ,the forest      
regions of the ,united ,states4  ,other 
,uses of the ,forest4--,in some         
localities forests are used as          
windbreaks and to protect mountain towns
 against avalanches4 ,in winter they    
moderate the cold1 and in summer reduce 
the heat and lessen the danger from     
storms4 ,birds nesting in the woods     
protect many valuable plants which      
otherwise might be destroyed by insects4
  ,forests have great commercial        
importance4 ,pyrogallic and other acids 
are obtained from trees1 as are tar1    
creosote1 resin1 turpentine1 and many   
useful oils4 ,the making of maple sirup 
and sugar forms a profitable industry in
 several states4  ,the ,forest ,regions 
of the ,united ,states4--,the combined  

area of all the forests in the ,united  
,states1 exclusive of ,alaska1 is about 
#ejj1jjj1jjj acres4 ,this seemingly     
immense area is rapidly decreasing in   
acreage and in quality1 thanks to the   
demands of an increasing population1 a  
woeful ignorance on the part of the     
owners of the land1 and wastefulness on 
the part of cutters and users alike4  ,a
 glance at the map on page #aji shows   
the distribution of our principal       
forests4 ,washington ranks first in the 
production of lumber4 ,here the great   
,douglas fir1 one of the evergreens1    
forms the chief source of supply4 ,in   
the ,southern states1 especially        
,louisiana and ,mississippi1 yellow pine
 and cypress are the trees most         
lumbered4  ,which states produce the    
most hardwoods8 ,from which states do we
 get most of our yellow pine1 spruce1   
red fir1 redwood8 ,where are the        
heaviest forests of the ,united ,states8
  ,illustration3 ,transportation of     
lumber in the ,west4 ,a logging train4  

,illustration3 ,transportation of lumber
 in the ,east4 ,logs are mostly floated 
down rivers to the mills4  ,uses of     
,wood4--,even in this day of coal1 wood 
is still by far the most used fuel4 ,it 
is useful in building4 ,it outlasts iron
 under water1 in addition to being      
durable and light4 ,it is cheap and1    
with care of the forests1 inexhaustible1
 while our mineral wealth may some day  
be used up4 ,distilled wood gives wood  
alcohol4 ,partially burned wood is      
charcoal4 ,in our forests much of the   
soft wood 7the cone-bearing trees1      
spruce1 balsam1 hemlock1 and pine71 and 
poplars1 aspens1 basswood1 with some    
other species1 make paper pulp4 ,the    
daily newspaper and cheap books are     
responsible for inroads on our forests  
which cannot well be repaired4 ,it is   
not necessary to take the largest trees 
to make pulp wood4 ,hence many young    
trees of not more than six inches in    
diameter are sacrificed4 ,of the        
hundreds of species of trees in our     

forests1 the conifers are probably most 
sought after for lumber4 ,pine1         
especially1 is probably used more       
extensively than any other wood4 ,it is 
used in all heavy construction work1    
frames of houses1 bridges1 masts1 spars 
and timber of ships1 floors1 railway    
ties1 and many other purposes4 ,cedar is
 used for shingles1 cabinetwork1 lead   
pencils1 etc42 hemlock and spruce for   
heavy timbers and1 as we have seen1 for 
paper pulp4 ,another use for our lumber1
 especially odds and ends of all kinds1 
is in the packing-box industry4 ,it is  
estimated that nearly #ej per cent of   
all lumber cut ultimately finds its way 
into the construction of boxes4 ,hemlock
 bark is used for tanning4  ,the hard   
woods--ash1 basswood1 beech1 birch1     
cherry1 chestnut1 elm1 maple1 oak1 and  
walnut--are used largely for the trim of
 our houses1 for manufacture of         
furniture1 wagon or car work1 and       
endless other purposes4  ,illustration3 
,diagrams of sections of timber4 a1     

cross section2 b1 radial2 c1 tangential4
 7,from ,pinchot1 ,u4 ,s4 ,dept4 of     
,agriculture47  ,methods of cutting     
,timber4--,a glance at the diagram of   
the sections of timber shows us that a  
tree may be cut radially through the    
middle of the trunk or tangentially to  
the middle portion4 ,most lumber is cut 
tangentially4 ,in wood cut in this      
manner the yearly rings take a more or  
less irregular course4 ,the grain in    
wood is caused by the fibers not taking 
straight lines in their course in the   
tree trunk4 ,in many cases the fibers of
 the wood take a spiral course up the   
trunk1 or they may wave outward to form 
little projections4 ,boards cut out of  
such a piece of wood will show the      
effect seen in many of the school desks1
 where the annual rings appear to form  
elliptical markings4 ,quite a difference
 in color and structure is often seen   
between the heartwood1 composed of the  
dead walls of cells occupying the       
central part of the tree trunk1 and the 

sapwood1 the living part of the stem4   
,illustration3 ,section of a tree trunk 
showing knot4  ,knots4--,knots1 as can  
be seen from the diagram1 are branches  
which at one time started in their      
outward growth and were for some reason 
killed4 ,later1 the tree1 continuing in 
its outward growth1 surrounded them and 
covered them up4 ,a dead limb should be 
pruned before such growth occurs4 ,the  
markings in bird's-eye maple are caused 
by buds which have not developed1 and   
have been overgrown with the wood of the
 tree4  ,destruction of the             
,forest4--,by ,waste in ,cutting4--,man 
is responsible for the destruction of   
one of this nation's most valuable      
assets4 ,this is primarily due to wrong 
and wasteful lumbering4 ,hundreds of    
thousands of dollars' worth of lumber is
 left to rot annually because the       
lumbermen do not cut the trees close    
enough to the ground1 or because through
 careless felling of trees many other   
smaller trees are injured4 ,there is    

great waste in the mills4 ,in fact1 man 
wastes in every step from the forest to 
the finished product4  ,illustration3 ,a
 forest in the far west totally         
destroyed by fire and wasteful          
lumbering4  ,by ,fire4--,indirectly1 man
 is responsible for fire1 one of the    
greatest enemies of the forest4 ,most of
 the great forest fires of recent years1
 the losses from which total in the     
hundreds of millions1 have been due     
either to railroads or to carelessness  
in making fires in the woods4 ,it is    
estimated that in forest lands traversed
 by railroads from #be per cent to #ij  
per cent of the fires are caused by     
coal-burning locomotives4 ,for this     
reason laws have been made in ,new ,york
 ,state requiring locomotives passing   
through the ,adirondack forest preserve 
to burn oil instead of coal4 ,this has  
resulted in a considerable reduction in 
the number of fires4 ,in addition to the
 loss in timber1 the fires often burn   
out the organic matter in the soil 7the 

duff7 forming the forest floor1 thus    
preventing the growth of forest there   
for many years to come4 ,in ,new ,york  
and other states fires are fought by an 
organized corps of fire wardens1 whose  
duty it is to watch the forest and to   
fight forest fires4  ,other             
,enemies4--,other enemies of the forest 
are numerous fungus plants1 insect      
parasites which bore into the wood or   
destroy the leaves1 and grazing animals1
 particularly sheep4 ,wind and snow also
 annually kill many trees4              
,forestry4--,in some parts of central   
,europe1 the value of the forests was   
seen as early as the year #acjj ,a4,d41 
and many towns consequently bought up   
the surrounding forests4 ,the city of   
,zurich has owned forests in its        
vicinity for at least #fjj years and has
 found them a profitable investment4 ,in
 this country only recently has the     
importance of preserving and caring for 
our forests been noted by our           
government4 ,now1 however1 we have a    

,forest ,survey of the ,department of   
,agriculture and numerous state and     
university schools of forestry which are
 rapidly teaching the people of this    
country the best methods for the        
preservation of our forests4 ,the       
,federal government has set aside a     
number of tracts of mountain forest in  
some of the ,western states1 making a   
total area of over #afg1jjj1jjj acres4  
,new ,york has established for the same 
purpose the ,adirondack ,park1 with     
nearly #a1ejj1jjj acres of timberland4  
,pennsylvania has one of #gjj1jjj acres1
 and many other states have followed    
their example4  ,illustration3 ,the     
forest primeval4 ,trees are killing each
 other in the struggle for light and    
air4  ,illustration3 ,a ,german beech   
forest4 ,the trees are kept thinned out 
so as to allow the young trees to get a 
start4 ,contrast this with the picture  
above4  ,methods for ,keeping and       
,protecting the ,forests4--,forests     
should be kept thinned4 ,too many trees 

are as bad as too few4 ,they struggle   
with one another for foothold and light1
 which only a few can enjoy4 ,in cutting
 the forest1 it should be considered as 
a harvest4 ,the oldest trees are the    
ripe grain1 the younger trees being left
 to grow to maturity4 ,several methods  
of renewing the forest are in use in    
this country4 7#a7 ,trees may be cut    
down and young ones allowed to sprout   
from cut stumps4 ,this is called coppice
 growth4 ,this growth is well seen in   
parts of ,new ,jersey4 7#b7 ,areas or   
strips may be cut out so that seeds from
 neighboring trees are carried there to 
start new growth4 7#c7 ,forests may be  
artificially planted4 ,two seedlings    
planted for every tree cut is a rule    
followed in ,europe4 7#d7 ,the most     
economical method is that shown in the  
lower picture on page #aad1 where the   
largest trees are thinned out over a    
large area so as to make room for the   
younger ones to grow up4 ,the greatest  
dangers to the forests are from fire and

 from careless cutting1 and these       
dangers may be kept in check by the     
efficient work of our national and state
 foresters4  ,illustration3 ,we must    
protect our city trees4 ,this tree was  
badly wounded by being gnawed by a      
horse4  ,a ,city's ,need for            
,trees4--,the city of ,paris1 well known
 as one of the most beautiful of        
,european capitals1 spends over #ajj1jjj
 annually in caring for and replacing   
some of the #ij1jjj trees owned by the  
city4 ,all over the ,united ,states the 
city governments are beginning to       
realize what ,european cities have long 
known1 that trees are of great value to 
a city4 ,they are now following the     
example of ,european cities by planting 
trees and by protecting the trees after 
they are planted4 ,thousands of city    
trees are annually killed by horses     
which gnaw the bark4 ,this may be       
prevented by proper protection of the   
trunk by means of screens or wire       
guards4 ,chicago has appointed a city   

forester1 who has given the following   
excellent reasons why trees should be   
planted in the city3--  7#a7 ,trees are 
beautiful in form and color1 inspiring a
 constant appreciation of nature4  7#b7 
,trees enhance the beauty of            
architecture4  7#c7 ,trees create       
sentiment1 love of country1 state1 city1
 and home4  7#d7 ,trees have an         
educational influence upon citizens of  
all ages1 especially children4  7#e7    
,trees encourage outdoor life4  7#f7    
,trees purify the air4  7#g7 ,trees cool
 the air in summer and radiate warmth in
 winter4  7#h7 ,trees improve climate   
and conserve soil and moisture4  7#i7   
,trees furnish resting places and       
shelter for birds4  7#aj7 ,trees        
increase the value of real estate4      
7#aa7 ,trees protect the pavement from  
the heat of the sun4  7#ab7 ,trees      
counteract adverse conditions of city   
life4  ,let us all try to make ,arbor   
,day what it should be1 a day for caring
 for and planting trees1 for thus we may

 preserve this most important heritage  
of our nation4                          
,,reference ,,books                     
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,mayne and ,hatch1 
,high ,school ,agriculture4 ,american   
,book        ,company4      ,murrill1   
,shade ,trees1 ,bul4 #bje1 ,cornell     
,university        ,agricultural        
,experiment ,station4      ,pinchot1 ,a 
,primer of ,forestry1 ,division of      
,forestry1 ,u4 ,s4        ,department of
 ,agriculture4                          
,,advanced       ,apgar1 ,trees of the  
,united ,states1 ,chaps4 ,,ii1 ,v1 ,,vi4
        ,american ,book ,company4       
,coulter1 ,barnes1 and ,cowles1 ,a      
,textbook of ,botany1 ,part ,i          
and ,vol4 ,,ii4 ,american ,book         
,company4      ,goebel1 ,organography of
 ,plants1 ,part ,v4 ,clarendon ,press4  
,strasburger1 ,noll1 ,schenck1 and      
,karston1 ,a ,textbook of               
,botany4 ,the ,macmillan ,company4      

,ward1 ,timber and ,some of its         
,diseases4 ,the ,macmillan              
,company4      ,yearbook1 ,u4 ,s4       
,department of ,agriculture1 ,division  
of        ,forestry1 ,buls4 #g1 #aj1    
#ac1 #af1 #ag1 #ah1 #bj1 #bf1 #bg4      
,x4 ,,the ,,economic ,,relation ,,of    
,,green ,,plants ,,to ,,man             
,problems4--,how green plants are useful
 to man4           7a7 ,as food4        
7b7 ,for clothing4           7c7 ,other 
uses4           ,how green plants are   
harmful to man4                         
,,suggested ,,laboratory ,,work         
,if a commercial museum is available1 a 
trip should be planned to work          
over the topics in this chapter4 ,the   
school collection may well       include
 most of the examples mentioned1 both of
 useful and harmful       plants4       
,a study of weeds and poisonous plants  
should be taken up in actual            
laboratory work1 either by collection   
and identification or by                
demonstration4   ,green ,plants have a  

,dollar and ,cents ,value4--,to the girl
 or boy living in the city green plants 
seem to have little direct value4       
,although we see vegetables for sale in 
stores and we know that fruits have a   
money value1 we are apt to forget that  
the wealth of our nation depends more   
upon its crops than it does on its      
manufactories and business houses4 ,the 
economic or dollars and cents value of  
plants is enormous and far too great for
 us to comprehend in terms of figures4  
,we have already seen some of the uses  
to mankind of the products of the       
forest2 let us now consider some other  
plant products4  ,illustration3         
,cabbage     ,onions     ,lettuce       
,leaves used as food4  ,leaves as       
,food4--,grazing animals feed almost    
entirely on tender shoots or leaves1    
blades of grass1 and other herbage4     
,certain leaves and buds are used by man
 as food4 ,lettuce1 beet tops1 kale1    
spinach1 broccoli1 are examples4 ,a     
cabbage head is nothing but a big bud   

which has been cultivated by man4 ,an   
onion is a compact budlike mass of      
thickened leaves which contain stored   
food4  ,illustration3    ,celery        
,kohl-rabi     ,potato     ,sugar cane  
,stems used as food4  ,stems as         
,food4--,a city child would1 if asked to
 name some stem used as food1 probably  
mention asparagus4 ,we sometimes forget 
that one of our greatest necessities1   
cane sugar1 comes from the stem of sugar
 cane4 ,over seventy pounds of sugar is 
used each year by every person in the   
,united ,states4 ,to supply the growing 
demand beets are now being raised for   
their sugar in many parts of the world1 
so that nearly half the total supply of 
sugar comes from this source4 ,maple    
sugar is a well-known commodity which is
 obtained by boiling the sap of sugar   
maple until it crystallizes4 ,over      
#af1jjj tons of maple sugar is obtained 
every spring1 ,vermont producing about  
#dj per cent of the total output4 ,the  
sago palm is another stem which supports

 the life of many natives in ,africa4   
,another stem1 living underground1 forms
 one of man's staple articles of diet4  
,this is the potato4  ,roots as         
,food4--,roots which store food for     
plants form important parts of man's    
vegetable diet4 ,beets1 radishes1       
carrots1 parsnips1 sweet potatoes1 and  
many others might be mentioned4  ,the   
following table shows the proportion of 
foods in some of the commoner roots and 
stems3--                                
----------------------------------------
----------------------------            
,,water ,,proteins ,,carbohydrates ,,fat
  ,,mineral ,,matter                    
----------------------------------------
-----------------------   ,potato       
#ge      #a4b        #ah        #j4c    
#a4j   ,carrot        #hi      #j4e     
#e        #j4b     #a4j   ,parsnip      
#ha      #a4b         #h4g      #a4e    
#a4j   ,turnip        #ib4h    #j4e     
#d4       #j4a     #j4h   ,onion        
#ia      #a4e         #d4h      #j4b    

#j4e   ,sweet potato  #gd      #a4e     
#bj4b      #j4a     #a4e   ,beet        
#hb4b    #j4d        #ac4d      #j4a    
#j4i                                    
----------------------------------------
----------------------------            
,illustration3      ,wheat   ,nuts      
,pear   ,melon    ,seeds and fruits used
 for food4  ,fruits and ,seeds as       
,foods4--,our cereal crops1 corn1 wheat1
 etc41 have played a very great part in 
the civilization of man and are now of  
so much importance to him as food       
products that bread made from flour from
 the wheat has been called the staff of 
life4 ,our grains are the cultivated    
progeny of wild grasses4 ,domestication 
of plants and animals marks epochs in   
the advance of civilization4 ,the man of
 the stone age hunted wild beasts for   
food1 and lived like one of them in a   
cave or wherever he happened to be2 he  
was a nomad1 a wanderer1 with no fixed  
home4 ,he may have discovered that wild 
roots or grains were good to eat2       

perhaps he stored some away for future  
use4 ,then came the idea of growing     
things at home instead of digging or    
gathering the wild fruits from the      
forest and plain4 ,the tribes which     
first cultivated the soil made a great  
step in advance1 for they had as a      
result a fixed place for habitation4    
,the cultivation of grains and cereals  
gave them a store of food which could be
 used at times when other food was      
scarce4 ,the word cereal 7derived from  
,ceres1 the ,roman ,goddess of          
,agriculture7 shows the importance of   
this crop to ,roman civilization4 ,from 
earliest times the growing of grain and 
the progress of civilization have gone  
hand in hand4 ,as nations have advanced 
in power1 their dependence upon the     
cereal crops has been greater and       
greater4  ,indian corn1 says ,john      
,fiske1 in ,the ,discovery of ,america1 
has played a most important part in the 
history of the ,new ,world4 ,it could be
 planted without clearing or plowing the

 soil4 ,there was no need of threshing  
or winnowing4 ,sown in tilled land1 it  
yields more than twice as much food per 
acre as any other kind of grain4 ,this  
was of incalculable advantage to the    
,english settlers in ,new ,england1 who 
would have found it much harder to gain 
a secure foothold upon the soil if they 
had had to begin by preparing it for    
wheat or rye4  ,to-day1 in spite of the 
great wealth which comes from our       
mineral resources1 live stock1 and      
manufactured products1 the surest index 
of our country's prosperity is the size 
of the corn and wheat crop4 ,according  
to the last census1 the amount of       
capital invested in agriculture was over
 #bj1jjj1jjj1jjj1 while that invested in
 manufacture was less than one half that
 amount4  ,corn4--,about three billion  
bushels of corn were raised in the      
,united ,states during the year #aiaj4  
,this figure is so enormous that it has 
but little meaning to us4 ,in the past  
half century our corn crop has increased

 over #cej per cent4 ,illinois and ,iowa
 are the greatest corn-producing states1
 each having a yearly record of over    
four hundred million bushels4 ,the      
figure on this page shows the principal 
corn-producing areas in the ,united     
,states4  ,illustration3 ,indian ,corn  
,production--,percentage  ,indian corn  
is put to many uses4 ,it is a valuable  
food4 ,it contains a large proportion of
 starch1 from which glucose 7grape      
sugar7 and alcohol are made4 ,machine   
oil and soap are made from it4 ,the     
leaves and stalk are an excellent       
fodder2 they can be made into paper and 
packing material4 ,mattresses can be    
stuffed with the husks4 ,the pith is    
used as a protective belt placed below  
the water line of our huge battleships4 
,corn cobs are used for fuel1 one       
hundred bushels having the fuel value of
 a ton of coal4  ,illustration3 ,wheat  
,crop in ,united ,states--,percentage   
,source  ,wheat4--,wheat is the crop of 
next greatest importance in size4       

,nearly seven hundred millions of       
bushels were raised in this country in  
#aiaj1 representing a total money value 
of over #gjj1jjj1jjj4 ,seventy-two per  
cent of all the wheat raised comes from 
the ,north ,central states and          
,california4 ,about three fourths of the
 wheat crop is exported1 nearly one half
 of it to ,great ,britain1 thus         
indirectly giving employment to         
thousands of people on railways and     
steamships4 ,wheat has its chief use in 
its manufacture into flour4 ,the germ1  
or young wheat plant1 is sifted out     
during this process and made into       
breakfast foods4 ,flour making forms the
 chief industry of ,minneapolis1        
,minnesota1 and of several other large  
and wealthy cities in this country4     
,illustration3 ,a field of rice1 showing
 the conditions of culture4  ,other     
,grains4--,of the other grain and       
cereals raised in this country1 oats are
 the most important crop1 over one      
billion bushels having been produced in 

#aiaj4 ,barley is another grain1 a      
staple of some of the northern countries
 of ,europe and ,asia4 ,in this country1
 it is largely used in making malt for  
the manufacture of beer4 ,rye is the    
most important cereal crop of northern  
,europe1 ,russia1 ,germany1 and         
,austro-,hungary producing over #ej per 
cent of the world's supply4 ,one of the 
most important grain crops for the world
 7although relatively unimportant in the
 ,united ,states7 is rice4 ,the fruit of
 this grasslike plant1 after thrashing1 
screening1 and milling1 forms the       
principal food of one third of the human
 race4 ,moreover1 its stems furnish     
straw1 its husks make a bran used as    
food for cattle1 and the grain1 when    
fermented and distilled1 yields alcohol4
  ,garden ,fruits4--,green plants and   
especially vegetables have come to play 
an important part in the dietary of man4
 ,the diseases known as scurvy and      
beri-beri1 the latter the curse of the  
far ,eastern navies1 have been largely  

prevented by adding vegetables and fruit
 juices to the dietary of the sailors4  
,people in this country are beginning to
 find that more vegetables and less meat
 are better than the meat diet so often 
used4 ,market gardening forms the       
lucrative business of many thousands of 
people near our great cities4 ,some of  
the more important fruits are squash1   
cucumbers1 pumpkins1 melons1 tomatoes1  
peppers1 strawberries1 raspberries1 and 
blackberries4 ,the latter fruits bring  
in an annual income of #be1jjj1jjj to   
our market gardeners4 ,beans and peas   
are important as foods because of their 
relatively large amount of protein4     
,canning green corn1 peas1 beans1 and   
tomatoes has become an important        
industry4  ,illustration3 ,picking      
apples1 an important crop in some parts 
of the ,united ,states4  ,orchard and   
,other ,fruits4--,in the ,united ,states
 over one hundred and seventy-five      
million bushels of apples are grown     
every year4 ,pears1 plums1 apricots1    

peaches1 and nectarines also form large 
orchards1 especially in ,california4    
,nuts form one of our important articles
 of food1 largely because of the large  
amount of protein contained in them4    
,the grape crop of the world is         
commercially valuable1 because of the   
raisins and wine produced4 ,the culture 
of lemons1 oranges1 and grapefruit has  
come in recent years to give a living to
 many people in this country as well as 
in other parts of the world4 ,figs1     
olives1 and dates are staple foods in   
the ,mediterranean countries and are    
sources of wealth to the people there1  
as are coconuts1 bananas1 and many other
 fruits in tropical countries4          
,beverages and ,condiments4--,the coffee
 and cacao beans1 and leaves of the tea 
plant1 products of tropical regions1    
form the basis of very important        
beverages of civilized man4 ,pepper1    
black and red1 mustard1 allspice1       
nutmegs1 cloves1 and vanilla are all    
products manufactured from various      

fruits or seeds of tropical plants4     
,alcoholic liquors are produced from    
various plants in different parts of the
 world1 the dried fruit of the hop vine 
being an important product of ,new ,york
 ,state used in the making of beer4     
,raw ,materials4--,besides use as food1 
green plants have many other uses4 ,many
 of our city industries would not be in 
existence1 were it not for certain plant
 products which furnish the raw         
materials for many manufacturing        
industries4 ,many cities of the east and
 south1 for example1 depend upon cotton 
to give employment to thousands of      
factory hands4  ,illustration3 ,cotton  
,crop in ,united ,states--,percentage   
,source                ,cotton ,crop in 
,united ,states--,percentage            
,consumption  ,cotton4--,of our native  
plant products cotton is probably of the
 most importance to the outside world4  
,over eleven million bales of five      
hundred pounds each are raised annually4
  ,the cotton plant thrives in warm     

regions4 ,its commercial importance is  
gained because the seeds of the fruit   
have long filaments attached to them4   
,bunches of these filaments1 after      
treatment1 are easily twisted into      
threads from which are manufactured     
cotton cloth1 muslin1 calico1 and       
cambric4 ,in addition to the fiber1     
cottonseed oil1 a substitute for olive  
oil1 is made from the seeds1 and the    
refuse remaining makes an excellent     
cattle fodder4  ,illustration3 ,map     
showing the spread of the cotton boll   
weevil4 ,it was introduced from ,mexico 
about #ahid4 ,what proportion of the    
cotton raising belt was infected in     
#aijh8  ,cotton ,boll ,weevil4--,the    
cotton crop of the ,united ,states has  
rather recently been threatened with    
destruction by a beetle called the      
cotton boll weevil4 ,this insect1 which 
bores into the young pod of the cotton1 
develops there1 stunting the growth of  
the fruit to such an extent that seeds  
are not produced4 ,the loss in ,texas   

alone is estimated at over #aj1jjj1jjj a
 year4 ,the boll weevil1 because of the 
protection offered by the cotton boll1  
is very difficult to exterminate4 ,the  
weevils are destroyed by birds1 the     
infected bolls and stalks are burnt1    
millions are killed each winter by cold1
 other insects prey on them1 but at the 
present time they are one of the        
greatest pests the south knows4         
,illustration3 ,mexican cotton boll     
weevil4 ,much enlarged1 above2 natural  
size1 below4 7,herrick47  ,the control  
of this pest seems to depend upon early 
planting so that the crop has an        
opportunity to ripen before the insects 
in the boll grow large enough to do     
harm4 ,ultimately the boll weevil may do
 more good than harm by bringing into   
the market a type of cotton plant that  
ripens very early4  ,vegetable          
,fibers4--,among the most important are 
,manila hemp1 which comes from the      
leaf-stalks of a plant of the banana    
family and true hemp1 which is the bast 

or woody fiber of a plant cultivated in 
most warm parts of the earth4 ,flax is  
also an important fiber plant1 grown    
largely in ,russia and other parts of   
,europe 7see picture on next page74     
,from the bast fibers of the stem of    
this herb linen cloth is made4          
,illustration3 ,flax grown for fiber4   
,vegetable ,oils4--,some of the same    
plants which give fiber also produce    
oil4 ,cotton seed oil pressed from the  
seeds1 linseed oil from the seeds of the
 flax plant1 and coconut oil 7the       
covering of the nut here producing the  
fiber7 are examples4  ,illustration3    
,poison ivy1 a climbing plant which is  
poisonous to touch4 ,notice the leaves  
in threes4  ,some ,harmful ,green       
,plants4--,we have seen that on the     
whole green plants are useful to man4   
,there are1 however1 some that are      
harmful4 ,for example1 the poison ivy is
 extremely poisonous to touch4 ,the     
poison ivy is a climbing plant which    
attaches itself to the trees or walls by

 means of tiny air roots which grow out 
from the stem4 ,it is distinguished from
 its harmless climbing neighbor1 the    
,virginia ,creeper1 by the fact that its
 leaves are notched in threes instead of
 fives4 ,every boy and girl should know 
poison ivy4  ,numerous other poisonous  
common plants are found1 but one other  
deserves special notice because of its  
presence in vacant city lots4 ,the      
,jimson ,weed 7,datura7 is a bushy      
plant1 from two to five feet high1      
bearing large leaves4 ,it has white or  
purplish flowers1 and later bears a     
four-valved seed pod containing several 
hundred seeds4 ,these plants contain a  
powerful poison1 and people are often   
made seriously ill by eating the roots  
or other parts by mistake4              
,weeds4--,from the economic standpoint  
the green plants which do the greatest  
damage are weeds4 ,those plants which   
provide best for their young are usually
 the most successful in life's race4    
,plants which combine with the ability  

to scatter many seeds over a wide       
territory the additional characteristics
 of rapid growth1 resistance to dangers 
of extreme cold or heat1 attacks of     
enemies1 inedibility1 and peculiar      
adaptations to cross-pollination or     
self-pollination1 are usually spoken of 
as weeds4 ,they flourish in the sterile 
soil of the roadside and in the fertile 
soil of the garden4 ,by means of rapid  
growth they kill other plants of slower 
growth by usurping their territory4     
,slow-growing plants are thus actually  
exterminated4 ,many of our common weeds 
have been introduced from other         
countries and have1 through their       
numerous adaptations1 driven out other  
plants which stood in their way4 ,such  
is the ,russian ,thistle4 ,a single     
plant of this kind will give rise to    
over #bj1jjj seeds4 ,first introduced   
from ,russia in #ahgc1 it spread so     
rapidly that in twenty years it had     
appeared as a common weed over an area  
of some twenty-five thousand square     

miles4 ,it is now one of the greatest   
pests in our ,northwest4                
,,reference ,,books                     
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,gannet1           
,commercial ,geography4 ,american ,book 
,company4      ,sargent1 ,plants and    
their ,uses4 ,henry ,holt and ,company4 
,toothaker1 ,commercial ,raw ,materials4
 ,ginn and ,company4      ,u4 ,s4 ,dept4
 of ,agriculture1 ,farmers' ,bulletin   
#hf1 ,thirty        ,poisonous ,plants  
of the ,united ,states1 ,v4 ,k4         
,chestnut4        ,bulletin #ag4 ,two   
,hundred ,weeds1 ,how to ,know ,them and
 ,how to        ,kill ,them1 ,l4 ,h4    
,dewey4                                 
,,advanced       ,bailey1 ,cyclopedia of
 ,american ,agriculture4 ,the ,macmillan
        ,company4     ,,xi4 ,,plants    
,,without ,,chlorophyll ,,in ,,their    
,,relation ,,to ,,man  ,problems4--7a7  
,how molds and other saprophytic fungi  
do harm to man4            7b7 ,what    

yeasts do for mankind4            7c7 ,a
 study of bacteria with reference to    
7#a7 ,conditions favorable and          
unfavorable to growth4                  
7#b7 ,their relations to mankind4       
7#c7 ,some methods of fighting harmful  
bacteria and diseases                   
caused by them4                         
,,laboratory ,,suggestions       ,field 
work4--,presence of bracket fungi and   
chestnut      canker4      ,home        
experiment4--,conditions favorable to   
growth of mold4      ,laboratory        
demonstration4--,growth of mold1        
structure1      drawing4      ,home     
experiment or laboratory                
demonstration4--,conditions             
unfavorable for growth of molds4        
,demonstration4--,process of            
fermentation4      ,microscopic         
demonstration4--,growing yeast cells4   
,drawing4      ,home                    
experiment4--,conditions favorable for  
growth of      yeast4      ,home        
experiment4--,conditions favorable for  

growth of yeast      in bread4          
,demonstration and experiment4--,where  
bacteria may be      found4             
,demonstration4--,methods of growth of  
bacteria1 pure      cultures and        
colonies shown4                         
,demonstration4--,foods preferred by    
bacteria4                               
,demonstration4--,conditions favorable  
for growth of      bacteria4            
,demonstration4--,conditions unfavorable
 for growth of      bacteria4           
,demonstration by charts1 diagrams1     
etc4--,the relation of      bacteria to 
disease in a large city4   ,,colorless  
,,plants ,,are ,,useful ,,and ,,harmful 
,,to ,,man  ,the ,fungi4--,we have found
 that green plants on the whole are     
useful to mankind4 ,but not all plants  
are green4 ,most of us are familiar with
 the edible mushroom sold in the markets
 or the so-called toadstools found in   
parks or lawns4 ,these plants contain no
 chlorophyll and hence do not make their
 own food4 ,they are members of the     

plant group called fungi4 ,such plants  
are almost as much dependent upon the   
green plants for food as are animals4   
,but the fungi require for the most part
 dead organic matter for their food4    
,this may be obtained from decayed      
vegetable or animal material in soil1   
from the bodies of dead plants and      
animals1 or even from foods prepared for
 man4 ,fungi which feed upon dead       
organic material are known as           
saprophytes4 ,examples are the          
mushrooms1 the yeasts1 molds1 and some  
bacteria1 of which more will be learned 
later4  ,illustration3 ,chestnut trees  
in a ,new ,york ,city park2 killed by a 
parasite1 the chestnut canker4  ,some   
,parasitic ,fungi4--,other fungi 7and we
 will find this applies to some animals 
as well7 prefer living plants or animals
 for their food4 ,thus a tiny plant1    
recently introduced into this country1  
known as the chestnut canker1 is killing
 our chestnut trees by the thousands in 
the eastern part of the ,united ,states4

 ,it produces millions of tiny          
reproductive cells known as spores2     
these spores1 blown about by the wind1  
light on the trees1 sprout1 and send in 
under the bark a threadlike structure   
which sucks in the food circulating in  
the living cells1 eventually causing the
 death of the tree4 ,a plant or animal  
which lives at the expense of another   
living plant or animal is called a      
parasite4 ,the chestnut canker is a     
dangerous parasite4 ,later we shall see 
that animal and plant parasites destroy 
yearly crops and trees valued at        
hundreds of millions of dollars and     
cause untold misery and suffering to    
humanity4  ,illustration3 ,shelf fungi4 
7,photographed by ,w4 ,c4 ,barbour47    
,another fungus which does much harm to 
the few trees found in large towns and  
cities is the shelf or bracket fungus4  
,the part of the body visible on the    
tree looks like a shelf or bracket1     
hence the name4 ,this bracket is in     
reality the reproductive part of the    

plant2 on its lower surface are formed  
millions of little bodies called spores4
 ,these spores are capable1 under       
favorable conditions1 of reproducing new
 plants4 ,the true body of the plant1 a 
network of threads1 is found under the  
bark4 ,this fungus begins its life as a 
spore in some part of the tree which has
 become diseased or broken4 ,once       
established1 it spreads rapidly4 ,there 
is no remedy except to kill the tree and
 burn it1 so as to destroy the spores4  
,many fine trees1 sound except for a    
slight bruise or other injury1 are      
annually infected and eventually killed4
 ,in cities thousands of trees become   
infected through careless hitching of   
horses so that the horse may gnaw the   
tree1 thus exposing a fresh surface on  
which spores may obtain lodgment and    
grow 7see page #aae74  ,suggestions for 
,field ,work4--,a field trip to a park  
or grove near home may show the great   
destruction of timber by this means4    
,count the number of perfect trees in a 

given area4 ,compare it with the number 
of trees attacked by the fungus4 ,does  
the fungus appear to be transmitted from
 one tree to another near at hand8 ,in  
how many instances can you discover the 
point where the fungus first attacked   
the tree8  ,fungi of our ,homes4--,but  
not all fungi are wild4 ,some have      
become introduced into our homes and    
these live on food or other materials4  
,these plants are very important because
 of their relation to life in a town or 
crowded city4#ag       ,footnote #ag3   
,experiments on conditions favorable to 
growth      of mold should be introduced
 here4  ,illustration3 ,bread mold2 r1  
rhizoids2 s1 fruiting bodies containing 
spores4  ,the ,growth of ,bread         
,mold4--,if a piece of moist bread is   
exposed to the air of the schoolroom1 or
 in your own kitchen for a few minutes  
and then covered with a glass tumbler   
and kept in a warm place1 in a day or   
two a fuzzy whitish growth will appear  
on the surface of the bread4 ,this      

growth shortly turns black4 ,if we now  
examine a little piece of the bread with
 a lens or low-powered microscope1 we   
find a tangled mass of threads 7the     
mycelium7 covering the surface of the   
bread4 ,from this mass of threads       
project tiny upright stalks bearing     
round black bodies1 the fruit4 ,little  
rootlike structures known as rhizoids   
dip down into the bread1 and absorb food
 for its threadlike body4 ,the upright  
threads with the balls at the end       
contain many tiny bodies called spores4 
,these spores have been formed by the   
division of the protoplasm making up the
 fruiting bodies into many separate     
cells4 ,when grown under favorable      
conditions1 the spores will produce more
 mycelia1 which in turn bear fruiting   
bodies4  ,physiology of the ,growth of  
,mold4--,molds1 in order to grow        
rapidly1 need oxygen1 moisture1 and     
moderate heat4 ,they seem to prefer     
dark1 damp places where there is not a  
free circulation of air1 for if the bell

 jar is removed from growing mold for   
even a short time1 the mold wilts4 ,too 
great or very little heat will prevent  
growth and kill everything except the   
spores4 ,they obtain their food from the
 material on which they live4 ,this they
 are able to do by means of digestive   
enzymes given out by the rootlike parts1
 by means of which the molds cling to   
the bread4 ,these digestive enzymes     
change the starch of the bread to sugar 
and the protein to a soluble form which 
will pass by osmosis into cells of the  
mold4 ,thus the mold is able to absorb  
food material4 ,these foods are then    
used to supply energy and make          
protoplasm4 ,this seems to be the usual 
method by which saprophytes make use of 
the materials on which they live4  ,what
 can ,molds live ,on8--,we have seen    
that black mold lives upon bread4 ,we   
would find that it or some other mold   
7e4g4 green or blue mold7 live upon     
decaying or overripe fruit1--apples1    
peaches1 and plums being especially     

susceptible to their growth4 ,molds feed
 upon all cakes or breads1 upon meat1   
cheese1 and many raw vegetables4 ,they  
are almost sure to grow upon flour if it
 is allowed to get damp4 ,moisture seems
 necessary for their growth4 ,jelly is a
 substance particularly favorable to    
molds for this reason4 ,shoes1 leather1 
cloth1 paper1 or even moist wood will   
give food enough to support their       
growth4 ,at least one troublesome       
disease1 ringworm1 is due to the growth 
of molds in the skin4  ,what ,mold does 
to ,foods4--,mold usually changes the   
taste of the material it grows upon1    
rendering it musty and sometimes unfit  
to eat4 ,eventually it will spoil food  
completely because decay sets in4       
,decay1 as we will see later1 is not    
entirely due to mold growth1 but is     
usually caused by another group of      
organisms1 the bacteria4 ,molds1        
however1 in feeding do cause chemical   
changes which result in decay or        
putrefaction4 ,some molds are useful4   

,they give the flavor to ,roquefort1    
,gorgonzola1 ,camembert1 and ,brie      
cheeses4 ,but on the whole molds are    
pests which the housekeeper wishes to   
get rid of4  ,how to prevent            
,molds4#ah--;,as we have seen1 moisture 
is favorable for mold growth2           
conversely1 dryness is unfavorable4     
,inasmuch as the spores of mold abound  
in the air1 materials which cannot be   
kept dry should be covered4 ,jelly after
 it is made should at once be tightly   
covered with a thin layer of paraffin1  
which excludes the air and possible mold
 spores4 ,or waxed paper may be fastened
 over the surface of the jelly so as to 
exclude the spores4 ,to prevent molds   
from attacking fresh fruit1 the surface 
of the fruit should be kept dry and1 if 
possible1 each piece of fruit should be 
wrapped in paper4 ,why8 ,heating with   
dry heat to #bab deg4 for a few moments 
will kill any mold spores that happen to
 be in food4 ,moldy food1 if heated     
after removing surface on which the mold

 grew1 is perfectly good to eat4        
,footnote #ah3 ,an experiment to show   
conditions unfavorable      for growth  
of molds should be shown at this point4 
,dry dusting or sweeping will raise     
dust1 which usually contains mold       
spores4 ,use a dampened broom or dust   
cloth frequently in the kitchen if you  
wish to preserve foods from molds4      
,other ,moldlike ,fungi4--,mildews are  
near relatives of the molds found in our
 homes4 ,they may attack leather1 cloth1
 etc41 in a damp house4 ,other allied   
forms may do damage to living plants4   
,some of these live upon the lilac1     
rose1 or willow4 ,these fungi do not    
penetrate the host plant to any depth1  
for they obtain their food from the     
outer layer of cells in the leaf of     
their host and cover the leaves with the
 whitish threads of the mycelium4 ,hence
 they may be killed by means of         
applications of some fungus-killing     
fluid1 as ,bordeaux mixture4#ai ,among  
the useful plants preyed upon by mildews

 are the plum1 cherry1 and peach trees4 
7,the diseases known as black knot and  
peach curl are thus caused47 ,another   
important member of this group is the   
tiny parasite found on rye and other    
grains1 which gives us the drug ergot4  
,footnote #ai3 ,see ,goff and ,mayne1   
,first ,principles of      ,agriculture1
 page #ei1 for formula of ,bordeaux     
mixture4  ,among other parasitic fungi  
are rusts and smuts4 ,wheat rust is     
probably the most destructive parasitic 
fungus4 ,indirectly this parasite is of 
considerable importance to the citizen  
of a great city because of its effect   
upon the price of wheat4   ,,yeasts ,,in
 ,,their ,,relation ,,to ,,man          
,fermentation4--,it is of common        
knowledge to country boys or girls that 
the juice of fresh apples1 grapes1 and  
some other fruits1 if allowed to stand  
exposed to the air for a short time will
 ferment4 ,that is1 the sweet juice will
 begin to taste sour and to have a      
peculiar odor1 which we recognize as    

that of alcohol4 ,the fermenting juice  
appears to be full of bubbles which rise
 to the surface4 ,if we collect enough  
of these bubbles of gas to make a test1 
we find it to be carbon dioxide4        
,evidently something changed some part  
of the apple or grape1 the sugar1       
7,c#f;,h#ab,o#f71 into alcohol1         
#b7;,c#b;,h#f,o71 and carbon dioxide1   
#b7;,,co#b74 ,this chemical process is  
known as fermentation4  ,illustration3  
,apparatus to show effect of            
fermentation4 ,n1 molasses1 water and   
yeast plants2 ,c1 bubbles of carbon     
dioxide4  ,yeast causes                 
,fermentation4--,let us now take a      
compressed yeast cake1 shake up a small 
portion of it in a solution of molasses 
and water1 and fill a fermentation tube 
with the mixture4 ,leave the tube in a  
warm place overnight4 ,in the morning a 
gas will be found to have been collected
 in the closed end of the tube 7see     
,figure on page #ach74 ,the taste and   
odor of the liquid shows alcohol to be  

present1 and the gas1 if tested1 is     
proven carbon dioxide4 ,evidently yeast 
causes fermentation4  ,what are         
,yeasts8--,if now part of the liquid    
from the fermentation tube which        
contains the settlings be drawn off1 a  
drop placed on a slide and a little weak
 iodine added and the mixture examined  
under the compound microscope1 two kinds
 of structures will be found 7see       
,figure below71 starch grains which are 
stained deep blue1 and other smaller    
ovoid structures of a brownish yellow   
color4 ,the latter are yeast plants4    
,illustration3 ,yeast and starch grains4
 ,notice that the starch grains around  
which are clustered yeast cells have    
been rounded off by the yeast plants4   
,how do you account for this8  ,size and
 ,shape1 ,manner of ,growth1 etc4--,the 
common compressed yeast cake contains   
millions of these tiny plants4 ,in its  
simplest form a yeast plant is a single 
cell4 ,the shape of such a plant is     
ovoid1 each cell showing under the      

microscope the granular appearance of   
the protoplasm of which it is formed4   
,look for tiny clear areas in the cells2
 these are vacuoles1 or spaces filled   
with fluid4 ,the nucleus is hard to find
 in a yeast cell4 ,many of the cells    
seem to have others attached to them1   
sometimes there being several in a row4 
,yeast cells reproduce very rapidly by a
 process of budding1 a part of the      
parent cell forming one or more smaller 
daughter cells which eventually become  
free from the parent4  ,conditions      
favorable to growth of                  
,yeast4--,experiment4--,label three pint
 fruit jars ,a1 ,b1 and ,c4 ,add one    
fourth of a compressed yeast cake to two
 cups of water containing two           
tablespoonfuls of molasses or sugar4    
,stir the mixture well and divide it    
into three equal parts and pour them    
into the jars4 ,place covers on the     
jars4 ,put jar ,a in the ice box on the 
ice1 and jar ,b over the kitchen stove  
or near a radiator2 pour the contents of

 jar ,c into a small pan and boil for a 
few minutes4 ,pour back into ,c1 cover  
and place it next to ,b4 ,after         
forty-eight hours1 look to see if any   
bubbles have made their appearance in   
any of the jars4 ,if the experiment has 
been successful1 only jar ,b will show  
bubbles4 ,after bubbles have begun to   
appear at the surface1 the fluid in jar 
,b will be found to have a sour taste   
and will smell unpleasantly4 ,the gas   
which rises to the surface1 if collected
 and tested1 will be found to be carbon 
dioxide4 ,the contents of jar ,b have   
fermented4 ,evidently1 the growth of    
yeast will take place only under        
conditions of moderate warmth and       
moisture4  ,carbohydrates necessary to  
,fermentation4--,sugar must be present  
in order for fermentation to take place4
 ,the wild yeasts cause fermentation of 
the apple or grape juice because they   
live on the skin of the apple or grape4 
,various peoples recognize this when    
they collect the juice of certain fruits

 and1 exposing it to the air1 allow it  
to ferment4 ,such is the saki or rice   
wine of the ,japanese1 the tuba or sap  
of the coconut palm of the ,filipinos   
and the pulque of the ,mexicans4  ,beer 
and ,wine ,making4--,brewers' yeasts are
 cultivated with the greatest care2 for 
the different flavors of beer seem to   
depend largely upon the condition of the
 yeast plants4 ,beer is made in the     
following manner4 ,sprouted barley1     
called malt1 in which the starch of the 
grain has been changed to grape sugar by
 digestion1 is killed by drying in a hot
 kiln4 ,the malt is dissolved in water1 
and hops are added to give the mixture a
 bitter taste4 ,now comes the addition  
of the yeast plants1 which multiply     
rapidly under the favorable conditions  
of food and heat4 ,fermentation results 
on a large scale from the breaking down 
of the grape sugar1 the alcohol         
remaining in the fluid1 and the carbon  
dioxide passing off into the air4 ,at   
the right time the beer is stored either

 in bottles or casks1 but fermentation  
slowly continues1 forming carbon dioxide
 in the bottles4 ,this gives the sparkle
 to beer when it is poured from the     
bottle4  ,in wine making the wild yeasts
 growing on the skin of the grapes set  
up a slow fermentation4 ,it takes       
several weeks before the wine is ready  
to bottle4 ,in sparkling wines a second 
fermentation in the bottles gives rise  
to carbon dioxide in such quantity as to
 cause a decided frothing when the      
bottle is opened4  ,commercial          
,yeast4--,cultivated yeasts are now     
supplied in the home as compressed or   
dried yeast cakes4 ,in both cases the   
yeast plants are mixed with starch and  
other substances and pressed into a     
cake4 ,but the compressed yeast cake    
must be used fresh1 as the yeast plants 
begin to die rapidly after two or three 
days4 ,the dried yeast cake1 while it   
contains a much smaller number of yeast 
plants1 is nevertheless probably more   
reliable if the yeast cannot be obtained

 fresh4  ,illustration3 a  b  c  ,the   
cut illustrates an experiment that shows
 how yeast plants depend upon food in   
order to grow4 ,in each of three        
fermentation tubes were placed an equal 
amount of a compressed yeast cake4 ,then
 tube a was filled with distilled water1
 tube b with a solution of glucose and  
water1 and tube c with a nutrient       
solution containing nitrogenous matter  
as well as glucose4 ,the quantity of gas
 7,,co#b7 in each tube is an index of   
the amount of growth of the yeast cells4
 ,in which tube did the greatest growth 
take place8  ,bread ,making4--,most of  
us are familiar with the process of     
bread making4 ,the materials used are   
flour1 milk or water or both1 salt1 a   
little sugar to hasten the process of   
fermentation1 or rising1 as it is       
called1 some butter or lard1 and yeast4 
,after mixing the materials thoroughly  
by a process called kneading1 the bread 
is put aside in a warm place 7about #ge 
deg4 ,fahrenheit7 to rise4 ,if we       

examine the dough at this time1 we find 
it filled with holes1 which give the    
mass a spongy appearance4 ,the yeast    
plants1 owing to favorable conditions1  
have grown rapidly and filled the       
cavities with carbon dioxide4 ,alcohol  
is present1 too1 but this is evaporated 
when the dough is baked4 ,the baking    
cooks the starch of the bread1 drives   
off the carbon dioxide and alcohol1 and 
kills the yeast plants1 besides forming 
a protective crust on the loaf4  ,sour  
,bread4--,if yeast cakes are not fresh1 
sour bread may result from their use4   
,in such yeast cakes there are apt to be
 present other tiny one-celled plants1  
known as bacteria4 ,certain of these    
plants form acids after fermentation    
takes place4 ,the sour taste of the     
bread is usually due to this cause4 ,the
 remedy would be to have fresh yeast1 to
 have good and fresh flour1 and to have 
clean vessels with which to work4       
,importance of ,yeasts4--,yeasts in     
their relation to man are thus seen to  

be for the most part useful4 ,they may  
get into canned substances put up in    
sugar and cause them to work1 giving    
them a peculiar flavor4 ,but they can be
 easily killed by heating to the        
temperature of boiling4 ,on the other   
hand1 yeast plants are necessary for the
 existence of all the great industries  
which depend upon fermentation4 ,and    
best of all they give us leavened bread1
 which has become a necessity to most of
 mankind4   ,,bacteria ,,in ,,their     
,,relation ,,to ,,man  ,what ,bacteria  
do and ,where ,they ,may be ,found4--,a 
walk through a crowded city street on   
any warm day makes one fully alive to   
odors which pervade the atmosphere4     
,some of these unpleasant odors1 if     
traced1 are found to come from garbage  
pails1 from piles of decaying fruit or  
vegetables1 or from some butcher shop in
 which decayed meat is allowed to stand4
 ,this characteristic phenomena of decay
 is one of the numerous ways in which we
 can detect the presence of bacteria4   

,these tiny plants1 man's invisible     
friends and foes1 are to be found       
anywhere1 but not everywhere1 in nature4
 ,they swarm in stale milk1 in impure   
water1 in soil1 in the living bodies of 
plants and animals and in their dead    
bodies as well4 ,most catching diseases 
we know to be caused directly by them2  
the processes of decay1 souring of milk1
 acid fermentation1 the manufacture of  
nitrogen for plants are directly or     
indirectly due to their presence4 ,it   
will be the purpose of the next         
paragraphs to find some of the places   
where bacteria may be found and how we  
may know of their presence4             
,illustration3 ,a steam sterilizer4     
,how we catch ,bacteria to ,study       
,them4--,to study bacteria it is first  
necessary to find some material in which
 they will grow1 then kill all living   
matter in this food material by heating 
to boiling point 7#bab deg47 for half an
 hour or more 7this is called           
sterilization71 and finally protect the 

culture medium1 as this food is called1 
from other living things that might grow
 upon it4  ,one material in which       
bacteria seem to thrive is a mixture of 
beef extract1 digested protein and      
gelatine or agar-agar1 the latter a     
preparation derived from seaweed4 ,this 
mixture1 after sterilization1 is poured 
into flat dishes with loose-fitting     
covers4 ,these petri dishes1 so called  
after their inventor1 are the traps in  
which we collect and study bacteria4    
,where ,bacteria might ,grow4--,expose a
 number of these sterilized dishes1 each
 for the same length of time1 to some of
 the following conditions3    7a7       
exposed to the air of the schoolroom4   
7b7 exposed in the halls of the school  
while pupils are passing4   7c7 exposed 
in the halls of the school when pupils  
are not moving4   7d7 exposed at the    
level of a dirty and much-used city     
street4   7e7 exposed at the level of a 
well-swept and little-used city street4 
7f7 exposed in a city park4   7g7       

exposed in a factory building4   7h7    
dirt from hands placed in dish4   7i7   
rub interior of mouth with finger and   
touch surface of dish4   7j7 touch      
surface of dish with decayed vegetable  
or meat4   7k7 touch surface of dish    
with dirty coin or bill4   7l7 place in 
dish two or three hairs from boy's head4
  ,this list might be prolonged         
indefinitely4  ,illustration3 ,colonies 
of bacteria growing in a petri dish4    
,now let us place all of the dishes     
together in a moderately warm place 7a  
closet in the schoolroom will do7 and   
watch for results4 ,after a day or two  
little spots1 brown1 yellow1 white1 or  
red1 will begin to appear4 ,these spots1
 which grow larger day by day1 are      
colonies made up of millions of         
bacteria4 ,but probably each colony     
arose from a single bacterium which got 
into the dish when it was exposed to the
 air4  ,how we may isolate ,bacteria of 
,certain ,kinds from ,others4--,in order
 to get a number of bacteria of a given 

kind to study1 it becomes necessary to  
grow them in what is known as a pure    
culture4 ,this is done by first growing 
the bacteria in some medium such as beef
 broth1 gelatin1 or on potato4#bj ,then 
as growth follows the colonies of       
bacteria appear in the culture media or 
the beef broth becomes cloudy4 ,if now  
we wish to study one given form1 it     
becomes necessary to isolate them from  
the others4 ,this is done by the        
following process3 a platinum needle is 
first passed through a flame to         
sterilize it2 that is1 to kill all      
living things that may be on the needle 
point4 ,then the needle1 which cools    
very quickly1 is dipped in a colony     
containing the bacteria we wish to      
study4 ,this mass of bacteria is quickly
 transferred to another sterilized      
plate1 and this plate is immediately    
covered to prevent any other forms of   
bacteria from entering4 ,when we have   
succeeded in isolating a certain kind of
 bacterium in a given dish1 we are said 

to have a pure culture4 ,having obtained
 a pure culture of bacteria1 they may   
easily be studied under the compound    
microscope4       ,footnote #bj3 ,for   
directions for making a culture medium1 
see      ,hunter1 ,laboratory ,problems 
in ,civic ,biology4 ,culture      tubes 
may be obtained1 already prepared1 from 
,parke1 ,davis1      and ,company or    
other good chemists4  ,illustration3 ,a 
pure culture of bacteria4 ,notice that  
the bacteria are all the same size and  
shape4  ,size and ,form4--,in size1     
bacteria are the most minute plants     
known4 ,a bacterium of average size is  
about #a_/ajjjj of an inch in length1   
and perhaps #a_/ejjjj of an inch in     
diameter4 ,some species are much larger1
 others smaller4 ,a common spherical    
form is #a_/ejjjj of an inch in         
diameter4 ,they are so small that       
several million are often found in a    
single drop of impure water or sour     
milk4 ,three well-defined forms of      
bacteria are recognized3 a spherical    

form called a coccus1 a rod-shaped      
bacterium1 the bacillus1 and a spiral   
form1 the spirillum4 ,some bacteria are 
capable of movement when living in a    
fluid4 ,such movement is caused by tiny 
lashlike threads of protoplasm called   
flagella4 ,the flagella project from the
 body1 and by a rapid movement cause    
locomotion to take place4 ,bacteria     
reproduce with almost incredible        
rapidity4 ,it is estimated that a single
 bacterium1 by a process of division    
called fission1 will give rise to over  
#af1gjj1jjj others in twenty-four hours4
 ,under unfavorable conditions they stop
 dividing and form rounded bodies called
 spores4 ,this spore is usually         
protected by a wall and may withstand   
very unfavorable conditions of dryness  
or heat2 even boiling for several       
minutes will not kill some forms4       
,illustration3 ,a figure to show the    
relative size and shape of 7#a7 a green 
mold1 7#b7 yeast cells1 and 7#c7        
different forms of bacteria2 ,b1        

bacillus2 ,c1 coccus2 ,s1 spirillum     
forms4 ,the yeast and bacteria are drawn
 to scale1 they are much enlarged in    
proportion to the green mold1 being     
actually much smaller than the mold     
spores seen at the top of the picture4  
,where ,bacteria are most               
,numerous4--,as the result of our       
experiments1 we can make some           
generalizations concerning the presence 
of bacteria in our own environment4     
,they are evidently present in the air1 
and in greater quantity in air that is  
moving than quiet air4 ,why8 ,that they 
stick to particles of dust can be proven
 by placing a little dust from the      
schoolroom in a culture dish4 ,bacteria 
are present in greater numbers where    
crowds of people live and move1 the air 
from dusty streets of a populous city   
contains many more bacteria than does   
the air of a village street4 ,the air of
 a city park contains relatively few    
bacteria as compared with the near-by   
street4 ,the air of the woods or high   

mountains fewer still4 ,why8 ,our       
previous experiment has shown that dirt 
on our hands1 the mouth and teeth1      
decayed meat and vegetables1 dirty      
money1 the very hairs of our head are   
all carriers of bacteria4  ,fluids the  
,favorite ,home of ,bacteria4--,tap     
water1 standing water1 milk1 vinegar1   
wine1 cider all can be proven to contain
 bacteria by experiments similar to     
those quoted above4 ,spring or artesian 
well water would have very few1 if any1 
bacteria1 while the same quantity of    
river water1 if it held any sewage1     
might contain untold millions of these  
little organisms4  ,foods preferred by  
,bacteria4--,if bacteria are living and 
contain no chlorophyll1 we should expect
 them to obtain protein food in order to
 grow4 ,such is not always the case1 for
 some bacteria seem to be able to build 
up protein out of simple inorganic      
nitrogenous substances4 ,if1 however1 we
 take several food substances1 some     
containing much protein and others not  

so much1 we will find that the bacteria 
cause decay in the proteins almost at   
once1 while other food substances are   
not always attacked by them4            
,illustration3 ,growth of bacteria in a 
drop of impure water allowed to run down
 a sterilized culture in a dish4  ,what 
,bacteria do to ,foods4--,when bacteria 
feed upon a protein they use part of the
 materials in the food so that it falls 
to pieces and eventually rots4 ,the     
material left behind after the bacteria 
have finished their meal is quite       
different from its original form4 ,it is
 broken down by the action of the       
bacteria into gases1 fluids1 and some   
solids4 ,it has a characteristic rotten 
odor and it has in it poisons which come
 as a result of the work of the         
bacteria4 ,these poisonous wastes1      
called ptomaines1 we shall learn more   
about later4  ,conditions ,favorable and
 ,unfavorable to the ,growth of         
,bacteria4--,moisture and               
,dryness4--,experiment4--,take two      

beans1 remove the skins1 crush one1 soak
 the second bean overnight and then     
crush it4 ,place in test tubes1 one dry1
 the second with water4 ,leave in a warm
 place two or three days1 then smell    
each tube4 ,in which is decay taking    
place8 ,in which tube are bacteria at   
work8 ,how do you know8                 
,moisture4--,moisture is an absolute    
need for bacterial growth1 consequently 
keeping material dry will prevent the   
growth of germs upon its surface4       
,foods1 in order to decay1 must contain 
enough water to make them moist4        
,bacteria grow most freely in fluids4   
,light4--,if we cover one half of a     
petri dish in which bacteria are growing
 with black paper and then place the    
dish in a light warm place for a few    
days1 the growth of bacteria in the     
light part of the dish will be found to 
be checked1 while growth continues in   
the covered part4 ,it is a matter of    
common knowledge that disease germs     
thrive where dirt and darkness exist and

 are killed by any long exposure to     
sunlight4 ,this shows us the need of    
light in our homes1 especially in our   
bedrooms4  ,air4--,we have seen that    
plants need oxygen in order to perform  
the work that they do4 ,this is equally 
true of all animals4 ,but not all       
bacteria need air to live2 in fact1 some
 are killed by the presence of air4     
,just how these organisms get the oxygen
 necessary to oxidize their food is not 
well understood4 ,the fact that some    
bacteria grow without air makes it      
necessary for us to use the one sure    
weapon we have for their extermination1 
and that is heat4                       
,heat4--,experiment4--,take four        
cultures containing bouillon1 inoculate 
each tube with bacteria and plug each   
tube with absorbent cotton4 ,place one  
tube in the ice box1 a second tube in a 
dark closet at a moderate temperature1 a
 third in a warm place 7about #ajj deg4 
,fahrenheit71 and boil the contents of  
the fourth tube for ten minutes1 then   

place it with tube number two4 ,in which
 tubes does growth take place most      
rapidly8 ,why8  ,bacteria grow very     
slowly if at all in the temperature of  
an ice box1 very rapidly at the room    
temperature of from #gj deg4 to #ij deg4
 and much less rapidly at a higher      
temperature4 ,all bacteria except those 
which have formed spores can be         
instantly killed as soon as boiling     
point is reached1 and most spores are   
killed by a few minutes boiling4        
,sterilization4--,the practical lessons 
drawn from sterilization are many4 ,we  
know enough now to boil our drinking    
water if we are uncertain of its purity2
 we sterilize any foods that we believe 
might harbor bacteria1 and thus keep    
them from spoiling4 ,the industry of    
canning is built upon the principle of  
sterilization4  ,canning4--,canning is  
simply a method by which first the      
bacteria in a substance are killed by   
heating and then the substance is put   
into vessels into which no more bacteria

 may gain entrance4 ,this is usually    
done at home by boiling the fruit or    
vegetable to be canned either in salt   
and water or with sugar and water1      
either of which substances aids in      
preventing the growth of bacteria4 ,the 
time of boiling will be long or short1  
depending upon the materials to be      
canned4 ,some vegetables1 as peas1      
beans1 and corn1 are very difficult to  
can1 probably because of spores of      
bacteria which may be attached to them4 
,fruits1 on the other hand1 are usually 
much easier to preserve4 ,after boiling 
for the proper time1 the food1 now free 
from all bacteria1 must be put into jars
 or cans that are themselves absolutely 
sterile or free from germs4 ,this is    
done by first boiling the jars1 then    
pouring the boiling hot material into   
the hot jars and sealing them so as to  
prevent the entrance of bacteria later4 
,uses of ,canning4--,canning as an      
industry is of immense importance to    
mankind4 ,not only does it provide him  

with fruits and vegetables at times when
 he could not otherwise get them1 but it
 also cheapens the cost of such things4 
,it prevents the waste of nature's      
products at a time when she is most     
lavish with them1 enabling man to store 
them and utilize them later4 ,canning   
has completely changed the life of the  
sailor and the soldier1 who in former   
times used to suffer from various       
diseases caused by lack of a proper     
balance of food4  ,illustration3        
,pasteurizing milk4 ,why should this be 
done8  ,pasteurization4--,milk is one of
 the most important food supplies of a  
great city4 ,it is also one of the most 
difficult supplies to get in good       
condition4 ,this is in part due to the  
fact that milk is produced at long      
distances from the city and must be     
brought first from farms to the         
railroads1 then shipped by train1 again 
taken to the milk supply depot by wagon1
 there bottled1 and again shipped by    
delivery wagons to the consumers4 ,when 

we remember that much of the milk used  
in ,new ,york ,city is forty-eight hours
 old and when we realize that bacteria  
grow very rapidly in milk1 we see the   
need of finding some way to protect the 
supply so as to make it safe1           
particularly for babies and young       
children4  ,this is done by             
pasteurization1 a method named after the
 ,french bacteriologist ,louis ,pasteur4
 ,to pasteurize milk we heat it to a    
temperature of not over #agj deg4       
,fahrenheit for from ten minutes to half
 an hour4 ,by such a process all harmful
 germs will be killed and the keeping   
qualities of the milk greatly           
lengthened4 ,most large milk companies  
pasteurize their city supply by a rapid 
pasteurization at a much higher         
temperature1 but this method slightly   
changes the flavor of the milk4  ,cold  
,storage4--,man has also come to use    
cold to keep bacteria from growing in   
foods4 ,the ice box at home and cold    
storage on a larger scale enables one to

 keep foods for a more or less lengthy  
period4 ,if food is frozen1 as in cold  
storage1 it might keep without growth of
 bacteria for years4 ,but fruits and    
vegetables cannot be frozen without     
spoiling their flavor4 ,and all foods   
after freezing seem particularly        
susceptible to the bacteria of decay4   
,for that reason products taken from    
cold storage must be used at once4      
,ptomaines4--,many foods get their      
flavor from the growth of molds or      
bacteria in them4 ,cheese1 butter1 the  
gamey taste of certain meats1 the flavor
 of sauerkraut1 are all due to the work 
of bacteria4 ,but if bacteria are       
allowed to grow so as to become very    
numerous1 the ptomaines which result    
from their growth in foods may poison   
the person eating such foods4           
,frequently ptomaine poisoning occurs in
 the summer time because of the rapid   
growth of bacteria4 ,much of the        
indigestion and diarrhoea which attack  
people during the summer is doubtless   

due to this kind of poisoning4          
,preservatives4#ba--,this leads us to   
ask if we may not preserve food in ways 
other than those mentioned so as to     
protect ourselves from danger of        
ptomaine poisoning4 ,many substances    
check the development of bacteria and in
 this way they preserve the food4       
,preservatives are of two kinds1 those  
harmless to man and those that are      
poisonous4 ,of the former1 salt and     
sugar are examples2 of the latter1      
formaldehyde and possibly benzoic acid4 
,footnote #ba3 ,perform experiment here 
to determine the value      of different
 preservatives4 ,use sugar1 salt1       
vinegar1      boracic acid1 benzoic     
acid1 formaldehyde1 and alcohol4        
,sugar4--,we have noted the use of sugar
 in canning4 ,small amounts of sugar    
will be readily attacked by yeasts1     
molds1 and bacteria1 but a #dj to #ej   
per cent solution will effectually keep 
out bacteria4 ,preserves are fruits     
boiled in about their own weight of     

sugar4 ,condensed milk is preserved by  
the sugar added to it2 so are candied   
and1 in part1 dried fruits4             
,salt4--,salt has been used for         
centuries to keep foods4 ,meats are     
smoked1 dried1 and salted2 some are put 
down in strong salt solutions4 ,fish1   
especially cod and herring1 are dried   
and salted4 ,the keeping of butter is   
also due to the salt mixed with it4     
,vinegar is another preservative4 ,it1  
like salt1 changes the flavor of        
materials kept in it and so cannot come 
into wide use4 ,spices are also used as 
preservatives4  ,harmful                
,preservatives4--,certain chemicals and 
drugs1 used as preservatives1 seem to be
 on the border line of harmfulness4     
,such are benzoic acid1 borax1 or       
boracic acid4 ,such drugs may be        
harmless in small quantities1 but       
unfortunately in canned goods we do not 
always know the amount used4 ,the       
national government in #aijf passed what
 is known as the ,pure ,food ,law1 which

 makes it illegal to use any of these   
preservatives 7excepting benzoic acid in
 very small amounts74 ,food which       
contains this preservative will be so   
labeled and should not be given to      
children or people with weak digestion4 
,unfortunately people do not always read
 the labels and thus the pure food law  
is ineffective in its working4          
,infrequently formaldehyde or other     
preservatives are used in milk4 ,such   
treatment renders milk unfit for        
ordinary use and is an illegal process4 
,disinfectants4#bb--;,frequently it     
becomes necessary to destroy bacteria   
which cause diseases of various kinds4  
,this process is called disinfecting4   
,the substances commonly used are       
carbolic acid1 formalin or formaldehyde1
 lysol1 and bichloride of mercury4 ,of  
these1 the last named is the most       
powerful as well as the most dangerous  
to use4 ,as it attacks metal1 it should 
not be used in a metal pail or dish4 ,it
 is commonly put up in tablets which are

 mixed to form a #a to #ajjj solution4  
,such tablets should be carefully       
safeguarded because of possible         
accidental poisoning4       ,footnote   
#bb3 ,experiment to determine the most  
effective      disinfectants4 ,use tubes
 of bouillon containing different       
strength solutions of formaldehyde1     
lysol1 iodine1 carbolic      acid1 and  
bichloride of mercury4 ,results4        
,conclusions4  ,formaldehyde used in    
liquid form is an excellent             
disinfectant4 ,when burned in a formalin
 candle1 it sets free an intensely      
pungent gas which is often used for     
disinfecting sick rooms after the       
patient has been removed4  ,carbolic    
acid is perhaps the best disinfectant of
 all4 ,if used in a solution of about #a
 part to #be of water1 it will not burn 
the skin4 ,it is of particular value to 
disinfect skin wounds1 as it heals as   
well as cleanses when used in a weak    
solution4 ,its rather pleasant odor     
makes it useful to cover up unpleasant  

smells of the sick room4  ,the fumes of 
burning sulphur1 which are so often used
 for disinfecting1 are of little real   
value4  ,illustration3 ,this shows how  
organic matter is broken down by        
bacteria so it may be used again by     
green plants4  ,bacteria cause          
,decay4--,let us next see in what ways  
the bacteria directly influence man upon
 the earth4 ,have you ever stopped to   
consider what life would be like on the 
earth if things did not decay8 ,the sea 
would soon be filled and the land       
covered with dead bodies of plants and  
animals4 ,conditions of life would      
become impossible and living things on  
the earth would cease to exist4         
,fortunately1 bacteria cause decay4 ,all
 organic matter1 in whatever form1 is   
sooner or later decomposed by the action
 of untold millions of bacteria which   
live in the air1 water1 and soil4 ,these
 soil bacteria are most numerous in rich
 damp soils containing large amounts of 
organic material4 ,they are very        

numerous around and in the dead bodies  
of plants and animals4 ,to a            
considerable degree1 then1 these        
bacteria are useful in feeding upon     
these dead bodies1 which otherwise would
 soon cover the surface of the earth to 
the exclusion of everything else4       
,bacteria may thus be scavengers4 ,they 
oxidize organic materials1 changing them
 to compounds that can be absorbed by   
plants and used in building protoplasm4 
,without bacteria and fungi it would be 
impossible for life to exist on the     
earth1 for green plants would be unable 
to get the raw food materials in forms  
that could be used in making food and   
living matter4 ,in this respect bacteria
 are of the greatest service to mankind4
  ,illustration3 ,microscopic appearance
 of ordinary milk1 showing fat globules 
and bacteria which cause the souring of 
milk4  ,relation to                     
,fermentation4--,they may incidentally1 
as a result of this process of decay1   
continue the process of fermentation    

begun by the yeasts4 ,in making vinegar 
the yeasts first make alcohol 7see page 
#ace7 which the bacteria change to      
acetic acid4 ,the lactic acid bacteria1 
which sour milk1 changing the milk sugar
 to an acid1 grow very rapidly in a warm
 temperature2 hence milk which is cooled
 immediately and kept cool or which is  
pasteurized and kept in a cool place    
will not sour readily4 ,why8 ,these same
 lactic acid bacteria may be useful when
 they sour the milk for the cheese      
maker4  ,other ,useful                  
,bacteria4--,certain bacteria give      
flavor to cheese and butter1 while still
 other bacteria aid in the curing of    
tobacco1 in the production of the dye   
indigo1 in the preparation of certain   
fibers of plants for the market1 as     
hemp1 flax1 etc41 in the rotting of     
animal matter from the skeletons of     
sponges1 and in the process of tanning  
hides to make leather4  ,illustration3  
,a field of alfalfa1 a plant which      
harbors the nitrogen-fixing bacteria4   

,nitrogen-fixing ,bacteria4--,still     
other bacteria1 as we have seen before1 
change over nitrogen in organic material
 in the soil and even the free nitrogen 
of the air so that it can be used by    
plants in the form of a compound of     
nitrogen4 ,the bacteria living in       
tubercles on the roots of clover1 beans1
 peas1 etc41 have the power of thus     
fixing the free nitrogen in the air     
found between particles of soil4 ,this  
fact is made use of by farmers who      
rotate their crops1 growing first a crop
 of clover or other plants having root  
tubercles1 which produce the bacteria1  
then plowing these in and planting      
another crop1 as wheat or corn1 on the  
same area4 ,the latter plants1 making   
use of the nitrogen compounds there1    
produce a larger crop than when grown in
 ground containing less nitrogenous     
material4  ,bacteria cause              
,disease4--,the most harmful bacteria   
are those which cause diseases of plants
 and animals4 ,certain diseases of      

plants--blights1 rots1 and wilts--are of
 bacterial nature4 ,these do much annual
 damage to fruits and other parts of    
growing plants useful to man as food4   
,but by far the most important are the  
bacteria which cause disease in man4    
,they accomplish this by becoming       
parasites in the human body4 ,millions  
upon millions of bacteria exist in the  
human body at all times--in the mouth1  
on the teeth1 in the blood1 and         
especially in the lower part of the food
 tube4 ,some in the food tube are       
believed to be useful1 some harmless1   
and some harmful2 others in the mouth   
cause decay of the teeth1 while a few   
kinds1 if present in the body1 may cause
 disease4  ,illustration3 ,tubercles on 
the roots of the soy bean4 ,they contain
 the nitrogen-fixing bacteria4          
7,fletcher's ,soils47 ,copyright by     
,doubleday1 ,page and ,company4  ,it is 
known that bacteria1 like other living  
things1 feed and give off organic waste 
from their own bodies4 ,this waste1     

called a toxin1 is poison to the host on
 which the bacteria live1 and it is     
usually the production of this toxin    
that causes the symptoms of disease4    
,some forms1 however1 break down tissues
 and plug up the small blood vessels1   
thus causing disease4  ,diseases caused 
by ,bacteria4--,it is estimated that    
bacteria cause annually over #ej per    
cent of the deaths of the human race4   
,as we will later see1 a very large     
proportion of these diseases might be   
prevented if people were educated       
sufficiently to take the proper         
precautions to prevent their spread4    
,these precautions might save the lives 
of some #c1jjj1jjj of people yearly in  
,europe and ,america4 ,tuberculosis1    
typhoid fever1 diphtheria1 pneumonia1   
blood poisoning1 syphilis1 and a score  
of other germ diseases ought not to     
exist4 ,a good deal more than half of   
the present misery of this world might  
be prevented and this earth made cleaner
 and better by the cooperation of the   

young people now growing up to be our   
future home makers4  ,illustration3 ,a  
single cell scraped from the roof of the
 mouth and highly magnified4 ,the little
 dots are bacteria1 most of which are   
harmless4 ,notice the comparative size  
of bacteria and cell4  ,how we take     
,germ ,diseases4--,germ or contagious   
diseases either enter the body by way of
 the mouth1 nose1 or other body         
openings1 or through a break in the     
skin4 ,they may be carried by means of  
air1 food1 or water1 but are usually    
transmitted directly from the person who
 has the disease to a well person4 ,this
 may be done through personal contact or
 by handling articles used by the sick  
person or by drinking or eating foods   
which have received some of the germs4  
,from this it follows that if we know   
the methods by which a given disease is 
communicated1 we may protect ourselves  
from it and aid the civic authorities in
 preventing its spread4  ,illustration3 
,deaths from tuberculosis compared with 

other contagious diseases in the city of
 ,new ,york in #aijh4                   
,tuberculosis4--,the one disease        
responsible for the greatest number of  
deaths--perhaps one seventh of the total
 on the globe--is tuberculosis4 ,it is  
estimated that of all people alive in   
the ,united ,states to-day1 #e1jjj1jjj  
will die of this disease4 ,but this     
disease is slowly but surely being      
overcome4 ,it is believed that within   
perhaps one hundred years1 with the aid 
of good laws and sanitary living1 it    
will be almost extinct4  ,illustration3 
,this curve shows a decreasing death    
rate from tuberculosis4 ,explain4       
,tuberculosis is caused by the growth of
 bacteria1 called the tubercle bacilli1 
within the lungs or other tissues of the
 human body4 ,here they form little     
tubers full of germs1 which close up the
 delicate air passages in the lungs1    
while in other tissues they give rise to
 hip-joint disease1 scrofula1 lupus1 and
 other diseases1 depending on the part  

of the body they attack4 ,tuberculosis  
may be contracted by taking the bacteria
 into the throat or lungs or possibly by
 eating meat or drinking milk from      
tubercular cattle4 ,especially is it    
communicated from a consumptive to a    
well person by kissing1 by drinking or  
eating from the same cup or plate1 using
 the same towels1 or in coming in direct
 contact with the person having the     
germs in his body4 ,although there are  
always some of the germs in the air of  
an ordinary city street1 and though we  
may take some of these germs into our   
bodies at any time1 yet the bacteria    
seem able to gain a foothold only under 
certain conditions4 ,it is only when the
 tissues are in a worn-out condition1   
when we are run down1 as we say1 that   
the parasite may obtain a foothold in   
the lungs4 ,even if the disease gets a  
foothold1 it is quite possible to cure  
it if it is taken in time4 ,the germ of 
tuberculosis is killed by exposure to   
bright sunlight and fresh air4 ,thus the

 course of the disease may be arrested1 
and a permanent cure brought about1 by a
 life in the open air1 the patient      
sleeping out of doors1 taking plenty of 
nourishing food and very little         
exercise4 ,see also ,chapter ,,xxiv4    
,illustration3 ,this figure shows how   
sewage from a cesspool 7c7 might get    
into the water supply3 lm1 layer of     
rock2 w1 wash water4  ,typhoid          
,fever4--,one of the most common germ   
diseases in this country and ,europe is 
typhoid fever4 ,this is a disease which 
is conveyed by means of water and food1 
especially milk1 oysters1 and uncooked  
vegetables4 ,typhoid fever germs live in
 the intestine and from there get into  
the blood and are carried to all parts  
of the body4 ,a poison which they give  
off causes the fever so characteristic  
of the disease4 ,the germs multiply very
 rapidly in the intestine and are passed
 off from the body with the excreta from
 the food tube4 ,if these germs get into
 the water supply of a town1 an epidemic

 of typhoid will result4 ,among the     
recent epidemics caused by the use of   
water containing typhoid germs have been
 those in ,butler1 ,pa41 where #acfd    
persons were made ill2 ,ithaca1 ,n4 ,y41
 with #acej cases2 and ,watertown1 ,n4  
,y41 where over #ejjj cases occurred4   
,another source of infection is milk4   
,frequently epidemics have occurred     
which were confined to users of milk    
from a certain dairy4 ,upon             
investigation it was found that a case  
of typhoid had occurred on the farm     
where the milk came from1 that the germs
 had washed into the well1 and that this
 water was used to wash the milk cans4  
,once in the milk1 the bacteria         
multiplied rapidly1 so that the milkman 
gave out cultures of typhoid in his milk
 bottles4 ,proper safeguarding of our   
water and milk supply is necessary if we
 are to keep typhoid away4  ,blood      
,poisoning4--,the bacterium causing     
blood poisoning is another toxin-forming
 germ4 ,it lives in dust and dirt and is

 often found on the skin4 ,it enters the
 body through cuts or bruises4 ,it seems
 to thrive best in less oxygen than is  
found in the air4 ,it is therefore      
important not to close up with          
court-plaster wounds which such germs   
may have entered4 ,it1 with typhoid1 is 
responsible for four times as many      
deaths as bullets and shells in time of 
battle4 ,the wonderfully small death    
rate of the ,japanese army in their war 
with ,russia was due to the fact that   
the ,japanese soldiers always boiled    
their drinking water before using it1   
and their surgeons always dressed all   
wounds on the battlefield1 using        
powerful antiseptics in order to kill   
any bacteria that might have lodged in  
the exposed wounds4  ,illustration3     
,this figure shows how a milk route     
might be instrumental in spreading      
diphtheria4 ,x is a farm on which a case
 of diphtheria occurred that was        
responsible for all the cases along milk
 routes ,a and ,f in ,hyde ,park1       

,dorchester1 and ,milton4 ,how would you
 explain this8  ,other ,diseases4--,many
 other diseases have been traced to     
bacteria4 ,diphtheria is one of the best
 known4 ,as it is a throat disease1 it  
may easily be conveyed from one person  
to another by kissing1 putting into the 
mouth objects which have come in contact
 with the mouth of the patient1 or by   
food into which the germs have been     
carried4 ,another disease which probably
 causes more misery in the world than   
any other germ disease is syphilis4     
,hundreds of thousands of new-born      
babies die annually or grow up          
handicapped by deformities from this    
dread scourge4 ,syphilis and gonorrhea1 
both diseases of the same sort and      
contracted in the same manner1 hand down
 to innocent wives and still more       
innocent children a heritage of disease 
even unto the third and fourth          
generation4 ,grippe1 pneumonia1 whooping
 cough1 and colds are believed to be    
caused by bacteria4 ,other diseases1 as 

malaria1 yellow fever1 sleeping         
sickness1 and probably smallpox1 scarlet
 fever1 and measles1 are due to the     
attack of one-celled animal parasites4  
,of these we shall learn later in       
,chapter ,,xv4  ,immunity4--,it has been
 found that after an attack of a germ   
disease the body will not soon be again 
attacked by the same disease4 ,this     
immunity1 of which we will learn more   
later1 seems to be due to a manufacture 
in the blood of substances which fight  
the bacteria or their poisons4 ,if a    
person keeps his body in good physical  
condition and lives carefully1 he will  
do much toward acquiring this natural   
immunity4  ,acquired ,immunity4--,modern
 medicine has discovered means of       
protecting the body from some contagious
 diseases4 ,vaccination as protection   
against smallpox1 the use of antitoxins 
7of which more later7 against           
diphtheria1 and inoculation against     
typhoid are all ways in which we may be 
protected against diseases4  ,methods of

 fighting ,germ ,diseases4--,as we have 
seen1 diseases produced by bacteria may 
be caused by the bacteria being directly
 transferred from one person to another1
 or the disease may obtain a foothold in
 the body from food1 water1 or by taking
 them into the blood through a cut or a 
wound or a body opening4  ,it is evident
 that as individuals we may each do     
something to prevent the spread of germ 
diseases1 especially in our homes4 ,we  
may keep our bodies1 especially our     
hands and faces1 clean4 ,sweeping and   
dusting may be done with damp cloths so 
as not to raise a dust2 our milk and    
water1 when from a suspicious supply1   
may be sterilized or pasteurized4       
,wounds through which bacteria might    
obtain foothold in the body should be   
washed with some antiseptic such as     
carbolic acid 7#a part to #be water71   
which kills the germs4 ,in a later      
chapter we shall learn more of how we   
may cooperate with the authorities to   
combat disease and make our city or town

 a better place in which to live4#bc    
,footnote #bc3 ,teachers may take up    
parts or all of ,chapter      ,,xxiv at 
this point4 ,i have found it advisable  
to repeat much      of the work on      
bacteria after the students have taken  
up      the study of the human organism4
                            ,,reference 
,,books                                 
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,bigelow1          
,introduction to ,biology4 ,the         
,macmillan ,company4      ,conn1        
,bacteria1 ,yeasts1 and ,molds in the   
,home4 ,ginn and        ,company4       
,conn1 ,story of ,germ ,life4 ,d4       
,appleton and ,company4      ,davison1  
,the ,human ,body and ,health4 ,american
 ,book ,company4      ,frankland1       
,bacteria in ,daily ,life4 ,longmans1   
,green1 and        ,company4            
,overton1 ,general ,hygiene4 ,american  
,book ,company4      ,prudden1 ,dust and
 its ,dangers4 ,g4 ,p4 ,putnam's ,sons4 

,prudden1 ,the ,story of the ,bacteria4 
,g4 ,p4 ,putnam's ,sons4      ,ritchie1 
,primer of ,sanitation4 ,world ,book    
,company4      ,sharpe1 ,laboratory     
,manual in ,biology1 pages #abc-acb4    
,american ,book ,company4               
,,advanced       ,conn1 ,agricultural   
,bacteriology4 ,p4 ,blakiston's ,sons   
and        ,company4      ,coulter1     
,barnes1 and ,cowles1 ,a ,textbook of   
,botany1 ,vol4 ,i4        ,american     
,book ,company4      ,de ,bary1         
,comparative ,morphology and ,biology of
 the ,fungi1        ,mycetozoa1 and     
,bacteria4 ,clarendon ,press4           
,duggar1 ,fungous ,diseases of ,plants4 
,ginn and ,company4      ,hough and     
,sedgwick1 ,the ,human ,mechanism4 ,ginn
 and ,company4      ,hutchinson1        
,preventable ,diseases4 ,houghton1      
,mifflin and        ,company4      ,lee1
 ,scientific ,features of ,modern       
,medicine4 ,columbia        ,university 
,press4      ,muir and ,ritchie1 ,manual
 of ,bacteriology4 ,the ,macmillan      

,company4      ,newman1 ,the ,bacteria4 
,g4 ,p4 ,putnam's ,sons4      ,sedgwick1
 ,principles of ,sanitary ,science and  
,public        ,health4 ,the ,macmillan 
,company4      ,,xii4 ,,the ,,relations 
,,of ,,plants ,,to ,,animals            
,problems4--,to determine the general   
biological relations existing between   
plants and animals4           7a7 ,as   
shown in a balanced aquarium4           
7b7 ,as shown in hay infusion4          
,,suggestions ,,for ,,laboratory ,,work 
,demonstration of life in a balanced and
 unbalanced                             
aquarium4--,determination of factors    
causing balance4      ,demonstration of 
hay infusion4--,examination to show     
forms of animal        and plant life4  
,tabular comparison between balanced    
aquarium and hay infusion4   ,some ,ways
 in which ,plants affect ,animals4--,we 
have been studying the life of plants in
 order better to understand the life of 
animals and men4 ,we have seen first    
that green plants play indirectly a     

tremendous part in man's welfare by     
supplying him with food4 ,we have found 
that the colorless plants directly      
affected his welfare by causing disease1
 and by causing decay1 thus making      
usable the nitrogen locked up in dead   
bodies of plants and animals1 and by    
some even supplying nitrogen from the   
atmosphere4 ,the dependence of animals  
upon plants has been shown and the      
interdependence of plants on animals has
 also been seen in cross-pollination and
 in the supply of raw food materials to 
plants by animals4  ,study of a         
,balanced ,aquarium4--,perhaps the best 
way for us to understand the            
interrelation between plants and animals
 is to study an aquarium in which plants
 and animals live and in which a balance
 has been established between the plant 
life on one side and animal life on the 
other4 ,aquaria containing green pond   
weeds1 either floating or rooted1 a few 
snails1 some tiny animals known as water
 fleas1 and a fish or two will1 if kept 

near a light window1 show this relation4
  ,illustration3 ,a balanced aquarium4  
,explain the term balanced4  ,we have   
seen that green plants under favorable  
conditions of sunlight1 heat1 moisture1 
and with a supply of raw food materials1
 give off oxygen as a by-product while  
manufacturing food in their green cells4
 ,we know the necessary raw materials   
for starch manufacture are carbon       
dioxide and water1 while nitrogenous    
material is necessary for the making of 
proteins within the plant4 ,in previous 
experiments we have proved that carbon  
dioxide is given off by any living thing
 when oxidation occurs in the body4 ,the
 crawling snails and the swimming fish  
give off carbon dioxide1 which is       
dissolved in the water2 the plants      
themselves1 at all times1 oxidize food  
within their bodies1 and so must pass   
off some carbon dioxide4 ,the green     
plants in the daytime use up the carbon 
dioxide obtained from the various       
sources and1 with the water taken in1   

manufacture starch4 ,while this process 
is going on1 oxygen is given off to the 
water of the aquarium1 and this free    
oxygen is used by the animals there4    
,illustration3 ,this diagram shows that 
plants and animals on the earth hold the
 same relation to each other as plants  
and animals in a balanced aquarium4     
,explain the diagram in your notebook4  
,illustration3 ,the carbon and oxygen   
cycle in the balanced aquarium4 ,trace  
by means of the arrows the carbon from  
the time plants take it in as ,,co#b    
until animals give it off4 ,show what   
happens to the oxygen4  ,but the plants 
are continually growing larger4 ,the    
snails and fish1 too1 eat parts of the  
plants4 ,thus the plant life gives food 
to the animals within the aquarium4 ,the
 animals give off certain nitrogenous   
wastes of which we shall learn more     
later4 ,these materials1 with other     
nitrogenous matter from the dead parts  
of the plants or animals1 form part of  
the raw material used for protein       

manufacture in the plant4 ,this         
nitrogenous matter is prepared for use  
by several different kinds of bacteria  
which first break the dead bodies down  
and then give it to the plants in the   
form of soluble nitrates4 ,the green    
plants manufacture food1 the animals eat
 the plants and give off organic waste1 
from which the plants in turn make their
 food and living matter4 ,the plants    
give off oxygen to the animals1 and the 
animals give carbon dioxide to the      
plants4 ,thus a balance exists between  
the plants and animals in the aquarium4 
,make a table to show this balance4     
,illustration3 ,the relations between   
green plants and animals4  ,relations   
between ,green ,plants and              
,animals4--,what goes on in the aquarium
 is an example of the relation existing 
between all green plants and all        
animals4 ,everywhere in the world green 
plants are making food which becomes1   
sooner or later1 the food of animals4   
,man does not feed to a great extent    

upon leaves1 but he eats roots1 stems1  
fruits1 and seeds4 ,when he does not    
feed directly upon plants1 he eats the  
flesh of plant eating animals1 which in 
turn feed directly upon plants4 ,and so 
it is the world over2 the plants are the
 food makers and supply the animals4    
,green plants also give a very          
considerable amount of oxygen to the    
atmosphere every day1 which the animals 
may use4  ,illustration3 ,the nitrogen  
cycle4 ,trace the nitrogen from its     
source in the air until it gets back    
again into the air4  ,the ,nitrogen     
,cycle4--,the animals in their turn     
supply much of the carbon dioxide that  
the plant uses in starch making4 ,they  
also supply some of the nitrogenous     
matter used by the plants1 part being   
given the plants from the dead bodies of
 their own relatives and part being     
prepared from the nitrogen of the air   
through the agency of bacteria1 which   
live upon the roots of certain plants4  
,these bacteria are the only organisms  

that can take nitrogen from the air4    
,thus1 in spite of all the nitrogen of  
the atmosphere1 plants and animals are  
limited in the amount available4 ,and   
the available supply is used over and   
over again1 perhaps in nitrogenous food 
by an animal1 then it may be given off  
as organic waste1 get into the soil1 and
 be taken up by a plant through the     
roots4 ,eventually the nitrogen forms   
part of the food supply in the body of  
the plant1 and then may become part of  
its living matter4 ,when the plant dies1
 the nitrogen is returned to the soil4  
,thus the usable nitrogen is kept in    
circulation4#bd       ,footnote #bd3 ,a 
small amount of nitrogen gas is returned
 to      the atmosphere by the action of
 the decomposing bacteria on      the   
ammonia compounds in the soil4 7,see    
figure of nitrogen      cycle47         
,symbiosis4--,we have seen that in the  
balanced aquarium the animals and       
plants1 in a wide sense1 form a sort of 
unconscious partnership4 ,this process  

of living together for mutual advantage 
is called symbiosis4 ,some animals thus 
combine with plants2 for example1 the   
tiny animal known as the hydra with     
certain of the one-celled algae1 and1 if
 we accept the term in a wide sense1 all
 green plants and animals live in this  
relation of mutual give and take4       
,animals also frequently live in this   
relation to each other1 as the crab1    
which lives within the shell of the     
oyster2 the sea anemones1 which are     
carried around on the backs of some     
hermit crabs1 aiding the crab in        
protecting it from its enemies1 and     
being carried about by the crab to      
places where food is plentiful4         
,illustration3 ,life in the late stage  
of a hay infusion4 ,b1 bacteria1        
swimming or forming masses of food upon 
which the one-celled animals1 the       
paramoecia1 are feeding2 ,g1 gullet2    
,f4,v41 food vacuole2 ,c4,v41           
contractile vacuole2 ,p1 pleurococcus2  
,p4,d41 pleurococcus dividing4 7,drawn  

from nature by ,j4 ,w4 ,teitz47  ,a ,hay
 ,infusion4--,still another example of  
the close relation between plants and   
animals may be seen in the study of a   
hay infusion4 ,if we place a wisp of hay
 or straw in a small glass jar nearly   
full of water1 and leave it for a few   
days in a warm room1 certain changes are
 seen to take place in the contents of  
the jar2 after a little while the water 
gets cloudy and darker in color1 and a  
scum appears on the surface4 ,if some of
 this scum is examined under the        
compound microscope1 it will be found to
 consist almost entirely of bacteria4   
,these bacteria evidently aid in the    
decay which 7as the unpleasant odor from
 the jar testifies7 is beginning to take
 place4 ,as we have learned1 bacteria   
flourish wherever the food supply is    
abundant4 ,the water within the jar has 
come to contain much of the food        
material which was once within the      
leaves of the grass1--organic nutrients1
 starch1 sugar1 and proteins1 formed in 

the leaf by the action of the sun on the
 chlorophyll of the leaf1 and now       
released into the water by the breaking 
down of the walls of the cells of the   
leaves4 ,the bacteria themselves release
 this food from the hay by causing it to
 decay4 ,after a few days small         
one-celled animals appear2 these        
multiply with wonderful rapidity1 so    
that in some cases the surface of the   
water seems to be almost white with     
active one-celled forms of life4 ,if we 
ask ourselves where these animals come  
from1 we are forced to the conclusion   
that they must have been in the water1  
in the air1 or on the hay4 ,hay is dried
 grass and may have been cut in a field 
near a pool containing these creatures4 
,when the pool dried up1 the wind may   
have scattered some of these little     
organisms in the dried mud or dust4     
,some may have existed in a dormant     
state on the hay and the water awakened 
them to active life4 ,in the water1 too1
 there may have been some living cells1 

plants and animals4  ,at first the      
multiplication of the tiny animals      
within the hay infusion is extremely    
rapid2 there is food in abundance and   
near at hand4 ,after a few days more1   
however1 several kinds of one-celled    
animals may appear1 some of which prey  
upon others4 ,consequently a struggle   
for life takes place1 which becomes more
 and more intense as the food from the  
hay is used up4 ,eventually the end     
comes for all the animals unless some   
green plants obtain a foothold within   
the jar4 ,if such a thing happens1 food 
will be manufactured within their       
bodies1 a new food supply arises for the
 animals within the jar1 and a balance  
of life may result4                     
,,reference ,,books                     
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,sharpe1 ,a        
,laboratory ,manual for the ,solution of
 ,problems in        ,biology1 pp4      
#acc-ach4 ,american ,book ,company4     

,,advanced       ,eggerlin and          
,ehrenberg1 ,the ,fresh ,water ,aquarium
 and its        ,inhabitants4 ,henry    
,holt and ,company4      ,furneaux1     
,life in ,ponds and ,streams4 ,longmans1
 ,green1 and        ,company4           
,parker1 ,biology4 ,the ,macmillan      
,company4      ,sedgwick and ,wilson1   
,biology4 ,henry ,holt and ,company4    
,,xiii4 ,,single-,,celled ,,animals     
,,considered ,,as ,,organisms           
,problems4--,to determine3           7a7
 ,how a one-celled animal is influenced 
by its environment4           7b7 ,how a
 single cell performs its functions4    
7c7 ,the structure of a single-celled   
animal4                                 
,,laboratory ,,suggestions              
,laboratory study4--,study of           
paramoecium under compound              
microscope in its relation to food1     
oxygen1 etc4        ,determination of   
method of movement1 turning1 avoiding   
obstructions1 sensitiveness to stimuli4 
,drawings to        illustrate above    

points4      ,laboratory                
demonstration4--,living paramoecium to  
show        structure of cell4          
,demonstration with carmine to show food
        vacuoles1 and action of cilia4  
,use of charts and stained              
specimens to show other points of cell  
structure4 ,laboratory                  
demonstration of fission4               
,illustration3 ,pleurococcus4 ,a very   
simple plant cell4  ,the ,simplest      
,plants4--,we have seen that perhaps the
 simplest plant would be exemplified by 
one of the tiny bacteria we have just   
read about4 ,a typical one-celled plant1
 however1 would contain green coloring  
matter or chlorophyll1 and would have   
the power to manufacture its own food   
under conditions giving it a moderate   
temperature1 a supply of water1 oxygen1 
carbon dioxide1 and sunlight4 ,such a   
simple plant is the pleurococcus1 the   
green slime seen on the shady sides of  
trees1 stones1 or city houses4 ,this    
plant would meet one definition of a    

cell1 as it is a minute mass of         
protoplasm containing a nucleus4 ,it is 
surrounded by a wall of a woody material
 formed by the activity of the living   
matter within the cell4 ,it also        
contains a little mass of protoplasm    
colored green4 ,of the work of the      
chlorophyll in the manufacture of       
organic food we have already learned4   
,such is a simple plant cell4 ,let us   
now examine a simple animal cell in     
order to compare it with that of a      
plant4  ,where to find                  
,paramoecium4--,if we examine very      
carefully the surface of a hay infusion1
 we are likely to notice in addition to 
the scum formed of bacteria1 a mass of  
whitish tiny dots collected along the   
edge of the jar close to the surface of 
the water4 ,more attentive observation  
shows us that these objects move1 and   
that they are never found far from the  
surface4  ,the ,life ,habits of         
,paramoecium4--,if we place on a slide a
 drop of water containing some of these 

moving objects and examine it under the 
compound microscope1 we find each minute
 whitish dot is a cell1 elongated1 oval1
 or elliptical in outline and somewhat  
flattened4 ,this is a one-celled animal 
known as the paramoecium or the slipper 
animalcule 7because of its shape74      
,seen under the low power of the        
microscope1 it appears to be extremely  
active1 rushing about now rapidly1 now  
more slowly1 but seemingly always taking
 a definite course4 ,the narrower end of
 the body 7the anterior7 usually goes   
first4 ,if it pushes its way past any   
dense substance in the water1 the cell  
body is seen to change its shape        
temporarily as it squeezes through4     
,response to ,stimuli4--,many of these  
little creatures may be found collected 
around masses of food1 showing that they
 are attracted by it4 ,in another part  
of the slide we may find a number of the
 paramoecia lying close to the edge of  
an air bubble with the greatest possible
 amount of their surface exposed to its 

surface4 ,these animals are evidently   
taking in oxygen by osmosis4 ,they are  
breathing4 ,a careful inspection of the 
jar containing paramoecia shows         
thousands of tiny whitish bodies        
collected near the surface of the jar4  
,in the paramoecium1 as in the          
one-celled plants1 the protoplasm       
composing the cell responds to certain  
agencies acting upon it1 coming from    
without2 these agencies we call stimuli4
 ,such stimuli may be light1 differences
 of temperature1 presence of food1      
electricity1 or other factors of its    
surroundings4 ,plant and animal cells   
may react differently to the same       
stimulus4 ,in general1 however1 we know 
that protoplasm is irritable to some of 
these factors4 ,to severe stimuli1      
protoplasm usually responds by          
contracting1 another power which it     
possesses4 ,we know1 too1 that plant and
 animal cells take in food and change   
the food to protoplasm1 that is1 that   
they assimilate food2 and that they may 

waste away and repair themselves4       
,finally1 we know that new plant and    
animal cells are reproduced from the    
original bit of protoplasm1 a single    
cell4  ,illustration3 ,a paramoecium4   
c4v41 contractile vacuole2 f4v41 food   
vacuole2 m1 mouth2 ma4n41 macronucleus2 
mi4n41 micronucleus2 w4v41 water        
vacuole4  ,the ,structure of            
,paramoecium4--,the cell body is almost 
transparent1 and consists of semifluid  
protoplasm which has a granular grayish 
appearance under the microscope4 ,this  
protoplasm appears to be bounded by a   
very delicate membrane through which    
project numerous delicate threads of    
protoplasm called cilia4 7,these are    
usually invisible under the microscope74
  ,the locomotion of the paramoecium is 
caused by the movement of these cilia1  
which lash the water like a multitude of
 tiny oars4 ,the cilia also send        
particles of food into a funnel-like    
opening1 the gullet1 on one side of the 
cell4 ,once inside the cell body1 the   

particles of food materials are gathered
 into little balls within the almost    
transparent protoplasm4 ,these masses of
 food seem to be inclosed within a      
little area containing fluid1 called a  
vacuole4 ,other vacuoles appear to be   
clear2 these are spaces in which food   
has been digested4 ,one or two larger   
vacuoles may be found2 these are the    
contractile vacuoles2 their purpose     
seems to be to pass off waste material  
from the cell body4 ,this is done by    
pulsation of the vacuole1 which         
ultimately bursts1 passing fluid waste  
to the outside4 ,solid wastes are passed
 out of the cell in somewhat the same   
manner4 ,no breathing organs are seen1  
because osmosis of oxygen and carbon    
dioxide may take place anywhere through 
the cell membrane4 ,the nucleus of the  
cell is not easily visible in living    
specimens4 ,in a cell that has been     
stained it has been found to be a double
 structure1 consisting of one large and 
one small portion1 called1 respectively1

 the macronucleus and the micronucleus4 
,illustration3 ,paramoecium dividing by 
fission4 ,m1 mouth2 ,,mac41             
macronucleus2 ,,mic41 micronucleus4     
7,after ,sedgwick and ,wilson47         
,reproduction of                        
,paramoecium4--,sometimes a paramoecium 
may be found in the act of dividing by  
the process known as fission1 to form   
two new cells1 each of which contains   
half of the original cell4 ,this is a   
method of asexual reproduction4 ,the    
original cell may thus form in          
succession many hundreds of cells in    
every respect like the original parent  
cell4  ,illustration3 ,amoeba1 with     
pseudopodia 7,p47 extended2 ,,ec1       
ectoplasm2 ,,end1 endoplasm2 the dark   
area 7,n47 is the nucleus4 7,from a     
photograph loaned by ,professor ,g4 ,n4 
,calkins47  ,amoeba4#be--;,in order to  
understand more fully the life of a     
simple bit of protoplasm1 let us take up
 the study of the amoeba1 a type of the 
simplest form of animal life4 ,unlike   

the plant and animal cells we have      
examined1 the amoeba has no fixed form4 
,viewed under the compound microscope1  
it has the appearance of an irregular   
mass of granular protoplasm4 ,its form  
is constantly changing as it moves      
about4 ,this is due to the pushing out  
of tiny projections of the protoplasm of
 the cell1 called pseudopodia 7false    
feet74 ,the locomotion is accomplished  
by a streaming or flowing of the        
semifluid protoplasm4 ,the pseudopodia  
are pushed forward in the direction     
which the animal is to go1 the rest of  
the body following4 ,in the central part
 of the cell is the nucleus4 ,this      
important organ is difficult to see     
except in cells that have been stained4 
,footnote #be3 ,amoebae may be obtained 
from the hay infusion1      from the    
dead leaves in the bottom of small      
pools1 from the      same source in     
fresh-water aquaria1 from the roots of  
duckweed or other small water plants1 or
 from green algae      growing in quiet 

localities4 ,no sure method of obtaining
      them can be given4  ,although but 
a single cell1 still the amoeba appears 
to be aware of the existence of food    
when it is near at hand4 ,food may be   
taken into the body at any point1 the   
semifluid protoplasm simply rolling over
 and engulfing the food material4       
,within the body1 as in the paramoecium1
 the food becomes inclosed within a     
fluid space or vacuole4 ,the protoplasm 
has the power to take out such material 
as it can use to form new protoplasm or 
give energy4 ,circulation of food       
material is accomplished by the constant
 streaming of the protoplasm within the 
cell4  ,illustration3 ,amoeba1 showing  
the changes which take place during     
division of the cell4 ,the dark body in 
each figure is the nucleus2 the         
transparent circle1 the contractile     
vacuole2 the large granular masses1 the 
food vacuoles4 ,much magnified4  ,the   
cell absorbs oxygen from the water by   
osmosis through its delicate membrane1  

giving up carbon dioxide in return4     
,thus the cell breathes through any part
 of its body covering4  ,waste          
nitrogenous products formed within the  
cell when work is done are passed out by
 means of the contractile vacuole4  ,the
 amoeba1 like other one-celled          
organisms1 reproduces by the process of 
fission4 ,a single cell divides by      
splitting into two others1 each of which
 resembles the parent cell1 except that 
they are of less bulk4 ,when these      
become the size of the parent amoeba1   
they each in turn divide4 ,this is a    
kind of asexual reproduction4  ,when    
conditions unfavorable for life come1   
the amoeba1 like some one-celled plants1
 encysts itself within a membranous     
wall4 ,in this condition it may become  
dried and be blown through the air4     
,upon return to a favorable environment1
 it begins life again1 as before4 ,in   
this respect it resembles the spore of a
 plant4  ,illustration3 ,vorticella4 e1 
gullet2 n1 nucleus2 cv1 contractile     

vacuole2 a1 axis2 s1 sheath2 fv1 food   
vacuole4 7,from ,herrick's ,general     
,zoology47  ,the ,cell as a ,unit4--,in 
the daily life of a one-celled animal we
 find the single cell performing all the
 general activities which we shall later
 find the many-celled animal is able to 
perform4 ,in the amoeba no definite     
parts of the cell appear to be set off  
to perform certain functions2 but any   
part of the cell can take in food1 can  
absorb oxygen1 can change the food into 
protoplasm1 and excrete the waste       
material4 ,the single cell is1 in fact1 
an organism able to carry on the        
business of living almost as effectually
 as a very complex animal4  ,complex    
,one-celled ,animals4--,in the          
paramoecium we find a single cell1 but  
we find certain parts of the cell having
 certain definite functions3 the cilia  
are used for locomotion2 a definite part
 of the cell takes in food1 while the   
waste passes out at another definite    
spot4 ,in another one-celled animal     

called vorticella1 part of the cell has 
become elongated and is contractile4 ,by
 this stalk the little animal is        
fastened to a water plant or other      
object4 ,the stalk may be said to act   
like a muscle fiber1 as its sole        
function seems to be movement2 the cilia
 are located at one end of the cell and 
serve to create a current of water which
 will bring food particles to the mouth4
 ,here we have several parts of the     
cell1 each doing a different kind of    
work4 ,this is known as physiological   
division of labor4  ,habitat of         
,protozoa4--,protozoa are found almost  
everywhere in shallow water1 especially 
close to the surface4 ,they appear to be
 attracted near to the surface by the   
supply of oxygen4 ,every fresh-water    
lake swarms with them2 the ocean        
contains countless myriads of many      
different forms4  ,use as ,food4--,they 
are so numerous in lakes1 rivers1 and   
the ocean as to form the food for many  
animals higher in the scale of life4    

,almost all fish that do not take the   
hook and that travel in schools1 or     
companies1 migrating from one place to  
another1 live partly on such food4 ,many
 feed on slightly larger animals1 which 
in turn eat the ,protozoa4 ,such fish   
have on each side of the mouth attached 
to the gills a series of small          
structures looking like tiny rakes4     
,these are called the gill rakers1 and  
aid in collecting tiny organisms from   
the water as it passes over the gills4  
,the whale1 the largest of all mammals1 
strains protozoans and other small      
animals and plants out of the water by  
means of hanging plates of whalebone or 
baleen1 the slender filaments of which  
form a sieve from the top to the bottom 
of the mouth4  ,protozoa cause          
,disease4--,protozoa of certain kinds   
play an important part in causing       
malaria1 yellow fever1 and other        
diseases1 as we shall see later4#bf     
7,see page #bag47       ,footnote #bf3  
,teachers may find it expedient to take 

up the      study of protozoan diseases 
at this point4                          
,,reference ,,books                     
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,davison1 ,human   
,body and ,health4 ,american ,book      
,company4      ,jordan1 ,kellogg and    
,heath1 ,animal ,studies4 ,d4 ,appleton 
and        ,company4      ,sharpe1      
,laboratory ,manual1 pp4 #adj-adc4      
,american ,book        ,company4        
,,advanced       ,calkins1 ,the         
,protozoa4 ,macmillan ,company4         
,jennings1 ,study of the ,lower         
,organisms4 ,carnegie                   
,institution ,report4      ,parker1     
,lessons in ,elementary ,biology4 ,the  
,macmillan        ,company4             
,wilson1 ,the ,cell in ,development and 
,inheritance4 ,the        ,macmillan    
,company4     ,,xiv4 ,,division ,,of    
,,labor4 ,,the ,,various ,,forms ,,of   
,,plants ,,and ,,animals                
,problems4--,the development and forms  

of plants4           ,the development of
 a simple animal4           ,what is    
division of labor8 ,in what does it     
result8           ,how to know the chief
 characters of some great animal groups4
                        ,,laboratory    
,,suggestions       ,a visit to a       
botanical garden or laboratory          
demonstration4--,some of the forms of   
plant life4 ,review of        essential 
facts in development of bean or corn    
embryo4      ,demonstration4--,charts or
 models showing the development         
of a many-celled animal from egg through
 gastrula stage4                        
,demonstration4--,types which illustrate
 increasing        complexity of body   
form and division of labor4      ,museum
 trip4--,to afford pupil a means of     
identification of        examples of    
principal phyla4 ,this should be        
preceded by        objective            
demonstration work in school laboratory4
   ,reproduction in ,plants4--,although 
there are very many plants and animals  

so small and so simple as to be composed
 of but a single cell1 by far the       
greater part of the animal and plant    
world is made up of individuals which   
are collections of cells living         
together4  ,illustration3 ,a cell of    
pond scum4 ,how might it divide to form 
a long thread made up of cells8  ,in a  
simple plant like the pond scum1 a      
string or filament of cells is formed by
 a single cell dividing crosswise1 the  
two cells formed each dividing into two 
more4 ,eventually a long thread of cells
 is thus formed4 ,at times1 however1 a  
cell is formed by the union of two      
cells1 one from each of two adjoining   
filaments of the plant4 ,at length a    
hard coat forms around this cell1 which 
has now become a spore4 ,the tough      
covering protects it from unfavorable   
changes in the surroundings4 ,later1    
when conditions become favorable for its
 germination1 the spore may form a new  
filament of pond scum4 ,in molds1 in    
yeasts1 and in the bacteria we also     

found spores could be formed by the     
protoplasm of the plant cutting up into 
a number of tiny spores4 ,these spores  
are called asexual 7without sex7 because
 they are not formed by the union of two
 cells1 and may give rise to other tiny 
plants like themselves4 ,still other    
plants1 mosses and ferns1 give rise to  
two kinds of spores1 sexual and asexual4
 ,all of these collectively are called  
spore plants4  ,illustration3 ,the      
formation of spores in pond scum4 zs1   
zygospore2 f1 fusion in progress4       
,reproduction in ,seed                  
,plants4--,another great group of plants
 we have studied1 plants of varied      
shapes and sizes1 produce seeds4 ,they  
bear flowers and fruits4  ,illustration3
 ,the formation and growth of a plant   
embryo4 #a1 the sperm and egg cell      
uniting2 #b1 a fertilized egg2 #c1 two  
cells formed by division2 #d1 four cells
 formed from two2 #e1 a many-celled     
embryo2 #f1 young plant2 ,h1 hypocotyl2 
,p1 plumule2 ,c1 cotyledons4  ,the      

embryo develops from a single fertilized
 egg1 growing by cell division into two1
 four1 eight1 and a constantly          
increasing number of cells until after a
 time a baby plant is formed1 which as  
in the bean1 either contains some stored
 food to give it a start in life1 or1 as
 in the corn1 is surrounded with food   
which it can digest and absorb into its 
own tiny body4 ,we have seen that these 
young plants in the seed are able to    
develop when conditions are favorable4  
,furthermore1 the young of each kind of 
plant will eventually develop into the  
kind of plant its parent was and into no
 other kind4 ,thus the plant world is   
divided into many tribes or groups4     
,plants are placed in ,groups4--,if we  
plant a number of peas so that they will
 all germinate under the same conditions
 of soil1 temperature1 and sunlight1 the
 seedlings that develop will each differ
 one from another in a slight degree4#bg
 ,but in a general way they will have   
many characters in common1 as the shape 

of the leaves1 the possession of        
tendrils1 form of the flower and fruit4 
,a species of plants or animals is a    
group of individuals so much alike in   
their characters that they might have   
had the same parents4 ,individuals of   
such species differ slightly2 for no two
 individuals are exactly alike4         
,footnote #bg3 ,,note ,,to              
,,teachers4--,a trip to the ,botanical  
,garden or to a ,museum should be taken 
at this time4  ,illustration3 ,a colony 
of trilliums1 a flowering plant4        
7,photograph by ,w4 ,c4 ,barbour47      
,illustration3 ,rock fern1 polypody4    
,notice the underground stem giving off 
roots from its lower surface1 and leaves
 7,c71 7,s71 from its upper surface4    
,species are grouped together in a      
larger group called a genus4 ,for       
example1 many kinds of peas--the wild   
beach peas1 the sweet peas1 and many    
others--are all grouped in one genus    
7called ,lathyrus1 or vetchling7 because
 they have certain structural           

characteristics in common4  ,plant and  
animal genera are brought together in   
still larger groups1 the classification 
based on general likenesses in          
structure4 ,such groups are called1 as  
they become successively larger1        
,family1 ,order1 and ,class4 ,thus both 
the plant and animal kingdoms are       
grouped into divisions1 the smallest of 
which contains individuals very much    
alike2 and the largest of which contains
 very many groups of individuals1 the   
groups having some characters in common4
 ,this is called a system of            
classification4  ,classification of the 
,plant ,kingdom4--,the entire plant     
kingdom has been divided into four      
sub-kingdoms by botanists3--    #a4     
,spermatophytes4  ,angiosperms1 true    
flowering plants4                       
,gymnosperms1 the pines and their       
allies4   #b4 ,pteridophytes4  ,the fern
 plants and their allies4   #c4         
,bryophytes4     ,the moss plants and   
their allies   #d4 ,thallophytes4   ,the

 ,thallophytes form two groups3 the     
,algae and the                          
,fungi2 the algae being green1 while the
 fungi have                        no   
chlorophyll4  ,illustration3 ,rockweed1 
a brown algae1 showing its distribution 
on rocks below highwater mark4  ,the    
extent of the plant kingdom can only be 
hinted at2 each year new species are    
added to the lists4 ,there are about    
#aaj1jjj species of flowering plants and
 nearly as many flowerless plants4 ,the 
latter consist of over #cejj species of 
fernlike plants1 some #af1ejj species of
 mosses1 over #efjj lichens 7plants     
consisting of a partnership between     
algae and fungi71 approximately #ee1jjj 
species of fungi1 and about #af1jjj     
species of algae4  ,illustration3 ,a    
moss plant4 ,g1 the moss body2 ,s1 the  
spore-bearing stalk 7fruiting body74    
,development of a ,simple               
,animal4--,many-celled animals are      
formed in much the same way as are      
many-celled seed plants4 ,a common bath 

sponge1 an earthworm1 a fish1 or a      
dog1--each and all of them begin life in
 the same manner4 ,in a many-celled     
animal the life history begins with a   
single cell1 the fertilized egg4 ,as in 
the flowering plant1 this cell has been 
formed by the union of two other cells1 
a tiny 7usually motile7 cell2 the sperm1
 and a large cell1 the egg4 ,after the  
egg is fertilized by a sperm cell1 it   
splits into two1 four1 eight1 and       
sixteen cells2 as the number of cells   
increases1 a hollow ball of cells called
 the blastula is formed2 later this ball
 sinks in on one side1 and a            
double-walled cup of cells1 now called a
 gastrula1 results4 ,practically all    
animals pass through the above stages in
 their development from the egg1        
although these stages are often not     
plain to see because of the presence of 
food material 7yolk7 in the egg4  ,in   
animals the body consists of three      
layers of cells3 those of the outside1  
developed from the outer layer of the   

gastrula1 are called ectoderm1 which    
later gives rise to the skin1 nervous   
system1 etc42 an inner layer1 developed 
from the inner layer of the gastrula1   
the endoderm1 which forms the lining of 
the digestive organs1 etc42 a middle    
layer1 called the mesoderm1 lying       
between the ectoderm and the endoderm1  
is also found4 ,in higher animals this  
layer gives rise to muscles1 the        
skeleton1 and parts of other internal   
structures4  ,illustration3 ,stages in  
the development of a fertilized egg into
 the gastrula stage4 ,read your text1   
then draw these stages and name each    
stage4  ,physiological ,division of     
,labor4--,if we compare the amoeba and  
the paramoecium1 we find the latter a   
more complex organism than the former4  
,an amoeba may take in food through any 
part of the body2 the paramoecium has a 
definite gullet2 the amoeba may use any 
part of the body for locomotion2 the    
paramoecium has definite parts of the   
cell1 the cilia1 fitted for this work4  

,since the structure of the paramoecium 
is more complex1 we say that it is a    
higher animal4 ,in the vorticella1 a    
still more complex cell1 part of the    
cell has grown out like a stalk1 has    
become contractile1 and acts like       
muscle4  ,illustration3 ,photograph of a
 living vorticella1 showing the         
contractile stalk and the cilia around  
the mouth4 ,compare this figure with    
that of the paramoecium4 ,which cell    
shows greater division of labor8  ,as we
 look higher in the scale of life1 we   
invariably find that certain parts of a 
plant or animal are set apart to do     
certain work1 and only that work4 ,just 
as in a community of people1 there are  
some men who do rough manual work1      
others who are skilled workmen1 some who
 are shopkeepers1 and still others who  
are professional men1 so among plants   
and animals1 wherever collections of    
cells live together to form an organism1
 there is division of labor1 some cells 
being fitted to do one kind of work1    

while others are fitted to do work of   
another sort4 ,this is called           
physiological division of labor4        
,illustration3 ,enlarged lengthwise     
section of the hydra1 a very simple     
animal which shows slight division of   
labor4 ba1 base2 b1 bud2 m1 mouth2 ov1  
ovary2 sp1 spermary4  ,illustration3    
,different forms of tissue cells4 ,c1   
bone making cells2 ,e1 epithelial cells2
 ,f1 fat cells2 ,l1 liver cells2 ,m1    
muscle cell2 i1 involuntary2 v1         
voluntary2 ,n1 nerve cell2 ,c ,b1 cell  
body2 ,n4,f41 nerve fiber2 ,t4,b41 nerve
 endings2 ,w1 colorless blood cells4    
,as we have seen1 the higher plants are 
made up of a vast number of cells of    
many kinds4 ,collections of cells alike 
in structure and performing the same    
function we have called a tissue4       
,examples of animal tissues are the     
highly contractile cells set apart for  
movement1 muscles2 those which cover the
 body or line the inner parts of organs1
 the skin1 or epithelium2 the cells     

which form secretions or glands and the 
sensitive cells forming the nervous     
tissues4  ,frequently several tissues   
have certain functions to perform in    
conjunction with one another4 ,the arm  
of the human body performs movement4 ,to
 do this1 several tissues1 as muscles1  
nerves1 and bones1 must act together4 ,a
 collection of tissues performing       
certain work we call an organ4          
,illustration3 ,part of a sponge1       
showing how cells perform division of   
labor4 ect1 ectoderm2 mes1 mesoderm2    
end1 endoderm2 c4c41 ciliated cells1    
which take in food by means of their    
flagellae or large cilia 7fla74  ,in a  
simple animal like a sponge1 division of
 labor occurs between the cells2 some   
cells which line the pores leading      
inward create a current of water1 and   
feed upon the minute organisms which    
come within reach1 other cells build the
 skeleton of the sponge1 and still      
others become eggs or sperms4 ,in higher
 animals more complicated in structure  

and in which the tissues are found      
working together to form organs1        
division of labor is much more highly   
specialized4 ,in the human arm1 an organ
 fitted for certain movements1 think of 
the number of tissues and the           
complicated actions which are possible4 
,the most extreme division of labor is  
seen in the organism which has the most 
complex actions to perform and whose    
organs are fitted for such work1 for    
there the cells or tissues which do the 
particular work do it quickly and very  
well4  ,in our daily life in a town or  
city we see division of labor between   
individuals4 ,such division of labor may
 occur among other animals1 as1 for     
example1 bees or ants4 ,but it is seen  
at its highest in a great city or in a  
large business or industry4 ,in the     
stockyards of ,chicago1 division of     
labor has resulted in certain men       
performing but a single movement during 
their entire day's work1 but this       
movement repeated so many times in a day

 has resulted in wonderful accuracy and 
speed4 ,thus division of labor obtains  
its end4  ,organs and ,functions ,common
 to ,all ,animals4--,the same general   
functions performed by a single cell are
 performed by a many-celled animal4 ,but
 in the many-celled animals the various 
functions of the single cell are taken  
up by the organs4 ,in a complex         
organism1 like man1 the organs and the  
functions they perform may be briefly   
given as follows3--  7#a7 ,the organs of
 food taking3 food may be taken in by   
individual cells1 as those lining the   
pores of the sponge1 or definite parts  
of a food tube may be set apart for this
 purpose1 as the mouth and parts which  
place food in the mouth4  7#b7 ,the     
organs of digestion3 the food tube and  
collections of cells which form the     
glands connected with it4 ,the enzymes  
in the fluids secreted by the latter    
change the foods from a solid form      
7usually insoluble7 to that of a fluid4 
,such fluid may then pass by osmosis1   

through the walls of the food tube into 
the blood4  7#c7 ,the organs of         
circulation3 the tubes through which the
 blood1 bearing its organic foods and   
oxygen1 reaches the tissues of the body4
 ,in simple animals1 as the sponge and  
hydra1 no such organs are needed1 the   
fluid food passing from cell to cell by 
osmosis4  7#d7 ,the organs of           
respiration3 the organs in which the    
blood receives oxygen and gives up      
carbon dioxide4 ,the outer layer of the 
body serves this purpose in very simple 
animals2 gills or lungs are developed in
 more complex animals4  7#e7 ,the organs
 of excretion3 such as the kidneys and  
skin1 which pass off nitrogenous and    
other waste matters from the body4  7#f7
 ,the organs of locomotion3 muscles and 
their attachments and connectives2      
namely1 tendons1 ligaments1 and bones4  
7#g7 ,the organs of nervous control3 the
 central nervous system1 which has      
control of coordinated movement4 ,this  
consists of scattered cells in low forms

 of life2 such cells are collected into 
groups and connected with each other in 
higher animals4  7#h7 ,the organs of    
sense3 collections of cells having to do
 with the reception and transmission of 
sight1 hearing1 smell1 taste1 touch1    
pressure1 and temperature sensations4   
7#i7 ,the organs of reproduction3 the   
sperm and egg-forming organs4  ,almost  
all animals have the functions mentioned
 above4 ,in most1 the various organs    
mentioned are more or less developed1   
although in the simpler forms of animal 
life some of the organs mentioned above 
are either very poorly developed or     
entirely lacking4 ,but in the so-called 
higher animals each of the above-named  
functions is assigned to a certain organ
 or group of organs4 ,the work is done  
better and more quickly than in the     
lower animals4 ,division of labor is    
thus a guide in helping us to determine 
the place of animals in the groups that 
exist on the earth4  ,the ,animal       
,series4--,we have found that a         

one-celled animal can perform certain   
functions in a rather crude manner4 ,man
 can perform these same functions in an 
extremely efficient manner4 ,division of
 labor is well worked out1 extreme      
complexity of structure is seen4        
,between these two extremes are a great 
many groups of animals which can be     
arranged more or less as a series1      
showing the gradual evolution or        
development of life on the earth4 ,it   
will be the purpose of the following    
pages to show the chief characteristics 
of the great groups of the animal       
kingdom4  ,illustration3 ,the glasslike 
skeleton of a radiolarian1 a protozoan4 
7,from model at ,american ,museum of    
,natural ,history47  ,i4                
,protozoa4--,animals composed of a      
single cell1 reproducing by cell        
division4  ,the following are the       
principal classes of ,protozoa1 examples
 of which we may have seen or read      
about3--  ,,class ,i4 ,rhizopoda 7,greek
 for root-footed74 ,having no fixed     

form1 with pseudopodia4 ,either naked as
 ,amoeba or building limy               
7,foraminifera7 or glasslike skeletons  
7,radiolaria74  ,,class ,,ii4 ,infusoria
 7in infusions74 ,usually active        
ciliated ,protozoa4 ,examples1          
,paramoecium1 ,vorticella4  ,,class     
,,iii4 ,sporozoa 7spore animals74       
,parasitic and usually nonactive4       
,example1 ,plasmodium malariae4         
,illustration3 ,a horny fiber sponge4   
,notice that it is a colony4 ,one fourth
 natural size4  ,,ii4                   
,sponges4--,because the body contains   
many pores through which water bearing  
food particles enters1 these animals are
 called ,porifera4 ,they are classed    
according to the skeleton they possess  
into limy1 glasslike1 and horny fiber   
sponges4 ,the latter are the sponges of 
commerce4 ,with but few exceptions      
sponges live in salt water and are never
 free swimming4  ,illustration3 ,sea    
anemones4 ,one half natural size4 ,the  
right hand specimen is expanded and     

shows the mouth surrounded by the       
tentacles4 ,the left hand specimen is   
contracted4 7,from model at the         
,american ,museum of ,natural ,history47
  ,,iii4 ,coelenterates4--,the hydra and
 its salt-water allies1 the jellyfish1  
hydroids1 and corals1 belong to a group 
of animals known as the ,coelenterata4  
,the word coelenterate 7coelom  body    
cavity1 enteron  food tube7 explains the
 structure of the group4 ,they are      
animals in which the real body cavity is
 lacking1 the animal in its simplest    
form being little more than a bag4 ,some
 examples are the hydra1 shown on page  
#agi1 salt-water forms known as         
hydroids1 colonial forms which have part
 of their life free swimming as         
jellyfish2 sea anemones and coral       
polyps1 tiny colonial hydra like forms  
which build a living or secreted        
covering4  ,,iv4 ,worms4--,the wormlike 
animals are grouped into flatworms1     
roundworms1 and segmented or jointed    
worms4  7a7 ,flatworms are sometimes    

parasitic1 examples being the tapeworm  
and liver fluke4 ,they are usually      
small1 ribbon- or leaf-like and flat and
 live in water4  7b7 ,roundworms1 minute
 threadlike creatures1 are not often    
seen by the city girl or boy4 ,vinegar  
eels1 the horsehair worm1 the pork worm 
or trichina and the dread hookworm are  
examples4  7c7 ,segmented worms are     
long1 jointed creatures composed of body
 rings or segments4 ,examples are the   
earthworm1 the sandworm 7known to ,new  
,york boys as the fishworm71 and the    
leeches or bloodsuckers4  ,illustration3
 ,a jointed worm4 ,the sandworm4        
,slightly reduced4  ,illustration3 ,the 
common starfish seen from below to show 
the tube feet4 ,about one half natural  
size4  ,illustration3 ,the crayfish1 a  
crustacean4 ,a1 antenna2 ,m1 mouth2 ,e1 
compound stalked eye2 ,ch1 pincher claw2
 ,c4,p41 cephalothorax2 ,ab1 abdomen2   
,c4,f41 caudal fin4 ,a little reduced4  
,v4 ,echinoderms4--,these are           
spiny-skinned animals1 which live in    

salt water4 ,they are still more        
complicated in structure than the worms 
and may be known by the spines in their 
skin4 ,they show radial symmetry4       
,starfish or sea urchins are examples4  
,,vi4 ,arthropods4--,these animals are  
distinguished by having jointed body and
 legs4 ,they form two great groups4 ,the
 higher forms of the ,crustacea have    
only two regions in the body1 a fused   
head and thorax1 called the             
cephalothorax1 and an abdominal region4 
,a second group is the ,insecta1 of     
which we know something already4        
,crustacea breathe by means of gills1   
which are structures for taking oxygen  
out of the water1 while adult insects   
breathe through air tubes called        
trachea4  ,two smaller groups of        
arthropods also exist1 the ,arachnida1  
consisting of spiders1 scorpions1 ticks1
 and mites1 and the ,myriapoda1 examples
 being the thousand leggers found in    
some city houses4  ,illustration3 ,a    
common snail1 a mollusk4 7,from a       

photograph by ,davison47  ,,vii4        
,mollusca4--,another large group is the 
,mollusca4 ,this phylum gets its name   
from the soft1 unsegmented body 7mollis 
soft74 ,mollusks usually have a shell1  
which may be of one piece1 as a snail1  
or two pieces or valves1 as the clam or 
oyster4  ,illustration3 ,the skeleton of
 a dog2 a typical vertebrate4  ,,viii4  
,the ,vertebrates4--,all of the animals 
we have studied thus far agree in having
 whatever skeleton or hard parts they   
possess on the outside of the body4     
,collectively1 they are called          
,invertebrates4 ,this exoskeleton       
differs from the main or axial skeleton 
of the higher animals1 the latter being 
inside of the body4 ,the exoskeleton is 
dead1 being secreted by the cells lining
 the body1 while the endoskeleton is1 in
 part at least1 alive and is capable of 
growth1 e4g4 a broken arm or leg bone   
will grow together4 ,but a man has      
certain parts of the skeleton1 as nails 
or hair1 formed by the skin and in      

addition possesses inside bones to which
 the muscles are attached4 ,some of the 
bones are arranged in a flexible column 
in the dorsal 7the back7 side of the    
body4 ,this vertebral column1 as it is  
called1 is distinctive of all           
vertebrates4 ,within its bony protection
 lies the delicate central nervous      
system1 and to this column are attached 
the big bones of the legs and arms4 ,the
 vertebrate animals deserve more of our 
attention than other forms of life      
because man himself is a vertebrate4    
,illustration3 ,the sand shark1 an      
elasmobranch4 ,note the slits leading   
from the gills4 7,from a photograph     
loaned by the ,american ,museum of      
,natural ,history47  ,five groups or    
classes of vertebrates exist4 ,fishes1  
,amphibians1 ,reptiles1 ,birds1 and     
,mammals4 ,let us see how to distinguish
 one class from another4  ,illustration3
 ,the sturgeon1 a ganoid fish4          
,fishes4--,fishes are familiar animals  
to most of us4 ,we know that they live  

in the water1 have a backbone1 and that 
they have fins4 ,they breathe by means  
of gills1 delicate organs fitted for    
taking oxygen out of the water4 ,the    
heart has two chambers1 an auricle and a
 ventricle4 ,they have a skin in which  
are glands secreting mucus1 a slimy     
substance which helps them go through   
the water easily4 ,they usually lay very
 many eggs4  ,,classification ,,of      
,,fishes       ,,order ,i4 ,the         
,elasmobranchs4 ,fishes which have a    
soft skeleton made      of cartilage and
 exposed gill slits4 ,examples3 sharks1 
skates1 and      rays4       ,,order    
,,ii4 ,the ,ganoids4 ,fishes which once 
were very numerous on the      earth1   
but which are now almost extinct4 ,they 
are protected by      platelike scales4 
,examples3 gars1 sturgeon1 and bowfin4  
,illustration3 ,a bony fish4            
,,order ,,iii4 ,the ,teleosts1 or ,bony 
,fishes4 ,they compose #ie per cent of  
all living fishes4 ,in this group the   
skeleton is bony1 the gills are         

protected by an operculum1 and the eggs 
are numerous4 ,most of our      common  
food fishes belong to this class4       
,,order ,,iv4 ,the ,dipnoi1 or ,lung    
,fishes4 ,this is a very small group4   
,in      many respects they are more    
like amphibians than fishes1 the swim   
bladder being used as a lung4 ,they live
 in tropical ,africa1 ,south            
,america1 and ,australia1 inhabiting the
 rivers and lakes there4                
,characteristics of ,amphibia4--,the    
frog belongs to the class of vertebrates
 known as ,amphibia4 ,as the name       
indicates 7amphi1 both1 and bia1 life71 
members of this group live both in water
 and on land4 ,in the earlier stages of 
their development they take oxygen into 
the blood by means of gills4 ,when      
adult1 however1 they breathe by means of
 lungs4 ,at all times1 but especially   
during the winter1 the skin serves as a 
breathing organ4 ,the skin is soft and  
unprotected by bony plates or scales4   
,the heart has three chambers1 two      

auricles and one ventricle4 ,most       
amphibians undergo a complete           
metamorphosis1 or change of form1 the   
young being unlike the adults4          
,illustration3 ,newt4 7,from a          
photograph loaned by the ,american      
,museum of ,natural ,history47 ,about   
natural size4  ,illustration3 ,the      
leopard frog1 an amphibian4             
,,classification ,,of ,,amphibia        
,,order ,i4 ,urodela4 ,amphibia having  
usually poorly developed                
appendages4 ,tail persistent through    
life4 ,examples3 mud puppy1 newt1       
salamander4        ,,order ,,ii4 ,anura4
 ,tailless ,amphibia1 which undergo a   
metamorphosis1       breathing by gills 
in larval state1 by lungs in adult      
state4       ,examples3 toad and frog4  
,characteristics of ,reptilia4--,these  
animals are characterized by having     
scales developed from the skin4 ,in the 
turtle they have become bony and are    
connected with the internal skeleton4   
,reptiles always breathe by means of    

lungs1 differing in this respect from   
the amphibians4 ,they show their distant
 relationship to birds in that their    
large eggs are incased in a leathery1   
limy shell4  ,illustration3 ,box        
tortoise1 a land reptile4 7,from        
photograph loaned by the ,american      
,museum of ,natural ,history47 ,about   
one fourth natural size4  ,illustration3
 ,the gila monster1 a poisonous lizard4 
,about one twelfth natural size4        
,,classification ,,of ,,reptiles        
,,order ,i4 ,chelonia 7turtles and      
tortoises74 ,flattened reptiles with    
body inclosed in bony case4 ,no teeth or
 sternum 7breastbone74      ,examples3  
snapping turtle1 box tortoise4          
,,order ,,ii4 ,lacertilia 7lizards74    
,body covered with scales1 usually      
having two-paired appendages4 ,breathe  
by lungs4 ,examples3 fence      lizard1 
horned toad4  ,illustration3 ,the common
 garter snake4 ,reduced to about one    
tenth natural size4       ,,order ,,iii4
 ,ophidia 7snakes74 ,body elongated1    

covered with scales4 ,no      limbs     
present4 ,examples3 garter snake1       
rattlesnake4       ,,order ,,iv4        
,crocodilia4 ,fresh-water reptiles with 
elongated body and      bony scales on  
skin4 ,two-paired limbs4 ,examples3     
alligator1 crocodile4  ,birds4--,birds  
among all other animals are known by    
their covering of feathers and the      
presence of wings4 ,the feathers are    
developed from the skin4 ,these aid in  
flight1 and protect the body from the   
cold4  ,illustration3 ,adaptations in   
the bills of birds4 ,could we tell      
anything about the food of a bird from  
its bill8 ,do these birds all get their 
food in the same manner8 ,do they all   
eat the same kind of food8  ,the form of
 the bill in particular shows adaptation
 to a wonderful degree4 ,a duck has a   
flat bill for pushing through the mud   
and straining out the food2 a bird of   
prey has a curved or hooked beak for    
tearing2 the woodpecker has a sharp1    
straight bill for piercing the bark of  

trees in search of the insect larvae    
which are hidden underneath4 ,birds do  
not have teeth4  ,illustration3 ,common 
tern and young1 showing nesting and     
feeding habits4 7,from group at         
,american ,museum of ,natural ,history47
  ,the rate of respiration1 of          
heartbeat1 and the body temperature are 
all higher in the bird than in man4 ,man
 breathes from twelve to fourteen times 
per minute4 ,birds breathe from twenty  
to sixty times a minute4 ,because of the
 increased activity of a bird1 there    
comes a necessity for a greater and more
 rapid supply of oxygen1 an increased   
blood supply to carry the material to be
 used up in the release of energy1 and a
 means of rapid excretion of the wastes 
resulting from the process of oxidation4
 ,birds are large eaters1 and the       
digestive tract is fitted to digest the 
food quickly1 by having a large crop in 
which food may be stored in a much      
softened condition4 ,as soon as the food
 is part of the blood1 it may be sent   

rapidly to the places where it is       
needed1 by means of the large           
four-chambered heart and large blood    
vessels4  ,the high temperature of the  
bird is a direct result of this rapid   
oxidation2 furthermore1 the feathers and
 the oily skin form an insulation which 
does not readily permit of the escape of
 heat4 ,this insulating cover is of much
 use to the bird in its flights at high 
altitudes1 where the temperature is     
often very low4 ,birds lay eggs and     
usually care for their young4           
,illustration3 ,african ostrich1 one of 
the largest living birds4               
,,classification ,,of ,,birds  ,,order  
,i4 ,cursores4 ,running birds with no   
keeled breastbone4 ,examples3 ostrich1  
cassowary4  ,,order ,,ii4 ,passeres4    
,perching birds2 three toes in front1   
one behind4 ,over one half of all       
species of birds are included in this   
order4 ,examples3 sparrow1 thrush1      
swallow4  ,,order ,,iii4 ,gallinae4     
,strong legs2 feet adapted to           

scratching4 ,beak stout4 ,examples3     
jungle fowl1 grouse1 quail1 domestic    
fowl4  ,,order ,,iv4 ,raptores4 ,birds  
of prey4 ,hooked beak4 ,strong claws4   
,examples3 eagle1 hawk1 owl4  ,,order   
,v4 ,grallatores4 ,waders4 ,long neck1  
beak1 and legs4 ,examples3 snipe1 crane1
 heron4  ,,order ,,vi4 ,natatores4      
,divers and swimmers4 ,legs short1 toes 
webbed4 ,examples3 gull1 duck1          
albatross4  ,,order ,,vii4 ,columbinae4 
,like ,gallinae1 but with weaker legs4  
,examples3 dove1 pigeon4  ,,order       
,,viii4 ,pici4 ,woodpeckers4 ,two toes  
point forward1 two backward1 and        
adaptation for climbing4 ,long1 strong  
bill4  ,,order ,,ix4 ,psittaci4         
,parrots1 hooked beak and fleshy tongue4
  ,,order ,x4 ,coccyges4 ,climbing      
birds1 with powerful beak4 ,examples3   
kingfisher1 toucan1 and cuckoo4  ,,order
 ,,xi4 ,macrochires4 ,birds having      
long-pointed wings1 without scales on   
metatarsus4 ,examples3 swift1 humming   
bird1 and goatsucker4  ,mammals4--,dogs 

and cats1 sheep and pigs1 horses and    
cows1 all of our domestic animals 7and  
man himself7 have characters of         
structure which cause them to be classed
 as mammals4 ,they1 like some other     
vertebrates1 have lungs and warm blood4 
,they also have a hairy covering and    
bear young developed to a form similar  
to their own1#bh and nurse them with    
milk secreted by glands known as the    
mammary glands2 hence the term mammal4  
,footnote #bh3 ,with the exception of   
the monotremes4  ,illustration3 ,the    
bison1 an almost extinct mammal4        
,adaptations in ,mammalia4--,of the     
thirty-five hundred species1 most       
inhabit continents2 a few species are   
found on different islands1 and some1 as
 the whale1 inhabit the ocean4 ,they    
vary in size from the whale and the     
elephant to tiny shrew mice and moles4  
,adaptations to different habitat and   
methods of life abound2 the seal and    
whale have the limbs modified into      
flippers1 the sloth and squirrel have   

limbs peculiarly adapted to climbing1   
while the bats have the fore limbs      
modeled for flight4  ,lowest            
,mammals4--,the lowest are the          
monotremes1 animals which lay eggs like 
the birds1 although they are provided   
with hairy covering like other mammals4 
,such are the ,australian spiny anteater
 and the duck mole4  ,all other mammals 
bring forth their young developed to a  
form similar to their own4 ,the kangaroo
 and opossum1 however1 are provided with
 a pouch on the under side of the body  
in which the very immature1 blind1 and  
helpless young are nourished until they 
are able to care for themselves4 ,these 
pouched animals are called marsupials4  
,the other mammals may be briefly       
classified as follows3--                
,,classification ,,of ,,higher ,,mammals
  ,,order ,i4 ,edentata4 ,toothless or  
with very simple teeth4 ,examples3      
anteater1 sloth1 armadillo4  ,,order    
,,ii4 ,rodentia4 ,incisor teeth         
chisel-shaped1 usually two above and two

 below4 ,examples3 beaver1 rat1         
porcupine1 rabbit1 squirrel4  ,,order   
,,iii4 ,cetacea4 ,adapted to marine     
life4 ,examples3 whale1 porpoise4       
,,order ,,iv4 ,ungulata4 ,hoofs1 teeth  
adapted for grinding4 ,examples3 7a7    
odd-toed1 horse1 rhinoceros1 tapir2 7b7 
even-toed1 ox1 pig1 sheep1 deer4        
,,order ,v4 ,carnivora4 ,long canine    
teeth1 sharp and long claws4 ,examples3 
dog1 cat1 lion1 bear1 seal1 and sea     
lion4  ,,order ,,vi4 ,insectivora4      
,example3 mole4  ,,order ,,vii4         
,cheiroptera4 ,fore limbs adapted to    
flight1 teeth pointed4 ,example3 bat4   
,,order ,,viii4 ,primates4 ,erect or    
nearly so1 fore appendage provided with 
hand4 ,examples3 monkey1 ape1 man4      
,illustration3 ,the geological history  
of the horse4 7,after ,mathews1 in the  
,american ,museum of ,natural ,history47
 ,ask your teacher to explain this      
diagram4  ,increasing ,complexity of    
,structure and of ,habits in ,plants and
 ,animals4--,in our study of biology so 

far we have attempted to get some notion
 of the various factors which act upon  
living things4 ,we have seen how plants 
and animals interact upon each other4   
,we have learned something about the    
various physiological processes of      
plants and animals1 and have found them 
to be in many respects identical4 ,we   
have found grades of complexity in      
plants from the one-celled plant1       
bacterium or pleurococcus1 to the       
complicated flowering plants of         
considerable size and with many organs4 
,so in animal life1 from the ,protozoa  
upward1 there is constant change1 and   
the change is toward greater complexity 
of structure and functions4 ,an insect  
is a higher type of life than a         
protozoan1 because its structure is more
 complex and it can perform its work    
with more ease and accuracy4 ,a fish is 
a higher type of animal than the insect 
for these same reasons1 and also for    
another4 ,the fish has an internal      
skeleton which forms a pointed column of

 bones on the dorsal side 7the back7 of 
the animal4 ,it is a vertebrate animal4 
,illustration3 ,the evolutionary tree4  
,modified from ,galloway4 ,copy this    
diagram in your notebook4 ,explain it as
 well as you can4  ,the ,doctrine of    
,evolution4--,we have now learned that  
animal forms may be arranged so as to   
begin with very simple one-celled forms 
and culminate with a group which        
contains man himself4 ,this arrangement 
is called the evolutionary series4      
,evolution means change1 and these      
groups are believed by scientists to    
represent stages in complexity of       
development of life on the earth4       
,geology teaches that millions of years 
ago1 life upon the earth was very       
simple1 and that gradually more and more
 complex forms of life appeared1 as the 
rocks formed latest in time show the    
most highly developed forms of animal   
life4 ,the great ,english scientist1    
,charles ,darwin1 from this and other   
evidence1 explained the theory of       

evolution4 ,this is the belief that     
simple forms of life on the earth slowly
 and gradually gave rise to those more  
complex and that thus ultimately the    
most complex forms came into existence4 
,the ,number of ,animal ,species4--,over
 #ejj1jjj species of animals are known  
to exist to-day1 as the following table 
shows4    ,protozoa          #h1jjj     
,arachnids     #af1jjj   ,sponges       
#b1ejj     ,crustaceans   #af1jjj       
,coelenterates     #d1ejj     ,mollusks 
#fa1jjj   ,echinoderms       #d1jjj     
,fishes        #ac1jjj   ,flat-worms    
#e1jjj     ,amphibians     #a1djj       
,roundworms        #a1ejj     ,reptiles 
#c1ejj   ,annelids          #d1jjj      
,birds         #ac1jjj   ,insects       
#cfj1jjj     ,mammals        #c1ejj     
,myriapods         #b1jjj               
-------                                 
,total      #eah1ijj  ,man's ,place in  
,nature4--,although we know that man is 
separated mentally by a wide gap from   
all other animals1 in our study of      

physiology we must ask where we are to  
place man4 ,if we attempt to classify   
man1 we see at once he must be placed   
with the vertebrate animals because of  
his possession of a vertebral column4   
,evidently1 too1 he is a mammal1 because
 the young are nourished by milk        
secreted by the mother and because his  
body has at least a partial covering of 
hair4 ,anatomically we find that we must
 place man with the apelike mammals1    
because of these numerous points of     
structural likeness4 ,the group of      
mammals which includes the monkeys1     
apes1 and man we call the primates4     
,although anatomically there is a       
greater difference between the lowest   
type of monkey and the highest type of  
ape than there is between the highest   
type of ape and the lowest savage1 yet  
there is an immense mental gap between  
monkey and man4  ,instincts4--,mammals  
are considered the highest of vertebrate
 animals1 not only because of their     
complicated structure1 but because their

 instincts are so well developed4       
,monkeys certainly seem to have many of 
the mental attributes of man4           
,professor ,thorndike of ,columbia      
,university sums up their habits of     
learning as follows3--       ,in their  
method of learning1 although monkeys do 
not reach the human      stage of a rich
 life of ideas1 yet they carry the      
animal method of      learning1 by the  
selection of impulses and association of
 them with      different               
sense-impressions1 to a point beyond    
that reached by any      other of the   
lower animals4 ,in this1 too1 they      
resemble man2 for he      differs from  
the lower animals not only in the       
possession of a new      sort of        
intelligence1 but also in the tremendous
 extension of that      sort which he   
has in common with them4 ,a fish learns 
slowly a few      simple habits4 ,man   
learns quickly an infinitude of habits  
that may be      highly complex4 ,dogs  
and cats learn more than the fish1 while

 monkeys      learn more than they4 ,in 
the number of things he learns1 the     
complex      habits he can form1 the    
variety of lines along which he can     
learn      them1 and in their permanence
 when once formed1 the monkey justifies 
his inclusion with man in a separate    
mental genus4  ,evolution of            
,man4--,undoubtedly there once lived    
upon the earth races of men who were    
much lower in their mental organization 
than the present inhabitants4 ,if we    
follow the early history of man upon the
 earth1 we find that at first he must   
have been little better than one of the 
lower animals4 ,he was a nomad1         
wandering from place to place1 feeding  
upon whatever living things he could    
kill with his hands4 ,gradually he must 
have learned to use weapons1 and thus   
kill his prey1 first using rough stone  
implements for this purpose4 ,as man    
became more civilized1 implements of    
bronze and of iron were used4 ,about    
this time the subjugation and           

domestication of animals began to take  
place4 ,man then began to cultivate the 
fields1 and to have a fixed place of    
abode other than a cave4 ,the beginnings
 of civilization were long ago1 but even
 to-day the earth is not entirely       
civilized4  ,the ,races of ,man4--,at   
the present time there exist upon the   
earth five races or varieties of man1   
each very different from the other in   
instincts1 social customs1 and1 to an   
extent1 in structure4 ,these are the    
,ethiopian or negro type1 originating in
 ,africa2 the ,malay or brown race1 from
 the islands of the ,pacific2 the       
,american ,indian2 the ,mongolian or    
yellow race1 including the natives of   
,china1 ,japan1 and the ,eskimos2 and   
finally1 the highest type of all1 the   
,caucasians1 represented by the         
civilized white inhabitants of ,europe  
and ,america4                           
,,reference ,,books                     
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology1 ,american 

,book ,company4      ,bulletin of ,u4   
,s4 ,department of ,agriculture1        
,division of        ,biological ,survey1
 ,nos4 #a1 #f1 #ac1 #ag4      ,davison1 
,practical ,zoology4 ,american ,book    
,company4      ,ditmars1 ,the ,reptiles 
of ,new ,york4 ,guide ,leaflet #bj4     
,amer4        ,mus4 of ,nat4 ,history4  
,sharpe1 ,a ,laboratory ,manual in      
,biology1 pp4 #adj-aej1        ,american
 ,book ,company4      ,walker1 ,our     
,birds and ,their ,nestlings4 ,american 
,book        ,company4      ,walter1 ,h4
 ,e4 and ,h4 ,a41 ,wild ,birds in ,city 
,parks4        ,published by authors4   
,,advanced       ,apgar1 ,birds of the  
,united ,states4 ,american ,book        
,company4      ,beebe1 ,the ,bird4      
,henry ,holt and ,company4              
,ditmars1 ,the ,reptile ,book4          
,doubleday1 ,page and ,company4         
,hegner1 ,zoology4 ,the ,macmillan      
,company4      ,hornaday1 ,american     
,natural ,history4      ,jordan and     
,evermann1 ,food and ,game ,fishes4     

,doubleday1 ,page        and ,company4  
,parker and ,haswell1 ,textbook of      
,zoology4 ,the ,macmillan               
,company4      ,riverside ,natural      
,history4 ,houghton1 ,mifflin and       
,company4      ,weed and ,dearborn1     
,relation of ,birds to ,man4            
,lippincott4     ,,xv4 ,,the ,,economic 
,,importance ,,of ,,animals             
,problems4--,i4 ,to determine the uses  
of animals4           7a7 ,indirectly as
 food4           7b7 ,directly as food4 
7c7 ,as domesticated animals4           
7d7 ,for clothing4           7e7 ,other 
direct economic uses4           7f7     
,destruction of harmful plants and      
animals4          --,,ii4 ,to determine 
the harm done by animals4           7a7 
,animals destructive to those used for  
food4           7b7 ,animals harmful to 
crops and gardens4           7c7        
,animals harmful to fruit and forest    
trees4           7d7 ,animals           
destructive to stored food or clothing4 
7e7 ,animals indirectly or directly     

responsible for disease4                
,,laboratory ,,suggestions              
,inasmuch as this work is planned for   
the winter months the      laboratory   
side must be largely museum and         
reference work4      ,it is to be       
expected that the teacher will wish to  
refer to      much of this work at the  
time work is done on a given group4     
,but it is pedagogically desirable that 
the work as planned      should be      
varied4 ,interest is thus held4         
,outlines prepared      by the teacher  
to be filled in by the student are      
desirable      because they lead the    
pupil to individual selection of what   
seems to him as important material4     
,opportunity should be      given for   
laboratory exercises based on original  
sources4      ,the pupils should be made
 to use reports of the ,u4 ,s4          
,department of ,agriculture1 the        
,biological ,survey1 various            
,states ,reports1 and others4           
,special home laboratory reports may be 

well made at this      time1 for        
example3 determination at a local fish  
market of      the fish that are cheap  
and fresh at a given time4 ,have the    
students give reasons for this4 ,study  
conditions in the meat      market in a 
similar manner4 ,other local food       
conditions may      also be studied     
first hand4   ,,uses ,,of ,,animals     
,indirect ,use as ,food4--,just as      
plants form the food of animals1 so some
 animals are food for others4 ,man may  
make use of such food directly or       
indirectly4 ,many mollusks1 as the      
barnacle and mussel1 are eaten by       
fishes4 ,other fish live upon tiny      
organisms1 water fleas and other small  
crustaceans4 ,these in turn feed upon   
still smaller animals1 and we may go    
back and back until finally we come to  
the ,protozoa and one-celled water      
plants as an ultimate source of food4   
,direct ,use as ,food4 ,lower           
,forms4--,the forms of life lower than  
the ,crustacea are of little use        

directly as food1 although the ,chinese 
are very fond of one of the             
,echinoderms1 a holothurian4            
,illustration3 ,north ,american lobster4
 ,this specimen1 preserved at the ,u4   
,s4 ,fish ,commission at ,woods ,hole1  
was of unusual size and weighed over    
twenty pounds4  ,crustacea as           
,food4--,crustaceans1 however1 are of   
considerable value for food1 the lobster
 fisheries in particular being of       
importance4 ,the lobster is highly      
esteemed as food1 and is rapidly        
disappearing from our coasts as the     
result of overfishing4 ,between twenty  
and thirty million are yearly taken on  
the ,north ,atlantic coast4 ,this means 
a value at present prices of about      
#ae1jjj1jjj4 ,laws have been enacted in 
,new ,york and other states against     
overfishing4 ,egg-carrying lobsters must
 be returned to the water2 all smaller  
than six to nine inches in length 7the  
law varies in different states7 must be 
put back2 other restrictions are placed 

upon the taking of the animals1 in hope 
of saving the race from extinction4     
,some states now hatch and care for the 
young for a period of time2 the ,united 
,states ,bureau of ,fisheries is also   
doing much good work1 in the hope of    
restocking to some extent the now almost
 depleted waters4  ,several other common
 crustaceans are near relatives of the  
crayfish4 ,among them are the shrimp and
 prawn1 thin-shelled1 active crustaceans
 common along our eastern coast4 ,in    
spite of the fact that they form a large
 part of the food supply of many marine 
animals1 especially fish1 they do not   
appear to be decreasing in numbers4     
,they are also used as food by man1 the 
shrimp fisheries in this country        
aggregating over #a1jjj1jjj yearly4     
,illustration3 ,the edible blue crab4   
7,from a photograph loaned by the       
,american ,museum of ,natural ,history47
  ,another edible crustacean of         
considerable economic importance is the 
blue crab4 ,crabs are found inhabiting  

muddy bottoms2 in such localities they  
are caught in great numbers in nets or  
traps baited with decaying meat4 ,they  
are1 indeed1 among our most valuable sea
 scavengers1 although they are          
carnivorous hunters as well4 ,the young 
crabs differ considerably in form from  
the adult4 ,they undergo a complete     
metamorphosis 7change of form74         
,immediately after molting or shedding  
of the outer shell in order to grow     
larger1 crabs are greatly desired by man
 as an article of food4 ,they are then  
known as shedders1 or soft-shelled      
crabs4  ,illustration3 ,the oyster4     
,mollusks as ,food4--,oysters are never 
found in muddy localities1 for in such  
places they would be quickly smothered  
by the sediment in the water4 ,they are 
found in nature clinging to stones or on
 shells or other objects which project a
 little above the bottom4 ,here food is 
abundant and oxygen is obtained from the
 water surrounding them4 ,hence oyster  
raisers throw oyster shells into the    

water and the young oysters attach      
themselves4  ,in some parts of ,europe  
and this country where oysters are      
raised artificially1 stakes or brush are
 sunk in shallow water so that the young
 oyster1 which is at first              
free-swimming1 may escape the danger of 
smothering on the bottom4 ,after the    
oysters are a year or two old1 they are 
taken up and put down in deeper water as
 seed oysters4 ,at the age of three and 
four years they are ready for the       
market4  ,the oyster industry is one of 
the most profitable of our fisheries4   
,nearly #ae1jjj1jjj a year has been     
derived during the last decade from such
 sources4 ,hundreds of boats and        
thousands of men are engaged in dredging
 for oysters4 ,three of the most        
important of our oyster grounds are     
,long ,island ,sound1 ,narragansett     
,bay1 and ,chesapeake ,bay4             
,illustration3 ,this diagram shows how  
cases of intestinal disease 7typhoid and
 diarrhoea7 have been traced to oysters 

from a locality where they were fattened
 in water contaminated with sewage4     
7,loaned by ,american ,museum of        
,natural ,history47  ,sometimes oysters 
are artificially fattened by placing    
them on beds near the mouths of         
fresh-water streams4 ,too often these   
streams are the bearers of much sewage1 
and the oyster1 which lives on          
microscopic organisms1 takes in a number
 of bacteria with other food4 ,thus a   
person might become infected with the   
typhoid bacillus by eating raw oysters4 
,state and city supervision of the      
oyster industry makes this possibility  
very much less than it was a few years  
ago1 as careful bacteriological analysis
 of the surrounding water is constantly 
made by competent experts4              
,clams4--,other bivalve mollusks used   
for food are clams and scallops4 ,two   
species of the former are known to ,new 
,yorkers1 one as the round1 another as  
the long or soft-shelled clams4 ,the    
former 7,venus mercenaria7 was called by

 the ,indians quahog1 and is still so   
called in the ,eastern states4 ,the blue
 area of its shell was used by the      
,indians to make wampum1 or money4 ,the 
quahog is now extensively used as food4 
,the long clam 7,mya arenaria7 is       
considered better eating by the         
inhabitants of ,massachusetts and ,rhode
 ,island4 ,this clam was highly prized  
as food by the ,indians4 ,the clam      
industries of the eastern coast         
aggregate nearly #a1jjj1jjj a year4 ,the
 dredging for scallops1 another         
molluscan delicacy1 forms an important  
industry along certain parts of the     
eastern coast4  ,illustration3 ,salmon  
leaping a fall on their way to their    
spawning beds4 7,photographed by ,dr4   
,john ,a4 ,sampson47  ,fish as          
,food4--,fish are used as food the world
 over4 ,from very early times the       
herring were pursued by the ,norsemen4  
,fresh-water fish1 such as whitefish1   
perch1 pickerel1 pike1 and the various  
members of the trout family1 are        

esteemed food and1 especially in the    
,great ,lake region1 form important     
fisheries4 ,but by far the most         
important food fishes are those which   
are taken in salt water4 ,here we have  
two types of fisheries1 those where the 
fish comes up a river to spawn1 as the  
salmon1 sturgeon1 or shad1 and those in 
which fishes are taken on their feeding 
grounds in the open ocean4 ,herring are 
the world's most important catch1 though
 not in this country4 ,here the salmon  
of the western coast is taken to the    
value of over #ac1jjj1jjj a year4 ,cod  
fishing also forms an important         
industry2 over #gjjj men being employed 
and over #b1jjj1jjj of codfish being    
taken each year in this country4        
,illustration3 ,globe ,fisheries4       
,hundreds of other species of fish are  
used as food1 the fish that is nearest  
at hand being often the cheapest and    
best4 ,why1 for example1 is the flounder
 so cheap in the ,new ,york markets8 ,in
 what waters are the cod and herring    

fisheries1 sardine1 oyster1 sponge1     
pearl oyster8 7,see chart on page #bja47
  ,amphibia and ,reptiles as            
,food4--,frogs' legs are esteemed a     
delicacy4 ,certain reptiles are used as 
food by people of other nationalities1  
the ,iguana1 a ,mexican lizard1 being an
 example4 ,many of the sea-water turtles
 are of large size1 the leatherback and 
the green turtle often weighing six     
hundred to seven hundred pounds each4   
,the flesh of the green turtle and      
especially of the diamond-back terrapin1
 an animal found in the salt marshes    
along our southeastern coast1 is highly 
esteemed as food4 ,unfortunately for the
 preservation of the species1 these     
animals are usually taken during the    
breeding season when they go to sandy   
beaches to lay their eggs4  ,birds as   
,food4--,birds1 both wild and           
domesticated1 form part of our food     
supply4 ,unfortunately our wild game    
birds are disappearing so fast that we  
should not consider them as a source of 

food4 ,our domestic fowls1 turkey1      
ducks1 etc41 form an important food     
supply and poultry farms give lucrative 
employment to many people4 ,eggs of     
domesticated birds are of great         
importance as food1 and egg albumin is  
used for other purposes1--clarifying    
sugars1 coating photographic papers1    
etc4  ,mammals as ,food4--,when we      
consider the amount of wealth invested  
in cattle and other domesticated animals
 bred and used for food in the ,united  
,states1 we see the great economic      
importance of mammals4 ,the ,united     
,states1 ,argentina1 and ,australia are 
the greatest producers of cattle4 ,in   
this country hogs are largely raised for
 food4 ,they are used fresh1 salted1    
smoked as ham and bacon1 and pickled4   
,sheep1 which are raised in great       
quantities in ,australia1 ,argentina1   
,russia1 ,uruguay1 and this country1 are
 one of the world's greatest meat       
supplies4  ,goats1 deer1 many larger    
game animals1 seals1 walruses1 etc41    

give food to people who live in parts of
 the earth that are less densely        
populated4  ,domesticated ,animals4--   
,when man emerged from his savage state 
on the earth1 one of the first signs of 
the beginning of civilization was the   
domestication of animals4 ,the dog1 the 
cow1 sheep1 and especially the horse1   
mark epochs in the advance of           
civilization4 ,beasts of burden are used
 the world over1 horses almost all over 
the world1 certain cattle1 as the water 
buffalo1 in tropical ,malaysia2 camels1 
goats1 and the llama are also used as   
draft animals in some other countries4  
,illustration3 ,feeding silkworms4 ,the 
caterpillars are the white objects in   
the trays4  ,man's wealth in many parts 
of the world is estimated in terms of   
his cattle or herds of sheep4 ,so many  
products come from these sources that a 
long list might be given1 such as meats1
 milk1 butter1 cheese1 wool1 or other   
body coverings1 leather1 skins1 and     
hides used for other purposes4 ,great   

industries are directly dependent upon  
our domesticated animals1 as the making 
of shoes1 the manufacture of woolen     
cloth1 the tanning industry1 and many   
others4  ,uses for ,clothing4--,the     
manufacture of silk is due to the       
production of raw silk by the silkworm1 
the caterpillar of a moth4 ,it lives    
upon the mulberry and makes a cocoon    
from which the silk is wound4 ,the      
,chinese silkworm is now raised to a    
slight extent in southern ,california4  
,china1 ,japan1 ,italy1 and ,france1    
because of cheaper labor1 are the most  
successful silk-raising countries4  ,the
 use of wool gives rise to many great   
industries4 ,after the wool is cut from 
the sheep1 it has to be washed and      
scoured to get out the dirt and grease4 
,this wool fat or lanoline is used in   
making soap and ointments4 ,the wool is 
next carded1 the fibers being interwoven
 by the fine teeth of the carding       
machine or combed1 the fibers here being
 pulled out parallel to each other4     

,carded wool becomes woolen goods2      
combed wool1 worsted goods4 ,the wastes 
are also utilized1 being mixed with     
shoddy 7wool from cloth cuttings or     
rags7 to make woolen goods of a cheap   
grade4  ,goat hair1 especially that of  
the ,angora and the ,cashmere goat1 has 
much use in the clothing industries4    
,camel's hair and alpaca are also used4 
,illustration3 ,polar bear1 a           
fur-bearing mammal which is rapidly     
being exterminated4 ,why8  ,fur4--,the  
furs of many domesticated and wild      
animals are of importance4 ,the         
,carnivora as a group are of much       
economic importance as the source of    
most of our fur4 ,the fur seal fisheries
 alone amount to many millions of       
dollars annually4 ,otters1 skunks1      
sables1 weasels1 foxes1 and minks are of
 considerable importance as fur         
producers4 ,even cats are now used for  
fur1 usually masquerading under some    
other name4 ,the fur of the beaver1 one 
of the largest of the rodents or gnawing

 mammals1 is of considerable value1 as  
are the coats of the chinchilla1        
muskrats1 squirrels1 and other rodents4 
,the fur of the rabbit and nutria are   
used in the manufacture of felt hats4   
,the quills of the porcupines 7greatly  
developed and stiffened hairs7 have a   
slight commercial value4  ,conservation 
of ,fur-bearing ,animals ,needed4--,as  
time goes on and the furs of wild       
animals become scarcer and scarcer      
through overkilling1 we find the need   
for protection and conservation of many 
of these fast-vanishing wild forms more 
and more imperative4 ,already breeding  
of some fur-bearing animals has been    
tried with success1 and cheap           
substitutes for wild animal skins are   
coming more and more into the markets4  
,black-fox breeding has been tried      
successfully in ,prince ,edward ,island1
 ,canada1 #bejj to #cjjj being given for
 a single skin4 ,skunk1 marten1 and mink
 are also being bred for the market4    
,game preserves in this country and     

,canada are also helping to preserve our
 wild fur-bearing animals4  ,animal     
,oils4--,whale oil1 obtained from the   
fat or blubber of whales1 is used       
extensively for lubricating4            
,neat's-foot oil comes from the feet of 
cattle and is also used in lubrication4 
,tallow and lard1 two fats from cattle1 
sheep1 and pigs1 have so many well-known
 uses that comment is unnecessary4      
,cod-liver oil is used medically and is 
well known4 ,but it is not so widely    
known that a fish called the menhaden or
 moss bunkers of the ,atlantic coast    
produces over #c1jjj1jjj gallons of oil 
every year and is being rapidly         
exterminated in consequence4  ,hides1   
,horns1 ,hoofs1 etc4--,leathers1 from   
cattle1 horses1 sheep1 and goats1 are   
used everywhere4 ,leather manufacture is
 one of the great industries of the     
,eastern states1 hundreds of millions of
 dollars being invested in its          
manufacturing plants4 ,horns and bones  
are utilized for making combs1 buttons1 

handles for brushes1 etc4 ,glue is made 
from the animal matter in bones4 ,ivory1
 obtained from elephant1 walrus1 and    
other tusks1 forms a valuable commercial
 product4 ,it is largely used for knife 
handles1 piano keys1 combs1 etc4        
,perfumes4--,the musk deer1 musk ox1 and
 muskrat furnish a valuable perfume     
called musk4 ,civet cats also give us a 
somewhat similar perfume4 ,ambergris1 a 
basis for delicate perfumes1 comes from 
the intestines of the sperm whale4      
,protozoa4--,the ,protozoa have played  
an important part in rock building4 ,the
 chalk beds of ,kansas and other chalk  
formations are made up to a large extent
 of the tiny skeletons of ,protozoa1    
called ,foraminifera4 ,some limestone   
rocks are also composed in large part of
 such skeletons4 ,the skeletons of some 
species are used to make a polishing    
powder4  ,sponges4--,the sponges of     
commerce have the skeleton composed of  
tough fibers of material somewhat like  
that of cow's horn4 ,this fiber is      

elastic and has the power of absorbing  
water4 ,in a living state1 the horny    
fiber sponge is a dark-colored fleshy   
mass1 usually found attached to rocks4  
,the warm waters of the ,mediterranean  
,sea and the ,west ,indies furnish most 
of our sponges4 ,the sponges are pulled 
up from their resting place on the      
bottom1 by means of long-handled rakes  
operated by men in boats or are secured 
by divers4 ,they are then spread out on 
the shore in the sun1 and the living    
tissues allowed to decay2 then after    
treatment consisting of beating1        
bleaching1 and trimming1 the bath sponge
 is ready for the market4 ,some forms of
 coral are of commercial value4 ,the red
 coral of the ,mediterranean ,sea is the
 best example4  ,illustration3 ,in some 
countries little metal images of ,buddha
 are placed within the shells of living 
pearl oysters or clams4 ,over these the 
mantle of the animal secretes a layer of
 mother of pearl as is shown in the     
picture4  ,pearls and ,mother of        

,pearl4--,pearls are prized the world   
over4 ,it is a well-known fact that even
 in this country pearls of some value   
are sometimes found within the shells of
 the fresh-water mussel and the oyster4 
,most of the finest1 however1 come from 
the waters around ,ceylon4 ,if a pearl  
is cut open and examined carefully1 it  
is found to be a deposit of the         
mother-of-pearl layer of the shell      
around some central structure4 ,it has  
been believed that any foreign          
substance1 as a grain of sand1 might    
irritate the mantle at a given point1   
thus stimulating it to secrete around   
the substance4 ,it now seems likely that
 most perfect pearls are due to the     
growth within the mantle of the clam or 
oyster of certain parasites1 stages in  
the development of a flukeworm4 ,the    
irritation thus set up in the tissue    
causes mother of pearl to be deposited  
around the source of irritation1 with   
the subsequent formation of a pearl4    
,the pearl-button industry in this      

country is largely dependent upon the   
fresh-water mussel1 the shells of which 
are used4 ,this mussel is being so      
rapidly depleted that the national      
government is working out a means of    
artificial propagation of these animals4
  ,honey and ,wax4--,honeybees#bi are   
kept in hives4 ,a colony consists of a  
queen1 a female who lays the eggs for   
the colony1 the drones1 whose duty it is
 to fertilize the eggs1 and the workers4
       ,footnote #bi3 ,their daily life 
may be easily watched in the            
schoolroom1 by means of one of the many 
good and cheap      observation hives   
now made to be placed in a window frame4
      ,directions for making a small    
observation hive for school      work   
can be found in ,hodge1 ,nature ,study  
and ,life1 ,chap4      ,,xiv4 ,bulletin 
,no4 #a1 ,u4 ,s4 ,department of         
,agriculture1      entitled ,the ,honey 
,bee1 by ,frank ,benton1 is valuable for
      the amateur beekeeper4 ,it may be 
obtained for twenty-five      cents from

 the ,superintendent of ,documents1     
,union ,building1      ,washington1     
,d4,c4  ,illustration3 ,cells of        
honeycomb1 queen cell on right at       
bottom4  ,the cells of the comb are     
built by the workers out of wax secreted
 from the under surface of their bodies4
 ,the wax is cut off in thin plates by  
means of the wax shears between the two 
last joints of the hind legs4 ,these    
cells are used to place the eggs of the 
queen in1 one egg to each cell1 and the 
young are hatched after three days1 to  
begin life as footless white grubs4     
,the young are fed for several days1    
then shut up in the cells and allowed to
 form pupae4 ,eventually they break     
their cells and take their place as     
workers in the hive1 first as nurses for
 the young and later as pollen gatherers
 and honey makers4  ,we have already    
seen 7pages #cg to #ci7 that the        
honeybee gathers nectar1 which she      
swallows1 keeping the fluid in her crop 
until her return to the hive4 ,here it  

is forced out into cells of the comb4   
,it is now thinner than what we call    
honey4 ,to thicken it1 the bees swarm   
over the open cells1 moving their wings 
very rapidly1 thus evaporating some of  
the water4 ,a hive of bees have been    
known to make over thirty-one pounds of 
honey in a single day1 although the     
average is very much less than this4 ,it
 is estimated from twenty to thirty     
millions of dollars' worth of honey and 
wax are produced each year in this      
country4  ,cochineal and ,lac4--,among  
other products of insect origin is      
cochineal1 a red coloring matter1 which 
consists of the dried bodies of a tiny  
insect1 one of the plant lice which     
lives on the cactus plants in ,mexico   
and ,central ,america4 ,the lac insect1 
another one of the plant lice1 feeds on 
the juices of certain trees in ,india   
and pours out a substance from its body 
which after treatment forms shellac4    
,shellac is of much use as a basis for  
varnish4  ,gall ,insects4--,oak galls1  

growths caused by the sting of wasp-like
 insects1 give us products used in ink  
making1 in tanning1 and in making       
pyrogallic acid which is much used in   
developing photographs4  ,insects       
destroy ,harmful ,plants or             
,animals4--,some forms of animal life   
are of great importance because of their
 destruction of harmful plants or       
animals4  ,illustration3 ,an insect     
friend of man4 ,an ichneumon fly boring 
in a tree to lay its eggs in the burrow 
of a boring insect harmful to that tree4
  ,a near relative of the bee1 called   
the ichneumon fly1 does man indirectly  
considerable good because of its habit  
of laying its eggs and rearing the young
 in the bodies of caterpillars which are
 harmful to vegetation4 ,some of the    
ichneumons even bore into trees in order
 to deposit their eggs in the larvae of 
wood-boring insects4 ,it is safe to say 
that the ichneumons save millions of    
dollars yearly to this country4         
,several beetles are of value to man4   

,most important of these is the natural 
enemy of the orange-tree scale1 the     
ladybug1 or ladybird beetle4 ,in ,new   
,york state it may often be found       
feeding upon the plant lice1 or aphids1 
which live on rosebushes4 ,the carrion  
beetles and many water beetles act as   
scavengers4 ,the sexton beetles bury    
dead carcasses of animals4 ,ants in     
tropical countries are particularly     
useful as scavengers4  ,insects1 besides
 pollinating flowers1 often do a service
 by eating harmful weeds4 ,thus many    
harmful plants are kept in check4 ,we   
have noted that they spin silk1 thus    
forming clothing2 that in many cases    
they are preyed upon1 and that they     
supply an enormous multitude of birds1  
fishes1 and other animals with food4    
,illustration3 ,the common toad1 an     
insect eater4  ,use of the ,toad4--,the 
toad is of great economic importance to 
man because of its diet4 ,no less than  
eighty-three species of insects1 mostly 
injurious1 have been proved to enter    

into the dietary4 ,a toad has been      
observed to snap up one hundred and     
twenty-eight flies in half an hour4     
,thus at a low estimate it could easily 
destroy one hundred insects during a day
 and do an immense service to the garden
 during the summer4 ,it has been        
estimated by ,kirkland that a single    
toad may1 on account of the cutworms    
which it kills1 be worth #ai4hh each    
season it lives1 if the damage done by  
each cutworm be estimated at only one   
cent4 ,toads also feed upon slugs and   
other garden pests4  ,birds eat         
,insects4--,the food of birds makes them
 of the greatest economic importance to 
our country4 ,this is because of the    
relation of insects to agriculture4 ,a  
large part of the diet of most of our   
native birds includes insects harmful to
 vegetation4 ,investigations undertaken 
by the ,united ,states ,department of   
,agriculture 7,division of ,biological  
,survey7 show that a surprisingly large 
number of birds once believed to harm   

crops really perform a service by       
killing injurious insects4 ,even the    
much maligned crow lives to some extent 
upon insects4 ,swallows in the ,southern
 states kill the cotton-boll weevil1 one
 of our worst insect pests4 ,our        
earliest visitor1 the bluebird1 subsists
 largely on injurious insects1 as do    
woodpeckers1 cuckoos1 kingbirds1 and    
many others4 ,the robin1 whose presence 
in the cherry tree we resent1 during the
 rest of the summer does much good by   
feeding upon noxious insects4 ,birds use
 the food substances which are most     
abundant around them at the time4#cj    
,footnote #cj3 ,the following quotation 
from ,i4 ,p4 ,trimble1 ,a      ,treatise
 on the ,insect ,enemies of ,fruit and  
,shade ,trees1      bears out this      
statement3 ,on the fifth of ,may1 #ahfd1
 444      seven different birds 444 had 
been feeding freely upon small          
beetles4444 ,there was a great flight of
 beetles that day2      the atmosphere  
was teeming with them4 ,a few days      

after1 the      air was filled with     
,ephemera flies1 and the same species of
      birds were then feeding upon them4
       ,during the outbreak of ,rocky   
,mountain locusts in ,nebraska in       
#ahgd-ahgg1 ,professor ,samuel ,aughey  
saw a long-billed marsh      wren carry 
thirty locusts to her young in an hour4 
,at this      rate1 for seven hours a   
day1 a brood would consume #baj         
locusts per day1 and the passerine birds
 of the eastern half      of ,nebraska1 
allowing only twenty broods to the      
square mile1      would destroy daily   
#afb1gga1jjj of the pests4 ,the average 
locust weighs about fifteen grains1 and 
is capable each day      of consuming   
its own weight of standing forage crops1
 which      at #aj per ton would be     
worth #agdc4bf4 ,this case may serve    
as an illustration of the vast good that
 is done every year      by the         
destruction of insect pests fed to      
nestling birds4      ,and it should be  
remembered that the nesting season is   

also      that when the destruction of  
injurious insects is most      needed2  
that is1 at the period of greatest      
agricultural      activity and before   
the parasitic insects can be depended on
      to reduce the pests4 ,the         
encouragement of birds to nest on       
the farm and the discouragement of nest 
robbing are      therefore more than    
mere matters of sentiment2 they return  
an actual cash equivalent1 and have a   
definite bearing on      the success or 
failure of the crops4--,year ,book of   
the      ,department of ,agriculture4   
,illustration3 ,food of some common     
birds4 ,which of the above birds should 
be protected by man and why8  ,birds eat
 ,weed ,seeds4--,not only do birds aid  
man in his battles with destructive     
insects1 but seed-eating birds eat the  
seeds of weeds4 ,our native sparrows    
7not the ,english sparrow71 the mourning
 dove1 bobwhite1 and other birds feed   
largely upon the seeds of many of our   
common weeds4 ,this fact alone is       

sufficient to make birds of vast        
economic importance4  ,not all birds are
 seed or insect feeders4 ,some1 as the  
cormorants1 ospreys1 gulls1 and terns1  
are active fishers4 ,near large cities  
gulls especially act as scavengers1     
destroying much floating garbage that   
otherwise might be washed ashore to     
become a menace to health4 ,the vultures
 of ,india and semitropical countries   
are of immense value as scavengers4     
,birds of prey 7owls7 eat living        
mammals1 including many rodents2 for    
example1 field mice1 rats1 and other    
pests4  ,extermination of our ,native   
,birds4--,within our own times we have  
witnessed the almost total extermination
 of some species of our native birds4   
,the ,american passenger pigeon1 once   
very abundant in the ,middle ,west1 is  
now extinct4 ,audubon1 the greatest of  
all ,american bird lovers1 gives a      
graphic account of the migration of a   
flock of these birds4 ,so numerous were 
they that when the flock rose in the air

 the sun was darkened1 and at night the 
weight of the roosting birds broke down 
large branches of the trees in which    
they rested4 ,to-day not a single wild  
specimen of this pigeon can be found1   
because they were slaughtered by the    
hundreds of thousands during the        
breeding season4 ,the wholesale killing 
of the snowy egret to furnish ornaments 
for ladies' headwear is another example 
of the improvidence of our              
fellow-countrymen4 ,charles ,dudley     
,warner said1 ,feathers do not improve  
the appearance of an ugly woman1 and a  
pretty woman needs no such aid4         
,wholesale killing for plumage1 eggs1   
and food1 and1 alas1 often for mere     
sport1 has reduced the number of our    
birds more than one half in thirty      
states and territories within the past  
fifteen years4 ,every crusade against   
indiscriminate killing of our native    
birds should be welcomed by all thinking
 ,americans4 ,the recent ,mc,lane bill  
which aims at the protection of         

migrating birds and the bird-protecting 
clause of the recently passed tariff    
bill shows that this country is awaking 
to the value of her bird life4 ,without 
the birds the farmer would have a       
hopeless fight against insect pests4    
,the effect of killing native birds is  
now well seen in ,italy and ,japan1     
where insects are increasing and do     
greater damage each year to crops and   
trees4  ,of the eight hundred or more   
species of birds in the ,united ,states1
 only six species of hawks 7,cooper's   
and the sharp-shinned hawk in           
particular71 and the great horned owl1  
which prey upon useful birds2 the       
sapsucker1 which kills or injures many  
trees because of its fondness for the   
growing layer of the tree2 the bobolink1
 which destroys yearly #b1jjj1jjj worth 
of rice in the ,south2 the crow1 which  
feeds on crops as well as insects2 and  
the ,english sparrow1 may be considered 
as enemies of man4  ,the ,english       
,sparrow4--,the ,english sparrow is an  

example of a bird introduced for the    
purpose of insect destruction1 that has 
done great harm because of its relation 
to our native birds4 ,introduced at     
,brooklyn in #ahej for the purpose of   
exterminating the cankerworm1 it soon   
abandoned an insect diet and has driven 
out most of our native insect feeders4  
,investigations by the ,united ,states  
,department of ,agriculture have shown  
that in the country these birds and     
their young feed to a large extent upon 
grain1 thus showing them to be injurious
 to agriculture4 ,dirty and very        
prolific1 it already has worked its way 
from the ,east as far as the ,pacific   
coast4 ,in this area the bluebird1 song 
sparrow1 and yellowbird have all been   
forced to give way1 as well as many     
larger birds of great economic value and
 beauty4 ,the ,english sparrow has      
become a pest especially in our cities1 
and should be exterminated in order to  
save our native birds4 ,it is feared in 
some quarters that the ,english starling

 which has recently been introduced into
 this country may in time prove a pest  
as formidable as the ,english sparrow4  
,illustration3 ,this shows how some     
snakes 7constrictors7 kill and eat their
 prey4 7,series photographed by ,c4 ,w4 
,beebe and ,clarence ,halter47  ,food of
 ,snakes4--,probably the most disliked  
and feared of all animals are the       
snakes4 ,this feeling1 however1 is      
rarely deserved1 for1 on the whole1 our 
common snakes are beneficial to man4    
,the black snake and the milk snake feed
 largely on injurious rodents 7rats1    
mice1 etc471 the pretty green snake eats
 injurious insects1 and the little      
,de,kay snake feeds partially on slugs4 
,if it were not that the rattlesnake and
 the copperhead are venomous1 they also 
could be said to be useful1 for they    
live on ,english sparrows1 rats1 mice1  
moles1 and rabbits4  ,food of           
,herbivorous ,animals4--,we must not    
forget that other animals besides       
insects and birds help to keep down the 

rapidly growing weeds4 ,herbivorous     
animals the world over destroy1 besides 
the grass which they eat1 untold        
multitudes of weeds1 which1 if          
unchecked1 would drive out the useful   
occupants of the pasture1 the grasses   
and grains4   ,,harm ,,done ,,by        
,,animals  ,economic ,loss from         
,insects4--,the money value of crops1   
forest trees1 stored foods1 and other   
material destroyed annually by insects  
is beyond belief4 ,it is estimated that 
they get one tenth of the country's     
crops1 at the lowest estimate a matter  
of some #cjj1jjj1jjj yearly4 ,the common
 schools of the country cost in #aijb   
the sum of #bce1jjj1jjj1 and all higher 
institutions of learning cost less than 
#ej1jjj1jjj1 making the total cost of   
education in the ,united ,states        
considerably less than the farmers lost 
from insect ravages4       ,furthermore1
 the yearly losses from insect ravages  
aggregate nearly twice as much as it    
costs to maintain our      army and     

navy2 more than twice the loss by fire2 
twice the      capital invested in      
manufacturing agricultural implements2  
and nearly three times the estimated    
value of the products      of all the   
fruit orchards1 vineyards1 and small    
fruit farms      in the                 
country4--,,slingerland4  ,the total    
yearly value of all farm and forest     
products in ,new ,york is perhaps       
#aej1jjj1jjj1 and the one tenth that the
 insects get is worth #ae1jjj1jjj4      
,insects which damage ,garden and ,other
 ,crops4--,the grasshoppers and the     
larvae of various moths do considerable 
harm here1 especially the cabbage worm1 
the cutworm1 a feeder on all kinds of   
garden truck1 and the corn worm1 a pest 
on corn1 cotton1 tomatoes1 peas1 and    
beans4  ,among the beetles which are    
found in gardens is the potato beetle1  
which destroys the potato plant4 ,this  
beetle formerly lived in ,mexico upon a 
wild plant of the same family as the    
potato1 and came north upon the         

introduction of the potato into         
,colorado1 evidently preferring         
cultivated forms to wild forms of this  
family4  ,illustration3 ,cotton-boll    
weevil4 a1 larva2 b1 pupa2 c1 adult4    
,enlarged about four times4             
7,photographed by ,davison47  ,the one  
beetle doing by far the greatest harm in
 this country is the cotton-boll weevil4
 ,imported from ,mexico1 since #ahib it 
has spread over eastern ,texas and into 
,louisiana4 ,the beetle lays its eggs in
 the young cotton fruit or boll1 and the
 larvae feed upon the substance within  
the boll4 ,it is estimated that if      
unchecked this pest would destroy yearly
 one half of the cotton crop1 causing a 
loss of #bej1jjj1jjj4 ,fortunately1 the 
,united ,states ,department of          
,agriculture is at work on the problem1 
and1 while it has not found any way of  
exterminating the beetle as yet1 it has 
been found that1 by planting more hardy 
varieties of cotton1 the crop matures   
earlier and ripens before the weevils   

have increased in sufficient numbers to 
destroy the crop 7see page #abf74  ,the 
bugs are among our most destructive     
insects4 ,the most familiar examples of 
our garden pests are the squash bug2 the
 chinch bug1 which yearly does damage   
estimated at #bj1jjj1jjj1 by sucking the
 juice from the leaves of grain2 and the
 plant lice1 or aphids4 ,one1 living on 
the grape1 yearly destroys immense      
numbers of vines in the vineyards of    
,france1 ,germany1 and ,california4     
,illustration3 ,female tussock moth     
which has just emerged from the cocoon  
at the left1 upon which it has deposited
 over two hundred eggs4 7,photograph by 
,davison47  ,illustration3 ,caterpillar 
of tussock moth4 7,photograph by        
,davison47  ,insects which harm ,fruit  
and ,forest ,trees4--,great damage is   
annually done trees by the larvae of    
moths4 ,massachusetts has already spent 
over #c1jjj1jjj in trying to exterminate
 the imported gypsy moth4 ,the codling  
moth1 which bores into apples and pears1

 is estimated to ruin yearly #c1jjj1jjj 
worth of fruit in ,new ,york alone1     
which is by no means the most important 
apple region of the ,united ,states4    
,among these pests1 the most important  
to the dweller in a large city is the   
tussock moth1 which destroys our shade  
trees4 ,the caterpillar may easily be   
recognized by its hairy1 tufted red     
head4 ,the eggs are laid on the bark of 
shade trees in what look like masses of 
foam4 7,see figure on page #bae47 ,by   
collecting and burning the egg masses in
 the fall1 we may save many shade trees 
the following year4  ,the larvae of some
 moths damage the trees by boring into  
the wood of the tree on which they live4
 ,such are the peach1 apple1 and other  
fruit-tree borers common in our         
orchards4 ,many beetle larvae also live 
in trees and kill annually thousands of 
forest and shade trees4 ,the hickory    
borer threatens to kill all the hickory 
trees in the ,eastern states4  ,among   
the bugs most destructive to trees are  

the scale insect and the plant lice4    
,the ,san ,jose scale1 a native of      
,china1 was introduced into the fruit   
groves of ,california about #ahgj and   
has spread all over the country4 ,a     
ladybird beetle1 which has also been    
imported1 is the most effective agent in
 keeping this pest in check4  ,insects  
of the ,house or ,storehouse4--,weevils 
are the greatest pests1 frequently      
ruining tons of stored corn1 wheat1 and 
other cereals4 ,roaches will eat almost 
anything1 even clothing2 they are       
especially fond of all kinds of         
breadstuffs4 ,the carpet beetle is a    
recognized foe of the housekeeper1 the  
larvae feeding upon all sorts of woolen 
material4 ,the larvae of the clothes    
moth do an immense amount of damage1    
especially to stored clothing4 ,fleas1  
lice1 and particularly bedbugs are among
 man's personal foes4 ,besides being    
unpleasant they are believed to be      
disease carriers and as such should be  
exterminated4#ca       ,footnote #ca3   

,directions for the treatment of these  
pests may      be found in pamphlets    
issued by the ,u4 ,s4 ,department of    
,agriculture4  ,food of                 
,starfish4--,starfish are enormously    
destructive to young clams and oysters1 
as the following evidence1 collected by 
,professor ,a4 ,d4 ,mead1 of ,brown     
,university1 shows4 ,a single starfish  
was confined in an aquarium with        
fifty-six young clams4 ,the largest clam
 was about the length of one arm of the 
starfish1 the smallest about ten        
millimeters in length4 ,in six days     
every clam in the aquarium was devoured4
 ,hundreds of thousands of dollars'     
damage is done annually to the oysters  
in ,connecticut alone by the ravages of 
starfish4 ,during the breeding season of
 the clam and oyster the boats dredge up
 tons of starfish which are thrown on   
shore to die or to be used as           
fertilizer4   ,,the ,,relations ,,of    
,,animals ,,to ,,disease  ,illustration3
 ,the life history of the malarial      

parasite4 ,this cut of the malarial     
parasite shows parts of the body of the 
mosquito and of man4 ,to understand the 
life history begin at the point where   
the mosquito injects the crescent-shaped
 bodies into the blood of man4 ,notice  
that after the spores are released from 
the corpuscles of man two kinds of cells
 may be formed4 ,these are probably a   
sexual stage4 ,development within the   
body of the mosquito will only take     
place when the parasite is taken into   
its body at this sexual stage4  ,the    
,cause of ,malaria4--,the study of the  
life history and habits of the ,protozoa
 has resulted in the finding of many    
parasitic forms1 and the consequent     
explanation of some kinds of disease4   
,one parasitic protozoan like an amoeba 
is called ,plasmodium malariae4 ,it     
causes the disease known as malaria4    
,when a mosquito 7the anopheles7 sucks  
the blood from a person having malaria  
this parasite passes into the stomach of
 the mosquito4 ,after completing a part 

of its life history within the          
mosquito's body the parasite establishes
 itself within the glands which secrete 
the saliva of the mosquito4 ,after about
 eight days1 if the infected mosquito   
bites a person1 some of the parasites   
are introduced into the blood along with
 the saliva4 ,these parasites enter the 
corpuscles of the blood1 increase in    
size1 and then form spores4 ,the rapid  
process of spore formation results in   
the breaking down of the blood          
corpuscles and the release of the       
spores1 and the poisons they            
manufacture1 into the blood4 ,this      
causes the chill followed by the fever  
so characteristic of malaria4 ,the      
spores may again enter the blood        
corpuscles and in forty-eight or        
seventy-two hours repeat the process    
thus described1 depending on the kind of
 malaria they cause4 ,the only cure for 
the disease is quinine in rather large  
doses4 ,this kills the parasites in the 
blood4 ,but quinine should not be taken 

except under a physician's directions4  
,illustration3 ,how to distinguish the  
harmless mosquito 7culex71 a1 from the  
malarial mosquito 7anopheles71 b1 when  
at rest4 ,notice the position of legs   
and body4  ,the ,malarial               
,mosquito4--,fortunately for mankind1   
not all mosquitoes harbor the parasite  
which causes malaria4 ,the harmless     
mosquito 7culex7 may be usually         
distinguished from the mosquito which   
carries malaria 7anopheles7 by the      
position taken when at rest4 ,culex lays
 eggs in tiny rafts of one hundred or   
more eggs in any standing water2 thus   
the eggs are distinguished from those of
 anopheles1 which are not in rafts4     
,rain barrels1 gutters1 or old cans may 
breed in a short time enough mosquitoes 
to stock a neighborhood4 ,the larvae are
 known as wigglers4 ,they breathe       
through a tube in the posterior end of  
the body1 and may be recognized by their
 peculiar movement when on their way to 
the surface to breathe4 ,the pupa1      

distinguished by a large thoracic       
region1 breathes through a pair of tubes
 on the thorax4 ,the fact that both     
larvae and pupae take air from the      
surface of the water makes it possible  
to kill the mosquito during these stages
 by pouring oil on the surface of the   
water where they breed4 ,the            
introduction of minnows1 gold fish1 or  
other small fish which feed upon the    
larvae in the water where the mosquitoes
 breed will do much to free a           
neighborhood from this pest4 ,draining  
swamps or low land which holds water    
after a rain is another method of       
extermination4 ,some of the             
mosquito-infested districts around ,new 
,york ,city have been almost freed from 
mosquitoes by draining the salt marshes 
where they breed4 ,long shallow trenches
 are so built as to tap and drain off   
any standing water in which the eggs    
might be laid4 ,in this way the mosquito
 has been almost exterminated along some
 parts of our ,new ,england coast4      

,illustration3 ,swamps are drained and  
all standing water covered with a film  
of oil in order to exterminate          
mosquitoes4 ,why is the oil placed on   
the surface of the water8  ,since the   
beginning of historical times1 malaria  
has been prevalent in regions infested  
by mosquitoes4 ,the ancient city of     
,rome was so greatly troubled by        
periodic outbreaks of malarial fever    
that a goddess of fever came to be      
worshiped in order to lessen the        
severity of what the inhabitants        
believed to be a divine visitation4 ,at 
the present time the malaria of ,italy  
is being successfully fought and        
conquered by the draining of the        
mosquito-breeding marshes4 ,by a little 
carefully directed oiling of water a few
 boys may make an almost uninhabitable  
region absolutely safe to live in4 ,why 
not try it if there are mosquitoes in   
your neighborhood8  ,yellow ,fever and  
,mosquitoes4--,another disease carried  
by mosquitoes is yellow fever4 ,in the  

year #ahgh there were #abe1jjj cases and
 #ab1jjj deaths in the ,united ,states1 
mostly in ,alabama1 ,louisiana1 and     
,mississippi4 ,during the ,french       
occupation of the ,panama ,canal zone   
the work was at a standstill part of the
 time because of the ravages of yellow  
fever4 ,before the war with ,spain      
thousands of people were ill in ,cuba4  
,but to-day this is changed1 and yellow 
fever is under almost complete control1 
both here and in the ,canal zone1 where 
the mosquito 7stegomyia7 which carries  
yellow fever exists4  ,illustration3    
,notice the difference in the number of 
yearly deaths from yellow fever before  
and after the ,american occupation of   
,havana4  ,this is due to the           
experiments during the summer of #aijj  
of a ,commission of ,united ,states army
 officers1 headed by ,dr4 ,walter ,reed4
 ,of these men one1 ,dr4 ,jesse ,lazear1
 gave up his life to prove              
experimentally that yellow fever was    
caused by mosquitoes4 ,he allowed       

himself to be bitten by a mosquito that 
was known to have bitten a yellow fever 
patient1 contracted the disease1 and    
died a martyr to science4 ,others1      
soldiers1 volunteered to further test by
 experiment how the disease was spread1 
so that in the end ,dr4 ,reed was able  
to prove to the world that if mosquitoes
 could be prevented from biting people  
who had yellow fever the disease could  
not be spread4 ,the accompanying        
illustration shows the result of this   
knowledge for the city of ,havana4 ,for 
years ,havana was considered one of the 
pest spots of the ,west ,indies4        
,visitors shunned this port and commerce
 was much affected by the constant      
menace of yellow fever4 ,at the time of 
the ,american occupation after the war  
with ,spain1 the experiments referred to
 above were undertaken4 ,the city was   
cleaned up1 proper sanitation           
introduced1 screens placed in most      
buildings1 and the breeding places of   
the mosquitoes were so nearly destroyed 

that the city was practically free from 
mosquitoes4 ,the result1 so far as      
yellow fever was concerned1 was         
startling1 as you can see by reference  
to the chart4 ,notice also the rise in  
the death rate when the young ,cuban    
,republic took control4 ,how do you     
account for that8 ,we all know what     
,american scientific medicine and       
sanitation is doing in ,panama and in   
the ,philippines4  ,illustration3       
,stegomyia1 the carrier of yellow fever4
 7,after ,howard47  ,other ,protozoan   
,diseases4--,many other diseases of man 
are probably caused by parasitic        
protozoans4 ,dysentery of one kind      
appears to be caused by the presence of 
an amoeba-like animal in the digestive  
tract which comes usually through an    
impure water supply4 ,smallpox1 rabies1 
and possibly other diseases are caused  
by protozoans4 ,smallpox1 which was once
 the most dreaded disease known to man1 
because of its spread in epidemics1 has 
been conquered by vaccination1 of which 

we shall learn more later4 ,the death   
rate from rabies or hydrophobia has in a
 like manner been greatly reduced by a  
treatment founded on the same principles
 as vaccination and invented by ,louis  
,pasteur4  ,another group of protozoan  
parasites are called trypanosomes4      
,these are parasitic in insects1 fish1  
reptiles1 birds1 and mammals in various 
parts of the world4 ,they cause various 
diseases of cattle and other domestic   
animals1 being carried to the animal in 
most cases by flies4 ,one of this family
 is believed to live in the blood of    
native ,african zebras and antelopes2   
seemingly it does them no harm4 ,but if 
one of these parasites is transferred by
 the dreaded tsetse fly to one of the   
domesticated horses or cattle of the    
colonist of that region1 death of the   
animal results4  ,another fly carries a 
species of trypanosome to the natives of
 ,central ,africa1 which causes the     
dreaded and incurable sleeping sickness4
 ,this disease carries off more than    

fifty thousand natives yearly1 and many 
,europeans have succumbed to it4 ,its   
ravages are now largely confined to an  
area near the large ,central ,african   
lakes and the ,upper ,nile1 for the fly 
which carries the disease lives near    
water1 seldom going more than #aej feet 
from the banks of streams or lakes4 ,the
 ,british government is now trying to   
control the disease in ,uganda by moving
 all the villages at least two miles    
from the lakes and rivers4 ,among other 
diseases that may be due to protozoans  
is kala-agar1 a fever in hot ,asiatic   
countries which is probably carried by  
the bedbug1 and ,african tick fever1    
probably carried by a small insect      
called the tick4 ,bubonic plague1 one of
 the most dreaded of all infectious     
diseases1 is carried to man by fleas    
from rats4 ,in this country many fatal  
diseases of cattle1 as tick1 or ,texas  
cattle fever1 are probably caused by    
protozoans4  ,illustration3 ,life       
history of house flies1 showing from    

left to right the eggs1 larvae1 pupae1  
and adult flies4 7,photograph1 about    
natural size1 by ,overton47  ,the ,fly a
 ,disease ,carrier4--,we have already   
seen that mosquitoes of different       
species carry malaria and yellow fever4 
,another rather recent addition to the  
black list is the house fly or typhoid  
fly4 ,we shall see later with what      
reason this name is given4 ,the         
development of the typhoid fly is       
extremely rapid4 ,a female may lay from 
one hundred to two hundred eggs4 ,these 
are usually deposited in filth or       
manure4 ,dung heaps about stables1 privy
 vaults1 ash heaps1 uncared-for garbage 
cans1 and fermenting vegetable refuse   
form the best breeding places for flies4
 ,in warm weather1 the eggs hatch a day 
or so after they are laid and become    
larvae1 called maggots4 ,after about one
 week of active feeding1 these wormlike 
maggots become quiet and go into the    
pupal stage1 whence under favorable     
conditions they emerge within less than 

another week as adult flies4 ,the adults
 breed at once1 and in a short summer   
there may be over ten generations of    
flies4 ,this accounts for the great     
number4 ,fortunately relatively few     
flies survive the winter4 ,the          
membranous wings of the adult fly appear
 to be two in number1 a second pair     
being reduced to tiny knobbed hairs     
called balancers4 ,the head is freely   
movable1 with large compound eyes4 ,the 
mouth parts form a proboscis1 which is  
tonguelike1 the animal obtaining its    
food by lapping and sucking4 ,the foot  
shows a wonderful adaptation for        
clinging to smooth surfaces4 ,two or    
three pads1 each of which bears tubelike
 hairs that secrete a sticky fluid1 are 
found on its under surface4 ,it is by   
this means that the fly is able to walk 
upside down1 and carry bacteria on its  
feet4  ,illustration3 ,the foot of a    
fly1 showing the hooks1 hairs1 and pads 
which collect and carry bacteria4 ,the  
fly doesn't wipe his feet4              

,illustration3 ,colonies of bacteria    
which have developed in a culture medium
 upon which a fly was allowed to walk4  
,the ,typhoid ,fly a ,pest4--,the common
 fly is recognized as a pest the world  
over4 ,flies have long been known to    
spoil food through their filthy habits1 
but it is more recently that the very   
serious charge of spread of diseases1   
caused by bacteria1 has been laid at    
their door4 ,in a recent experiment two 
young men from the ,connecticut         
,agricultural ,station found that a     
single fly might carry on its feet      
anywhere from #ejj to #f1fjj1jjj        
bacteria1 the average number being over 
#a1bjj1jjj4 ,not all of these germs are 
harmful1 but they might easily include  
those of typhoid fever1 tuberculosis1   
summer complaint1 and possibly other    
diseases4 ,a recent pamphlet published  
by the ,merchants' ,association in ,new 
,york ,city shows that the rapid        
increase of flies during the summer     
months has a definite correlation with  

the increase in the number of cases of  
summer complaint4 ,observations in other
 cities seem to show the increase in    
number of typhoid cases in the early    
fall is due1 in part at least1 to the   
same cause4 ,a terrible toll of disease 
and death may be laid at the door of the
 typhoid fly4  ,illustration3 ,showing  
how flies may spread disease by means of
 contaminating food4  ,recently the     
stable fly has been found to carry the  
dread disease known as infantile        
paralysis4  ,illustration3 ,there were  
#cbi typhoid cases in ,jacksonville1    
,florida1 in #aiaj1 #aeh in #aiaa1 #hg  
in first #aj months of #aiab4 #hj to #he
 per cent of outdoor toilets were made  
fly proof during winter of #aiaj4       
,account for the decrease in typhoid    
after the flies were kept out of the    
toilets4  ,remedies4--,cleanliness which
 destroys the breeding place of flies1  
the frequent removal and destruction of 
garbage1 rubbish1 and manure1 covering  
of all food when not in use and         

especially the careful screening of     
windows and doors during the breeding   
season1 will all play a part in the     
reduction of flies4 ,to the motto swat  
the fly should be added1 remove their   
breeding places6  ,illustration3 ,flea  
which transmits ,bubonic plague from rat
 to man4  ,other ,insect ,disease       
,carriers4--,fleas and bedbugs have been
 recently added to those insects proven 
to carry disease to man4 ,bubonic       
plague1 which is primarily a disease of 
rats1 is undoubtedly transmitted from   
the infected rats to man by the fleas4  
,fleas are also believed to transmit    
leprosy although this is not proven4    
,to rid a house of fleas we must first  
find their breeding places4 ,old        
carpets1 the sleeping places of cats or 
dogs or any dirty unswept corner may    
hold the eggs of the flea4 ,the young   
breed in cracks and crevices1 feeding   
upon organic matter there4 ,eventually  
they come to live as adults on their    
warm-blooded hosts1 cats1 dogs1 or man4 

,evidently destruction of the breeding  
places1 careful washing of all infected 
areas1 the use of benzine or gasoline in
 crevices where the larvae may be hid   
are the most effective methods of       
extermination4 ,pets which might harbor 
fleas should be washed frequently with a
 weak 7two to three per cent7 solution  
of creolin4  ,bedbugs are difficult to  
prove as an agent in the transmission of
 disease but their disgusting habits are
 sufficient reason for their            
extermination4 ,it has been proven by   
experiment that they may spread typhoid 
and relapsing fevers4 ,they prefer human
 blood to other food and have come to   
live in bedrooms and beds because this  
food can be obtained there4 ,they are   
extremely difficult to exterminate      
because their flat body allows them to  
hide in cracks out of sight4 ,wooden    
beds are thus better protection for them
 than iron or brass beds4 ,boiling water
 poured over the cracks when they breed 
or a mixture of strong corrosive        

sublimate four parts1 alcohol four parts
 and spirits of turpentine one part1 are
 effective remedies4  ,how the ,harm    
done by ,insects is ,controlled4--,the  
combating of insects is directed by     
several bodies of men1 all of which have
 the same end in view4 ,these are the   
,bureau of ,entomology of the ,united   
,states ,department of ,agriculture1 the
 various state experiment stations1 and 
medical and civic organizations4  ,the  
,bureau of ,entomology works in harmony 
with the other divisions of the         
,department of ,agriculture1 giving the 
time of its experts to the problems of  
controlling insects which1 for good or  
ill1 influence man's welfare in this    
country4 ,the destruction of the        
malarial mosquito and control of the    
typhoid fly2 the destruction of harmful 
insects by the introduction of their    
natural enemies1 plant or animal2 the   
perfecting of the honeybee 7see ,hodge1 
,nature ,study and ,life1 page #bdj71   
and the introduction of new species of  

insects to pollinate flowers not native 
to this country 7see ,blastophaga1 page 
#dc71 are some of the problems to which 
these men are now devoting their time4  
,all the states and territories have1   
since #ahhh1 established state          
experiment stations1 which work in      
cooperation with the government in the  
war upon injurious insects4 ,these      
stations are often connected with       
colleges1 so that young men who are     
interested in this kind of natural      
science may have opportunity to learn   
and to help4  ,the good done by these   
means directly and indirectly is very   
great4 ,bulletins are published by the  
various state stations and by the       
,department of ,agriculture1 most of    
which may be obtained free4 ,the most   
interesting of these from the high      
school standpoint are the ,farmers'     
,bulletins1 issued by the ,department of
 ,agriculture1 and the ,nature ,study   
pamphlets issued by the ,cornell        
,university in ,new ,york state4        

,illustration3 ,this diagram shows how  
bubonic plague is carried to man4       
,explain the diagram4  ,animals ,other  
than ,insects may be ,disease           
,carriers4--,the common brown rat is an 
example of a mammal1 harmful to         
civilized man1 which has followed in his
 footsteps all over the world4 ,starting
 from ,china1 it spread to eastern      
,europe1 thence to western ,europe1 and 
in #agge it had obtained a lodgment in  
this country4 ,in seventy-five years it 
reached the ,pacific coast1 and is now  
fairly common all over the ,united      
,states1 being one of the most prolific 
of all mammals4 ,rats are believed to   
carry bubonic plague1 the ,black ,death 
of the ,middle ,ages1 a disease         
estimated to have killed #be1jjj1jjj    
people during the fourteenth century4   
,the rat1 like man1 is susceptible to   
plague2 fleas bite the rat and then     
biting man transmit the disease to him4 
,a determined effort is now being made  
to exterminate the rat because of its   

connection with bubonic plague4  ,other 
,parasitic ,animals cause               
,disease4--,besides parasitic protozoans
 other forms of animals have been found 
that cause disease4 ,chief among these  
are certain round and flat worms1 which 
have come to live as parasites on man   
and other animals4 ,a one-sided         
relationship has thus come into         
existence where the worm receives its   
living from the host1 as the animal is  
called on which the parasite lives4     
,consequently the parasite frequently   
becomes fastened to its host during     
adult life and often is reduced to a    
mere bag through which the fluid food   
prepared by its host is absorbed4       
,sometimes a complicated life history   
has arisen from their parasitic habits4 
,such is seen in the life history of the
 liver fluke1 a flatworm which kills    
sheep1 and in the tapeworm4             
,illustration3 ,the life cycle of a     
tapeworm4 7#a7 ,the eggs are taken in   
with filthy food by the pig2 7#b7 man   

eats undercooked pork by means of which 
the bladder worm 7#c7 is transferred to 
his own intestine 7#d74  ,cestodes or   
,tapeworms4--,these parasites infest man
 and many other vertebrate animals4 ,the
 tapeworm 7,taenia solium7 passes       
through two stages in its life history1 
the first within a pig1 the second      
within the intestine of man4 ,the       
developing eggs are passed off with     
wastes from the intestine of man4 ,the  
pig1 an animal with dirty habits1 may   
take in the worm embryos with its food4 
,the worm develops within the intestine 
of the pig1 but soon makes its way into 
the muscle or other tissues4 ,it is here
 known as a bladderworm4 ,if man eats   
raw or undercooked pork containing these
 worms1 he may become a host for the    
tapeworm4 ,thus during its complete life
 history it has two hosts4 ,another     
common tapeworm parasitic on man lives  
part of its life as an embryo within the
 muscles of cattle4 ,the adult worm     
consists of a round headlike part       

provided with hooks1 by means of which  
it fastens itself to the wall of the    
intestine4 ,this head now buds off a    
series of segmentlike structures1 which 
are practically bags full of sperms and 
eggs4 ,these structures1 called         
proglottids1 break off from time to     
time1 thus allowing the developing eggs 
to escape4 ,the proglottids have no     
separate digestive systems1 but the     
whole body surface1 bathed in digested  
food1 absorbs it and is thus enabled to 
grow rapidly4  ,illustration3           
,trichinella spiralis imbedded in human 
muscle4 7,after ,leuckart47             
,roundworms4--,still other wormlike     
creatures called roundworms are of      
importance to man4 ,some1 as the vinegar
 eel found in vinegar1 or the pinworms  
parasitic in the lower intestine1       
particularly of children1 do little or  
no harm4 ,the pork worm or trichina1    
however1 is a parasite which may cause  
serious injury4 ,it passes through the  
first part of its existence as a        

parasite in a pig or other vertebrate   
7cat1 rat1 or rabbit71 where it lies1   
covered within a tiny sac or cyst1 in   
the muscles of its hosts4 ,if raw pork  
containing these worms is eaten by man1 
the cyst is dissolved off by the action 
of the digestive fluids1 and the living 
trichina becomes free in the intestine  
of man4 ,here it reproduces and the     
young bore their way through the        
intestine walls and enter the muscles1  
causing inflammation there4 ,this causes
 a painful and often fatal disease known
 as trichinosis4  ,the ,hookworm4--,the 
discovery by ,dr4 ,c4 ,w4 ,stiles of the
 ,bureau of ,animal ,industry1 that the 
laziness and shiftlessness of the poor  
whites of the ,south is partly due to a 
parasite called the hookworm1 reads like
 a fairy tale4  ,the people1 largely    
farmers1 become infected with a larval  
stage of the hookworm1 which develops in
 moist earth4 ,it enters the body       
usually through the skin of the feet1   
for children and adults alike1 in       

certain localities where the disease is 
common1 go barefoot to a considerable   
extent4  ,a complicated journey from the
 skin to the intestine now follows1 the 
larvae passing through the veins to the 
heart1 from there to the lungs2 here    
they bore into the air passages and     
eventually work their way by way of the 
windpipe into the intestine4 ,one result
 of the injury of the lungs is that many
 thus infected are subject to           
tuberculosis4 ,the adult worms1 once in 
the food tube1 fasten themselves and    
feed upon the blood of their host by    
puncturing the intestine wall4 ,the loss
 of blood from this cause is not        
sufficient to account for the           
bloodlessness of the person infected1   
but it has been discovered that the     
hookworm pours out a poison into the    
wound which prevents the blood from     
clotting rapidly 7see page #cae72 hence 
a considerable loss of blood occurs from
 the wound after the worm has finished  
its meal and gone to another part of the

 intestine4  ,illustration3 ,a family   
suffering from hookworm4  ,the cure of  
the disease is very easy2 thymol is     
given1 which weakens the hold of the    
worm1 this being followed by ,epsom     
salts4 ,for years a large area in the   
,south undoubtedly has been retarded in 
its development by this parasite2       
hundreds of millions of dollars and     
thousands of lives have been needlessly 
sacrificed4       ,the hookworm is not a
 bit spectacular3 it doesn't get itself 
discussed in legislative halls or       
furiously debated in political          
campaigns4 ,modest and unassuming1 it   
does not aspire to such dignity4        
,it is satisfied simply with 7#a7       
lowering the working efficiency and     
the pleasure of living in something like
 two hundred thousand persons      in   
,georgia and all other ,southern states 
in proportion2 with 7#b7      amassing a
 death rate higher than tuberculosis1   
pneumonia1 or typhoid      fever2 with  
7#c7 stubbornly and quite effectually   

retarding the      agricultural and     
industrial development of the section2  
with 7#d7      nullifying the benefit of
 thousands of dollars spent upon        
education2      with 7#e7 costing the   
,south1 in the course of a few decades1 
several      hundred millions of        
dollars4 ,more serious and closer at    
hand than the      tariff2 more costly1 
threatening1 and tangible than the      
,negro problem2      making the menace  
of the boll weevil laughable in         
comparison--it is      preeminently the 
problem of the ,south4--,atlanta        
,constitution4  ,animals that prey upon 
,man4--,the toll of death from animals  
which prey upon or harm man directly is 
relatively small4 ,snakes in tropical   
countries kill many cattle and not a few
 people4  ,the bite of the rattlesnake  
of our own country1 although dangerous1 
seldom kills4 ,the dreaded cobra of     
,india has a record of over two hundred 
and fifty thousand persons killed in the
 last thirty-five years4 ,the ,indian   

government yearly pays out large sums   
for the extermination of venomous       
snakes1 over two hundred thousand of    
which have been killed during a single  
year4  ,illustration3 ,a flesh-eating   
reptile1 the alligator4  ,alligators and
 ,crocodiles4--,these feed on fishes1   
but often attack large animals1 as      
horses1 cows1 and even man4 ,they seek  
their prey chiefly at night1 and spend  
the day basking in the sun4 ,the        
crocodiles of the ,ganges ,river in     
,india levy a yearly tribute of many    
hundred lives from the natives4         
,carnivorous animals such as lions and  
tigers still inflict damage in certain  
parts of the world1 but as the tide of  
civilization advances1 their numbers are
 slowly but surely decreasing so that as
 important factors in man's welfare they
 may be considered almost negligible4   
,,reference ,,books                     
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,beebe1 ,the ,bird4

 ,henry ,holt and ,company4             
,bigelow1 ,applied ,biology4 ,macmillan 
and ,company4      ,davison1 ,practical 
,zoology4 ,american ,book ,company4     
,herrick1 ,household ,insects and       
,methods of ,control4 ,cornell          
,reading ,courses4      ,hornaday1 ,our 
,vanishing ,wild ,life4 ,new ,york      
,zoological        ,society4            
,hodge1 ,nature ,study and ,life4 ,ginn 
and ,company4      ,kipling1 ,captains  
,courageous4 ,charles ,scribner's ,sons4
      ,sharpe1 ,laboratory ,manual1 pp4 
#aeg-aeh1 #ahb-bjc1 #cbj-cda4           
,american ,book ,company4      ,stone   
and ,cram1 ,american ,animals4          
,doubleday1 ,page and        ,company4  
,toothaker1 ,commercial ,raw ,materials4
 ,ginn and ,company4                    
,,advanced       ,flower1 ,the ,horse4  
,d4 ,appleton and ,company4             
,hornaday1 ,the ,american ,natural      
,history4 ,macmillan and                
,company4      ,jordan1 ,fishes4 ,henry 
,holt and ,company4      ,jordan and    

,evermann1 ,american ,food and ,game    
,fishes4        ,doubleday1 ,page and   
,company4      ,schaler1 ,domesticated  
,animals1 their ,relations to ,man and  
to ,his ,advancement in ,civilization4  
,charles ,scribner's        ,sons4      
,,xvi4 ,,the ,,fish ,,and ,,frog1 ,,an  
,,introductory ,,study ,,of             
,,vertebrates  ,problems4--,to determine
 how a fish and a frog are fitted for   
the life                they lead4      
,to determine some methods of           
development in vertebrate animals4      
7a7 ,fishes4              7b7 ,frogs4   
7c7 ,other animals4                     
,,laboratory ,,suggestions              
,laboratory exercise4--,study of a      
living fish--adaptations        for     
protection1 locomotion1 food getting1   
etc4      ,laboratory                   
demonstration4--,the development of the 
fish or        frog egg4      ,visit to 
the aquarium4--,study of adaptations1   
economic        uses of fishes1         
artificial propagation of fishes4   ,two

 ,methods of ,breathing in              
,vertebrates4--,vertebrate animals have 
at least two methods of getting their   
oxygen4 ,in other respects their life   
processes are nearly similar4 ,of all   
vertebrates fishes are the only ones    
fitted to breathe all their lives under 
water4 ,other vertebrates are provided  
with lungs and take their oxygen        
directly from the air4#cb ,we will next 
take up the study of a fish to see how  
it is fitted for its life in the water4 
,footnote #cb3 ,with the exception of a 
few lungless      salamanders4 ,most    
salamanders get much of their supply of 
oxygen through their moist skins4       
,,study ,,of ,a ,,fish  ,the            
,body4--,one of our common fresh-water  
fish is the bream1 or golden shiner4    
,the body of the bream runs insensibly  
into the head1 the neck being absent4   
,the long1 narrow body with its smooth  
surface fits the fish admirably for its 
life in the water4 ,certain cells in the
 skin secrete mucus or slime1 another   

adaptation4 ,the position of the scales1
 overlapping in a backward direction1 is
 yet another adaptation which aids in   
passing through the water4 ,its color1  
olive above and bright silver and gold  
below1 is protective4 ,can you see how8 
,illustration3 ,the bream4 ,a1 dorsal   
fin2 ,b1 caudal fin2 ,c1 anal fin2 ,d1  
pelvic fin2 ,e1 pectoral fin4  ,the     
,appendages and their ,uses4--,the      
appendages of the fish consist of paired
 and unpaired fins4 ,the paired fins are
 four in number1 and are believed to    
correspond in position and structure    
with the paired limbs of a man4 ,note   
the illustration above and locate the   
paired pectoral and pelvic fins4 7,these
 are so called because they are attached
 to the bones forming the pectoral and  
pelvic girdles4 ,see page #bfh47 ,find1 
by comparison with the ,figure1 the     
dorsal1 anal1 and caudal fins4 ,how many
 unpaired fins are there8  ,the         
flattened1 muscular body of the fish1   
tapering toward the caudal fin1 is moved

 from side to side with an undulating   
motion which results in the forward     
movement of the fish4 ,this movement is 
almost identical with that of an oar in 
sculling a boat4 ,turning movements are 
brought about by use of the lateral fins
 in much the same way as a boat is      
turned4 ,we notice the dorsal and other 
single fins are evidently useful in     
balancing and steering4  ,the           
,senses4--,the position of the eyes at  
the side of the head is an evident      
advantage to the fish4 ,why8 ,the eye is
 globular in shape4 ,such an eye has    
been found to be very nearsighted4 ,thus
 it is unlikely that a fish is able to  
perceive objects at any great distance  
from it4 ,the eyes are unprotected by   
eyelids1 but the tough outer covering   
and their position afford some          
protection4  ,feeding experiments with  
fishes show that a fish becomes aware of
 the presence of food by smelling it as 
well as by seeing it4 ,the nostrils of a
 fish can be proved to end in little    

pits1 one under each nostril hole4 ,thus
 they differ from our own1 which are    
connected with the mouth cavity4 ,in the
 catfish1 for example1 the barbels1 or  
horns1 receive sensations of smell and  
taste4 ,they do not perceive odors as we
 do for a fish perceives only substances
 that are dissolved in the water in     
which it lives4 ,the senses of taste and
 touch appear to be less developed than 
the other senses4  ,along each side of  
most fishes is a line of tiny pits1     
provided with sense organs and connected
 with the central nervous system of the 
fish4 ,this area1 called the lateral    
line1 is believed to be sensitive to    
mechanical stimuli of certain sorts4    
,the ear of the fish is under the skin  
and serves partly as a balancing organ4 
,food ,getting4--,a fish must go after  
its food and seize it1 but has no       
structures for grasping except the      
teeth4 ,consequently we find the teeth  
small1 sharp1 and numerous1 well adapted
 for holding living prey4 ,the tongue in

 most fishes is wanting or very slightly
 developed4  ,breathing4--,a fish1 when 
swimming quietly or when at rest1 seems 
to be biting when no food is present4 ,a
 reason for this act is to be seen when 
we introduce a little finely powdered   
carmine into the water near the head of 
the fish4 ,it will be found that a      
current of water enters the mouth at    
each of these biting movements and      
passes out through two slits found on   
each side of the head of the fish4      
,investigation shows us that under the  
broad1 flat plate1 or operculum1 forming
 each side of the head1 lie several     
long1 feathery1 red structures1 the     
gills4  ,illustration3 ,diagram of the  
gills of a fish4 7,h71 the heart which  
forces the blood into the tubes 7,v71   
which run out into the gill filaments4  
,a gill bar 7,g7 supports each gill4    
,the blood after exchanging its carbon  
dioxide for oxygen is sent out to the   
cells of the body through the artery    
7,a74  ,gills4--,if we examine the gills

 of any large fish1 we find that a      
single gill is held in place by a bony  
arch1 made of several pieces of bone    
which are hinged in such a way as to    
give great flexibility to the gill arch1
 as the support is called4 ,covering the
 bony framework1 and extending from it1 
are numerous delicate filaments covered 
with a very thin membrane or skin4 ,into
 each of these filaments pass two blood 
vessels2 in one blood flows downward and
 in the other upward4 ,blood reaches the
 gills and is carried away from these   
organs by means of two large vessels    
which pass along the bony arch          
previously mentioned4 ,in the gill      
filament the blood comes into contact   
with the free oxygen of the water       
bathing the gills4 ,an exchange of gases
 through the walls of the gill filaments
 results in the loss of carbon dioxide  
and a gain of oxygen by the blood4 ,the 
blood carries oxygen to the cells of the
 body and 7as work is done by the cells 
as a result of the oxidation of food7   

brings carbon dioxide back to the gills4
  ,gill ,rakers4--,if we open wide the  
mouth of any large fish and look inward1
 we find that the mouth cavity leads to 
a funnel-like opening1 the gullet4 ,on  
each side of the gullet we can see the  
gill arches1 guarded on the inner side  
by a series of sharp-pointed structures1
 the gill rakers4 ,in some fishes in    
which the teeth are not well developed1 
there seems to be a greater development 
of the gill rakers1 which in this case  
are used to strain out small organisms  
from the water which passes over the    
gills4 ,many fishes make such use of the
 gill rakers4 ,such are the shad and    
menhaden1 which feed almost entirely on 
plankton1 a name given to the small     
plants and animals found by millions in 
the water4  ,digestive ,system4--,the   
gullet leads directly into a baglike    
stomach4 ,there are no salivary glands  
in the fishes4 ,there is1 however1 a    
large liver1 which appears to be used as
 a digestive gland4 ,this organ1 because

 of the oil it contains1 is in some     
fishes1 as the cod1 of considerable     
economic importance4 ,many fishes have  
outgrowths like a series of pockets from
 the intestine4 ,these structures1      
called the pyloric caeca1 are believed  
to secrete a digestive fluid4 ,the      
intestine ends at the vent1 which is    
usually located on the under side of the
 fish1 immediately in front of the anal 
fin4  ,illustration3 ,a fish opened to  
show ,h1 the heart2 ,g1 the gills2 ,l1  
the liver2 ,s1 the stomach2 ,i1 the     
intestine2 ,o1 the ovary2 ,k1 the       
kidney1 and ,b1 the air bladder4  ,swim 
,bladder4--,an organ of unusual         
significance1 called the swim bladder1  
occupies the region just dorsal to the  
food tube4 ,in young fishes of many     
species this is connected by a tube with
 the anterior end of the digestive      
tract4 ,in some forms this tube persists
 throughout life1 but in other fishes it
 becomes closed1 a thin1 fibrous cord   
taking its place4 ,the swim bladder aids

 in giving the fish nearly the same     
weight as the water it displaces1 thus  
buoying it up4 ,the walls of the organ  
are richly supplied with blood vessels1 
and it thus undoubtedly serves as an    
organ for supplying oxygen to the blood 
when all other sources fail4 ,in some   
fishes 7the dipnoi1 page #ahg7 it has   
come to be used as a lung4  ,circulation
 of the ,blood4--,in the vertebrate     
animals the blood is said to circulate  
in the body1 because it passes through a
 more or less closed system of tubes in 
its course around the body4 ,in the     
fishes the heart is a two-chambered     
muscular organ1 a thin-walled auricle1  
the receiving chamber1 leading into a   
thick-walled muscular ventricle from    
which the blood is forced out4 ,the     
blood is pumped from the heart to the   
gills2 there it loses some of its carbon
 dioxide2 it then passes on to other    
parts of the body1 eventually breaking  
up into very tiny tubes called          
capillaries4 ,from the capillaries the  

blood returns1 in tubes of gradually    
increasing diameter1 toward the heart   
again4 ,the body cells lie between the  
smallest branches of the capillaries4   
,thus they get from the blood food and  
oxygen and return to the blood the      
wastes resulting from oxidation within  
the cell body4 ,during its course some  
of the blood passes through the kidneys 
and is there relieved of part of its    
nitrogenous waste4 ,circulation of blood
 in the body of the fish is rather slow4
 ,the temperature of the blood being    
nearly that of the surrounding media in 
which the fish lives1 the animal has    
incorrectly been given the term         
cold-blooded4  ,nervous ,system4--,as in
 all other vertebrate animals1 the brain
 and spinal cord of the fish are        
partially inclosed in bone4 ,the central
 nervous system consists of a brain1    
with nerves connecting the organs of    
sight1 taste1 smell1 and hearing1 and   
such parts of the body as possess the   
sense of touch2 a spinal cord2 and      

spinal nerves4 ,nerve cells located near
 the outside of the body send in        
messages to the central system1 which   
are there received as sensations4 ,cells
 of the central nervous system1 in turn1
 send out messages which result in the  
movement of muscles4  ,skeleton4--,in   
the vertebrates1 of which the bony fish 
is an example1 the skeleton is under the
 skin1 and is hence called an           
endoskeleton4 ,it consists of a bony    
framework1 the vertebral column which   
protects the spinal cord and certain    
attached bones1 the ribs1 with other    
spiny bones to which the unpaired fins  
are attached4 ,the paired fins are      
attached to the spinal column by two    
collections of bones1 known respectively
 as the pectoral and pelvic girdles4    
,the bones in the main skeleton serve in
 the fish for the attachment of powerful
 muscles1 by means of which locomotion  
is accomplished4 ,in most fishes1 the   
exoskeleton1 too1 is well developed1    
consisting usually of scales1 but       

sometimes of bony plates4  ,food of     
,fishes4--,we have already seen that in 
a balanced aquarium the balance of food 
was preserved by the plants1 which      
furnished food for the tiny animals or  
were eaten by larger ones1--for example1
 snails or fish4 ,the smaller animals in
 turn became food of larger ones4 ,the  
nitrogen balance was maintained through 
the excretions of the animals and their 
death and decay4  ,the marine world is a
 great balanced aquarium4 ,the upper    
layer of water is crowded with all kinds
 of little organisms1 both plant and    
animal4 ,some of these are microscopic  
in size2 others1 as the tiny            
crustaceans1 are visible to the eye4 ,on
 these little organisms some fish feed  
entirely1 others in part4 ,such are the 
menhaden#cc 7bony1 bunker1 mossbunker of
 our coast71 the shad1 and others4      
,other fishes are bottom feeders1 as the
 blackfish and the sea bass1 living     
almost entirely upon mollusks and       
crustaceans4 ,still others are hunters1 

feeding upon smaller species of fish1 or
 even upon their weaker brothers4 ,such 
are the bluefish1 squeteague or         
weakfish1 and others4       ,footnote   
#cc3 ,it has been discovered by         
,professor ,mead of      ,brown         
,university that the increase in        
starfish along certain      parts of the
 ,new ,england coast was in part due to 
overfishing of menhaden1 which at       
certain times in the year      feed     
almost entirely on the young starfish4  
,what is true of salt-water fish is     
equally true of those inhabiting our    
fresh-water streams and lakes4 ,it is   
one of the greatest problems of our     
,bureau of ,fisheries to discover this  
relation of various fishes to their food
 supplies so as to aid in the           
conservation and balance of life in our 
lakes1 rivers1 and seas4  ,migration of 
,fishes4--,some fishes change their     
habitat at different times during the   
year1 moving in vast schools northward  
in summer and southward in the winter4  

,in a general way such migrations follow
 the coast lines4 ,examples of such     
migratory fish are the cod1 menhaden1   
herring1 and bluefish4 ,the migrations  
are due to temperature changes1 to the  
seeking after food1 and to the spawning 
instinct4 ,some fish migrate to         
shallower water in the summer and to    
deeper water in the winter2 here the    
reason for the migration is doubtless   
the change in temperature4              
,illustration3 ,development of a trout4 
#a1 the embryo within the egg2 #b1 the  
young fish just hatched with the yoke   
sac still attached2 #c1 the young fish4 
,the ,egg-laying ,habits of the ,bony   
,fishes4--,the eggs of most bony fishes 
are laid in great numbers1 varying from 
a few thousand in the trout to many     
hundreds of thousands in the shad and   
several millions in the cod4 ,the time  
of egg-laying is usually spring or early
 summer4 ,at the time of spawning the   
male usually deposits milt1 consisting  
of millions of sperm cells1 in the water

 just over the eggs1 thus accomplishing 
fertilization4 ,some fishes1 as         
sticklebacks1 sunfish1 toadfish1 etc41  
make nests1 but usually the eggs are    
left to develop by themselves1 sometimes
 attached to some submerged object1 but 
more frequently free in the water4 ,in  
some eggs a tiny oil drop buoys up the  
egg to the surface1 where the heat of   
the sun aids development4 ,they are     
exposed to many dangers1 and both eggs  
and developing fish are eaten1 not only 
by birds1 fish of other species1 and    
other water inhabitants1 but also by    
their own relatives1 and even parents4  
,consequently a very small percentage of
 eggs ever produce mature fish4  ,the   
,relation of the ,spawning ,habits to   
,economic ,importance of ,fish4--,the   
spawning habits of fish are of great    
importance to us because of the economic
 value of fish to mankind1 not only     
directly as a food1 but indirectly as   
food for other animals in turn valuable 
to man4 ,many of our most desirable food

 fishes1 notably the salmon1 shad1      
sturgeon1 and smelt1 pass up rivers from
 the ocean to deposit their eggs1       
swimming against strong currents much of
 the way1 some species leaping rapids   
and falls1 in order to deposit their    
eggs in localities where the conditions 
of water and food are suitable1 and the 
water shallow enough to allow the sun's 
rays to warm it sufficiently to cause   
the eggs to develop4 ,the ,chinook      
salmon of the ,pacific coast1 the salmon
 used in the ,western canning industry1 
travels over a thousand miles up the    
,columbia and other rivers1 where it    
spawns4 ,the salmon begin to pass up the
 rivers in early spring1 and reach the  
spawning beds1 shallow deposits of      
gravel in cool mountain streams1 before 
late summer4 ,here the fish1 both males 
and females1 remain until the           
temperature of the water falls to about 
#ed deg4 ,fahrenheit4 ,the eggs and milt
 are then deposited1 and the old fish   
die1 leaving the eggs to be hatched out 

later by the heat of the sun's rays4    
,need of ,conservation4--,the instinct  
of this and other species of fish to go 
into shallow rivers to deposit their    
eggs has been made use of by man4 ,at   
the time of the spawning migration the  
salmon are taken in vast numbers1 for   
the salmon fisheries net over           
#af1jjj1jjj annually4  ,but the need for
 conservation of this important national
 asset is great4 ,the shad have within  
recent time abandoned their breeding    
places in the ,connecticut ,river1 and  
the salmon have been exterminated along 
our eastern coast within the past few   
decades4 ,it is only a matter of a few  
years when the ,western salmon will be  
extinct if fishing is continued at the  
present rate4 ,more fish must be allowed
 to reach their breeding places4 ,to do 
this a closed season on the rivers of   
two or three days out of each seven     
while the shad or the salmon run would  
do much good4  ,the sturgeon1 the eggs  
of which are used in the manufacture of 

the delicacy known as caviar1 is an     
example of a fish that is almost extinct
 in this part of the world4 ,other food 
fish taken at the breeding season are   
also in danger4  ,illustration3         
,artificial fertilization of fish eggs4 
,artificial ,propagation of             
,fishes4--,fortunately1 the government  
through the ,bureau of ,fisheries1 and  
various states by wise protective laws  
and by artificial propagation of fishes1
 are beginning to turn the tide4        
,certain days of the week the salmon are
 allowed to pass up the ,columbia       
unmolested4 ,closed breeding seasons    
protect our trout1 bass1 and other game 
fish1 also the catching of fish under a 
certain size is prohibited4             
,illustration3 ,early development of    
salmon4 ,natural size4  ,many fish      
hatcheries1 both government and state1  
are engaged in artificially fertilizing 
millions of fish eggs of various species
 and protecting the young fry until they
 are of such size that they can take    

care of themselves1 when they are placed
 in ponds or streams4 ,this artificial  
fertilization is usually accomplished by
 first squeezing out the ripe eggs from 
a female into a pan of water2 in a      
similar manner the milt or sperm cells  
are obtained1 and poured over the eggs4 
,the eggs are thus fertilized4 ,they are
 then placed in receptacles supplied    
with running water and left to develop  
under favorable conditions4 ,shortly    
after the egg has segmented 7divided    
into many cells7 the embryo may be seen 
developing on one side of the egg4 ,the 
rest of the egg is made up of food or   
yolk1 and when the baby fish hatches it 
has for some time the yolk attached to  
its ventral surface4 ,eventually the    
food is absorbed into the body of the   
fish4 ,the development of the fish is   
direct1 the young fish becoming an adult
 without any great change in form4 ,the 
young fry are kept under ideal          
conditions until later1 when they are   
shipped1 sometimes thousands of miles1  

to their new homes4  ,,note ,,to        
,,teacher4--,it is suggested that in the
 spring term the frog be studied1 but if
 animal biology be taken up during the  
fall term the fish only might be used4  
,,the ,,frog  ,adaptations for          
,life4--,the most common frog in the    
eastern part of the ,united ,states is  
the leopard frog4 ,it is recognized by  
its greenish brown body with dark spots1
 each spot being outlined in a          
lighter-colored background4 ,in spite of
 the apparent lack of harmony with their
 surroundings1 their color appears to   
give almost perfect protection4 ,in some
 species of frogs the color of the skin 
changes with the surroundings of the    
frog1 another means of protection4      
,adaptations for life in the water are  
numerous4 ,the ovoid body1 the head     
merging into the trunk1 the slimy       
covering 7for the frog is provided1 like
 the fish1 with mucus cells in the      
skin71 and the powerful legs with webbed
 feet1 are all evidences of the life    

which the frog leads4                   
,locomotion4--,you will notice that the 
appendages have the same general        
position on the body and same number of 
parts as do your own 7upper arm1        
forearm1 and hand2 thigh1 shank1 and    
foot1 the latter much longer relatively 
than your own74 ,note that while the    
hand has four fingers1 the foot has five
 toes1 the latter connected by a web4   
,in swimming the frog uses the stroke we
 all aim to make when we are learning to
 swim4 ,most of the energy is liberated 
from the powerful backward push of the  
hind legs1 which in a resting position  
are held doubled up close to the body4  
,on land1 locomotion may be by hopping  
or crawling4  ,illustration3 ,this      
diagram shows how the frog uses its     
tongue to catch insects4  ,sense        
,organs4--,the frog is well provided    
with sense organs4 ,the eyes are large1 
globular1 and placed at the side of the 
head4 ,when they are closed1 a delicate 
fold1 or third eyelid1 called the       

nictitating membrane1 is drawn over each
 eye4 ,frogs probably see best moving   
objects at a few feet from them4 ,their 
vision is much keener than that of the  
fish4 ,the external ear 7tympanum7 is   
located just behind the eye on the side 
of the body4 ,frogs hear sounds and     
distinguish various calls of their own  
kind1 as is proved by the fact that     
frogs recognize the warning notes of    
their mates when any one is approaching4
 ,the inner ear also has to do with     
balancing the body as it has in fishes  
and other vertebrates4 ,taste and smell 
are probably not strong sensations in a 
frog or toad4 ,they bite at moving      
objects of almost any kind when hungry4 
,the long flexible tongue1 which is     
fastened at the front1 is used to catch 
insects4 ,experience has taught these   
animals that moving things1 insects1    
worms1 and the like1 make good food4    
,these they swallow whole1 the tiny     
teeth being used to hold the food4      
,touch is a well-developed sense4 ,they 

also respond to changes in temperature  
under water1 remaining there in a       
dormant state for the winter when the   
temperature of the air becomes colder   
than that of the water4                 
,breathing4--,the frog breathes by      
raising and lowering the floor of the   
mouth1 pulling in air through the two   
nostril holes4 ,then the little flaps   
over the holes are closed1 and the frog 
swallows this air1 forcing it down into 
the baglike lungs4 ,the skin is provided
 with many tiny blood vessels1 and in   
winter1 while the frogs are dormant at  
the bottom of the ponds1 it serves as   
the only organ of respiration4          
,illustration3 ,internal organs of a    
frog3 ,m1 mouth2 ,t1 tongue2 ,lu1 lungs2
 ,h1 heart2 ,st1 stomach2 ,i1 small     
intestine2 ,l1 liver2 ,g1 gall bladder2 
,p1 pancreas2 ,c1 cloaca2 ,b1 urinary   
bladder2 ,s1 spleen2 ,k1 kidney2 ,od1   
oviduct2 ,o1 ovary2 ,br1 brain2 ,sc1    
spinal cord2 ,ba1 back bone4  ,the ,food
 ,tube and its ,glands4--,the mouth     

leads like a funnel into a short tube1  
the gullet4 ,on the lower floor of the  
mouth can be seen the slitlike glottis  
leading to the lungs4 ,the gullet widens
 almost at once into a long stomach1    
which in turn leads into a much coiled  
intestine4 ,this widens abruptly at the 
lower end to form the large intestine4  
,the latter leads into the cloaca       
7,latin1 sewer71 into which open the    
kidneys1 urinary bladder1 and           
reproductive organs 7ovaries or         
spermaries74 ,several glands1 the       
function of which is to produce         
digestive fluids1 open into the food    
tube4 ,these digestive fluids1 by means 
of the ferments or enzymes contained in 
them1 change insoluble food materials   
into a soluble form4 ,this allows of the
 absorption of food material through the
 walls of the food tube into the blood4 
,the glands 7having the same names and  
uses as those in man7 are the salivary  
glands1 which pour their juices into the
 mouth1 the gastric glands in the walls 

of the stomach1 and the liver and       
pancreas1 which open into the intestine4
  ,circulation4--,the frog has a        
well-developed heart1 composed of a     
thick-walled muscular ventricle and two 
thin-walled auricles4 ,the heart pumps  
the blood through a system of closed    
tubes to all parts of the body4 ,blood  
enters the right auricle from all parts 
of the body2 it then contains           
considerable carbon dioxide2 the blood  
entering the left auricle comes from the
 lungs1 hence it contains a considerable
 amount of oxygen4 ,blood leaves the    
heart through the ventricle1 which thus 
pumps some blood containing much and    
some containing little oxygen4 ,before  
the blood from the tissues and lungs has
 time to mix1 however1 it leaves the    
ventricle and by a delicate adjustment  
in the vessels leaving the heart most of
 the blood containing much oxygen is    
passed to all the various organs of the 
body1 while the blood deficient in      
oxygen1 but containing a large amount of

 carbon dioxide1 is pumped to the lungs1
 where an exchange of oxygen and carbon 
dioxide takes place by osmosis4  ,in the
 tissues of the body wherever work is   
done the process of burning or oxidation
 must take place1 for by such means only
 is the energy necessary to do the work 
released4 ,food in the blood is taken to
 the muscle cells or other cells of the 
body and there oxidized4 ,the products  
of the burning--carbon dioxide--and any 
other organic wastes given off from the 
tissues must be eliminated from the     
body4 ,as we know1 the carbon dioxide   
passes off through the lungs and to some
 extent through the skin of the frog1   
while the nitrogenous wastes1 poisons   
which must be taken from the blood1 are 
eliminated from it in the kidneys4      
,change of ,form in ,development of the 
,frog4--,not all vertebrates develop    
directly into an adult4 ,the frog1 for  
example1 changes its form completely    
before it becomes an adult4 ,this change
 in form is known as a metamorphosis4   

,let us examine the development of the  
common leopard frog4  ,illustration3    
,development of a frog4 #a1 two cell    
stage2 #b1 four cell stage2 #c1 #h cells
 are formed1 notice the upper cells are 
smaller2 in 7#d7 the lower cells are    
seen to be much larger because of the   
yolk2 #e1 the egg has continued to      
divide and has formed a gastrula2 #f1   
#g1 the body is lengthening1 head is    
seen at the right hand end2 #h1 the     
young tadpole with external gills2 #i1  
#aj1 the gills are internal1 hind legs  
beginning to form2 #aa1 the hind legs   
show plainly2 #ab1 #ac1 #ad1 later      
stages in development2 #ae1 the adult   
frog4 ,figures #a1 #b1 #c1 #d1 #e1 #f1  
and #g are very much enlarged4 7,drawn  
after ,leukart and ,kny by ,frank ,m4   
,wheat47  ,the eggs of this frog are    
laid in shallow water in the early      
spring4 ,masses of several hundred1     
which may be found attached to twigs or 
other supports under water1 are         
deposited at a single laying4           

,immediately before leaving the body of 
the female they receive a coating of    
jellylike material1 which swells up     
after the eggs are laid4 ,thus they are 
protected from the attack of fish or    
other animals which might use them as   
food4 ,the upper side of the egg is     
dark1 the light-colored side being      
weighted down with a supply of yolk     
7food74 ,the fertilized egg soon        
segments 7divides into many cells71 and 
in a few days1 if the weather is warm1  
these eggs have each grown into an      
oblong body which shows the form of a   
tadpole4 ,shortly after the tadpole     
wriggles out of the jellylike case and  
begins life outside the egg4 ,at first  
it remains attached to some water weed  
by means of a pair of suckerlike        
projections2 later a mouth is formed1   
and the tadpole begins to feed upon     
algae or other tiny water plants4 ,at   
this time1 about two weeks after the    
eggs were laid1 gills are present on the
 outside of the body4 ,soon after1 the  

external gills are replaced by gills    
which grow out under a fold of the skin 
which forms an operculum somewhat as in 
the fish4 ,water reaches the gills      
through the mouth and passes out through
 a hole on the left side of the body4   
,as the tadpole grows larger1 legs      
appear1 the hind legs first1 although   
for a time locomotion is performed by   
means of the tail4 ,in the leopard frog 
the change from the egg to adult is     
completed in one summer4 ,in late ,july 
or early ,august1 the tadpole begins to 
eat less1 the tail becomes smaller      
7being absorbed into other parts of the 
body71 and before long the              
transformation from the tadpole to the  
young frog is complete4 ,in the green   
frog and bullfrog the metamorphosis is  
not completed until the beginning of the
 second summer4 ,the large tadpoles of  
such forms bury themselves in the soft  
mud of the pond bottom during the       
winter4  ,shortly after the legs appear1
 the gills begin to be absorbed1 and    

lungs take their place4 ,at this time   
the young animal may be seen coming to  
the surface of the water for air4       
,changes in the diet of the animal also 
occur2 the long1 coiled intestine is    
transformed into a much shorter one4    
,the animal1 now insectivorous in its   
diet1 becomes provided with tiny teeth  
and a mobile tongue1 instead of keeping 
the horny jaws used in scraping off     
algae4 ,after the tail has been         
completely absorbed and the legs have   
become full grown1 there is no further  
structural change1 and the metamorphosis
 is complete4  ,illustration3 ,at the   
left is a hen's egg1 opened to show the 
embryo at the center 7the spot          
surrounded by a lighter area74 ,at the  
right is an ,english sparrow one day    
after hatching4  ,development of        
,birds4--,the white of the hen's egg is 
put on during the passage of the real   
egg 7which is in the yolk or yellow     
portion7 to the outside of the body4    
,before the egg is laid a shell is      

secreted over its surface4 ,if the      
fertilized egg of a hen be broken and   
carefully examined1 on the surface of   
the yolk will be found a little circular
 disk4 ,this is the beginning of the    
growth of an embryo chick4 ,if a series 
of eggs taken from an incubator at      
periods of twenty-four hours or less    
apart were examined1 this spot would be 
found at first to increase in size2     
later the little embryo would be found  
lying on the surface4 ,still later small
 blood vessels could be made out        
reaching into the yolk for food1 the    
tiny heart beating as early as the      
second day of incubation4 ,after about  
three weeks of incubation the little    
chick hatches2 that is1 breaks the      
shell1 and emerges in almost the same   
form as the adult4  ,illustration3 ,the 
embryo 7e7 of a mammal1 showing the     
absorbing organ in black1 the           
branch-like processes which absorb blood
 from the mother being shown at 7v72 ct1
 the tube connecting the embryo with the

 absorbing organ or placenta4           
,development of a ,mammal4--,in mammals 
after fertilization the egg undergoes   
development within the body of the      
mother4 ,instead of blood vessels       
connecting the embryo with the yolk as  
in the chick1 here the blood vessels are
 attached to an absorbing organ1 known  
as the placenta4 ,this structure sends  
branch-like processes into the wall of  
the uterus 7the organ which holds the   
embryo7 and absorbs nourishment and     
oxygen by osmosis from the blood of the 
mother4 ,after a length of time which   
varies in different species of mammals  
7from about three weeks in a guinea pig 
to twenty-two months in an elephant71   
the young animal is expelled by muscular
 contraction of the uterus1 or is born4 
,the young1 usually1 are born in a      
helpless condition1 then nourished by   
milk furnished by the mother until they 
are able to take other food4 ,thus we   
see as we go higher in the scale of life
 fewer eggs formed1 but those few eggs  

are more carefully protected and cared  
for by the parents4 ,the chances of     
their growth into adults are much       
greater than in the cases when many eggs
 are produced4                          
,,reference ,,books                     
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,bigelow1          
,introduction to ,biology4 ,the         
,macmillan ,company4      ,cornell      
,nature ,study ,leaflets4 ,bulletins    
,,xvi1 ,,xvii4      ,davison1 ,practical
 ,zoology1 pages #ahe-aii4 ,american    
,book        ,company4      ,hodge1     
,nature ,study and ,life1 ,chaps4 ,,xvi1
 ,,xvii4 ,ginn and        ,company4     
,sharpe1 ,laboratory ,manual1 pp4 #aie1 
#bjd-bji4 ,american ,book               
,company4                               
,,advanced       ,dickerson1 ,the ,frog 
,book4 ,doubleday1 ,page and ,company4  
,holmes1 ,the ,biology of the ,frog4    
,the ,macmillan ,company4      ,jordan1 
,fishes4 ,henry ,holt and ,company4     

,morgan1 ,the ,development of the       
,frog's ,egg4 ,the ,macmillan           
,company4      ,needham1 ,general       
,biology4 ,comstock ,publishing         
,company4     ,,xvii4 ,,heredity1       
,,variation1 ,,plant ,,and ,,animal     
,,breeding  ,problems4--,to determine   
what makes the offspring of animals or  
plants               tend to be like    
their parents4            ,to determine 
what makes the offspring of animals and 
plants               differ from their  
parents4            ,to learn about some
 methods of plant and animal breeding4  
7a7 ,by selection4              7b7 ,by 
hybridizing4              7c7 ,by other 
methods4            ,to learn about some
 methods of improving the human race4   
7a7 ,by eugenics4              7b7 ,by  
euthenics4                              
,,suggestions ,,for ,,laboratory ,,work 
,laboratory exercise4--,on variation and
 heredity among members of a            
class in the schoolroom4                
,laboratory exercise4--,on construction 

of curve of variation in                
measurements from given plants or       
animals4      ,laboratory               
demonstration4--,stained egg cells      
7ascaris7 to show        chromosomes4   
,laboratory demonstrations4--,to        
illustrate the part played in plant     
or animal breeding by        7a7        
selection4        7b7 hybridizing4      
7c7 budding and grafting4               
,laboratory demonstration4--,from charts
 to illustrate how human                
characteristics may be inherited4       
,,heredity ,,and ,,eugenics  ,heredity  
and what it ,means4--,as ,i look over   
the faces of the boys in my class ,i    
notice that each boy seems to be more or
 less like each other boy in the class2 
he has a head1 body1 arms1 and legs1 and
 even in minor ways he resembles each of
 the other boys in the room4 ,moreover1 
if ,i should ask him ,i have no doubt   
but that he would tell me that he       
resembled in many respects his mother or
 father4 ,likewise if ,i should ask his 

parents whom he resembled1 they would   
say1 ,i can see his grandmother or his  
grandfather in him4  ,this wonderful    
force which causes the likeness of the  
child to its parents and to their       
parents we call heredity4 ,heredity     
causes the plants as well as animals to 
be like their parents4 ,if we trace the 
workings of heredity in our own         
individual case1 we will probably find  
that we are molded like our ancestors   
not only in physical characteristics but
 in mental qualities as well4 ,the      
ability to play the piano or to paint is
 probably as much a case of inheritance 
as the color of our eyes or the shape of
 our nose4 ,we are a complex of physical
 and mental characters1 received in part
 from all our ancestors4  ,illustration3
 ,variations in the ,catalpa            
caterpillar4 7,photographed1 natural    
size1 by ,davison47  ,variation4--,but  
,i notice another thing2 no boy in the  
class before me is exactly like any     
other boy1 even twins having minute     

differences4 ,in this wonderful mold of 
nature each one of us tends to be       
slightly different from his or her      
parents4 ,each plant1 each animal1      
varies to a greater or lesser degree    
from its immediate ancestors and may    
vary to a very great degree4 ,this      
factor in the lives of plants and       
animals is called variation4 ,heredity  
and variation are the cornerstones on   
which all the work in the improvement of
 plants and animals1 including man      
himself1 are built4  ,the ,bearers of   
,heredity4--,we have seen that somewhere
 in every living cell is a structure    
known as a nucleus4 ,in this nucleus1   
which is a part of the living matter of 
the cell1 are certain very minute       
structures always present1 known as     
chromosomes4 ,these chromosomes 7so     
called because they take up color when  
stained7 are believed to be the         
structures which contain the determiners
 of the qualities which may be passed   
from parent plant to offspring or from  

animal to animal2 in other words1 the   
qualities that are inheritable 7see page
 #beb74  ,the ,germ ,cells4--,but it has
 been found that certain cells of the   
body1 the egg and the sperm cells1      
before uniting contain only half as many
 chromosomes as do the body cells4 ,in  
preparing for the process of            
fertilization1 half of these elements   
have been eliminated1 so that when the  
egg and sperm cell are united they will 
have the full number of chromosomes that
 the other cells have4  ,if the         
chromosomes carry the determiners of the
 characters which are inheritable1 then 
it is easy to see that a fertilized egg 
must contain an equal number of         
chromosomes from the bodies of each     
parent4 ,consequently characteristics   
from each parent are handed down to the 
new individual4 ,this seems to be the   
way in which nature succeeds in         
obtaining variation1 by providing cell  
material from two different individuals4
  ,offspring are ,part of their         

,ancestors4--,we can see that if you or 
,i receive characteristics from our     
parents and they received               
characteristics from their parents1 then
 we too must have some of the           
characteristics of the grandparents1 and
 it is a matter of common knowledge that
 each of us does have some trait or     
lineament which can be traced back to   
our grandfather or grandmother4 ,indeed1
 as far back as we are able to go1      
ancestors have added something4         
,illustration3 ,,comparison ,,of        
,,sexual ,,and ,,asexual ,,cell         
,,reproduction  ,charles ,darwin and    
,natural ,selection4--,the great        
,englishman ,charles ,darwin was one of 
the first scientists to realize how this
 great force of heredity applied to the 
development or evolution of plants and  
animals4 ,he knew that although animals 
and plants were like their ancestors1   
they also tended to vary4 ,in nature1   
the variations which best fitted a plant
 or animal for life in its own          

environment were the ones which were    
handed down because those having        
variations which were not fitted for    
life in that particular environment     
would die4 ,thus nature seized upon     
favorable variations and after a time1  
as the descendants of each of these     
individuals also tended to vary1 a new  
species of plant or animal1 fitted for  
the place it had to live in1 would be   
gradually evolved4                      
,mutations4--,recently a new method of  
variation has been discovered by a      
,dutch naturalist1 named ,hugo de       
,vries4 ,he found that new species of   
plants and animals arise suddenly by    
mutations or steps4 ,this means that new
 species instead of arising from very   
slight variations1 continuing during    
long periods of years 7as ,darwin       
believed71 might arise very suddenly as 
a very great variation which would at   
once breed true4 ,it is easily seen that
 such a condition would be of immense   
value to breeders1 as new plants or     

animals quite unlike their parents might
 thus be formed and perpetuated4 ,it    
will be one of the future problems of   
plant and animal breeders to isolate and
 breed mutants1 as such organisms are   
called4  ,illustration3 ,improvement in 
corn by selection4 ,to the left1 the    
corn improved by selection from the     
original type at the right4  ,artificial
 ,selection4--,darwin reasoned that if  
nature seized upon favorable variants1  
then man1 by selecting the variations he
 wanted1 could form new varieties of    
plants or animals much more quickly than
 nature4 ,and so to-day plant or animal 
breeders select the forms having the    
characters they wish to perpetuate and  
breed them together4 ,this method used  
by plant and animal breeders is known as
 selection4  ,selective ,planting4--,by 
selective planting we mean choosing the 
best plants and planting the seed from  
these plants with a view of improving   
the yield4 ,in doing this we must not   
necessarily select the most perfect     

fruits or grains1 but must select seeds 
from the best plants4 ,a wheat plant    
should be selected not from its yield   
alone1 but from its ability to stand    
disease and other unfavorable           
conditions4 ,in #ahfb a ,mr4 ,fultz1 of 
,pennsylvania1 found three heads of     
beardless or bald wheat while passing   
through a large field of bearded wheat4 
,these were probably mutants which had  
lost the chaff surrounding the kernel4  
,mr4 ,fultz picked them out1 sowed them 
by themselves1 and produced a quantity  
of wheat now known favorably all over   
the world as the ,fultz wheat4 ,in      
selecting wheat1 for example1 we might  
breed for a number of different         
characters1 such as more starch1 or more
 protein in the grain1 a larger yield   
per acre1 ability to stand cold or      
drought or to resist plant disease4     
,each of these characters would have to 
be sought for separately and could only 
be obtained after long and careful      
breeding4 ,the work of ,mendel 7see page

 #beg7 when applied to plant breeding   
will greatly shorten the time required  
to produce better plants of a given     
kind4 ,by careful seed selection1 some  
,western farmers have increased their   
wheat production by #be per cent4 ,this1
 if kept up all over the ,united        
,states1 would mean over #ajj1jjj1jjj a 
year in the pockets of the farmers4     
,hybridizing4--,we have already seen    
that pollen from one flower may be      
carried to another of the same species1 
thus producing seeds4 ,if pollen from   
one plant be placed on the pistil of    
another of an allied species or variety1
 fertilization may take place and new   
plants be eventually produced from the  
seeds4 ,this process is known as        
hybridizing1 and the plants produced by 
this process known as hybrids4          
,illustration3 ,in hybridizing1 all of  
the flower is removed at the line 7,w7  
except the pistil 7,p74 ,then pollen    
from another flower of a nearly related 
kind is placed on the pistil and the    

pollinated flower covered up with a     
paper bag4 ,can you explain why8        
,hybrids are extremely variable1 rarely 
breed from seeds1 and often are         
apparently quite unlike either parent   
plant4 ,they must be grown for several  
years1 and all plants that do not       
resemble the desired variety must be    
killed off1 if we expect to produce a   
hybrid that will breed more plants like 
itself4 ,luther ,burbank1 the great     
hybridizer of ,california1 destroys tens
 of thousands of plants in order to get 
one or two with the characters which he 
wishes to preserve4 ,thus he is yearly  
adding to the wealth of this country by 
producing new plants or fruits of       
commercial value4 ,a number of years ago
 he succeeded in growing a new variety  
of potato1 which has already enriched   
the farmers of this country about       
#bj1jjj1jjj4 ,one of his varieties of   
black walnut trees1 a very valuable hard
 wood1 grows ten to twelve times as     
rapidly as ordinary black walnuts4 ,with

 lumber yearly increasing in price1 a   
quick growing tree becomes a very       
valuable commercial product4 ,among his 
famous hybrids are the plumcot1 a cross 
between an apricot and a plum1 his      
numerous varieties of berries and his   
splendid ,climax plum1 the result of a  
cross between a bitter ,chinese plum and
 an edible ,japanese plum4 ,but none of 
,burbank's products grow from seeds2    
they are all produced asexually1 from   
hybrids by some of the processes        
described in the next paragraph4  ,the  
,department of ,agriculture and its     
,methods4--,the ,department of          
,agriculture is also doing splendid work
 in producing new varieties of oranges  
and lemons1 of grain and various garden 
vegetables4 ,the greatest possibilities 
have been shown by department workers to
 be open to the farmer or fruit grower  
through hybridizing1 and by budding1    
grafting1 or slipping4  ,illustration3  
,steps in budding4 a1 twig having       
suitable buds to use2 b1 method of      

cutting out bud2 c1 how the bark is cut2
 d1 how the bark is opened2 e1 inserting
 the bud2 f1 the bud in place2 g1 the   
bud properly bound in place4            
,budding4--,if a given tree1 for        
example1 produces a kind of fruit which 
is of excellent quality1 it is possible 
sometimes to attach parts of the tree to
 another strong tree of the same species
 that may not bear good fruit4 ,this is 
done by budding4 ,a ,t-shaped incision  
is cut in the bark2 a bud from the tree 
bearing the desired fruit is placed in  
the cut and bound in place4 ,when a     
shoot from the embedded bud grows out   
the following spring1 it is found to    
have all the characters of the tree from
 which it was taken4  ,illustration3    
,steps in tongue grafting4 a1 the two   
branches to be formed2 b1 a tongue cut  
in each2 c1 fitted together2 d1 method  
of wrapping4  ,grafting4--,of much the  
same nature is grafting4 ,here1 however1
 a small portion of the stem of the     
closely allied tree is fastened into the

 trunk of the growing tree in such a    
manner that the two cut layers just     
under the bark will coincide4 ,this will
 allow of the passage of food into the  
grafted part and insure the ultimate    
growth of the twig4 ,grafting and       
budding are of considerable economic    
value to the fruit grower1 as it enables
 him to produce at will1 trees bearing  
choice varieties of fruit4#cd           
,footnote #cd3 ,for full directions for 
budding and grafting1      see ,goff and
 ,mayne1 ,first ,principles of          
,agriculture1 ,chap4      ,,xix1 ,mayne 
and ,hatch1 ,high ,school ,agriculture1 
pp4      #aei-afe1 or ,hodge1 ,nature   
,study and ,life1 pages #afi-agi4       
,other ,methods4--,other methods of     
plant propagation are by means of       
runners1 as when strawberry plants      
strike root from long stems that run    
along the ground2 layering1 where roots 
may develop on covered up branches of   
blackberry or raspberry plants2 slips1  
roots developing from stems which are   

cut off and placed in moist sand2 from  
tubers1 as in planting potatoes2 and by 
means of bulbs1 as the tulip or         
hyacinth4 ,all of the above means of    
propagation are asexual and are of      
importance in our problem of plant      
breeding4  ,illustration3 ,plant        
breeding plots4 7,minnesota ,experiment 
,station47  ,the ,work of ,gregor       
,mendel4--,fifty years ago1 an ,austrian
 monk1 ,gregor ,mendel1 found in        
breeding garden peas that these plants  
passed on certain fixed characters1 as  
the shape of the seed1 the color of the 
pod when ripe1 and others1 and that when
 two pea plants of different characters 
were crossed1 one of these characters   
would be likely to appear in the        
offspring of the second generation in   
the ratio of three to one4 ,such        
characters as would appear to the       
exclusion of others in the first        
crossing of the plants were called      
dominant1 the ones not appearing1       
recessive characteristics4 ,when these  

seeds were again sown the ones bearing a
 recessive characteristic would produce 
only peas with this recessive           
characteristic1 but the ones with a     
dominant characteristic might give rise 
to a pure dominant or to offspring      
having partly a dominant and partly a   
recessive character2 pure dominants     
being to the mixed offspring in the     
ratio of #a to #b4 ,the pure dominants  
if bred with others like themselves     
would produce only pure dominants1 but  
the cross breeds would again produce    
mixed offspring of three kinds in the   
ratio of one dominant to two cross      
breeds and one recessive4 ,the feature  
of this work that interests us is that  
unit characters are passed along by     
heredity in the germ cells pure1 that   
is1 unchanged1 from one generation to   
another1 and independently of each      
other4  ,illustration3 ,illustration of 
,mendel's ,law4  ,determiners of        
,character4--,a child then resembles his
 parents in some definite particulars   

because certain determiners of          
characters have been present in the germ
 cells of one of the parents4 ,if the   
determiner of a certain character is    
absent from the germ cells of both      
parents1 it will be absent in all of    
their offspring4  ,these discoveries of 
,mendel are of the greatest importance  
in plant and animal breeding because    
they enable the breeder to isolate      
certain characters and by proper        
selection to breed varieties which have 
these desired characters1 instead of    
waiting for a chance union of the       
desired characters by nature4  ,animal  
,breeding4--,it has been pointed out    
that the domestication of wild animals1 
the horse1 cattle1 sheep1 goats1 and the
 dog1 marked a great advance in         
civilization in the history of the      
earth's peoples4 ,as the young of these 
animals came to be bred in captivity the
 peoples owning them would undoubtedly  
pick out the strongest and best of the  
offspring1 killing off the others for   

food4 ,thus they came unconsciously to  
select and aid nature in producing a    
stronger and better stock4 ,later man   
began to recognize certain characters   
that he wished to have in horses1 dogs1 
or cattle1 and so by slow processes of  
breeding and crossing or hybridizing one
 nearly allied form with another the    
numerous groups of domesticated animals 
began to appear4  ,illustration3 ,what  
has resulted from artificial selection  
among dogs4 7,after ,romanes47  ,in     
,darwin's time animal breeding was so   
far advanced that he got his ideas of   
selection by nature in evolution from   
the artificial selection practiced by   
animal breeders4 ,a glance at the       
pictures will give some idea of the     
changes that have taken place in the    
form of some animals since man began to 
breed them a few thousand years ago4    
,illustration3 ,the four-toed ancestor  
of the present horse1 restored from a   
study of its fossil skeleton4 7,after   
,knight in ,american ,museum of ,natural

 ,history47  ,some ,domesticated        
,animals4--,our domesticated dogs are   
descended from a number of wolflike     
forms in various parts of the world4    
,all the present races of cats1 on the  
other hand1 seem to be traced back to   
,egypt4 ,modern horses are first noted  
in ,europe and ,asia1 but far older     
forms flourished on the earth in former 
geologic periods4 ,it is interesting to 
note that ,america was the original home
 of the horse1 although at the time of  
the earliest explorers the horse was    
unknown here1 the wild horse of the     
,western plains having arisen from      
horses introduced by the ,spaniards4    
,long ages ago1 the first ancestors of  
the horse were probably little animals  
about the size of a fox4 ,the earliest  
horse we have knowledge of had four toes
 on the fore and three toes on the hind 
foot4 ,thousands of years later we find 
a larger horse1 the size of a sheep1    
with a three-toed foot4 ,by gradual     
changes1 caused by the tendency of the  

animals to vary and by the action of the
 surroundings upon the animal in        
preserving these variations1 there was  
eventually produced our present horse1  
an animal with legs adapted for rapid   
locomotion1 with feet particularly      
fitted for the life in open fields1 and 
with teeth which serve well to seize and
 grind herbage4 ,knowledge of this sort 
was also used by ,darwin to show that   
constant changes in the form of animals 
have been taking place since life began 
on the earth4  ,the horse1 which for    
some reason disappeared in this country1
 continued to exist in ,europe1 and man1
 emerging from his early savage         
condition1 began to make use of the     
animal4 ,we know the horse was          
domesticated in early ,biblical times1  
and that he soon became one of man's    
most valued servants4 ,in more recent   
times1 man has begun to change the horse
 by breeding for certain desired        
characteristics4 ,in this manner have   
been established and improved the       

various types of horses familiar to us  
as draft horses1 coach horses1 hackneys1
 and the trotters4  ,it is needless to  
say that all the various domesticated   
animals have been tremendously changed  
in a similar manner since civilized man 
has come to live on the earth4 ,when we 
realize the very great amount of money  
invested in domesticated animals2 that  
there are over #fj1jjj1jjj each of      
sheep1 cattle1 and swine and over       
#bj1jjj1jjj horses owned in this        
country1 then we may see how very       
important a part the domestic animals   
play in our lives4  ,improvement of     
,man4--,if the stock of domesticated    
animals can be improved1 it is not      
unfair to ask if the health and vigor of
 the future generations of men and women
 on the earth might not be improved by  
applying to them the laws of selection4 
,this improvement of the future race has
 a number of factors in which we as     
individuals may play a part4 ,these are 
personal hygiene1 selection of healthy  

mates1 and the betterment of the        
environment4  ,personal ,hygiene4--,in  
the first place1 good health is the one 
greatest asset in life4 ,we may be born 
with a poor bodily machine1 but if we   
learn to recognize its defects and care 
for it properly1 we may make it do its  
required work effectively4 ,if certain  
muscles are poorly developed1 then by   
proper exercise we may make them        
stronger4 ,if our eyes have some defect1
 we can have it remedied by wearing     
glasses4 ,if certain drugs or alcohol   
lower the efficiency of the machine1 we 
can avoid their use4 ,with proper care a
 poorly developed body may be improved  
and do effective work4                  
,eugenics4--,when people marry there are
 certain things that the individual as  
well as the race should demand4 ,the    
most important of these is freedom from 
germ diseases which might be handed down
 to the offspring4 ,tuberculosis1       
syphilis1 that dread disease which      
cripples and kills hundreds of thousands

 of innocent children1 epilepsy1 and    
feeble-mindedness are handicaps which it
 is not only unfair but criminal to hand
 down to posterity4 ,the science of     
being well born is called eugenics4     
,illustration3 ,in this and the         
following diagrams the circle represents
 a female1 the square a male4 ,n means  
normal2 ,f means feeble-minded2 ,a1     
alcoholic2 ,t1 tubercular2 ,sx1 sexually
 immoral2 ,sy1 having syphilis4 ,this   
chart shows the record of a certain     
family for three generations4 ,a normal 
woman married an alcoholic and          
tubercular man4 ,he must have been      
feeble-minded also as two of his        
children were born feeble-minded4 ,one  
of these children married another       
feeble-minded woman1 and of their five  
children two died in infancy and three  
were feeble-minded4 7,after ,davenport47
  ,illustration3 ,this chart shows that 
feeble-mindedness is a characteristic   
sure to be handed down in a family where
 it exists4 ,the feeble-minded woman at 

the top left of the chart married twice4
 ,the first children from a normal      
father are all normal1 but the other    
children from an alcoholic father are   
all feeble-minded4 ,the right-hand side 
of the chart shows a terrible record of 
feeble-mindedness4 ,should feeble-minded
 people be allowed to marry8 7,after    
,davenport47  ,the ,jukes4--,studies    
have been made on a number of different 
families in this country1 in which      
mental and moral defects were present in
 one or both of the original parents4   
,the ,jukes family is a notorious       
example4 ,the first mother is known as  
,margaret1 the mother of criminals4 ,in 
seventy-five years the progeny of the   
original generation has cost the state  
of ,new ,york over a million and a      
quarter of dollars1 besides giving over 
to the care of prisons and asylums      
considerably over a hundred             
feeble-minded1 alcoholic1 immoral1 or   
criminal persons4 ,another case recently
 studied is the ,kallikak family4#ce    

,this family has been traced back to the
 ,war of the ,revolution1 when a young  
soldier named ,martin ,kallikak seduced 
a feeble-minded girl4 ,she had a        
feeble-minded son from whom there have  
been to the present time #dhj           
descendants4 ,of these #cc were sexually
 immoral1 #bd confirmed drunkards1 #c   
epileptics1 and #adc feeble-minded4 ,the
 man who started this terrible line of  
immorality and feeble-mindedness later  
married a normal ,quaker girl4 ,from    
this couple a line of #dif descendants  
have come1 with no cases of             
feeble-mindedness4 ,the evidence and the
 moral speak for themselves6            
,footnote #ce3 ,the name ,kallikak is   
fictitious4  ,parasitism and its ,cost  
to ,society4--,hundreds of families such
 as those described above exist to-day1 
spreading disease1 immorality1 and crime
 to all parts of this country4 ,the cost
 to society of such families is very    
severe4 ,just as certain animals or     
plants become parasitic on other plants 

or animals1 these families have become  
parasitic on society4 ,they not only do 
harm to others by corrupting1 stealing1 
or spreading disease1 but they are      
actually protected and cared for by the 
state out of public money4 ,largely for 
them the poorhouse and the asylum exist4
 ,they take from society1 but they give 
nothing in return4 ,they are true       
parasites4  ,the ,remedy4--,if such     
people were lower animals1 we would     
probably kill them off to prevent them  
from spreading4 ,humanity will not allow
 this1 but we do have the remedy of     
separating the sexes in asylums or other
 places and in various ways preventing  
intermarriage and the possibilities of  
perpetuating such a low and degenerate  
race4 ,remedies of this sort have been  
tried successfully in ,europe and are   
now meeting with success in this        
country4  ,blood ,tells4--,eugenics show
 us1 on the other hand1 in a study of   
the families in which are brilliant men 
and women1 the fact that the descendants

 have received the good inheritance from
 their ancestors4 ,the following1 taken 
from ,davenport's ,heredity in ,relation
 to ,eugenics1 illustrates how one      
family has been famous in ,american     
,history4  ,in #affg ,elizabeth ,tuttle1
 of strong will1 and of extreme         
intellectual vigor1 married ,richard    
,edwards of ,hartford1 ,conn41 a man of 
high repute and great erudition4 ,from  
their one son descended another son1    
,jonathan ,edwards1 a noted divine1 and 
president of ,princeton ,college4 ,of   
the descendants of ,jonathan ,edwards   
much has been written2 a brief catalogue
 must suffice3 ,jonathan ,edwards1 ,jr41
 president of ,union ,college2 ,timothy 
,dwight1 president of ,yale2 ,sereno    
,edwards ,dwight1 president of ,hamilton
 ,college2 ,theodore ,dwight ,woolsey1  
for twenty-five years president of ,yale
 ,college2 ,sarah1 wife of ,tapping     
,reeve1 founder of ,litchfield ,law     
,school1 herself no mean lawyer2 ,daniel
 ,tyler1 a general in the ,civil ,war   

and founder of the iron industries of   
,north ,alabama2 ,timothy ,dwight1      
second1 president of ,yale ,university  
from #ahhf to #ahih2 ,theodore ,william 
,dwight1 founder and for thirty-three   
years warden of ,columbia ,law ,school2 
,henrietta ,frances1 wife of ,eli       
,whitney1 inventor of the cotton gin1   
who1 burning the midnight oil by the    
side of her ingenious husband1 helped   
him to his enduring fame2 ,merrill      
,edwards ,gates1 president of ,amherst  
,college2 ,catherine ,maria ,sedgwick of
 graceful pen2 ,charles ,sedgwick       
,minot1 authority on biology and        
embryology in the ,harvard ,medical     
,school2 ,edith ,kermit ,carow1 wife of 
,theodore ,roosevelt2 and ,winston      
,churchill1 the author of ,coniston and 
other well-known novels4  ,illustration3
 ,this record shows the inheritance of  
artistic ability 7black circles and     
squares74 7,after ,davenport47  ,of the 
daughters of ,elizabeth ,tuttle         
distinguished descendants also came4    

,robert ,treat ,paine1 signer of the    
,declaration of ,independence2 ,chief   
,justice of the ,united ,states         
,morrison ,r4 ,waite2 ,ulysses ,s4      
,grant and ,grover ,cleveland1          
presidents of the ,united ,states4      
,these and many other prominent men and 
women can trace the characters which    
enabled them to occupy the positions of 
culture and learning they held back to  
,elizabeth ,tuttle4                     
,euthenics4--,euthenics1 the betterment 
of the environment1 is another important
 factor in the production of a stronger 
race4 ,the strongest physical           
characteristics may be ruined if the    
surroundings are unwholesome and        
unsanitary4 ,the slums of a city are at 
once symptom1 effect1 and cause of evil4
 ,a city which allows foul tenements1   
narrow streets1 and crowded slums to    
exist will spend too much for police    
protection1 for charity1 and for        
hospitals4  ,every improvement in       
surroundings means improvement of the   

chances of survival of the race4 ,in the
 spring of #aiac the health department  
and street-cleaning department of the   
city of ,new ,york cooperated to bring  
about a clean up of all filth1 dirt1 and
 rubbish from the houses1 streets1 and  
vacant lots in that city4 ,during the   
summer of #aiac the health department   
reported a smaller percentage of deaths 
of babies than ever before4 ,we must    
draw our own conclusions4 ,clean streets
 and houses1 clean milk and pure water1 
sanitary housing1 and careful medical   
inspection all do their part in         
maintaining a low rate of illness and   
death1 thus reacting upon the health of 
the citizens of the future4 ,it will be 
the purpose of the following pages to   
show how we may best care for our own   
bodies and how we may better the        
environment in which we are placed4     
,,reference ,,books                     
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,bailey1 ,plant    

,breeding4 ,macmillan and ,company4     
,harwood1 ,new ,creations in ,plant     
,life4 ,the ,macmillan        ,company4 
,jordan1 ,the ,heredity of ,richard     
,roe4 ,american ,unitarian              
,association4      ,sharpe1 ,laboratory 
,manual1 pp4 #fd-gb1 #cde-cdg4 ,american
        ,book ,company4                 
,,advanced       ,allen1 ,civics and    
,health4 ,ginn and ,company4            
,coulter1 ,castle1 ,east1 ,tower1 and   
,davenport1 ,heredity and               
,eugenics4 ,university of ,chicago      
,press4      ,davenport1 ,heredity in   
,relation to ,eugenics4 ,henry ,holt    
and ,company4      ,de ,vries1 ,plant   
,breeding4 ,open ,court ,publishing     
,company4      ,goddard1 ,the ,kallikak 
,family4 ,the ,macmillan ,company4      
,kellicott1 ,the ,social ,direction of  
,human ,evolution4        ,appleton     
,company4      ,punnet1 ,mendelism4 ,the
 ,macmillan ,company4      ,richards1   
,helen ,m41 ,euthenics1 the ,science of 
,controllable        ,environment4      

,walter1 ,genetics4 ,the ,macmillan     
,company4     ,,xviii4 ,,the ,,human    
,,machine ,,and ,,its ,,needs           
,problem4--,to obtain a general         
understanding of the parts and uses of  
the bodily machine4                     
,,laboratory ,,suggestions              
,demonstration4--,review to show that   
the human body is a        complex of   
cells4      ,laboratory demonstration by
 means of 7a7 human skeleton        and 
7b7 manikin to show the position and    
gross structure        of the chief     
organs of man4   ,man and his           
,environment4--,in the last chapter we  
saw that one factor in the improvement  
of man lies in giving him better        
surroundings4 ,it will be the purpose of
 the following chapters to show how man 
is fitted to live in the environment in 
which he is placed4 ,he comes in contact
 with air1 light1 water1 soil1 food1 and
 shelter which make his somewhat        
artificial environment2 he must adapt   
himself to get the best he can out of   

this environment4  ,the ,needs of       
,living ,things4--,we have already found
 that the primary needs of plants and   
animals are the same4 ,they both need   
food1 they both need to digest their    
food and to have it circulate in a fluid
 form to the cells where it will be     
used4 ,they both need oxygen so as to   
release the energy locked up in their   
food4 ,and they both need to reproduce  
so that their kind may be continued on  
the earth4 ,what is true of plants and  
other animals is true of man4  ,the     
,needs of ,simple and ,complex ,animals 
the ,same4--,the simplest animal1 a     
single cell1 has the same needs as the  
most complex4 ,the cell paramoecium     
feeds1 digests1 oxidizes its food1 and  
releases energy4 ,the cells of the human
 body built up into tissues have the    
same needs and perform the same         
functions as the paramoecium4 ,it is the
 cells of the body working together in  
groups as tissues and organs that make  
the complicated actions of man possible4

 ,division of labor has arisen because  
of the complex needs and work of the    
organism4  ,illustration3 ,the human    
body seen from the side in longitudinal 
section4  ,the ,human ,body a           
,machine4--,in all animals1 and the     
human animal is no exception1 the body  
has been likened to a machine in that it
 turns over the latent or potential     
energy stored up in food into kinetic   
energy 7mechanical work and heat71 which
 is manifested when we perform work4    
,one great difference exists between an 
engine and the human body4 ,the engine  
uses fuel unlike the substance out of   
which it is made4 ,the human body1 on   
the other hand1 uses for fuel the same  
substances out of which it is formed2 it
 may1 indeed1 use part of its own       
substance for food4 ,it must as well do 
more than purely mechanical work4 ,the  
human organism must be so delicately    
adjusted to its surroundings that it    
will react in a ready manner to stimuli 
from without2 it must be able to utilize

 its fuel 7food7 in the most economical 
manner2 it must be fitted with machinery
 for transforming the energy received   
from food into various kinds of work2 it
 must properly provide the machine with 
oxygen so that the fuel will be         
oxidized1 and the products of oxidation 
must be carried away1 as well as other  
waste materials which might harm the    
effectiveness of the machine4 ,most     
important of all1 the human machine must
 be able to repair itself4  ,in order to
 understand better this complicated     
machine1 the human body1 let us briefly 
examine the structure of its parts and  
thus get a better idea of the           
interrelation of these parts and of     
their functions4  ,the ,skin4--,covering
 the body is a protective structure     
called the skin4 ,covered on the outside
 with dead cells1 yet it is provided    
with delicate sense organs1 which give  
us perception of touch1 taste1 smell1   
pressure1 and temperature4 ,it also aids
 in getting wastes out of the body by   

means of its sweat glands and plays an  
important part in equalizing the        
temperature of the body4  ,illustration3
 ,skeleton of a man4 ,,cr41 cranium2    
,,cl41 clavicle2 ,,st41 sternum2 ,h41   
humerus2 ,v4,c41 vertebral column2 ,r41 
radius2 ,u41 ulna2 ,p41 pelvic girdle2  
,c41 carpals2 ,m41 metacarpals2 ,ph41   
phalanges2 ,f41 femur2 ,fi41 fibula2    
,t41 tibia2 ,tar41 tarsals2 ,,mt41      
metatarsals4  ,bones and ,muscles4--,the
 body is built around a framework of    
bones4 ,these bones1 which are bound    
together by tough ligaments1 fall       
naturally into two great groups1 the    
bones of the body proper1 vertebral     
column1 ribs1 breast bone1 and skull1   
which form the axial skeleton1 and the  
appendages1 two sets of bones which form
 the framework of the arms and legs1    
which with the bones which attach them  
to the axial skeleton form the          
appendicular skeleton4  ,to the bones   
are attached the muscles of the body4   
,movement is accomplished by contraction

 of muscles1 which are attached so as to
 cause the bones to act as levers4      
,bones also protect the nervous system  
and other delicate organs4 ,they also   
help to give form and rigidity to the   
body4  ,illustration3 ,diagram showing  
action of biceps muscle4 a1 contracted2 
b1 extended2 h1 humerus2 s1 scapula4    
,hygiene of ,muscles and ,bones4--,young
 people especially need to know how to  
prevent certain defects which are       
largely the result of bad habits of     
posture4 ,standing erect is an example  
of a good habit1 round shoulders a bad  
habit of this sort4 ,the habit of a     
wrong position of bones and muscles once
 formed is very hard to correct4 ,this  
can best be done by certain corrective  
exercises at home or in the gymnasium4  
,round shoulders is most common among   
people whose occupation causes them to  
stoop4 ,drawing1 writing1 and a wrong   
position when at one's desk are among   
the causes4 ,exercises which strengthen 
the back muscles and cause the head to  

be kept erect are helpful in forming the
 habit of erect carriage4  ,slight      
curvature of the spine either backward  
or forward is helped most by exercises  
which tend to straighten the body1 such 
as stretching up with the hands above   
the head4 ,lateral curvature of the     
spine1 too often caused by a hunched-up 
position at the school desk1 may also be
 corrected by exercises which tend to   
lengthen the spinal column4             
,illustration3 ,three classes of levers 
in the human body2 bones and muscles act
 together4 ,a1 a lever of the first     
class2 ,b1 a lever of the second class2 
,c1 a lever of the third class4  ,it is 
the duty of every girl and boy to have  
good posture and erect carriage1 not    
only because of the better state of     
health which comes with it1 but also    
because one's self-respect demands that 
each one of us makes the best of the    
gifts that nature has given us4 ,an     
erect head1 straight shoulders1 and     
elastic carriage go far toward making   

their owner both liked and respected4   
,illustration3 ,bad posture in the      
schoolroom may cause permanent injury to
 the spine4  ,other ,body               
,structures4--,in spaces between the    
muscles are found various other         
structures1--blood vessels1 which carry 
blood to and from the great pumping     
station1 the heart1 and thence to all   
parts of the body2 connective tissue1   
which holds groups of muscle or other   
cells together2 fat cells1 scattered in 
various parts of the body2 various gland
 cells1 which manufacture enzymes2 and  
the cells of the nervous system1 which  
aid in directing the body parts4  ,body 
,cavity4--,within the body is a cavity1 
which in life is almost completely      
filled with various organs4 ,a thin wall
 of muscle called the diaphragm divides 
the body cavity into two unequal spaces4
 ,in the upper space are found the heart
 and lungs1 in the lower1 the digestive 
tract with its glands1 the liver1       
kidneys1 and other structures 7see page 

#bfg74  ,digestion1 ,absorption1 and    
,excretion4--,running through the body  
is a food tube in which undigested food 
is placed and from which digested or    
liquid food is absorbed into the blood  
so that the cells of the various organs 
which do the work may receive food4     
,emptying into this food tube are       
various groups of gland cells1 which    
pour digestive fluids over the solid    
foods1 thus aiding in changing them to  
liquids4 ,solid wastes are passed out   
through the posterior end of the food   
tube1 while liquid wastes are excreted  
by means of glands called kidneys4      
,work done by ,cells4--,food1 prepared  
in the digestive tract1 and oxygen from 
the lungs are taken by the blood to the 
cells4 ,bathed in liquid food1 the cells
 do their work2 they promote the        
oxidization of food and the exchange of 
carbon dioxide for oxygen in the blood1 
while other wastes of the cells are     
given off1 to pass eventually through   
the kidneys and out of the body4  ,the  

,nervous ,system4--,the smooth working  
of the bodily machine is due to another 
set of structures which direct the      
working of the parts so that they will  
act in unison4 ,this director is the    
nervous system4 ,we have seen that1 in  
the simplest of animals1 one cell       
performs the functions necessary to its 
existence4 ,in the more complex animals1
 where groups of cells form tissues1    
each having a different function1 a     
nervous system is developed4 ,the       
functions of the human nervous system   
are3 7#a7 the providing of man with     
sensation1 by means of which he gets in 
touch with the world about him2 7#b7 the
 connecting of organs in different parts
 of the body so that they act as a      
united and harmonious whole2 7#c7 the   
giving to the human being a will1 a     
provision for thought4 ,cooperation in  
word and deed is the end attained4 ,we  
are all familiar with examples of the   
cooperation of organs4 ,you see food2   
the thought comes that it is good to    

eat2 you reach out1 take it1 raise it to
 the mouth2 the jaws move in response to
 your will2 the food is chewed and      
swallowed4 ,while digestion and         
absorption of the food are taking place1
 the nervous system is still in control4
 ,the nervous system also regulates     
pumping of blood over the body1         
respiration1 secretion of glands1 and1  
indeed1 every bodily function4 ,man is  
the highest of all animals because of   
the extreme development of the nervous  
system4 ,man is the thinking animal1 and
 as such is master of the earth4        
,,reference ,,reading ,,for ,,this ,,and
 ,,succeeding ,,chapters ,,on ,,human   
,,biology                               
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,davison1 ,the     
,human ,body and ,health4 ,american     
,book ,company4      ,gulick1 ,the      
,gulick ,hygiene ,series4 ,ginn and     
,company4      ,overton1 ,general       
,hygiene4 ,american ,book ,company4     

,ritchie1 ,human ,physiology4 ,world    
,book ,company4      ,sharpe1           
,laboratory ,manual in ,botany1 pages   
#bah-bbe4        ,american ,book        
,company4                               
,,advanced       ,halliburton1 ,kirk's  
,handbook of ,physiology4 ,p4           
,blakiston's        ,son and ,company4  
,hough and ,sedgwick1 ,the ,human       
,mechanism4 ,ginn and ,company4         
,howell1 ,physiology1 #c;d edition4 ,w4 
,b4 ,saunders ,company4      ,schafer1  
,textbook of ,physiology4 ,the          
,macmillan ,company4      ,stiles1      
,nutritional ,physiology4 ,w4 ,b4       
,saunders ,company4      ,verworn1      
,general ,physiology4 ,the ,macmillan   
,company4     ,,xix4 ,,foods ,,and      
,,dietaries  ,problems4--,a study of    
foods to determine3--           7a7     
,their nutritive value4           7b7   
,the relation of work1 environment1 age1
 sex1 and             digestibility of  
foods to diet4           7c7 ,their     
relative cheapness4           7d7 ,the  

daily ,calorie requirement4             
7e7 ,food adulteration4           7f7   
,the relation of alcohol to the human   
system4                                 
,,laboratory ,,suggestions              
,laboratory exercise4--,composition of  
common foods4 ,the        series of food
 charts supplied by the ,united ,states 
,department of ,agriculture makes an    
excellent basis for a        laboratory 
exercise to determine common foods rich 
in 7a7        water1 7b7 starch1 7c7    
sugar1 7d7 fats or oils1 7e7            
protein1 7f7 salts1 7g7 refuse4         
,demonstration4--,method of using bomb  
calorimeter4      ,laboratory and home  
exercise4--,to determine the best       
individual balanced dietary 7using      
standard of ,atwater1                   
,chittenden1 or ,voit7 as determined by 
the use of the        #ajj-;,calorie    
portion4      ,demonstration4--,tests   
for some common adulterants4            
,demonstration4--,effect of alcohol on  
protein1 e4g4 white        of egg4      

,demonstration4--,alcohol in some patent
 medicines4                             
,demonstration4--,patent medicines      
containing acetanilid4                  
,determination of acetanilid4   ,why we 
,need ,food4--,a locomotive engine takes
 coal1 water1 oxygen1 from its          
environment4 ,a living plant or animal  
takes organic food1 water1 and oxygen   
from its environment4 ,both the living  
and nonliving machine do the same thing 
with this fuel or food4 ,they oxidize it
 and release the energy in it4 ,but the 
living organism in addition may use the 
food to repair parts that have broken   
down or even build new parts4 ,thus food
 may be defined as something that       
releases energy or that forms material  
for the growth or repair of the body of 
a plant or animal4 ,the millions of     
cells of which the body is composed must
 be given material which will form more 
living matter or material which can be  
oxidized to release energy when muscle  
cells move1 or gland cells secrete1 or  

brain cells think4  ,illustration3 ,the 
composition of milk4 ,why is it         
considered a good food8                 
,nutrients4--,certain nutrient materials
 form the basis of food of both plants  
and animals4 ,these have been stated to 
be proteins 7such as lean meat1 eggs1   
the gluten of bread71 carbohydrates     
7starches1 sugars1 gums1 etc471 fats and
 oils 7both animal and vegetable71      
mineral matter and water4               
,proteins4--,protein substances contain 
the element nitrogen4 ,hence such foods 
are called nitrogenous foods4 ,man must 
form the protoplasm of his body 7that   
is1 the muscles1 tendons1 nervous       
system1 blood corpuscles1 the living    
parts of the bone and the skin1 etc47 in
 part at least from nitrogenous food4   
,some of this he obtains by eating the  
flesh of animals1 and some he obtains   
directly from plants 7for example1 peas 
and beans74 ,proteins are the only foods
 available for tissue building4 ,they   
may be oxidized to release energy if    

occasion requires it4  ,fats and        
,oils4--,fats and oils1 both animal and 
vegetable1 are the materials from which 
the body derives part of its energy4    
,the chemical formula of a fat shows    
that1 compared with other food          
substances1 there is very little oxygen 
present2 hence the greater capacity of  
this substance for uniting with oxygen4 
,the rapid burning of fat compared with 
the slower combustion of a piece of meat
 or a piece of bread illustrates this4  
,a pound of butter releases over twice  
as much energy to the body as does a    
pound of sugar or a pound of steak4     
,human fatty tissue is formed in part   
from fat eaten1 but carbohydrate or even
 protein food may be changed and stored 
in the body as fat4                     
,carbohydrates4--,we see that the       
carbohydrates1 like the fats1 contain   
carbon1 hydrogen1 and oxygen4           
,carbohydrates are essentially          
energy-producing foods4 ,they are1      
however1 of use in building up or       

repairing tissue4 ,it is certainly true 
that in both plants and animals such    
foods pass directly1 together with foods
 containing nitrogen1 to repair waste in
 tissues1 thus giving the needed        
proportion of carbon1 oxygen1 and       
hydrogen to unite with the nitrogen in  
forming the protoplasm of the body4     
,illustration3 ,three portions of foods1
 each of which furnishes about the same 
amount of nourishment4  ,inorganic      
,foods4--,water forms a large part of   
almost every food substance4 ,it forms  
about five sixths of a normal daily     
diet4 ,the human body1 by weight1 is    
about two thirds water4 ,about #ij per  
cent of the blood is water4 ,water is   
absolutely essential in passing off     
waste of the body4 ,when we drink water1
 we take with it some of the inorganic  
salts used by the body in the making of 
bone and in the formation of protoplasm4
 ,sodium chloride 7table salt71 an      
important part of the blood1 is taken in
 as a flavoring upon our meats and      

vegetables4 ,phosphate of lime and      
potash are important factors in the     
formation of bone4  ,phosphorus is a    
necessary substance for the making of   
living matter1 milk1 eggs1 meat1 whole  
wheat1 and dried peas and beans         
containing small amounts of it4 ,iron   
also is an extremely important mineral1 
for it is used in the building of red   
blood cells4 ,meats1 eggs1 peas and     
beans1 spinach1 and prunes1 are foods   
containing some iron4  ,some other      
salts1 compounds of calcium1 magnesium1 
potassium1 and phosphorus1 have been    
recently found to aid the body in many  
of its most important functions4 ,the   
beating of the heart1 the contraction of
 muscles1 and the ability of the nerves 
to do their work appear to be due to the
 presence of minute quantities of these 
salts in the body4  ,uses of            
,nutrients4--,the following table sums  
up the uses of nutrients to man3#cf--   
,protein                          ,forms
 tissue             ,white of eggs      

7albumen71         7muscles1 tendon1    
curd of milk 7casein71 lean    and      
probably       ,all serve as       meat1
 gluten of wheat1 etc4    fat7          
fuel and yield                          
energy in form   ,fats                  
,form fatty tissue4  of heat and        
muscular     ,fat of meat1 butter1 olive
 oil1                     strength4     
oils of corn and wheat1 etc4            
,carbohydrates                          
,transformed into        ,sugar1 starch1
 etc4               fat4             _/ 
,mineral matters 7ash7             ,aid 
in forming bone1     ,phosphates of     
lime1 potash1       assist in digestion1
       soda1 etc4                       
aid in absorption                       
and in other ways                       
help the body parts                     
do their work4   ,water used as a       
vehicle to carry nutrients1 and enters  
into the   composition of living matter4
       ,footnote #cf3 ,adapted from     
,atwater1 ,principles of ,nutrition     

and ,nutritive ,value of ,food1 ,u4 ,s4 
,department of      ,agriculture1 #aijb4
  ,common ,foods contain the            
,nutrients4--,we have already found in  
our plant study that various plant foods
 are rich in different nutrients1       
carbohydrates forming the chief nutrient
 in the foods we call cereals1 breads1  
cake1 fleshy fruits1 sugars1 jellies1   
and the like4 ,fats and oils are most   
largely found in nuts and some grains4  
,animal foods are our chief supply of   
protein4 ,white of egg and lean meat are
 almost pure protein and water4         
,proteins are most abundant1 as we      
should expect1 in those plants which are
 richly supplied with nitrogen2 peas and
 beans1 and in grains and nuts4 ,fats1  
which are melted into oils at the       
temperature of the body1 are represented
 by the fat in meats1 bacon1 pork1 lard1
 butter1 and vegetable oils4            
,water4--,water is1 as we have seen1 a  
valuable part of food4 ,it makes up a   
very high percentage of fresh fruits and

 vegetables2 it is also present in milk 
and eggs1 less abundant in meats and    
fish1 and is lowest in dried foods and  
nuts4 ,the amount of water in a given   
food is often a decided factor in the   
cost of the given food1 as can easily be
 seen by reference to the chart on page 
#bhc4  ,refuse4--,some foods bought in  
the market may contain a certain        
unusable portion4 ,this we call refuse4 
,examples of refuse are bones in meat1  
shells of eggs or of shellfish1 the     
covering of plant cells which form the  
skins of potatoes or other vegetables4  
,the amount of refuse present also plays
 an important part in the values of     
foods for the table4 ,the table#cg on   
page #bgf gives the percentages of      
organic nutrients1 water1 and refuse    
present in some common foods4           
,illustration3 ,table of food values4   
,determine the percentage of water in   
codfish1 loin of beef1 milk1 potatoes4  
,percentage of refuse in leg of mutton1 
codfish1 eggs1 and potatoes4 ,what is   

the refuse in each case8 ,find three    
foods containing a high percentage of   
protein2 of fat2 of carbohydrate4 ,find 
some food in which the proportions of   
protein1 fat1 and carbohydrate are      
combined in a good proportion4  ,fuel   
,values of ,nutrients4--,in experiments 
performed by ,professor ,atwater and    
others1 and in the appended tables1 the 
value of food as a source of energy is  
stated in heat units called ,calories4  
,a ,calorie is the amount of heat       
required to raise the temperature of one
 kilogram of water from zero to one     
degree ,centigrade4 ,this is about      
equivalent to raising one pound four    
degrees ,fahrenheit4 ,the fuel value of 
different foods may be computed in a    
definite manner4 ,this is done by       
burning a given portion of a food 7say  
one gram7 in the apparatus known as a   
calorimeter4 ,by this means may be      
determined the number of degrees the    
temperature of a given amount of water  
is raised during the process of burning4

 ,it has thus been found that a gram of 
fat will liberate #i4c ,calories of     
heat1 while a gram of starch or sugar   
only about #d ,calories4 ,the burning   
value of fat is1 therefore1 over twice  
that of carbohydrates4 ,in a similar    
manner protein has been shown to have   
about the same fuel value as            
carbohydrates1 i4e4 #d ,calories to a   
gram4#ch       ,footnote #cg and #ch3   
,w4 ,o4 ,atwater1 ,principles of        
,nutrition      and ,nutritive ,value of
 ,food1 ,u4 ,s4 ,department of          
,agriculture1 #aijb4  ,the ,relation of 
,work to ,diet4--,it has been shown     
experimentally that a man doing hard1   
muscular work needs more food than a    
person doing light work4 ,the mere      
exercise gives the individual a hearty  
appetite2 he eats more and needs more of
 all kinds of food than a man or boy    
doing light work4 ,especially is it true
 that the person of sedentary habits1   
who does brain work1 should be careful  
to eat less food and food that will     

digest easily4 ,his protein food should 
also be reduced4 ,rich or hearty foods  
may be left for the man who is doing    
hard manual labor out of doors1 for any 
extra work put on the digestive organs  
takes away just so much from the ability
 of the brain to do its work4           
,illustration3 ,foods of plant origin4  
,select #e foods containing a high      
percentage of protein1 #e with a high   
percentage of carbohydrates1 #e with a  
high percentage of water4 ,do vegetable 
foods contain much fat8 ,which of the   
above-mentioned foods have the highest  
burning value8  ,illustration3 ,foods   
largely of animal origin4 ,compare with 
the previous chart with reference to    
amount of protein1 carbohydrate1 and fat
 in foods4 ,compare the burning value of
 plant and animal foods4 ,compare the   
relative percentage of water in both    
kinds of foods4  ,illustration3 ,the    
composition of milk4  ,the ,relation of 
,environment to ,diet4--,we are all     
aware of the fact that the body seems to

 crave more food in winter than in      
summer4 ,the temperature of the body is 
maintained at #ih4f deg4 in winter as in
 summer1 but much more heat is lost from
 the body in cold weather4 ,hence       
feeding in winter should be for the     
purpose of maintaining our fuel supply4 
,we need heat-producing food1 and we    
need more food in winter than in summer4
 ,we may use carbohydrates for this     
purpose1 as they are economical and     
digestible4 ,the inhabitants of cold    
countries get their heat-releasing foods
 largely from fats4 ,in tropical        
countries and in hot weather little     
protein should be eaten and a           
considerable amount of fresh fruit used4
  ,the ,relation of ,age to ,diet4--,as 
we will see a little later1 age is a    
factor not only in determining the kind 
but the amount of food to be used4      
,young children require far less food   
than do those of older growth or adults4
 ,the body constantly increases in      
weight until young manhood1 or          

womanhood1 then its weight remains      
nearly stationary1 varying with health  
or illness4 ,it is evident that food in 
adults simply repairs the waste of cells
 and is used to supply energy4 ,elderly 
people need much less protein than do   
younger persons4 ,but inasmuch as the   
amount of food to be taken into the body
 should be in proportion to the body    
weight1 it is also evident that growing 
children do not1 as is popularly        
supposed1 need as much food as          
grown-ups4  ,the ,relation of ,sex to   
,diet4--,as a rule boys need more food  
than girls1 and men than women4 ,this   
seems to be due to1 first1 the more     
active muscular life of the man and1    
secondly1 to the greater amount of fat  
in the tissues of the woman1 making loss
 of heat less4 ,larger bodies1 because  
of greater surface1 give off more heat  
than smaller ones4 ,men are usually     
larger in bulk than are women1--another 
reason for more food in their case4     
,the ,relation of ,digestibility to     

,diet4--,animal foods in general may be 
said to be more completely digested     
within the body than plant foods4 ,this 
is largely due to the fact that plant   
cells have woody walls that the         
digestive juices cannot act upon4       
,cereals and legumes are less digestible
 foods than are dairy products1 meat1 or
 fish4 ,this does not mean necessarily  
that these foods would not agree with   
you or me but that in general the body  
would get less nourishment out of the   
total amount available4  ,the agreement 
or disagreement of food with an         
individual is largely a personal matter4
 ,i1 for example1 cannot eat raw        
tomatoes without suffering from         
indigestion1 while some one else can    
digest tomatoes but not strawberries4   
,each individual should learn early in  
life the foods that disagree with him   
personally and leave such foods out of  
his dietary4 ,for what is one man's meat
 may be another man's poison4  ,the     
,relation of ,cost of ,food to          

,diet4--,it is a mistaken notion that   
the best foods are always the most      
expensive4 ,a glance at the table 7page 
#bhc7 will show us that both fuel value 
and tissue-building value is present in 
some foods from vegetable sources1 as   
well as in those from animal sources1   
and that the vegetable foods are much   
cheaper4 ,the ,american people are far  
less economical in their purchase of    
food than most other nations4 ,nearly   
one half of the total income of the     
average workingman is spent on food4    
,not only does he spend a large amount  
on food1 but he wastes money in         
purchasing the wrong kinds of food4 ,a  
comparison of the daily diets of persons
 in various occupations in this and     
other countries shows that as a rule we 
eat more than is necessary to supply the
 necessary fuel and repair1 and that our
 workingmen eat more than those of other
 countries4 ,another waste of money by  
the ,american is in the false notion    
that a large proportion of the daily    

dietary should be meat4 ,many people    
think that the most expensive cuts of   
meat are the most nutritious4 ,the      
falsity of this idea may be seen by a   
careful study of the tables on pages    
#bhc and #bhf4  ,the ,best              
,dietary4--,inasmuch as all living      
substance contains nitrogen1 it is      
evident that protein food must form a   
part of the dietary2 but protein alone  
is not usable4 ,if more protein is eaten
 than the body requires1 then           
immediately the liver and kidneys have  
to work overtime to get rid of the      
excess of protein which forms a         
poisonous waste harmful to the body4 ,we
 must take foods that will give us1 as  
nearly as possible1 the proportion of   
the different chemical elements as they 
are contained in protoplasm4 ,it has    
been found1 as a result of studies of   
,atwater and others1 that a man who does
 muscular work requires a little less   
than one quarter of a pound of protein1 
the same amount of fat1 and about one   

pound of carbohydrate to provide for the
 growth1 waste1 and repair of the body  
and the energy used up in one day4  ,the
 ,daily ,calorie ,requirement4--,put in 
another way1 ,atwater's standard for a  
man at light exercise is food enough to 
yield #bhaf ,calories2 of these1 #daj   
,calories are from protein1 #icj        
,calories from fat1 and #adgf ,calories 
from carbohydrate4 ,that is1 for every  
#ajj ,calories furnished by the food1   
#ad are from protein1 #cb from fat1 and 
#ed from carbohydrate4 ,in exact        
numbers1 the day's ration as advocated  
by ,atwater would contain about #ajj    
grams or #c4g ounces protein1 #ajj grams
 or #c4g ounces fat1 and #cfj grams or  
#ac ounces carbohydrate4 ,professor     
,chittenden of ,yale ,university1       
another food expert1 thinks we need     
proteins1 fats1 and carbohydrates in    
about the proportion of #a to #c to #f1 
thus differing from ,atwater in giving  
less protein in proportion4             
,chittenden's standard for the same man 

is food to yield a total of #bcfj       
,calories1 of which protein furnishes   
#bcf ,calories1 fat #gjh ,calories1 and 
carbohydrates #adaf ,calories4 ,for     
every #ajj ,calories furnished by the   
food1 #aj are from protein1 #cj from    
fat1 #fj from carbohydrate4 ,in actual  
amount the ,chittenden diet would       
contain #b4af ounces protein1 #b4hc     
ounces fat1 and #ac ounces carbohydrate4
 ,a ,german named ,voit gives as ideal  
#be ,calories from proteins1 #bj from   
fat1 and #ee from carbohydrate1 out of  
every #ajj ,calories2 this is nearer our
 actual daily ration4 ,in addition1 an  
ounce of salt and nearly one hundred    
ounces of water are used in a day4      
,illustration3 ,table showing the cost  
of various foods4 ,using this table1    
make up an economical dietary for one   
day1 three meals1 for a man doing       
moderate work4 ,give reasons for the    
amount of food used and for your choice 
of foods4 ,make up another dietary in   
the same manner1 using expensive foods4 

,what is the difference in your bill for
 the day8  ,a ,mixed ,diet              
,best4--,knowing the proportion of the  
different food substances required by   
man1 it will be an easy matter to       
determine from the tables and charts    
shown you the best foods for use in a   
mixed diet4 ,meats contain too much     
nitrogen in proportion to the other     
substances4 ,in milk1 the proportion of 
proteins1 carbohydrates1 and fats is    
nearly right to make protoplasm2 a      
considerable amount of mineral matter   
being also present4 ,for these reasons1 
milk is extensively used as a food for  
children1 as it combines food material  
for the forming of protoplasm with      
mineral matter for the building of bone4
 ,some vegetables 7for example1 peas and
 beans7 contain a large amount of       
nitrogenous material but in a less      
digestible form than is found in some   
other foods4 ,vegetarians1 then1 are    
correct in theory when they state that a
 diet of vegetables may contain         

everything necessary to sustain life4   
,but a mixed diet containing meat is    
healthier4 ,a purely vegetable diet     
contains much waste material1 such as   
the cellulose forming the walls of plant
 cells1 which is indigestible4 ,it has  
been recently discovered that the outer 
coats of some grains1 as rice1 contain  
certain substances 7enzymes7 which aid  
in digestion4 ,in the case of polished  
rice1 when this outer coat is removed   
the grain has much less food value4     
,daily ,fuel ,needs of the ,body4--,it  
has been pointed out that the daily diet
 should differ widely according to age1 
occupation1 time of year1 etc4 ,the     
following table shows the daily fuel    
needs for several ages and              
occupations3--            ,,daily       
,,calorie ,,needs 7,,approximately7     
#a4 ,for child under #b years           
#ijj ,calories    #b4 ,for child from   
#b-e years                        #abjj 
,calories    #c4 ,for child from #f-i   
years                        #aejj      

,calories    #d4 ,for child from #aj-ab 
years                      #ahjj        
,calories    #e4 ,for child from #ab-ad 
7woman1 light work1 also7  #bajj        
,calories    #f4 ,for boy 7#ab-ad71 girl
 7#ae-af71 man1 sedentary   #bdjj       
,calories    #g4 ,for boy 7#ae-af7 7man1
 light muscular work7      #bgjj        
,calories    #h4 ,for man1 moderately   
active muscular work        #cjjj       
,calories    #i4 ,for farmer 7busy      
season7                #cbjj to #djjj   
,calories   #aj4 ,for ditchers1         
excavators1 etc4          #djjj to #ejjj
 ,calories   #aa4 ,for lumbermen1 etc4  
#ejjj and more ,calories  ,normal ,heat 
,output4--,the following table gives the
 result of some experiments made to     
determine the hourly and daily          
expenditure of energy of the average    
normal grown person when asleep and     
awake1 at work or at rest3--            
,,average ,,normal ,,output ,,of ,,heat 
,,from ,,the ,,body                     
,,average       ,,conditions ,,of       

,,muscular ,,activity                   
,,calories                              
,,per ,,hour                            
----------------------------------------
-----------------   ,man at rest1       
sleeping                        #fe     
,calories   ,man at rest1 awake1 sitting
 up              #ajj ,calories   ,man  
at light muscular exercise              
#agj ,calories   ,man at moderately     
active muscular exercise  #bij ,calories
   ,man at severe muscular exercise     
#dej ,calories   ,man at very severe    
muscular exercise        #fjj ,calories 
,it is very simple to use such a table  
in calculating the number of ,calories  
which are spent in twenty-four hours    
under different bodily conditions4 ,for 
example1 suppose the case of a clerk or 
school teacher leading a relatively     
inactive life1 who    sleeps for #i     
hours                   x  #fe ,calories
  #ehe   works at desk #i hours         
x #ajj ,calories  #ijj   reads1 writes1 
or studies #d hours    x #ajj ,calories 

#djj   walks or does light exercise #b  
hours x #agj ,calories  #cdj            
----                                    
#bbbe  ,this comes out1 as we see1 very 
close to example #f of the table#ci on  
page #bhd4       ,footnote #ci3 ,the    
above tables have been taken from the   
excellent pamphlet of the ,cornell      
,reading ,course1 ,no4 #f1      ,human  
,nutrition4  ,how we may ,find whether  
we are ,eating a properly ,balanced     
,diet4--,we already know approximately  
our daily ,calorie needs and about the  
proportion of protein1 fat1 and         
carbohydrate needed4 ,dr4 ,irving       
,fisher of ,yale ,university has worked 
out a very easy method of determining   
whether one is living on a proper diet4 
,he has made up a number of tables1 in  
which he has designated portions of     
food1 each of which furnishes #ajj      
,calories of energy4 ,the tables show   
the proportion of protein1 fat1 and     
carbohydrate in each food1 so that it is
 a simple matter by using such a table  

to estimate the proportions of the      
various nutrients in our dietary4 ,we   
may depend upon taking somewhere near   
the proper amount of food if we take a  
diet based upon either ,atwater's1      
,chittenden's1 or ,voit's standard4 ,one
 of the most interesting and useful     
pieces of home work that you can do is  
to estimate your own personal dietary1  
using the tables giving the             
#ajj-;,calorie portion to see if you    
have a properly balanced diet4 ,from the
 table on page #bhf make out a simple   
dietary for yourself for one day1       
estimating your own needs in ,calories  
and then picking out #ajj-;,calorie     
portions of food which will give you the
 proper proportions of protein1 fat1 and
 carbohydrate4            ,,table ,,of  
#ajj ,,calorie ,,portions--,,modified   
,,from ,,fisher                         
,,wt4 ,,in ,,cal4 ,,furnished           
,,price                                 
,,oz4 ---------------------------       
,,port4 ,,containing    #ajj            

,,car-          #ajj         ,,food     
#ajj ,,calories      ,,cal4,,pro-       
,,fat,,bohy-  #a ,,lb4  ,,cal4          
,,port4,,tein    ,,drate         ,,por4 
----------------------------------------
-----------------------------   ,oysters
           #a doz4             #f4h     
#di #bb    #bi   4#age   4#jg   ,bean   
soup         #a_/b small serving  #b4f  
#bd #ab    #fd          4#jjg   ,cream  
of corn     #b_/c ordin4 serv4   #c4a   
#aa #eh    #ca          4#jb            
,vegetable soup    #a_/b ordin4 serv4   
#b4d    #h #hi     #c          4#ja     
,cod fish 7fresh7  ordin4 serv4       #e
     #ie  #e     #j   4#ab    4#jd      
,salmon 7canned7   small serv4          
#a4ge  #de #ee     #j   4#bb    4#jc    
,chicken           #a_/b large serv4    
#a4ge  #ci #ef     #e   4#bb    4#je    
,veal cutlet       #b_/c large serv4    
#b4d   #ed #df     #j   4#bh    4#jde   
,beef1 corned      #a_/b large serv4    
#a4j   #ae #he     #j   4#af    4#ja    
,beef1 sirloin       small serv4        

#a4f   #cc #fg     #j   4#cd    4#jd    
,beef1 round         small serv4        
#a4h   #ci #fa     #j   4#bd    4#jbe   
,ham1 lean           ordin4 serv4       
#a4a   #bh #gb     #j   4#bb    4#jae   
,lamb chops        #a_/b ordin4 serv4   
#a4j   #bd #gf     #j   4#bj    4#jac   
,mutton1 leg         ordin4 serv4       
#a4b   #ce #fe     #j   4#bj    4#jae   
,eggs1 boiled      #a large egg         
#b4a   #cb #fh     #j 4#cj doz4 4#jbe   
,eggs1 scrambled   #a-a_/c ordin4 serv4 
#b4e   #cg #eh     #e 4#cj doz4 4#jc    
,beans1 baked        side dish          
#b4ff  #ba #ah    #fa   4#jh    4#jac   
,potatoes1 mashed    ordin4 serv4       
#c4b   #aj #be    #fe   4#jb    4#jje   
,macaroni          #a_/c large serv4    
4#ie  #ae  #c    #hb   4#aj    4#ja     
,potato salad        ordin4 serv4       
#b4be  #aj #eg    #cc   4#bj    4#jbe   
,tomatoes1 sliced  #d large serv4       
#ae4    #ae #af    #fi   4#aj    4#aj   
,rolls1 plain      #a large roll        
#a4b   #ab  #g    #ha 4#aj doz4 4#ja    

,butter              ordin4 pat         
4#dd   #e #ii4e       4#ce    4#ja      
,wheat bread       #a small slice       
4#if  #ae  #e    #hj   4#jg    4#jje    
,chocolate cake    #a_/b ord4 sq4 piece 
4#ih   #g #bb    #ga   4#cb    4#jb     
,gingerbread       #a_/b ord4 sq4 piece 
4#if   #f #bc    #ga   4#af    4#ja     
,custard pudding     ordin4 serv4       
#c4be  #ah #db    #dj   4#ae    4#jc    
,rice pudding        very small serv4   
#b4fe   #h #ac    #gi   4#ac    4#jb    
,apple pie         #a_/c piece          
#a4c    #e #cb    #fc          4#jac    
,cheese1 ,american  #a-a_/b cu4 in4     
4#gg  #be #gc     #b   4#ai    4#ja     
,crackers 7soda7   #b crackers          
4#i   #aj #bj    #gj   4#aj    4#jjg    
,currant jelly     #b heap4 spoons      
#a4a    #b  #j    #ih   4#dj    4#jbe   
,sugar             #c teaspoons         
4#hf   #j  #j   #ajj   4#jf    4#jjc    
,milk as bought      small glass        
#d4i   #ai #eb    #bi   4#je    4#jae   
,milk1 cond41 sweet#d teaspoons         

#a4jf  #aj #bc    #fg          4#ja     
,oranges           #a large one         
#i4d    #f  #c    #ia          4#jbe    
,peanuts           #ac double ones      
4#fb  #bj #fc    #ag          4#jjd     
,almonds1 shelled  #h-ae                
4#ec  #ac #gg    #aj          4#jbe     
,from the preceding table plan a        
well-balanced and cheap dietary for one 
day for a family of five1 two adults and
 three children4 ,make a second dietary 
for the same time and same number of    
people which shall give approximately   
the same amount of tissue and energy    
producing food from more expensive      
materials4  ,food ,waste in the         
,kitchen4--,much loss occurs in the     
improper cooking of foods4 ,meats       
especially1 when overdone1 lose much of 
their flavor and are far less easily    
digested than when they are cooked rare4
 ,the chief reasons for cooking meats   
are that the muscle fibers may be       
loosened and softened1 and that the     
bacteria or other parasites in the meat 

may be killed by the heat4 ,the common  
method of frying makes foods less       
digestible4 ,stewing is an economical as
 well as healthful method4 ,a good way  
to prepare meat1 either for stew or     
soup1 is to place the meat1 cut in small
 pieces1 in cold water1 and allow it to 
simmer for several hours4 ,rapid boiling
 toughens the muscle fibers by the too  
rapid coagulation of the albuminous     
matter in them1 just as the white of egg
 becomes tough when boiled too long4    
,boiling and roasting are excellent     
methods of cooking meat4 ,in order to   
prevent the loss of the nutrients in    
roasting1 it is well to baste the meat  
frequently2 thus a crust is formed on   
the outer surface of the meat1 which    
prevents the escape of the juices from  
the inside4  ,vegetables are cooked in  
order that the cells containing starch  
grains may be burst open1 thus allowing 
the starch to be more easily attacked by
 the digestive fluids4 ,inasmuch as     
water may dissolve out nutrients from   

vegetable tissues1 it is best to boil   
them rapidly in a small amount of water4
 ,this gives less time for the solvent  
action to take place4 ,vegetables should
 be cooked with the outer skin left on  
when it is possible4  ,adulterations in 
,foods4--,the addition of some cheaper  
substance to a food1 or the subtraction 
of some valuable substance from a food1 
with the view to cheating the purchaser1
 is known as adulteration4 ,many foods  
which are artificially manufactured have
 been adulterated to such an extent as  
to be almost unfit for food1 or even    
harmful4 ,one of the commonest          
adulterations is the substitution of    
grape sugar 7glucose7 for cane sugar4   
,glucose1 however1 is not a harmful     
adulterant4 ,it is used largely in candy
 making4 ,flour and other cereal foods  
are sometimes adulterated with some     
cheap substitutes1 as bran or sawdust4  
,alum is sometimes added to make flour  
whiter4 ,probably the food which suffers
 most from adulteration is milk1 as     

water can be added without the average  
person being the wiser4 ,by means of an 
inexpensive instrument known as a       
lactometer1 this cheat may easily be    
detected4 ,in most cities1 the milk     
supply is carefully safeguarded1 because
 of the danger of spreading typhoid     
fever from impure milk 7see ,chapter    
,,xx74 ,before the pure food law was    
passed in #aijf1 milk was frequently    
adulterated with substances like        
formalin to make it keep sweet longer4  
,such preservatives are harmful1 and it 
is now against the law to add anything  
whatever to milk4  ,coffee1 cocoa1 and  
spices are subject to great             
adulteration2 cottonseed oil is often   
substituted for olive oil2 butter is too
 frequently artificial2 while honey1    
sirups of various kinds1 cider and      
vinegar1 have all been found to be      
either artificially made from cheaper   
substitutes or to contain such          
substitutes4  ,pure ,food               
,laws4--,thanks to the ,national ,pure  

,food and ,drug ,law passed by ,congress
 in #aijf1 and to the activity of       
various city and state boards of health1
 the opportunity to pass adulterated    
foods on the public is greatly lessened4
 ,this law compels manufacturers of     
foods or medicines to state the         
composition of their products on the    
labels placed on the jars or bottles4   
,so if a person reads the label he can  
determine exactly what he is getting for
 his money4  ,impure ,water4--,great    
danger comes from drinking impure water4
 ,this subject has already been         
discussed under ,bacteria1 where it was 
seen that the spread of typhoid fever in
 particular is due to a contaminated    
water supply4 ,as citizens1 we must aid 
all legislation that will safeguard the 
water used by our towns and cities4     
,boiling water for ten minutes or longer
 will render it safe from all organic   
impurities4  ,stimulants4--,we have     
learned that food is anything that      
supplies building material or releases  

energy in the body2 but some materials  
used by man1 presumably as food1 do not 
come under this head4 ,such are tea and 
coffee4 ,when taken in moderate         
quantities1 they produce a temporary    
increase in the vital activities of the 
person taking them4 ,this is said to be 
a stimulation2 and material taken into  
the digestive tract1 producing this1 is 
called a stimulant4 ,in moderation1 tea 
and coffee appear to be harmless4 ,some 
people1 however1 cannot use either      
without ill effects1 even in small      
quantity4 ,it is the habit formed of    
relying upon the stimulus given by tea  
or coffee that makes them a danger to   
man4 ,cocoa and chocolate1 although both
 contain a stimulant1 are in addition   
good foods1 having from #ab per cent to 
#ba per cent of protein1 from #bi per   
cent to #dh per cent fat1 and over #cj  
per cent carbohydrate in their          
composition4  ,is ,alcohol a            
,food8--,the question of the use of     
alcohol has been of late years a matter 

of absorbing interest and importance    
among physiologists4 ,a few years ago   
,dr4 ,atwater performed a series of very
 careful experiments by means of the    
respiration calorimeter1 to ascertain   
whether alcohol is of use to the body as
 food4#dj ,in these experiments the     
subjects were given1 instead of their   
daily allotment of carbohydrates and    
fats1 enough alcohol to supply the same 
amount of energy that these foods would 
have given4 ,the amount was calculated  
to be about two and one half ounces per 
day1 about as much as would be contained
 in a bottle of light wine4#da ,this    
alcohol was administered in small doses 
six times during the day4 ,professor    
,atwater's results may be summed up     
briefly as follows3--  #a4 ,the alcohol 
administered was almost all oxidized in 
the body4  #b4 ,the potential energy in 
the alcohol was transformed into heat or
 muscular work4  #c4 ,the body did about
 as well with the rations including     
alcohol as it did without it4           

,footnote #dj3 ,alcohol is made up of   
carbon1 oxygen1 and      hydrogen4 ,it  
is very easily oxidized1 but it cannot1 
as is      shown by the chemical        
formula1 be of use to the body in       
tissue building1 because of its lack of 
nitrogen4       ,footnote #da3          
,alcoholic beverages contain the        
following      proportions of alcohol3  
beer1 from #b to #e per cent2 wine1     
from #aj to #bj per cent2 liquors1 from 
#cj to #gj per cent4      ,patent       
medicines frequently contain as high as 
#fj per cent      alcohol4 7,see page   
#bid47  ,the committee of fifty eminent 
men appointed to report on the          
physiological aspects of the drink      
problem reported that a large number of 
scientific men state that they are in   
the habit of taking alcoholic liquor in 
small quantities1 and many report that  
they do not feel harm thereby4 ,a number
 of scientists seem to agree that within
 limits alcohol may be a kind of food1  
although a very poor food4  ,on the     

other hand1 we know that although       
alcohol may technically be considered as
 a food1 it is a very unsatisfactory    
food and1 as the following statements   
show1 it has an effect on the body      
tissues which foods do not have4        
,professor ,chittenden of ,yale         
,college1 in discussing the food problem
 of alcohol1 writes as follows3         
,it is true that alcohol in moderate    
quantities may serve as a food1         
i4e4 it can be oxidized with the        
liberation of heat4 ,it may to some     
extent take the place of fat and        
carbohydrates1 but it is not a          
perfect substitute for them1 and for    
this reason alcohol has an action       
that cannot be ignored4 ,it reduces     
liver oxidation4 ,it therefore          
presents a dangerous side wholly wanting
 in carbohydrates and fat4 ,the         
latter are simply burned up to carbonic 
acid and water or are      transformed  
to glycogen and fat1 but alcohol1       
although more easily      oxidized1 is  

at all times liable to obstruct1 in a   
measure at least1      the oxidative    
processes of the liver and probably of  
other tissues      also1 thereby        
throwing into the circulation bodies1   
such as uric acid1      which are       
harmful to health1 a fact which at once 
tends to draw a      distinct line of   
demarcation between alcohol and the two 
non-nitrogenous foods1 fat and          
carbohydrates4 ,another matter must be  
emphasized1 and it is that the form in  
which alcohol is taken is of            
importance4 ,port wine1 for instance1   
has more influence on the amount      of
 uric acid secreted than an equivalent  
amount of alcohol has in some      other
 form4 ,to conclude3 as an adjunct to   
the ordinary daily diet of      the     
healthy man alcohol cannot be considered
 as playing the part of a      true     
non-nitrogenous food4--,quoted in       
,american ,journal of      ,inebriety1  
,winter1 #aijf4  ,effect of ,alcohol on 
,living ,matter4--,if we examine raw    

white of egg1 we find a protein which   
closely resembles protoplasm in its     
chemical composition2 it is called      
albumen4 ,add to a little albumen in a  
test tube some #ie per cent alcohol and 
notice what happens4 ,as soon as the    
alcohol touches the albumen the latter  
coagulates and becomes hard like boiled 
white of egg4 ,shake the alcohol with   
the albumen and the entire mass soon    
becomes a solid4 ,this is because the   
alcohol draws the water out of the      
albumen4 ,it has been shown that albumen
 is somewhat like protoplasm in         
structure and chemical composition4     
,strong alcohol acts in a similar manner
 on living matter when it is absorbed by
 the living body cells4 ,it draws water 
from them and hardens them4 ,it has a   
chemical and physical action upon living
 matter4  ,alcohol a ,poison4--,but     
alcohol is also in certain quantities a 
poison4 ,a commonly accepted definition 
of a poison is that it is any substance 
which1 when taken into the body1 tends  

to cause serious detriment to health1 or
 the death of the organism4 ,that       
alcohol may do this is well known by    
scientists4  ,it is a matter of common  
knowledge that alcohol taken in small   
quantities does not do any apparent     
harm4 ,but if we examine the vital      
records of life insurance companies1 we 
find a large number of deaths directly  
due to alcohol and a still greater      
number due in part to its use4 ,in the  
,united ,states every year there are a  
third more deaths from alcoholism and   
cirrhosis of the liver 7a disease       
directly caused by alcohol7 than there  
are from typhoid fever4 ,the poisonous  
effect is not found in small doses1 but 
it ultimately shows its harmful effect4 
,hardening of the arteries1 an old-age  
disease1 is rapidly becoming in this    
country a disease of the middle aged4   
,from it there is no escape4 ,it is     
chiefly caused by the cumulative effect 
of alcohol4 ,the diagram following1     
compiled by two ,english life insurance 

companies that insure moderate drinkers 
and abstainers1 shows the death rate to 
be considerably higher among those who  
use alcohol4  ,illustration3 ,abstainers
 live longer than moderate drinkers4    
,dr4 ,kellogg1 the founder of the famous
 ,battle ,creek ,sanitarium1 points out 
that strychnine1 quinine1 and many other
 drugs are oxidized in the body but     
surely cannot be called foods4 ,the     
following reasons for not considering   
alcohol a food are taken from his       
writings3--       #a4 ,a habitual user  
of alcohol has an intense craving for   
his accustomed dram4 ,without it he is  
entirely unfitted for      business4    
,one never experiences such an insane   
craving for      bread1 potatoes1 or any
 other particular article of food4      
#b4 ,by continuous use the body acquires
 a tolerance for      alcohol4 ,that is1
 the amount which may be imbibed and the
      amount required to produce the    
characteristic effects first            
experienced gradually increase until    

very great quantities      are sometimes
 required to satisfy the craving which  
its      habitual use often produces4   
,this is never the case with      true  
foods4444 ,alcohol behaves in this      
regard just as does      opium or any   
other drug4 ,it has no resemblance to a 
food4       #c4 ,when alcohol is        
withdrawn from a person who has been    
accustomed to its daily use1 most       
distressing effects are                 
experienced4444 ,who ever saw a man's   
hand trembling or his      nervous      
system unstrung because he could not get
 a potato or      a piece of cornbread  
for breakfast8 ,in this respect1 also1  
alcohol behaves like opium1 cocaine1 or 
any other enslaving      drug4       #d4
 ,alcohol lessens the appreciation and  
the value of brain      and nerve       
activity1 while food reenforces nervous 
and mental      energy4       #e4       
,alcohol as a protoplasmic poison       
lessens muscular power1      whereas    
food increases energy and endurance4    

#f4 ,alcohol lessens the power to endure
 cold4 ,this is true      to such a     
marked degree that its use by persons   
accompanying      ,arctic expeditions is
 absolutely prohibited4 ,food1 on the   
other hand1 increases ability to endure 
cold4 ,the      temperature after taking
 food is raised4 ,after taking          
alcohol1 the temperature1 as shown by   
the thermometer1 is      lowered4       
#g4 ,alcohol cannot be stored in the    
body for future use1      whereas all   
food substances can be so stored4       
#h4 ,food burns slowly in the body1 as  
it is required to      satisfy the      
body's needs4 ,alcohol is readily       
oxidized and      eliminated1 the same  
as any other oxidizable drug4           
,illustration3 ,experiment 7by ,davison7
 to show how the nicotine in six        
cigarettes was sufficient to kill this  
fish4 ,the smoke from the cigarettes was
 passed through the water in which the  
fish is swimming4  ,the ,use of         
,tobacco4--,a well-known authority      

defines a narcotic as a substance which 
directly induces sleep1 blunts the      
senses1 and1 in large amounts1 produces 
complete insensibility4 ,tobacco1 opium1
 chloral1 and cocaine are examples of   
narcotics4 ,tobacco owes its narcotic   
influence to a strong poison known as   
nicotine4 ,its use in killing insect    
parasites on plants is well known4 ,in  
experiments with jellyfish and other    
lowly organized animals1 the author has 
found as small a per cent as one part of
 nicotine to one hundred thousand parts 
of sea water to be sufficient to        
profoundly affect an animal placed      
within it4 ,the illustration here given 
shows the effect of nicotine upon a     
fish1 one of the vertebrate animals4    
,nicotine in a pure form is so powerful 
a poison that two or three drops would  
be sufficient to cause the death of a   
man by its action upon the nervous      
system1 especially the nerves           
controlling the beating of the heart4   
,this action is well known among boys   

training for athletic contests4 ,the    
heart is affected2 boys become          
short-winded as a result of the action  
on the heart4 ,it has been demonstrated 
that tobacco has1 too1 an important     
effect on muscular development4 ,the    
stunted appearance of the young smoker  
is well known4  ,illustration3 ,the     
amounts of alcohol in some liquors and  
in some patent medicines4 a1 beer1 #e 2 
b1 claret1 #h 2 c1 champagne1 #i 2 d1   
whisky1 #ej 2 e1 well-known             
sarsaparilla1 #ah 2 f1 g1 h1            
much-advertised nerve tonics1 #bj 1 #ba 
1 #be 2 i1 another much-advertised      
sarsaparilla1 #bg 2 j1 a well-known     
tonic1 #bh 2 k1 l1 bitters1 #cg 1 #dd   
alcohol4  ,use and ,abuse of            
,drugs4--,the ,american people are      
addicted to the use of drugs1 and       
especially patent medicines4 ,a glance  
at the street-car advertisements shows  
this4 ,most of the medicines advertised 
contain alcohol in greater quantity than
 beer or wine1 and many of them have    

opium1 morphine1 or cocaine in their    
composition4 ,paregoric and laudanum1   
medicines sometimes given to young      
children1 are examples of dangerous     
drugs that contain opium4 ,dr4 ,george  
,d4 ,haggard of ,minneapolis has shown  
by many analyses that a large number of 
the so-called malts1 malt extracts1 and 
tonics1 including several of the best   
known and most advertised on the market1
 are simply disguised beers and1        
frequently1 very poor beers at that4    
,these drugs1 in addition to being      
harmful1 affect the person using them in
 such a manner that he soon feels the   
need for the drug4 ,thus the drug habit 
is formed1--a condition which has       
wrecked thousands of lives4 ,a number of
 articles on patent medicines recently  
appeared in a leading magazine and have 
been collected and published under the  
title of ,the ,great ,american ,fraud4  
,in this booklet the author points out a
 number of different kinds of cures and 
patent medicines4 ,the most dangerous   

are those headache or neuralgia cures   
containing acetanilid4 ,this drug is a  
heart depresser and should not be used  
without medical advice4 ,another drug   
which is responsible for habit formation
 is cocaine4 ,this is often found in    
catarrh or other cures4 ,alcohol is the 
basis of all tonics or bracers4 ,every  
boy and girl should read this booklet so
 as to be forearmed against evils of the
 sort just described4                   
,,reference ,,reading ,,on ,,foods      
,hunter1 ,laboratory ,problems in ,civic
 ,biology4 ,american ,book     ,company4
   ,allen1 ,civics and ,health4 ,ginn   
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numbers #bc1 #cd1 #db1 #he1 #ic1 #aba1  
#abh1 #acb1     #adb1 #ahb1 #bdi1 #bie1 
#bih4   ,reprint from ,yearbook1 #aija1 
,atwater1 ,dietaries in ,public         
,institutions4   ,reprint from          
,yearbook1 #aijb1 ,milner1 ,cost of     
,food related to     its ,nutritive     
,value4   ,experiment ,station1         
,circular #df1 ,langworthy1 ,functions  

and     ,uses of ,food4     ,,xx4       
,,digestion ,,and ,,absorption          
,problems4--,to determine where         
digestion takes place by examining3--   
7a7 ,the functions of glands4           
-7b7 ,the work done in the mouth4       
-7c7 ,the work done in the stomach4     
-7d7 ,the work done in the small        
intestine4           -7e7 ,the function 
of the liver4          ,to discover the 
absorbing apparatus and how it is used4 
,,laboratory ,,suggestions              
,demonstration of food tube of man      
7manikin74--,comparison        with food
 tube of frog4 ,drawing 7comparative7 of
 food tube        and digestive glands  
of frog and man4      ,demonstration of 
simple gland4--7,microscopic            
preparation47      ,home experiment and 
laboratory demonstration4--,the         
digestion of starch by saliva4          
,conditions favorable and               
unfavorable4      ,demonstration        
experiment4--,the digestion of proteins 
with        artificial gastric juice4   

,conditions favorable and               
unfavorable4      ,demonstration4--,an  
emulsion as seen under the compound     
microscope4                             
,demonstration4--,emulsification of fats
 with artificial        pancreatic      
fluid4 ,digestion of starch and protein 
with        artificial pancreatic fluid4
      ,demonstration of tripe to show   
increase of surface of        digestive 
tube4      ,laboratory or home          
exercise4--,make a table showing the    
changes produced upon food substances by
 each digestive        fluid1 the       
reaction 7acid or alkaline7 of the      
fluid1 when        the fluid acts1 and  
what results from its action4   ,purpose
 of ,digestion4--,we have learned that  
starch and protein food of plants are   
formed in the leaves4 ,a plant1 however1
 is unable to make use of the food in   
this condition4 ,before it can be       
transported from one part of the plant  
body to another1 it is changed into a   
soluble form4 ,in this state it can be  

passed from cell to cell by the process 
of osmosis4 ,much the same condition    
exists in animals4 ,in order that food  
may be of use to man1 it must be changed
 into a state that will allow of its    
passage in a soluble form through the   
walls of the alimentary canal1 or food  
tube4 ,this is done by the enzymes which
 cause digestion4 ,it will be the       
purpose of this chapter to discover     
where and how digestion takes place in  
our own body4  ,alimentary ,canal4--,in 
all vertebrate animals1 including man1  
food is taken in the mouth and passed   
through a food tube in which it is      
digested4 ,this tube is composed of     
different portions1 named1 respectively1
 as we pass from the mouth downward1 the
 gullet1 stomach1 small and large       
intestine1 and rectum4  ,illustration3  
,the digestive tract of the frog and    
man4 ,gul1 gullet2 ,s1 stomach2 ,l1     
liver2 ,g1 gall bladder2 ,p1 pancreas2  
,sp1 spleen2 ,,si1 small intestine2     
,,li1 large intestine2 ,v1 appendix2 ,a1

 anus4  ,comparison of ,food ,tube of a 
,frog and ,man4--,if we compare the food
 tube of a dissected frog with the food 
tube of man 7as shown by a manikin or   
chart71 we find part for part they are  
much the same4 ,but we notice that the  
intestines of man1 both small and large1
 are relatively longer than in the frog4
 ,we also notice in man the body cavity 
or space in which the internal organs   
rest is divided in two parts by a wall  
of muscle1 the diaphragm1 which         
separates the heart and lungs from the  
other internal organs4 ,in the frog no  
muscular diaphragm exists4 ,in the frog 
we can see plainly the silvery          
transparent mesentery or double fold of 
the lining of the body cavity in which  
the organs of digestion are suspended4  
,numerous blood vessels can be found    
especially in the walls of the food     
tube4  ,glands4--,in addition to the    
alimentary canal proper1 we find a      
number of digestive glands1 varying in  
size and position1 connected with the   

canal4  ,illustration3 ,diagram of a    
gland4 i1 the common tube which carries 
off the secretions formed in the cells  
lining the cavity c2 a1 arteries        
carrying blood to the glands2 v1 veins  
taking blood away from the glands4      
,what a ,gland ,does4 ,enzymes4--,in man
 there are the saliva gland of the      
mouth1 the gastric glands of the        
stomach1 the pancreas and liver1 the two
 latter connected with the small        
intestine1 and the intestinal glands in 
the walls of the intestine4 ,besides    
glands which aid in digestion there are 
several others of which we will speak   
later4 ,as we have already learned1 a   
gland is a collection of cells which    
takes up material from within the body  
and manufactures from it something which
 is later poured out as a secretion4 ,an
 example of a gland in plants is found  
in the nectar-secreting cells of a      
flower4  ,certain substances1 called    
enzymes1 formed by glands cause the     
digestion of food4 ,the enzymes secreted

 by the cells of the glands and poured  
out into the food tube act upon         
insoluble foods so as to change them to 
a soluble form4 ,they are the product of
 the activity of the cell1 although they
 are not themselves alive4 ,we do not   
know much about enzymes themselves1 but 
we can observe what they do4 ,some      
enzymes render soluble different foods1 
others work in the blood1 still others  
probably act within any cell of the body
 as an aid to oxidation1 when work is   
done4 ,enzymes are very sensitive to    
changes in temperature and to the degree
 of acidity or alkalinity#db of the     
material in which they act4 ,we will    
find that the enzymes found in glands in
 the mouth will not act long in the     
stomach because of the change from an   
alkaline surrounding in the mouth to    
that of an acid in the stomach4 ,enzymes
 seem to be able to work indefinitely1  
providing the surroundings are          
favorable4 ,a small amount of digestive 
fluid1 if it had long enough to work1   

could therefore digest an indefinite    
amount of food4       ,footnote #db3    
,the teacher should explain the meaning 
of these      terms4  ,gland            
,structure4--,the entire inner surface  
of the food tube is covered with a soft 
lining of mucous membrane4 ,this is     
always moist because certain cells1     
called mucus cells1 empty out their     
contents into the food tube1 thus       
lubricating its inner surface4 ,when a  
large number of cells which have the    
power to secrete fluids are collected   
together1 the surface of the food tube  
may become indented at this point to    
form a pitlike gland4 ,often such       
depressions are branched1 thus giving a 
greater secreting surface1 as is seen in
 the figure on page #bih4 ,the cells of 
the gland are always supplied with blood
 vessels and nerves1 for the secretions 
of the glands are under the control of  
the nervous system4  ,how a ,gland      
,secretes4--,we must therefore imagine  
that as the blood goes to the cells of a

 gland it there loses some substances   
which the gland cells take out and make 
over into the particular enzyme that    
they are called upon to manufacture4    
,under certain conditions1 such as the  
sight or smell of food1 or even the     
desire for it1 the activity of the gland
 is stimulated4 ,it then pours out its  
secretion containing the digestive      
enzyme4 ,thus a gland does its work4    
,salivary ,glands4--,we are all familiar
 with the substance called saliva which 
acts as a lubricant in the mouth4       
,saliva is manufactured in the cells of 
three pairs of glands which empty into  
the mouth1 and which are called1        
according to their position1 the parotid
 7beside the ear71 the submaxillary     
7under the jawbone71 and the sublingual 
7under the tongue74  ,illustration3     
,experiment showing non-osmosis of      
starch in tube ,a1 and osmosis of sugar 
in tube ,b4  ,digestion of ,starch4--,if
 we collect some saliva in a test tube1 
add to it a little starch paste1 place  

the tube containing the mixture for a   
few minutes in tepid water1 and then    
test with ,fehling's solution1 we shall 
find grape sugar present4 ,careful tests
 of the starch paste and of the saliva  
made separately will usually show no    
grape sugar in either4  ,if another test
 be made for grape sugar1 in a test tube
 containing starch paste1 saliva1 and a 
few drops of any weak acid1 the starch  
will be found not to have changed4 ,the 
digestion or change of starch to grape  
sugar is caused by the presence in the  
saliva of an enzyme1 or digestive       
ferment4 ,you will remember that starch 
in the growing corn grain was changed to
 grape sugar by an enzyme called        
diastase4 ,here a similar action is     
caused by an enzyme called ptyalin4     
,this ferment acts only in an alkaline  
medium at about the temperature of the  
body4  ,illustration3 ,the mouth cavity 
of man4 e1 ,eustachian tube2 hp1 hard   
palate2 sp1 soft palate2 ut1 upper      
teeth2 bc1 buccal cavity2 lt1 lower     

teeth2 t1 tongue2 ph1 pharynx2 ep1      
epiglottis2 lx1 voice box2 oe1 gullet2  
tr1 trachea4  ,mouth ,cavity in         
,man4--,in our study of a frog we find  
that the mouth cavity has two unpaired  
and four paired tubes leading from it4  
,these are 7a7 the gullet or food tube1 
7b7 the windpipe 7in the frog opening   
through the glottis71 7c7 the paired    
nostril holes 7posterior nares71 7d7 the
 paired ,eustachian tubes1 leading to   
the ear4 ,all of these openings are     
found in man4  ,in man the mouth cavity1
 and all internal surfaces of the food  
tube1 are lined with a mucous membrane4 
,the mucus secreted from gland cells in 
this lining makes a slippery surface so 
that the food may slip down easily4 ,the
 roof of the mouth is formed in front by
 a plate of bone called the hard palate1
 and a softer continuation to the back  
of the mouth1 the soft palate4 ,these   
separate the nose cavity from that of   
the mouth proper4 ,the part of the space
 back of the soft palate is called the  

pharynx1 or throat cavity4 ,from the    
pharynx lead off the gullet and         
windpipe1 the former back of the latter4
 ,the lower part of the mouth cavity is 
occupied by a muscular tongue4          
,examination of its surface with a      
looking-glass shows it to be almost     
covered in places by tiny projections   
called papillae4 ,these papillae contain
 organs known as taste buds1 the sensory
 endings of which determine the taste of
 substances4 ,the tongue is used in     
moving food about in the mouth1 and in  
starting it on its way to the gullet2 it
 also plays an important part in        
speaking4  ,illustration3 ,i4 ,teeth of 
the upper jaw1 from below4 #a1 #b1      
incisors2 #c1 canine2 #d1 #e1 premolars2
 #f1 #g1 #h1 molars4 ,,ii4 longitudinal 
section of a tooth4 ,e1 enamel2 ,d1     
dentine2 ,c1 cement2 ,p1 pulp cavity4   
,the ,teeth4--,in man the teeth1 unlike 
those of the frog1 are used in the      
mechanical preparation of the food for  
digestion4 ,instead of holding prey1    

they crush1 grind1 or tear food so that 
more surface may be given for the action
 of the digestive fluids4 ,the teeth of 
man are divided1 according to their     
functions1 into four groups4 ,in the    
center of both the upper and lower jaw  
in front are found eight teeth with     
chisel-like edges1 four in each jaw2    
these are the incisors1 or cutting      
teeth4 ,next is found a single tooth on 
each side 7four in all72 these have     
rather sharp points and are called the  
canines4 ,then come two teeth on each   
side1 eight in all1 called premolars4   
,lastly1 the flat-top molars1 or        
grinding teeth1 of which there are six  
in each jaw4 ,food is caught between    
irregular projections on the surface of 
the molars and crushed to a pulpy mass4 
,hygiene of the ,mouth4--,food should   
simply be chewed and relished1 with no  
thought of swallowing4 ,there should be 
no more effort to prevent than to force 
swallowing4 ,it will be found that if   
you attend only to the agreeable task of

 extracting the flavors of your food1   
,nature will take care of the           
swallowing1 and this will become1 like  
breathing1 involuntary4 ,the instinct by
 which most people eat is perverted     
through the hurry habit and the use of  
abnormal foods4 ,thorough mastication   
takes time1 and therefore one must not  
feel hurried at meals if the best       
results are to be secured4 ,the stopping
 point for eating should be at the      
earliest moment after one is really     
satisfied4  ,care of the ,teeth4--,it   
has been recently found that fruit acids
 are very beneficial to the teeth4      
,vinegar diluted to about half strength 
with water makes an excellent dental    
wash4 ,clean your teeth carefully each  
morning and before going to bed4 ,use   
dental silk after meals4 ,we must       
remember that the bacteria which cause  
decay of the teeth are washed down into 
the stomach and may do even more harm   
there than in the mouth4  ,how ,food is 
,swallowed4--,after food has been chewed

 and mixed with saliva1 it is rolled    
into little balls and pushed by the     
tongue into such position that the      
muscles of the throat cavity may seize  
it and force it downward4 ,food1 in     
order to reach the gullet from the mouth
 cavity1 must pass over the opening into
 the windpipe4 ,when food is in the     
course of being swallowed1 the upper    
part of this tube forms a trapdoor over 
the opening4 ,when this trapdoor is not 
closed1 and food goes down the wrong    
way1 we choke1 and the food is expelled 
by coughing4  ,illustration3            
,peristaltic waves on the gullet of man4
 7,a bolus means little ball47  ,the    
,gullet1 or ,esophagus4--,like the rest 
of the food tube the gullet is lined by 
soft and moist mucous membrane4 ,the    
wall is made up of two sets of          
muscles1--the inside ones running around
 the tube2 the outer layer of muscle    
taking a longitudinal course4 ,after    
food leaves the mouth cavity1 it gets   
beyond our direct control1 and the      

muscles of the gullet1 stimulated to    
activity by the presence of food in the 
tube1 push the food down to the stomach 
by a series of contractions until it    
reaches the stomach4 ,these wavelike    
movements 7called peristaltic movements7
 are characteristic of other parts of   
the food tube1 food being pushed along  
in the stomach and the small intestine  
by a series of slow-moving muscular     
waves4 ,peristaltic movement is caused  
by muscles which are not under voluntary
 nervous control1 although anger1 fear1 
or other unpleasant emotions have the   
effect of slowing them up or even       
stopping them entirely4  ,stomach of    
,man4--,the stomach is a pear-shaped    
organ capable of holding about three    
pints4 ,the end opposite to the gullet1 
which empties into the small intestine1 
is provided with a ring of muscle       
forming a valve called the pylorus4     
,there is also another ring of muscle   
guarding the entrance to the stomach4   
,gastric ,glands4--,if we open the      

stomach of the frog1 and remove its     
contents by carefully washing1 its wall 
is seen to be thrown into folds         
internally4 ,between the folds in the   
stomach of man1 as well as in the frog1 
are located a number of tiny pits4      
,these form the mouths of the gastric   
glands1 which pour into the stomach a   
secretion known as the gastric juice4   
,the gastric glands are little tubes1   
the lining of which secretes the fluid4 
,when we think of or see appetizing     
food1 this secretion is given out in    
considerable quantity4 ,the stomach1    
like the mouth1 waters at the sight of  
food4 ,gastric juice is slightly acid in
 its chemical reaction1 containing about
 4#b per cent free hydrochloric acid4   
,it also contains two very important    
enzymes1 one called pepsin1 and another 
less important one called rennin4       
,action of ,gastric ,juice4--,if protein
 is treated with artificial gastric     
juice at the temperature of the body1 it
 will be found to become swollen and    

then gradually to change to a substance 
which is soluble in water4 ,this is like
 the action of the gastric juice upon   
proteins in the stomach4  ,the other    
enzyme of gastric juice1 called rennin1 
curdles or coagulates a protein found in
 milk2 after the milk is curdled1 the   
pepsin is able to act upon it4 ,junket  
tablets1 which contain rennin1 are used 
in the kitchen to cause this change4    
,illustration3 ,a peptic gland1 from the
 stomach1 very much magnified4 ,a1      
central or chief cell1 which makes      
pepsin2 ,b1 border cells1 which make    
acid4 7,from ,miller's ,histology47     
,the hydrochloric acid found in the     
gastric juice acts upon lime and some   
other salts taken into the stomach with 
food1 changing them so that they may    
pass into the blood and eventually form 
the mineral part of bone or other       
tissue4 ,the acid also has a decided    
antiseptic influence in preventing      
growth of bacteria which cause decay1   
and some of which might cause disease4  

,movement of ,walls of ,stomach4--,the  
stomach walls1 provided with three      
layers of muscle which run in an        
oblique1 circular1 and longitudinal     
direction 7taken from the inside        
outward71 are well fitted for the       
constant churning of the food in that   
organ4 ,here1 as elsewhere in the       
digestive tract1 the muscles are        
involuntary1 muscular action being under
 the control of the so-called           
sympathetic nervous system4 ,food       
material in the stomach makes several   
complete circuits during the process of 
digestion in that organ4 ,contrary to   
common belief1 the greatest amount of   
food is digested after it leaves the    
stomach4 ,but this organ keeps the food 
in it in almost constant motion for a   
considerable time1 a meal of meat and   
vegetables remaining in the stomach for 
three or four hours4 ,while movement is 
taking place1 the gastric juice acts    
upon proteins1 softening them1 while the
 constant churning movement tends to    

separate the bits of food into finer    
particles4 ,ultimately the semifluid    
food1 much of it still undigested1 is   
allowed to pass in small amounts through
 the pyloric valve1 into the small      
intestine4 ,this is allowed by the      
relaxation of the ringlike muscles of   
the pylorus4  ,experiments on ,digestion
 in the ,stomach4--,some very           
interesting experiments have recently   
been made by ,professor ,cannon of      
,harvard with reference to movements of 
the stomach contents4 ,cats were fed    
with material having in it bismuth1 a   
harmless chemical that would be visible 
under the ,x-ray4 ,it was found that    
shortly after food reached the stomach a
 series of waves began which sent the   
food toward the pyloric end of the      
stomach4 ,if the cat was feeling happy  
and well1 these contractions continued  
regularly1 but if the cat was cross or  
bad tempered1 the movements would stop4 
,this shows the importance of           
cheerfulness at meals4 ,other           

experiments showed that food which was  
churned into a soft mass was only       
permitted to leave the stomach when it  
became thoroughly permeated by the      
gastric juice4 ,it is the acid in the   
partly digested food that causes the    
stomach valve to open and allow its     
contents to escape little by little into
 the small intestine4  ,the partly      
digested food in the small intestine    
almost immediately comes in contact with
 fluids from two glands1 the liver and  
pancreas4 ,we shall first consider the  
function of the pancreas4  ,position and
 ,structure of the ,pancreas4--,the most
 important digestive gland in the human 
body is the pancreas4 ,the gland is a   
rather diffuse structure2 its duct      
empties by a common opening with the    
bile duct into the small intestine1 a   
short distance below the pylorus4 ,in   
internal structure1 the pancreas        
resembles the salivary glands4          
,illustration3 ,appearance of milk under
 the microscope1 showing the natural    

grouping of the fat globules4 ,in the   
circle a single group is highly         
magnified4 ,milk is one form of an      
emulsion4 7,s4 ,m4 ,babcock1 ,wis4 ,bul4
 ,no4 #fa47  ,work done by the          
,pancreas4--,starch paste added to      
artificial pancreatic fluid and kept at 
blood heat is soon changed to sugar4    
,protein1 under the same conditions1 is 
changed to a peptone4 ,fats1 which so   
far have been unchanged except to be    
melted by the heat of the body1 are     
changed by the action of the pancreas   
into a form which can pass through the  
walls of the food tube4 ,if we test     
pancreatic fluid1 we find it strongly   
alkaline in its reaction4 ,if two test  
tubes1 one containing olive oil and     
water1 the other olive oil and a weak   
solution of caustic soda1 an alkali1 be 
shaken violently and then allowed to    
stand1 the oil and water will quickly   
separate1 while the oil1 caustic soda1  
and water will remain for some time in a
 milky emulsion4 ,if this emulsion be   

examined under the microscope1 it will  
be found to be made of millions of      
little droplets of fat1 floating in the 
liquid4 ,the presence of the caustic    
soda helped the forming of the emulsion4
 ,pancreatic fluid similarly emulsifies 
fats and changes them into soft soaps   
and fatty acids4 ,fat in this form may  
be absorbed4 ,the process of this       
transformation is not well understood4  
,conditions under which the ,pancreas   
does its ,work4--,the secretion from    
this gland seems to be influenced by the
 overflow of acid material from the     
stomach4 ,this acid1 on striking the    
lining of the small intestine1 causes   
the formation in its walls of a         
substance known as secretin4 ,this      
secretin reaches the blood and seems to 
stimulate all the glands pouring fluid  
into the intestine to do more work4 ,a  
pint or more of pancreatic fluid is     
secreted every day4  ,the ,intestinal   
,fluid4--,three different pancreatic    
enzymes do the work of digestion1 one   

acting on starch1 another on protein1   
and a third on fats4 ,it has been found 
that some of these enzymes will not do  
their work unless aided by the          
intestinal fluid1 a secretion formed in 
glands in the walls of the small        
intestine4 ,this fluid1 though not much 
is known about it1 is believed to play  
an important part in the digestion of   
all kinds of foods left undigested in   
the small intestine4  ,liver4--,the     
liver is the largest gland in the body4 
,in man1 it hangs just below the        
diaphragm1 a little to the right side of
 the body4 ,during life1 its color is   
deep red4 ,it is divided into three     
lobes1 between two of which is found the
 gall bladder1 a thin-walled sac which  
holds the bile1 a secretion of the      
liver4 ,bile is a strongly alkaline     
fluid of greenish color4 ,it reaches the
 intestine through the same opening as  
the pancreatic fluid4 ,almost one quart 
of bile is passed daily into the        
digestive canal4 ,the color of bile is  

due to certain waste substances which   
come from the destruction of worn-out   
red corpuscles of the blood4 ,this      
destruction takes place in the liver4   
,illustration3 ,diagram of a bit of the 
wall of the small intestine1 greatly    
magnified1 a1 mouths of intestinal      
glands2 b1 villus cut lengthwise to show
 blood vessels and lacteal 7in center72 
e1 lacteal sending branches to other    
villi2 i1 intestinal glands2 m1 artery2 
v1 vein2 l1 t1 muscular coats of        
intestine wall4  ,functions of          
,bile4--,the action of bile is not very 
well known4 ,it has the very important  
faculty of aiding the pancreatic fluid  
in digestion1 though alone it has slight
 if any digestive power4 ,certain       
substances in the bile aid especially in
 the absorption of fats4 ,bile seems to 
be mostly a waste product from the blood
 and as such incidentally serves to keep
 the contents of the intestine in a more
 or less soft condition1 thus preventing
 extreme constipation4  ,the ,liver a   

,storehouse4--,perhaps the most         
important function of the liver is the  
formation within it of a material called
 glycogen1 or animal starch4 ,the liver 
is supplied by blood from two sources4  
,the greater amount of blood received by
 the liver comes directly from the walls
 of the stomach and intestine to this   
organ4 ,it normally contains about one  
fifth of all the blood in the body4     
,this blood is very rich in food        
materials1 and from it the cells of the 
liver take out sugars to form           
glycogen4#dc ,glycogen is stored in the 
liver until such a time as a food is    
needed that can be quickly oxidized2    
then it is changed to sugar and carried 
off by the blood to the tissue which    
requires it1 and there used for this    
purpose4 ,glycogen is also stored in the
 muscles1 where it is oxidized to       
release energy when the muscles are     
exercised4       ,footnote #dc3 ,it is  
known that glycogen may be formed in    
the body from protein1 and possibly from

 fatty foods4  ,the ,absorption of      
,digested ,food into the ,blood4--,the  
object of digestion is to change foods  
from an insoluble to a soluble form4    
,this has been seen in the study of the 
action of the various digestive fluids  
in the body1 each of which is seen to   
aid in dissolving solid foods1 changing 
them to a fluid1 and1 in case of the    
bile1 actually assisting them to pass   
through the wall of the intestine4 ,a   
small amount of digested food may be    
absorbed by the blood in the blood      
vessels of the walls of the stomach4    
,most of the absorption1 however1 takes 
place through the walls of the small    
intestine4  ,structure of the ,small    
,intestine4--,the small intestine in man
 is a slender tube nearly twenty feet in
 length and about one inch in diameter4 
,if the chief function of the small     
intestine is that of absorption1 we must
 look for adaptations which increase the
 absorbing surface of the tube4 ,this is
 gained in part by the inner surface of 

the tube being thrown into transverse   
folds which not only retard the rapidity
 with which food passes down the        
intestine1 but also give more absorbing 
surface4 ,but far more important for    
absorption are millions of little       
projections which cover the inner       
surface of the small intestine4  ,the   
,villi4--,so numerous are these         
projections that the whole surface      
presents a velvety appearance4          
,collectively1 these structures are     
called the villi 7singular villus74     
,they form the chief organs of          
absorption in the intestine1 several    
thousand being distributed over every   
square inch of surface4 ,by means of the
 folds and villi the small intestine is 
estimated to have an absorbing surface  
equal to twice that of the surface of   
the body4 ,between the villi are found  
the openings of the intestinal glands4  
,internal ,structure of a ,villus4--,the
 internal structure of a villus is best 
seen in a longitudinal section4 ,we find

 the outer wall made up of a thin layer 
of cells1 the epithelial layer4 ,it is  
the duty of these cells to absorb the   
semifluid food from within the          
intestine4 ,underneath these cells lies 
a network of very tiny blood vessels1   
while inside of these1 occupying the    
core of the villus1 are found spaces    
which1 because of their white appearance
 after absorption of fats1 have been    
called lacteals4 7,see figure1 page     
#cjg47  ,illustration3 ,diagram to show 
how the nutrients reach the blood4      
,absorption of ,foods4--,let us now     
attempt to find out exactly how foods   
are passed from the intestines into the 
blood4 ,food substances in solution may 
be soaked up as a sponge would take up  
water1 or they may pass by osmosis into 
the cells lining the villus4 ,these     
cells break down the peptones into a    
substance that will pass into and become
 part of the blood4 ,once within the    
villus1 the sugars and digested proteins
 pass through tiny blood vessels into   

the larger vessels comprising the portal
 circulation4 ,these pass through the   
liver1 where1 as we have seen1 sugar is 
taken from the blood and stored as      
glycogen4 ,from the liver1 the food     
within the blood is sent to the heart1  
from there is pumped to the lungs1 from 
there returns to the heart1 and is      
pumped to the tissues of the body4 ,a   
large amount of water and some salts are
 also absorbed through the walls of the 
stomach and intestine as the food passes
 on its course4 ,the fats in the form of
 soaps and fatty acids pass into the    
space in the center of the villus4      
,later they are changed into fats again1
 probably in certain groups of gland    
cells known as mesenteric glands1 and   
eventually reach the blood by way of the
 thoracic duct without passing through  
the liver4  ,large ,intestine4--,the    
large intestine has somewhat the same   
structure as the small intestine1 except
 that it lacks the villi and has a      
greater diameter4 ,considerable         

absorption1 however1 takes place through
 its walls as the mass of food and      
refuse material is slowly pushed along  
by the muscles within its walls4        
,vermiform ,appendix4--,at the point    
where the small intestine widens to form
 the large intestine1 a baglike pouch is
 formed4 ,from one side of this pouch is
 given off a small tube about four      
inches long1 closed at the lower end4   
,this tube1 the rudiment of what is an  
important part of the food tube in the  
lower vertebrates1 is called the        
vermiform appendix4 ,it has come to have
 unpleasant notoriety in late years1 as 
the site of serious inflammation4       
,constipation4--,in the large intestine 
live millions of bacteria1 some of which
 make and give off poisonous substances 
known as toxins4 ,these substances are  
easily absorbed through the walls of the
 large intestine1 and1 when they pass   
into the blood1 cause headaches or      
sometimes serious trouble4 ,hence it    
follows that the lower bowel should be  

emptied of this matter as frequently as 
possible1 at least once a day4          
,constipation is one of the most serious
 evils the ,american people have to deal
 with1 and it is largely brought about  
by the artificial life which we lead1   
with its lack of exercise1 fresh air1   
and sleep4 ,fruit with meals1 especially
 at breakfast1 plenty of water between  
meals and before breakfast1 exercise1   
particularly of the abdominal muscles1  
and regular habits will all help to     
correct this evil4  ,hygienic ,habits of
 ,eating2 the ,causes and ,prevention of
 ,dyspepsia4--,from the contents of the 
foregoing chapter it is evident that the
 object of the process of digestion is  
to break up solid food so that it may be
 absorbed to form part of the blood4    
,any habits we may form of thoroughly   
chewing our food will evidently aid in  
this process4 ,undoubtedly much of the  
distress known as dyspepsia is due to   
too hasty meals with consequent lack of 
proper mastication of food4 ,the message

 of ,mr4 ,horace ,fletcher in bringing  
before us the need of proper mastication
 of food and the attendant evils of     
overeating is one which we cannot afford
 to ignore4 ,it is a good rule to go    
away from the table feeling a little    
hungry4 ,eating too much overtaxes the  
digestive organs and prevents their     
working to the best advantage4 ,still   
another cause of dyspepsia is eating    
when in a fatigued condition4 ,it is    
always a good plan to rest a short time 
before eating1 especially after any hard
 manual work4 ,we have seen how great a 
part unpleasant emotions play in        
preventing peristaltic movements of the 
food tube4 ,conversely1 pleasant        
conversation1 laughter1 and fun will    
help you to digest your meal4 ,eating   
between meals is condemned by physicians
 because it calls the blood to the      
digestive organs at a time when it      
should be more active in other parts of 
the body4  ,effect of ,alcohol on       
,digestion4--,it is a well-known fact   

that alcohol extracts water from tissues
 with which it is in contact4 ,this fact
 works much harm to the interior surface
 of the food tube1 especially the walls 
of the stomach1 which in the case of a  
hard drinker are likely to become       
irritated and much toughened4 ,in very  
small amounts alcohol stimulates the    
secretion of the salivary and gastric   
glands1 and thus appears to aid in      
digestion4  ,the following results of   
experiments on dogs1 published in the   
,american ,journal of ,physiology1 ,vol4
 ,i1 ,professor ,chittenden of ,yale    
,university gives as strictly           
comparable1 because they were carried   
out in succession on the same day4 ,they
 show that alcohol retards rather than  
aids in digestion3--         ,,number   
,,of ,,experiment  #a_/af ,,lb4 ,,meat  
,,with ,,water #a_/af ,,lb4 ,,meat      
,,with                                  
,,dilute ,,alcohol                      
----------------------------------------
--------------------------------        

,,xvii  alpha #i3ae ,a4,m4  ,digested in
 #c hours       ,,xvii  beta #c3jj      
,p4,m4                                  
,digested in #c3ae hours   ,,xviii alpha
 #h3cj ,a4,m4  ,digested in #b3cj hours 
,,xviii beta #b3aj ,p4,m4               
,digested in #c3jj hours   ,,xix   alpha
 #i3jj ,a4,m4  ,digested in #b3cj hours 
,,xix   beta #b3cj ,p4,m4               
,digested in #c3jj hours   ,,xx    alpha
 #i3ae ,a4,m4                           
,digested in #b3de hours   ,,xx    beta 
#b3cj ,p4,m4   ,digested in #b3ae hours 
,,vi    alpha #i3ae ,a4,m4              
,digested in #c3de hours   ,,vi    beta 
#a3jj ,p4,m4   ,digested in #c3ae hours 
----------------------------------------
--------------------------------        
,average                        #b3db   
hours              #c3ji hours          
----------------------------------------
--------------------------------  ,as a 
result of his experiments1 ,professor   
,chittenden remarks3 ,we believe that   
the results obtained justify the        

conclusion that gastric digestion as a  
whole is not materially modified by the 
introduction of alcoholic fluids with   
the food4 ,in other words1 the          
unquestionable acceleration of gastric  
secretion which follows the ingestion of
 alcoholic beverages is1 as a rule1     
counterbalanced by the inhibitory effect
 of the alcoholic fluids upon the       
chemical process of gastric digestion1  
with perhaps at times a tendency towards
 preponderance of inhibitory action4    
,others have come to the same or        
stronger conclusions as to the          
undesirable action of alcohol on        
digestion1 as a result of their own     
experiments4  ,effect of ,alcohol on the
 ,liver4--,the effect of heavy drinking 
upon the liver is graphically shown in  
the following table prepared by the     
,scientific ,temperance ,federation of  
,boston1 ,mass43--  ,illustration3      
,proportion of deaths from disease in a 
certain area due to alcohol4 ,the black 
area shows deaths due to alcohol4#dd    

,footnote #dd3 ,does not include deaths 
from general alcoholic      paralysis or
 other organic diseases due to alcohol4 
,liver      cirrhosis due to alcohol    
conservatively estimated at #ge per     
cent of total cases4       ,alcoholic   
indulgence stands almost if not         
altogether in the      front rank of the
 enemies to be combated in the battle   
for      health4--,,professor ,,william 
,t4 ,,sedgwick4     ,,xxi4 ,,the ,,blood
 ,,and ,,its ,,circulation              
,problems4--,to discover the composition
 and uses of the different parts of     
the blood4            ,to find out the  
means by which the blood is circulated  
about the               body4           
,,laboratory ,,suggestions              
,demonstration4--,structure of blood1   
fresh frog's blood and        human     
blood4 ,drawings4                       
,demonstration4--,clotting of blood4    
,demonstration4--,use of models to      
demonstrate that the        heart is a  
force pump4                             

,demonstration4--,capillary circulation 
in web of frog's        foot or         
tadpole's tail4 ,drawing4      ,home or 
laboratory exercise4--,on relation of   
exercise on        rate of heart beat4  
,function of the ,blood4--,the chief    
function of the digestive tract is to   
change foods to such form that they can 
be absorbed through the walls of the    
food tube and become part of the        
blood4#de       ,footnote #de3 ,this    
change is due to the action of certain  
enzymes upon the nutrients in various   
foods4 ,but we also      find that      
peptones are changed back again to      
proteins when      once in the blood4   
,this appears to be due to the          
reversible action of the enzymes acting 
upon them4 7,see      page #cjg47  ,if  
we examine under the microscope a drop  
of blood taken from the frog or man1 we 
find it made up of a fluid called plasma
 and two kinds of bodies1 the so-called 
red corpuscles and colorless corpuscles1
 floating in this plasma4  ,composition 

of ,plasma4--,the plasma of blood is    
found to be largely 7about #ij per cent7
 water4 ,it also contains a considerable
 amount of protein1 some sugar1 fat1 and
 mineral material4 ,it is1 then1 the    
medium which holds the fluid food that  
has been absorbed from within the       
intestine4 ,this food is pumped to the  
body cells where1 as work is performed1 
oxidation takes place and heat is given 
off as a form of energy4 ,the almost    
constant temperature of the body is also
 due to the blood1 which brings to the  
surface of the body much of the heat    
given off by oxidation of food in the   
muscles and other tissues4 ,when the    
blood returns from the tissues where the
 food is oxidized1 the plasma brings    
back with it to the lungs part of the   
carbon dioxide liberated where oxidation
 has taken place4 ,some waste products1 
to be spoken of later1 are also found in
 the plasma4  ,illustration3 ,human     
blood as seen under the high power of   
the compound microscope2 at the extreme 

right is a colorless corpuscle4  ,the   
,red ,blood ,corpuscle2 its ,structure  
and ,functions4--,the red corpuscle in  
the blood of the frog is a true cell of 
disklike form1 containing a nucleus4    
,the red corpuscle of man is made in the
 red marrow of bones and in its young   
stages has a nucleus4 ,in its adult     
form1 however1 it lacks a nucleus4 ,its 
form is that of a biconcave disk4 ,so   
small and so numerous are these         
corpuscles that over five million are   
found in a cubic centimeter of normal   
blood4 ,they make up almost one half the
 total volume of the blood4 ,the color1 
which is found to be a dirty yellow when
 separate corpuscles are viewed under   
the microscope1 is due to a protein     
material called haemoglobin4            
,haemoglobin contains a large amount of 
iron4 ,it has the power of uniting very 
readily with oxygen whenever that gas is
 abundant1 and1 after having absorbed   
it1 of giving it up to the surrounding  
media1 when oxygen is there present in  

smaller amounts than in the corpuscle4  
,this function of carrying oxygen is the
 most important function of the red     
corpuscle1 although the red corpuscle   
also removes part of the carbon dioxide 
from the tissues on their return to the 
lungs4 ,the taking up of oxygen is      
accompanied by a change in color of the 
mass of corpuscles from a dull red to a 
bright scarlet4  ,clotting of           
,blood4--,if fresh beef blood is allowed
 to stand overnight1 it will be found to
 have separated into two parts1 a dark  
red1 almost solid clot and a thin1      
straw-colored liquid called serum4      
,serum is found to be made up of about  
#ij per cent water1 #h per cent protein1
 #a per cent other organic foods1 and #a
 per cent mineral substances4 ,in these 
respects it very closely resembles the  
fluid food that is absorbed from the    
intestines4  ,if another jar of fresh   
beef blood is poured into a pan and     
briskly whipped with a bundle of little 
rods 7or with an egg beater71 a stringy 

substance will be found to stick to the 
rods4 ,this1 if washed carefully1 is    
seen to be almost colorless4 ,tested    
with nitric acid and ammonia1 it is     
found to contain a protein substance    
which is called fibrin4  ,blood plasma1 
then1 is made up of a fluid portion of  
serum1 and fibrin1 which1 although in a 
fluid state in the blood vessels within 
the body1 coagulates when blood is      
removed from the blood vessels4 ,this   
coagulation aids in making a blood clot4
 ,a clot is simply a mass of fibrin     
threads with a large number of          
corpuscles tangled within4 ,the clotting
 of blood is of great physiological     
importance1 for otherwise we might bleed
 to death even from a small wound4      
,blood ,plates4--,in blood within the   
circulatory system of the body1 the     
fibrin is held in a fluid state called  
fibrinogen4 ,an enzyme1 acting upon this
 fibrinogen1 the soluble protein in the 
blood1 causes it to change to an        
insoluble form1 the fibrin of the clot4 

,this change seems to be due to the     
action of minute bodies in the blood    
known as blood plates4 ,under abnormal  
conditions these blood plates break     
down1 releasing some substances which   
eventually cause this enzyme to do its  
work4  ,illustration3 ,a small artery   
7,a7 breaking up into capillaries 7c7   
which unite to form a vein 7,v74 ,note  
at 7,p7 several colorless corpuscles1   
which are fighting bacteria at that     
point4  ,the ,colorless ,corpuscle2     
,structure and ,functions4--,a colorless
 corpuscle is a cell irregular in       
outline1 the shape of which is          
constantly changing4 ,these corpuscles  
are somewhat larger than the red        
corpuscles1 but less numerous1 there    
being about one colorless corpuscle to  
every three hundred red ones4 ,they have
 the power of movement1 for they are    
found not only inside but outside the   
blood vessels1 showing that they have   
worked their way between the cells that 
form the walls of the blood tubes4      

,illustration3 ,a colorless corpuscle   
catching and eating germs4  ,a ,russian 
zoologist1 ,metchnikoff1 after studying 
a number of simple animals1 such as     
medusae and sponges1 found that in such 
animals some of the cells lining the    
inside of the food cavity take up or    
engulf minute bits of food4 ,later1 this
 food is changed into the protoplasm of 
the cell4 ,metchnikoff believed that the
 colorless corpuscles of the blood have 
somewhat the same function4 ,this he    
later proved to be true4 ,like the      
amoeba1 they feed by engulfing their    
prey4 ,this fact has a very important   
bearing on the relation of colorless    
corpuscles to certain diseases caused by
 bacteria within the body4 ,if1 for     
example1 a cut becomes infected by      
bacteria1 inflammation may set in4      
,colorless corpuscles at once surround  
the spot and attack the bacteria which  
cause the inflammation4 ,if the bacteria
 are few in number1 they are quickly    
eaten by certain of the colorless       

corpuscles1 which are known as          
phagocytes4 ,if bacteria are present in 
great quantities1 they may prevail and  
kill the phagocytes by poisoning them4  
,the dead bodies of the phagocytes thus 
killed are found in the pus1 or matter1 
which accumulates in infected wounds4   
,in such an event1 we must come to the  
aid of nature by washing the wound with 
some antiseptic1 as weak carbolic acid  
or hydrogen peroxide4  ,antibodies and  
their ,uses4--,in case of disease where1
 for example1 fever is caused by poison 
given off from bacteria we find the     
cells of the body manufacture and pour  
into the blood a substance known as an  
antibody4 ,this substance does not of   
necessity kill the harmful germs or even
 stop their growth4 ,it does1 however1  
unite with the toxin or poison given off
 by the germs and renders it entirely   
harmless4  ,function of ,lymph4--,the   
tissues and organs of the body are      
traversed by a network of tubes which   
carry the blood4 ,inside these tubes is 

the blood proper1 consisting of a fluid 
plasma1 the colorless corpuscles1 and   
the red corpuscles4 ,outside the blood  
tubes1 in spaces between the cells which
 form tissues1 is found another fluid1  
which is in chemical composition very   
much like plasma of the blood4 ,this is 
the lymph4 ,it is1 in fact1 fluid food  
in which some colorless amoeboid        
corpuscles are found4 ,blood gives up   
its food material to the lymph4 ,this it
 does by passing it through the walls of
 the capillaries4 ,the food is in turn  
given up to the tissue cells1 which are 
bathed by the lymph4  ,illustration3    
,the exchange between blood and the     
cells of the body4  ,some of the        
amoeboid corpuscles from the blood make 
their way between the cells forming the 
walls of the capillaries4 ,lymph1 then1 
is practically blood plasma plus some   
colorless corpuscles4 ,it acts as the   
medium of exchange between the blood    
proper and the cells in the tissues of  
the body4 ,by means of the food supply  

thus brought1 the cells of the body are 
able to grow1 the fluid food being      
changed to the protoplasm of the cells4 
,by means of the oxygen passed over by  
the lymph1 oxidation may take place     
within the cells4 ,lymph not only gives 
food to the cells of the body1 but also 
takes away carbon dioxide and other     
waste materials1 which are ultimately   
passed out of the body by means of the  
lungs1 skin1 and kidneys4  ,internal    
,secretions4--,in addition to all the   
functions given above1 the blood has    
recently been shown to carry the        
secretions of a number of glands through
 which it passes1 although these glands 
have no ducts to carry off their        
secretions4 ,these internal secretions  
seem absolutely necessary for the health
 of the body4 ,several glands1 the      
thyroid1 adrenal bodies1 the testes1 and
 ovaries1 as well as the pancreas1 give 
off these remarkable substances4  ,the  
,amount of ,blood and its               
,distribution4--,blood forms1 by weight1

 about one sixteenth of the body4 ,this 
would be about four quarts to a body    
weight of #acj pounds4 ,normally1 about 
one half of the blood of the body is    
found in or near the organs lying in the
 body cavity below the diaphragm1 about 
one fourth in the muscles1 and the rest 
in the head1 heart1 lungs1 large        
arteries1 and veins4  ,blood            
,temperature4--,the temperature of blood
 in the human body is normally about    
#ih4f deg4 ,fahrenheit when tested under
 the tongue by a thermometer1 although  
the temperature drops almost two degrees
 after we have gone to sleep at night4  
,it is highest about #e ,p4,m4 and      
lowest about #d ,a4,m4 ,in fevers1 the  
temperature of the body sometimes rises 
to #ajg deg42 but unless this           
temperature is soon reduced1 death      
follows4 ,any considerable drop in      
temperature below the normal also means 
death4 ,body heat results from the      
oxidation of food1 and the circulation  
of blood keeps the temperature nearly   

uniform in all parts of the body4       
,cold-blooded ,animals4--,in animals    
which are called cold-blooded1 the blood
 has no fixed temperature1 but varies   
with the temperature of the medium in   
which the animal lives4 ,frogs1 in the  
summer1 may sit for hours in water with 
a temperature of almost #ajj deg4 ,in   
winter1 they often endure freezing so   
that the blood and lymph within the     
spaces under the loose skin are frozen  
into ice crystals4 ,this change in body 
temperature is evidently an adaptation  
to the mode of life4  ,circulation of   
the ,blood in ,man4--,the blood is the  
carrying agent of the body4 ,like a     
railroad or express company1 it takes   
materials from one part of the human    
organism to another4 ,this it does by   
means of the organs of circulation1--the
 heart and blood vessels4 ,these blood  
vessels are called arteries where they  
carry blood away from the heart1 veins  
where they bring blood back to the      
heart1 and capillaries where they       

connect the larger blood vessels4 ,the  
organs of circulation thus form a system
 of connected tubes through which the   
blood flows4  ,the ,heart2 ,position1   
,size1 ,protection4--,the heart is a    
cone-shaped muscular organ about the    
size of a man's fist4 ,it is located    
immediately above the diaphragm1 and    
lies so that the muscular apex1 which   
points downward1 moves while beating    
against the fifth and sixth ribs1 just a
 little to the left of the midline of   
the body4 ,this fact gives rise to the  
notion that the heart is on the left    
side of the body4 ,the heart is         
surrounded by a loose membranous bag    
called the pericardium1 the inner lining
 of which secretes a fluid in which the 
heart lies4 ,when1 for any reason1 the  
pericardial fluid is not secreted1      
inflammation arises in that region4     
,illustration3 ,diagram showing the     
front half of the heart cut away3 a1    
aorta2 l1 arteries to the lungs2 la1    
left auricle2 lv1 left ventricle2 m1    

tricuspid valve open2 n1 bicuspid or    
mitral valve closed2 p and r1 veins from
 the lungs2 ra1 right auricle2 rv1 right
 ventricle2 v1 vena cava4 ,arrows show  
direction of circulation4  ,internal    
,structure of ,heart4--,if we should cut
 open the heart of a mammal down the    
midline1 we could divide it into a right
 and a left side1 each of which would   
have no internal connection with the    
other4 ,each side is made up of an upper
 thin-walled portion with a rather large
 internal cavity1 the auricle1 which    
opens into a lower smaller portion with 
heavy muscular walls1 the ventricle4    
,communication between auricles and     
ventricles is guarded by little flaps or
 valves4 ,the auricles receive blood    
from the veins4 ,the ventricles pump the
 blood into the arteries4  ,the ,heart  
in ,action4--,the heart is constructed  
on the same plan as a force pump1 the   
valves preventing the reflux of blood   
into the auricle when it is forced out  
of the ventricle4 ,blood enters the     

auricles from the veins because the     
muscles of that part of the heart relax2
 this allows the space within the       
auricles to fill4 ,almost immediately   
the muscles of the ventricles relax1    
thus allowing blood to pass into the    
chambers within the ventricles4 ,then1  
after a short pause1 during which time  
the muscles of the heart are resting1 a 
wave of muscular contraction begins in  
the auricles and ends in the ventricles1
 with a sudden strong contraction which 
forces the blood out into the arteries4 
,blood is kept on its course by the     
valves1 which act in the same manner as 
do the valves in a pump4 ,the blood is  
thus made to pass into the arteries upon
 the contraction of the ventricle walls4
  ,illustration3 ,the heart is a force  
pump2 prove it from these diagrams4     
,illustration3  ,i4 ,circulation in a   
fish4 ,g1 gills2 ,c1 capillaries of the 
body4 ,notice the two-chambered heart4  
,,ii4 ,the circulation in a frog4 ,l1   
the lungs2 ,c1 the capillaries4 ,notice 

the heart has three chambers4 ,what is  
the condition of blood leaving the      
ventricle to go to the cells of the     
body8  ,,iii4 ,the circulation in man4  
,h1 head2 ,a1 arms2 ,l1 lungs2 ,s1      
stomach2 ,li1 liver2 ,k1 kidney2 ,s4,i41
 small intestine2 ,l4,i41 large         
intestine2 ,le1 legs2 #a1 right auricle2
 #b1 right ventricle2 #c1 left          
ventricle2 #d1 left auricle2 #e1 dorsal 
aorta2 #f1 vein to lungs4   ,the ,course
 of the ,blood in the ,body4--,although 
the two sides of the heart are separate 
and distinct from each other1 yet every 
drop of blood that passes through the   
right heart likewise passes later       
through the left heart4 ,there are two  
distinct systems of circulation in the  
body4 ,the pulmonary circulation takes  
the blood through the right auricle and 
ventricle1 to the lungs1 and passes it  
back to the left auricle4 ,this is a    
relatively short circulation1 the blood 
receiving in the lungs its supply of    
oxygen1 and there giving up some of its 

carbon dioxide4 ,the greater circulation
 is known as the systemic circulation2  
in this system1 the blood leaves the    
left ventricle through the great dorsal 
aorta4 ,a large part of the blood passes
 directly to the muscles2 some of it    
goes to the nervous system1 kidneys1    
skin1 and other organs of the body4 ,it 
gives up its supply of food and oxygen  
in these tissues1 receives the waste    
products of oxidation while passing     
through the capillaries1 and returns to 
the right auricle through two large     
vessels known as the venae cavae4 ,it   
requires only from twenty to thirty     
seconds for the blood to make the       
complete circulation from the ventricle 
back again to the starting point4 ,this 
means that the entire volume of blood in
 the human body passes three or four    
thousand times a day through the various
 organs of the body4#df       ,footnote 
#df3 ,see ,hough and ,sedgwick1 ,the    
,human ,mechanism1      page #acf4      
,portal ,circulation4--,some of the     

blood1 on its way back to the heart1    
passes to the walls of the food tube and
 to its glands4 ,from there it is sent  
with its load of absorbed food to the   
liver4 ,here the vein which carries the 
blood 7called the portal vein7 breaks up
 into capillaries around the cells of   
the liver1 when it gives up sugar to be 
stored as glycogen4 ,from the liver1    
blood passes directly to the right      
auricle4 ,the portal circulation1 as it 
is called1 is the only part of the      
circulation where the blood passes      
through two sets of capillaries on its  
way from auricle to auricle4            
,illustration3 ,capillary circulation in
 the web of a frog's foot1 as seen under
 the compound microscope4 a1 b1 small   
veins2 c1 pigment cells in the skin2 d1 
capillaries in which the oval corpuscles
 are seen to follow one another in      
single series4  ,circulation in the ,web
 of a ,frog's ,foot4--,if the web of the
 foot of a live frog or the tail of a   
tadpole is examined under the compound  

microscope1 a network of blood vessels  
will be seen4 ,in some of the larger    
vessels the corpuscles are moving       
rapidly and in spurts2 these are        
arteries4 ,the arteries lead into       
smaller vessels hardly greater in       
diameter than the width of a single     
corpuscle4 ,this network of capillaries 
may be followed into larger veins in    
which the blood moves regularly4 ,this  
illustrates the condition in any tissue 
of man where the arteries break up into 
capillaries1 and these in turn unite to 
form veins4  ,structure of the          
,arteries4--,a distinct difference in   
structure exists between the arteries   
and the veins in the human body4 ,the   
arteries1 because of the greater strain 
received from the blood which is pumped 
from the heart1 have thicker muscular   
walls1 and in addition are very elastic4
  ,cause of the ,pulse4--,the pulse1    
which can easily be detected by pressing
 the large artery in the wrist or the   
small one in front of and above the     

external ear1 is caused by the gushing  
of blood through the arteries after each
 pulsation of the heart4 ,as the large  
arteries pass away from the heart1 the  
diameter of each individual artery      
becomes smaller4 ,at the very end of    
their course1 these arteries are so     
small as to be almost microscopic in    
size and are very numerous4 ,there are  
so many that if they were placed        
together1 side by side1 their united    
diameter would be much greater than the 
diameter of the large artery 7aorta7    
which passes blood from the left side of
 the heart4 ,this fact is of very great 
importance1 for the force of the blood  
as it gushes through the arteries       
becomes very much less when it reaches  
the smaller vessels4 ,this gushing      
movement is quite lost when the         
capillaries are reached1 first1 because 
there is so much more space for the     
blood to fill1 and second1 because there
 is considerable friction caused by the 
very tiny diameter of the capillaries4  

,capillaries4--,the capillaries form a  
network of minute tubes everywhere in   
the body1 but especially near the       
surface and in the lungs4 ,it is through
 their walls that the food and oxygen   
pass to the tissues1 and carbon dioxide 
is given up to the plasma4 ,they form   
the connection that completes the system
 of circulation of blood in the body4   
,function and ,structure of the         
,veins4--,if the arteries are supply    
pipes which convey fluid food to the    
tissues1 then the veins may be likened  
to drain pipes which carry away waste   
material from the tissues4 ,extremely   
numerous in the extremities and in the  
muscles and among other tissues of the  
body1 they1 like the branches of a tree1
 become larger and unite with each other
 as they approach the heart4            
,illustration3 ,valves in a vein4       
,notice the thin walls of the vein4  ,if
 the wall of a vein is carefully        
examined1 it will be found to be neither
 so thick nor so tough as an artery     

wall4 ,when empty1 a vein collapses2 the
 wall of an artery holds its shape4 ,if 
you hold your hand downward for a little
 time and then examine it1 you will find
 that the veins1 which are relatively   
much nearer the surface than are the    
arteries1 appear to be very much        
knotted4 ,this appearance is due to the 
presence of tiny valves within4 ,these  
valves open in the direction of the     
blood current1 but would close if the   
direction of the blood flow should be   
reversed 7as in case a deep cut severed 
a vein74 ,as the pressure of blood in   
the veins is much less than in the      
arteries1 the valves thus aid in keeping
 the flow of blood in the veins toward  
the heart4 ,the higher pressure in      
arteries and the suction in the veins   
7caused by the enlargement of the chest 
cavity in breathing7 are the chief      
factors which cause a steady flow of    
blood through the veins in the body4    
,lymph ,vessels4--,the lymph is         
collected from the various tissues of   

the body by means of a number of very   
thin-walled tubes1 which are at first   
very tiny1 but after repeated connection
 with other tubes ultimately unite to   
form large ducts4 ,these lymph ducts are
 provided1 like the veins1 with valves4 
,the pressure of the blood within the   
blood vessels forces continually more   
plasma into the lymph2 thus a slow      
current is maintained4 ,on its course   
the lymph passes through many           
collections of gland cells1 the lymph   
glands4 ,in these glands some impurities
 appear to be removed and colorless     
corpuscles made4 ,the lymph ultimately  
passes into a large tube1 the thoracic  
duct1 which flows upward near the       
ventral side of the spinal column1 and  
empties into the large subclavian vein  
in the left side of the neck4 ,another  
smaller lymph duct enters the right     
subclavian vein4  ,illustration3 ,the   
lymph vessels2 the dark spots are lymph 
glands3 lac1 lacteals2 rc1 thoracic     
duct4  ,the ,lacteals4--,we have already

 found that part of the digested food   
7chiefly carbohydrates1 proteins1 salts1
 and water7 is absorbed directly into   
the blood through the walls of the villi
 and carried to the liver4 ,fat1        
however1 is passed into the spaces in   
the central part of the villi1 and from 
there into other spaces between the     
tissues1 known as the lacteals4 ,the    
lacteals carry the fats into the blood  
by way of the thoracic duct4 ,the       
lacteals and lymph vessels have in part 
the same course4  ,it will be thus seen 
that lymph at different parts of its    
course would have a very different      
composition4  ,the ,nervous ,control of 
the ,heart and ,blood                   
,vessels4--,although the muscles of the 
heart contract and relax without our    
being able to stop them or force them to
 go faster1 yet in cases of sudden      
fright1 or after a sudden blow1 the     
heart may stop beating for a short      
interval4 ,this shows that the heart is 
under the control of the nervous system4

 ,two sets of nerve fibers1 both of     
which are connected with the central    
nervous system1 pass to the heart4 ,one 
set of fibers accelerates1 the other    
slows or inhibits1 the heart beat4 ,the 
arteries and veins are also under the   
control of the sympathetic nervous      
system4 ,this allows of a change in the 
diameter of the blood vessels4 ,thus1   
blushing is due to a sudden rush of     
blood to the surface of the body caused 
by an expansion of the blood vessels at 
the surface4 ,the blood vessels of the  
body are always full of blood4 ,this    
results from an automatic regulation of 
the diameter of the blood tubes by a    
part of the nervous system called the   
vasomotor nerves4 ,these nerves act upon
 the muscles in the walls of the blood  
vessels4 ,in this way1 each vessel      
adapts itself to the amount of blood in 
it at a given time4 ,after a hearty     
meal1 a large supply of blood is needed 
in the walls of the stomach and         
intestines4 ,at this time1 the arteries 

going to this region are dilated so as  
to receive an extra supply4 ,when the   
brain performs hard work1 blood is      
supplied in the same manner to that     
region4 ,hence1 one should not study or 
do mental work immediately after a      
hearty meal1 for blood will be drawn    
away to the brain1 leaving the digestive
 tract with an insufficient supply4     
,indigestion may follow as a result4    
,the ,effect of ,exercise on the        
,circulation4--,it is a fact familiar to
 all that the heart beats more violently
 and quickly when we are doing hard work
 than when we are resting4 ,count your  
own pulse when sitting quietly1 and then
 again after some brisk exercise in the 
gymnasium4 ,exercise in moderation is of
 undoubted value1 because it sends the  
increased amount of blood to such parts 
of the body where increased oxidation   
has been taking place as the result of  
the exercise4 ,the best forms of        
exercise are those which give as many   
muscles as possible work--walking1      

out-of-door sports1 any exercise that is
 not violent4 ,exercise should not be   
attempted immediately after eating1 as  
this causes a withdrawal of blood from  
the digestive tract to the muscles of   
the body4 ,neither should exercise be   
continued after becoming tired1 as      
poisons are then formed in the muscles1 
which cause the feeling we call fatigue4
 ,remember that extra work given to the 
heart by extreme exercise may injure it1
 causing possible trouble with the      
valves4  ,illustration3 ,stopping flow  
of blood from an artery by applying a   
tight bandage 7ligature7 between the cut
 and the heart4  ,treatment of ,cuts and
 ,bruises4--,blood which oozes slowly   
from a cut will usually stop flowing by 
the natural means of the formation of a 
clot4 ,a cut or bruise should1 however1 
be washed in a weak solution of carbolic
 acid or some other antiseptic in order 
to prevent bacteria from obtaining a    
foothold on the exposed flesh4 ,if      
blood1 issuing from a wound1 gushes in  

distinct pulsations1 then we know that  
an artery has been severed4 ,to prevent 
the flow of blood1 a tight bandage known
 as a tourniquet must be tied between   
the cut and the heart4 ,a handkerchief  
with a knot placed over the artery may  
stop bleeding if the cut is on one of   
the limbs4 ,if this does not serve1 then
 insert a stick in the handkerchief and 
twist it so as to make the pressure     
around the limb still greater4 ,thus we 
may close the artery until the doctor is
 called1 who may sew up the injured     
blood vessel4  ,the ,effect of ,alcohol 
upon the ,blood4--,it has recently been 
discovered that alcohol has an extremely
 injurious effect upon the colorless    
corpuscles of the blood1 lowering their 
ability to fight disease germs to a     
marked degree4 ,this is well seen in a  
comparison of deaths from certain       
infectious diseases in drinkers and     
abstainers1 the percentage of mortality 
being much greater in the former4  ,dr4 
,t4 ,alexander ,mac,nichol1 in a recent 

address1 said3--       ,massart and     
,bordet1 ,metchnikoff and ,sims         
,woodhead1 have      proved that        
alcohol1 even in very dilute solution1  
prevents      the white blood corpuscles
 from attacking invading germs1         
thus depriving the system of the        
cooperation of these      important     
defenders1 and reducing the powers of   
resisting      disease4 ,the experiments
 of ,richardson1 ,harley1 ,kales1 and   
others have demonstrated the fact that  
one to five per cent      of alcohol in 
the blood of the living human body in a 
notable degree alters the appearance of 
the corpuscular      elements1 reduces  
the oxygen bearing elements1 and        
prevents      their reoxygenation4      
,alcohol weakens ,resistance to         
,disease4--,in acute illnesses1 grippe1 
fevers1 blood poisoning1 etc41          
substances formed in the blood termed   
antibodies antagonize the action of     
bacteria1 facilitating their destruction
 by the white blood cells and           

neutralizing their poisonous influence4 
,in a person with good resistance this  
protective machinery1 which we do not   
yet thoroughly understand1 works with   
beautiful precision1 and the patient    
gets well4 ,experiments by scientific   
experts have demonstrated that alcohol  
restrains the formation of these        
marvelous antibodies4 ,alcohol puts to  
sleep the sentinels that guard your body
 from disease4  ,the ,effect of ,alcohol
 on the ,circulation4--,alcoholic drinks
 affect the very delicate adjustment of 
the nervous center's controlling the    
blood vessels and heart4 ,even very     
dilute alcohol acts upon the muscles of 
the tiny blood vessels2 consequently1   
more blood is allowed to enter them1    
and1 as the small vessels are usually   
near the surface of the body1 the       
habitual redness seen in the face of    
hard drinkers is the ultimate result4   
,the first effect of diluted alcohol is 
to make the heart      beat faster4     
,this fills the small vessels near the  

surface4      ,a feeling of warmth is   
produced which causes the drinker to    
feel that he was warmed by the drink4   
,this feeling1 however1      soon passes
 away1 and is succeeded by one of       
chilliness4 ,the      body temperature1 
at first raised by the rather rapid     
oxidation of the alcohol1 is soon       
lowered by the increased      radiation 
from the surface4       ,the immediate  
stimulation to the heart's action soon  
passes      away and1 like other        
muscles1 the muscles of the heart lose  
power and contract with less force after
 having been excited      by            
alcohol4--,,macy1 ,physiology4          
,alcohol1 when brought to act directly  
on heart muscle1 lessens the force of   
the beat4 ,it may even cause changes in 
the tissues1 which eventually result in 
the breaking of the walls of a blood    
vessel or the plugging of a vessel with 
a blood clot4 ,this condition may cause 
the disease known as apoplexy4  ,effects
 of ,tobacco upon the                   

,circulation4--,the frequent use of     
cigars or      cigarettes by the young  
seriously affects the quality of the    
blood4      ,the red blood corpuscles   
are not fully developed and charged with
      their normal supply of life-giving
 oxygen4 ,this causes paleness of the   
skin1 often noticed in the face of the  
young smoker4 ,palpitation of      the  
heart is also a common result1 followed 
by permanent weakness1 so      that the 
whole system is enfeebled1 and mental   
vigor is impaired as      well as       
physical strength4--,,macy1 ,physiology4
     ,,xxii4 ,,respiration ,,and        
,,excretion  ,problems4--,a study of    
respiration to find out3--              
7a7 ,what changes in blood and air take 
place within the                lungs4  
7b7 ,the mechanics of respiration4      
,a study of ventilation to discover3--  
7a7 ,the reason for ventilation4        
7b7 ,the best method of ventilation4    
,a study of the organs of excretion4    
,,laboratory ,,suggestions              

,demonstration4--,comparison of lungs of
 frog with those of        bird or      
mammal4      ,experiment4--,the changes 
of blood within the lungs4              
,experiment4--,changes taking place in  
air in the lungs4                       
,experiment4--,the use of the ribs in   
respiration4      ,demonstration        
experiment4--,what causes the filling of
 air        sacs of the lungs8          
,demonstration experiment4--,what are   
the best methods of        ventilating a
 room8      ,demonstration4--,best      
methods of dusting and cleaning4        
,demonstration4--,beef or sheep's kidney
 to show areas4   ,necessity for        
,respiration4--,we have seen that plants
 and animals need oxygen in order that  
the life processes may go on4 ,food is  
oxidized to release energy1 just as coal
 is burned to give heat to run an       
engine4 ,as a draft of air is required  
to make fire under the boiler1 so1 in   
the human body1 oxygen must be given so 
that food in tissues may be oxidized to 

release energy used in work4 ,this      
oxidation takes place in the cells of   
the body1 be they part of a muscle1 a   
gland1 or the brain4 ,blood1 in its     
circulation to all parts of the body1 is
 the medium which conveys the oxygen to 
that place in the body where it will be 
used4  ,illustration3 ,air passages in  
the human lungs4 a1 larynx2 b1 trachea  
7or windpipe72 c1 d1 bronchi2 e1        
bronchial tubes2 f1 cluster of air      
cells4  ,the ,organs of ,respiration in 
,man4--,we have alluded to the fact that
 the lungs are the organs which give    
oxygen to the blood and take from it    
carbon dioxide4 ,the course of the air  
passing to the lungs in man is much the 
same as in the frog4 ,air passes through
 the nose1 and into the windpipe4 ,this 
cartilaginous tube1 the top of which may
 easily be felt as the ,adam's apple of 
the throat1 divides into two bronchi4   
,the bronchi within the lungs break up  
into a great number of smaller tubes1   
the bronchial tubes1 which divide       

somewhat like the small branches of a   
tree4 ,the bronchial tubes1 indeed all  
the air passages1 are lined with        
ciliated cells4 ,the cilia of these     
cells are constantly in motion1 beating 
with a quick stroke toward the outer end
 of the tube1 that is1 toward the mouth4
 ,hence any foreign material will be    
raised from the throat first by the     
action of the cilia and then by coughing
 or clearing the throat4 ,the bronchi   
end in very minute air sacs1 little     
pouches having elastic walls1 into which
 air is taken when we inspire1 or take a
 deep breath4 ,in the walls of these    
pouches are numerous capillaries1 the   
ends of arteries which pass from the    
heart into the lung4 ,it is through the 
very thin walls of the air sacs that an 
interchange of gases takes place which  
results in the blood giving up part of  
its load of carbon dioxide1 and taking  
up oxygen in its place4 ,this exchange  
appears to be aided by the presence of  
an enzyme in the lung tissues4 ,this is 

another example of the various kinds of 
work done by the enzymes of the body4   
,illustration3 ,diagram to show what the
 blood loses and gains in one of the air
 sacs of the lungs4  ,changes in the    
,blood within the ,lungs4--,blood1 after
 leaving the lungs1 is much brighter red
 than just before entering them4 ,the   
change in color is due to a taking up of
 oxygen by the haemoglobin of the red   
corpuscles4 ,changes taking place in    
blood are obviously the reverse of those
 which take place in air in the lungs4  
,every hundred cubic centimeters of     
blood going into the lungs contains #h  
to #ab c4c4 of oxygen1 #de to #ej c4c4  
of carbon dioxide1 and #a to #b c4c4 of 
nitrogen4 ,the same amount of blood     
passing out of the lungs contains #bj   
c4c4 of oxygen1 #ch c4c4 of carbon      
dioxide1 and #a to #b c4c4 of nitrogen4 
,the water1 of which about half a pint  
is given off daily1 is mostly lost from 
the blood4  ,changes in ,air in the     
,lungs4--,air is much warmer after      

leaving the lungs than before it enters 
them4 ,breathe on the bulb of a         
thermometer to prove this4 ,expired air 
contains a considerable amount of       
moisture1 as may be proved by breathing 
on a cold polished surface4 ,this it has
 taken up in the air sacs of the lungs4 
,the presence of carbon dioxide in      
expired air may easily be detected by   
the limewater test4 ,air such as we     
breathe out of doors contains1 by       
volume3--    ,nitrogen                  
#gf4ie   ,oxygen                  #bj4fa
   ,carbon dioxide            4#jc      
,argon                    #a4jj   ,water
 vapor 7average7    #a4dj  ,air expired 
from the lungs contains3--    ,nitrogen 
#gf4ie   ,oxygen                  #ae4fg
   ,carbon dioxide           #d4ch      
,water vapor              #b   ,argon   
#a  ,in other words1 there is a loss    
between #d and #e per cent oxygen1 and  
nearly a corresponding gain in carbon   
dioxide1 in expired air4 ,there are also
 some other organic substances present4 

,illustration3 ,the respiration of      
cells4  ,cell ,respiration4--,it has    
been shown1 in the case of very simple  
animals1 such as the amoeba1 that when  
oxidation takes place in a cell1 work   
results from this oxidation4 ,the oxygen
 taken into the lungs is not used there1
 but is carried by the blood to such    
parts of the body as need oxygen to     
oxidize food materials in the cells4    
,since work is done in the cells of the 
body1 food and oxygen are therefore     
required4 ,the quantity of oxygen used  
by the body is nearly dependent on the  
amount of work performed4 ,oxygen is    
constantly taken from the blood by      
tissues in a state of rest and is used  
up when the body is at work4 ,this is   
suggested by the fact that in a given   
time a man1 when working1 gives off more
 oxygen 7in carbon dioxide7 than he     
takes in during that time4  ,while work 
is being done certain wastes are formed 
in the cell4 ,carbon dioxide is given   
off when carbon is burned4 ,but when    

proteins are burned1 another waste      
product containing nitrogen is formed4  
,this must be passed off from the cells1
 as it is a poison4 ,here again the     
lymph and blood1 the common carriers1   
take the waste material to points where 
it may be excreted or passed out of the 
body4  ,the ,mechanics of ,respiration4 
,the ,pleura4--,the lungs are covered   
with a thin elastic membrane1 the       
pleura4 ,this forms a bag in which the  
lungs are hung4 ,between the walls of   
the bag and the lungs is a space filled 
with lymph4 ,by this means the lungs are
 prevented from rubbing against the     
walls of the chest4  ,illustration3 ,the
 chest cavity 7a7 at the time of a full 
breath2 7b71 after an expiration4       
,explain how the cavity for lungs is    
made larger4  ,breathing4--,in every    
full breath there are two distinct      
movements1 inspiration 7taking air in7  
and expiration 7forcing air out74 ,in   
man an inspiration is produced by the   
contraction of the muscles between the  

ribs1 together with the contraction of  
the diaphragm1 the muscular wall just   
below the heart and lungs2 this results 
in pulling down the diaphragm and       
pulling upward and outward of the ribs1 
thus making the space within the chest  
cavity larger4 ,the lungs1 which lie    
within this cavity1 are filled by the   
air rushing into the larger space thus  
made4 ,that this cavity is larger than  
it was at first may be demonstrated by a
 glance at the accompanying figure4 ,an 
expiration is simpler than an           
inspiration1 for it requires no muscular
 effort2 the muscles relax1 the         
breastbone and ribs sink into place1    
while the diaphragm returns to its      
original position4  ,illustration3      
,apparatus to show the mechanics of     
breathing4  ,a piece of apparatus which 
illustrates to a degree the mechanics of
 breathing may be made as follows3      
,attach a string to the middle of a     
piece of sheet rubber4 ,tie the rubber  
over the large end of a bell jar4 ,pass 

a glass ,y-tube through a rubber        
stopper4 ,fasten two small toy balloons 
to the branches of the tube4 ,close the 
small end of the jar with the stopper4  
,adjust the tube so that the balloons   
shall hang free in the jar4 ,if now the 
rubber sheet is pulled down by means of 
the string1 the air pressure in the jar 
is reduced and the toy balloons within  
expand1 owing to the air pressure down  
the tube4 ,when the rubber is allowed to
 go back to its former position1 the    
balloons collapse4  ,illustration3      
,diagram showing the relative amounts of
 tidal1 complemental1 reserve1 and      
residual air4 ,the brace shows the      
average lung capacity for the adult man4
  ,rate of ,breathing and ,amount of    
,air ,breathed4--,during quiet          
breathing1 the rate of inspiration is   
from fifteen to eighteen times per      
minute2 this rate largely depends on the
 amount of physical work performed4     
,about #cj cubic inches of air are taken
 in and expelled during the ordinary    

quiet respiration4 ,the air so breathed 
is called tidal air4 ,in a long breath1 
we take in about #ajj cubic inches in   
addition to the tidal air4 ,this is     
called complemental air4 ,by means of a 
forced expiration1 it is possible to    
expel from #ge to #ajj cubic inches more
 than tidal air2 this air is called     
reserve air4 ,what remains in the lungs1
 amounting to about #ajj cubic inches1  
is called the residual air4 ,the value  
of deep breathing is seen by a glance at
 the diagram4 ,it is only by this means 
that we clear the lungs of the reserve  
air with its accompanying load of carbon
 dioxide4  ,respiration under ,nervous  
,control4--,the muscular movements which
 cause an inspiration are partly under  
the control of the will1 but in part the
 movement is beyond our control4 ,the   
nerve centers which govern inspiration  
are part of the sympathetic nervous     
system4 ,anything of an irritating      
nature in the trachea or larynx will    
cause a sudden expiration or cough4     

,when a boy runs1 the quickened         
respiration is due to the fact that     
oxygen is used up rapidly and a larger  
quantity of carbon dioxide is formed4   
,the carbon dioxide in the blood        
stimulates the nervous center which has 
control of respiration to greater       
activity1 and quickened inspiration     
follows4  ,need of                      
,ventilation4--,during the course of a  
day the lungs lose to the surrounding   
air nearly two pounds of carbon dioxide4
 ,this means that about three fifths of 
a cubic foot is given off by each person
 during an hour4 ,when we are confined  
for some time in a room1 it becomes     
necessary to get rid of this carbon     
dioxide4 ,this can be done only by means
 of proper ventilation4 ,a considerable 
amount of moisture is given off from the
 body1 and this moisture in a crowded   
room is responsible for much of the     
discomfort4 ,the air becomes humid and  
uncomfortable4 ,it has been found that  
by keeping the air in motion in such a  

room 7as through the use of electric    
fans7 much of this discomfort is        
obviated4  ,the presence of impurities  
in the air of a room may easily be      
determined by its odor4 ,the odor of a  
poorly ventilated room is due to organic
 impurities given off with the carbon   
dioxide4 ,this1 fortunately1 gives us an
 index of the amount of waste material  
in the air4 ,among the factors which    
take oxygen from the air in a closed    
room and produce carbon dioxide are     
burning gas or oil lamps and stoves1 and
 the presence of a number of people4    
,illustration3 ,three ways of           
ventilating a room4 i1 inlet for air2 o1
 outlet for air4 ,which is the best     
method of ventilation8 ,explain4        
,proper ,ventilation4--,ventilation     
consists in the removal of air that has 
been used1 and the introduction of a    
fresh supply to take its place4 ,heated 
air rises1 carrying with it much of the 
carbon dioxide and other impurities4 ,a 
good method of ventilation for the home 

is to place a board two or three inches 
high between the lower sash and the     
frame of a window or to have the window 
open an inch or so at the top and the   
bottom4 ,an open fireplace in a room    
aids in ventilation because of the      
constant draft up the flue4  ,sweeping  
and ,dusting4--,it is very easy to      
demonstrate the amount of dust in the   
air by following the course of a beam of
 light in a darkened room4 ,we have     
already proved that spores of mold and  
yeast exist in the air4 ,that bacteria  
are also present can be proved by       
exposing a sterilized gelatin plate to  
the air in a schoolroom for a few       
moments4#dg       ,footnote #dg3 ,expose
 two sterilized dishes containing       
culture      media2 one in a room being 
swept with a damp broom1 and the        
other in a room which is being swept in 
the usual manner4      ,note the        
formation of colonies of bacteria in    
each dish4 ,in      which dish does the 
more abundant growth take place8  ,many 

of the bacteria present in the air are  
active in causing diseases of the       
respiratory tract1 such as diphtheria1  
membranous croup1 and tuberculosis4     
,other diseases1 as colds1 bronchitis   
7inflammation of the bronchial tubes71  
and pneumonia 7inflammation of the tiny 
air sacs of the lungs71 are also caused 
by bacteria4  ,illustration3 ,plate     
culture exposed for five minutes in a   
school hall where pupils were passing to
 recitations4 ,each spot is a colony of 
bacteria or mold4  ,dust1 with its load 
of bacteria1 will settle on any         
horizontal surface in a room not used   
for three or four hours4 ,dusting and   
sweeping should always be done with a   
damp cloth or broom1 otherwise the      
bacteria are simply stirred up and sent 
into the air again4 ,the proper watering
 of streets before they are swept is    
also an important factor in health4     
,much dust is composed largely of dried 
excreta of animals4 ,soft-coal smoke    
does its share to add to the impurities 

of the air1 while sewer gas and         
illuminating gas are frequently found in
 sufficient quantities to poison people4
 ,pure air is1 as can be seen1 almost an
 impossibility in a great city4         
,illustration3 ,a sleeping porch1 an    
ideal way to get fresh air at night4    
,how to get ,fresh ,air4--,as we know1  
green plants give off in the sunlight   
considerable more oxygen than they use1 
and they use up carbon dioxide4 ,the air
 in the country is naturally purer than 
in the city1 as smoke and bacteria are  
not so prevalent there1 and the plants  
in abundance give off oxygen4 ,in the   
city the night air is purer than day    
air1 because the factories have stopped 
work1 the dust has settled1 and fewer   
people are on the streets4 ,the old myth
 of night air being injurious has long  
since been exploded1 and thousands of   
people of delicate health1 especially   
those who have weak throat or lungs1 are
 regaining health by sleeping out of    
doors or with the windows wide open4    

,the only essential in sleeping out of  
doors or in a room with a low           
temperature is that the body be kept    
warm and the head be protected from     
strong drafts by a nightcap or hood4    
,proper ventilation at all times is one 
of the greatest factors in good health4 
,change of ,air4--,persons in poor      
health1 especially those having         
tuberculosis1 are often cured by a      
change of air4 ,this is not always so   
much due to the composition of the air  
as to change of occupation1 rest1 and   
good food4 ,mountain air is dry1 and    
relatively free from dust and bacteria1 
and often helps a person having         
tuberculosis4 ,air at the seaside is    
beneficial for some forms of disease1   
especially hay fever and bone           
tuberculosis4 ,many sanitariums have    
been established for this latter disease
 near the ocean1 and thousands of lives 
are being annually saved in this way4   
,illustration3 ,unfavorable sleeping    
conditions4 ,explain why unfavorable4   

,ventilation of ,sleeping               
,rooms4--,sleeping in close rooms is the
 cause of much illness4 ,beds ought to  
be placed so that a constant supply of  
fresh air is given without a direct     
draft4 ,this may often be managed with  
the use of screens4 ,bedroom windows    
should be thrown open in the morning to 
allow free entrance of the sun and air1 
bedclothes should be washed frequently1 
and sheets and pillow covers often      
changed4 ,bedroom furniture should be   
simple1 and but little drapery allowed  
in the room4  ,hygienic ,habits of      
,breathing4--,every one ought to        
accustom himself upon going into the    
open air to inspire slowly and deeply to
 the full capacity of the lungs4 ,a slow
 expiration should follow4 ,take care to
 force the air out4 ,breathe through the
 nose1 thus warming the air you inspire 
before it enters the lungs and chills   
the blood4 ,repeat this exercise several
 times every day4 ,you will thus prevent
 certain of the air sacs which are not  

often used from becoming hardened and   
permanently closed4  ,relation of       
,proper ,exercise to ,health4--,we are  
all aware that exercise in moderation   
has a beneficial effect upon the human  
organism4 ,the pale face1 drooping      
shoulders1 and narrow chest of the boy  
or girl who takes no regular exercise is
 too well known4 ,exercise1 besides     
giving direct use of the muscles1       
increases the work of the heart and     
lungs1 causing deeper breathing and     
giving the heart muscles increased work2
 it liberates heat and carbon dioxide   
from the tissues where the work is      
taking place1 thus increasing the       
respiration of the tissues themselves1  
and aids mechanically in the removal of 
wastes from tissues4 ,it is well known  
that exercise1 when taken some little   
time after eating1 has a very beneficial
 effect upon digestion4 ,exercise and   
especially games are of immense         
importance to the nervous system as a   
means of rest4 ,the increasing number of

 playgrounds in this country is due to  
this acknowledged need of exercise1     
especially for growing children4        
,proper exercise should be moderate and 
varied4 ,walking in itself is a valuable
 means of exercising certain muscles1 so
 is bicycling1 but neither is ideal as  
the only form to be used4 ,vary your    
exercise so as to bring different       
muscles into play1 take exercise that   
will allow free breathing out of doors  
if possible1 and the natural fatigue    
which follows will lead you to take the 
rest and sleep that every normal body   
requires4  ,exercise should always be   
limited by fatigue1 which brings with it
 fatigue poisons4 ,this is nature's     
signal when to rest4 ,if one's use of   
diet and air is proper1 the fatigue     
point will be much further off than     
otherwise4 ,one should learn to relax   
when not in activity4 ,the habit        
produces rest1 even between exertions   
very close together1 and enables one to 
continue to repeat those exertions for a

 much longer time than otherwise4 ,the  
habit of lying down when tired is a good
 one4  ,the ,relation of ,tight         
,clothing to ,correct ,breathing4--,it  
is impossible to breathe correctly      
unless the clothing is worn loosely over
 the chest and abdomen4 ,tight corsets  
and tight belts prevent the walls of the
 chest and the abdomen from pushing     
outward and interfere with the drawing  
of air into the lungs4 ,they may also   
result in permanent distortion of parts 
of the skeleton directly under the      
pressure4 ,other organs of the body     
cavity1 as the stomach and intestines1  
may be forced downward1 out of place1   
and in consequence cannot perform their 
work properly4  ,suffocation and        
,artificial ,respiration4--,suffocation 
results from the shutting off of the    
supply of oxygen from the lungs4 ,it may
 be brought about by an obstruction in  
the windpipe1 by a lack of oxygen in the
 air1 by inhaling some other gas in     
quantity1 or by drowning4 ,a severe     

electric shock may paralyze the nervous 
centers which control respiration1 thus 
causing a kind of suffocation4 ,in the  
above cases1 death often may be         
prevented by prompt recourse to         
artificial respiration4 ,to accomplish  
this1 place the patient on his back with
 the head lower than the body2 grasp the
 arms near the elbows and draw them     
upward and outward until they are       
stretched above the head1 on a line with
 the body4 ,by this means the chest     
cavity is enlarged and an inspiration   
produced4 ,to produce an expiration1    
carry the arms downward1 and press them 
against the chest1 thus forcing the air 
out of the lungs4 ,this exercise1       
regularly repeated every few seconds1 if
 necessary for hours1 has been the      
source of saving many lives4  ,common   
,diseases of the ,nose and              
,throat4--,catarrh is a disease to which
 people with sensitive mucous membrane  
of the nose and throat are subject4 ,it 
is indicated by the constant secretion  

of mucus from these membranes4 ,frequent
 spraying of the nose and throat with   
some mild antiseptic solutions is found 
helpful4 ,chronic catarrh should be     
attended to by a physician4 ,often we   
find children breathing entirely through
 the mouth1 the nose being seemingly    
stopped up4 ,when this goes on for some 
time the nose and throat should be      
examined by a physician for adenoids1 or
 growths of soft masses of tissue which 
fill up the nose cavity1 thus causing a 
shortage of the air supply for the body4
 ,many a child1 backward at school1 thin
 and irritable1 has been changed to a   
healthy1 normal1 bright scholar by the  
removal of adenoids4 ,sometimes the     
tonsils at the back of the mouth cavity 
may become enlarged1 thus shutting off  
the air supply and causing the same     
trouble as we see in a case of adenoids4
 ,the simple removal of the obstacle by 
a doctor soon cures this condition4     
7,see page #cie47  ,organs of           
,excretion4--,all the life processes    

which take place in a living thing      
result ultimately1 in addition to giving
 off of carbon dioxide1 in the formation
 of organic wastes within the body4 ,the
 retention of these wastes which contain
 nitrogen1 is harmful to animals4 ,in   
man1 the skin and kidneys remove this   
waste from the body1 hence they are     
called the organs of excretion4         
,illustration3 ,longitudinal section    
through a kidney4  ,the ,human          
,kidney4--,the human kidney is about    
four inches long1 two and one half      
inches wide1 and one inch in thickness4 
,its color is dark red4 ,if the         
structure of the medulla and cortex 7see
 figure above7 is examined under the    
compound microscope1 you will find these
 regions to be composed of a vast number
 of tiny branched and twisted tubules4  
,the outer end of each of these tubules 
opens into the pelvis1 the space within 
the kidney2 the inner end1 in the       
cortex1 forms a tiny closed sac4 ,in    
each sac1 the outer wall of the tube has

 grown inward and carried with it a very
 tiny artery4 ,this artery breaks up    
into a mass of capillaries4 ,these      
capillaries1 in turn1 unite to form a   
small vein as they leave the little sac4
 ,each of these sacs with its contained 
blood vessels is called a glomerulus4   
,illustration3 ,diagram of kidney       
circulation1 showing a glomerulus and   
tubule3 a1 artery bringing blood to     
part2 b1 capillary bringing blood to    
glomerulus2 b'1 vessel continuing with  
blood to vein2 c1 vein2 t1 tubule2 ,g1  
glomerulus4  ,wastes given off by the   
,blood in the ,kidney4--,in the         
glomerulus the blood loses by osmosis1  
through the very thin walls of the      
capillaries1 first1 a considerable      
amount of water 7amounting to nearly    
three pints daily72 second1 a           
nitrogenous waste material known as     
urea2 third1 salts and other waste      
organic substances1 uric acid among     
them4  ,these waste products1 together  
with the water containing them1 are     

known as urine4 ,the total amount of    
nitrogenous waste leaving the body each 
day is about twenty grams4 ,it is passed
 through the ureter to the urinary      
bladder2 from this reservoir it is      
passed out of the body1 through a tube  
called the urethra4 ,after the blood has
 passed through the glomeruli of the    
kidneys it is purer than in any other   
place in the body1 because1 before      
coming there1 it lost a large part of   
its burden of carbon dioxide in the     
lungs4 ,after leaving the kidney it has 
lost much of its nitrogenous waste4 ,so 
dependent is the body upon the excretion
 of its poisonous material that1 in     
cases where the kidneys do not do their 
work properly1 death may ensue within a 
few hours4  ,illustration3 ,diagram of a
 section of the skin4 7,highly          
magnified47  ,structure and ,use of     
,sweat ,glands4--,if you examine the    
palm of your hand with a lens1 you will 
notice the surface is thrown into little
 ridges4 ,in these ridges may be found a

 large number of very tiny pits2 these  
are the pores or openings of the        
sweat-secreting glands4 ,from each      
opening a little tube penetrates deep   
within the epidermis2 there1 coiling    
around upon itself several times1 it    
forms the sweat gland4 ,close around    
this coiled tube are found many         
capillaries4 ,from the blood in these   
capillaries1 cells lining the wall of   
the gland take water1 and with it a     
little carbon dioxide1 urea1 and some   
salts 7common salt among others74 ,this 
forms the excretion known as sweat4 ,the
 combined secretions from these glands  
amount normally to a little over a pint 
during twenty-four hours4 ,at all times1
 a small amount of sweat is given off1  
but this is evaporated or is absorbed by
 the underwear2 as this passes off      
unnoticed1 it is called insensible      
perspiration4 ,in hot weather or after  
hard manual labor the amount of         
perspiration is greatly increased4      
,regulation of ,heat of the ,body4--,the

 bodily temperature of a person engaged 
in manual labor will be found to be but 
little higher than the temperature of   
the same person at rest4 ,we know from  
our previous experiments that heat is   
released4 ,muscles1 nearly one half the 
weight of the body1 release about five  
sixths of their energy as heat4 ,at all 
times they are giving up some heat4 ,how
 is it that the bodily temperature does 
not differ greatly at such times8 ,the  
temperature of the body is largely      
regulated by means of the activity of   
the sweat glands4 ,the blood carries    
much of the heat1 liberated in the      
various parts of the body by the        
oxidation of food1 to the surface of the
 body1 where it is lost in the          
evaporation of sweat4 ,in hot weather   
the blood vessels of the skin are       
dilated2 in cold weather they are made  
smaller by the action of the nervous    
system4 ,the blood thus loses water in  
the skin1 the water evaporates1 and we  
are cooled off4 ,the object of increased

 perspiration1 then1 is to remove heat  
from the body4 ,with a large amount of  
blood present in the skin1 perspiration 
is increased2 with a small amount1 it is
 diminished4 ,hence1 we have in the skin
 an automatic regulator of bodily       
temperature4  ,sweat ,glands under      
,nervous ,control4--,the sweat glands1  
like the other glands in the body1 are  
under the control of the sympathetic    
nervous system4 ,frequently the nerves  
dilate the blood vessels of the skin1   
thus helping the sweat glands to        
secrete1 by giving them more blood4     
,thus regulation is carried out by the  
nervous system      determining1 on the 
one hand1 the loss by governing the     
supply of blood to the skin and the     
action of the sweat      glands2 and on 
the other1 the production by diminishing
 or      increasing the oxidation of the
 tissues4--,,foster ,,and ,,shore1      
,physiology4  ,colds and ,fevers4--,the 
regulation of blood passing through the 
blood vessels is under control of the   

nervous system4 ,if this mechanism is   
interfered with in any way1 the sweat   
glands may not do their work1           
perspiration may be stopped1 and the    
heat from oxidation held within the     
body4 ,the body temperature goes up1 and
 a fever results4  ,illustration3 ,a1   
blood vessels in skin normal2 ,b1 when  
congested4  ,if the blood vessels in the
 skin are suddenly cooled when full of  
blood1 they contract and send the blood 
elsewhere4 ,as a result a congestion or 
cold may follow4 ,colds are1 in reality1
 a congestion of membranes lining       
certain parts of the body1 as the nose1 
throat1 windpipe1 or lungs4  ,when      
suffering from a cold1 it is therefore  
important not to chill the skin1 as a   
full blood supply should be kept in it  
and so kept from the seat of the        
congestion4 ,for this reason hot baths  
7which call the blood to the skin71 the 
avoiding of drafts 7which chill the     
skin71 and warm clothing are useful     
factors in the care of colds4  ,hygiene 

of the ,skin4--,the skin is of          
importance both as an organ of excretion
 and as a regulator of bodily           
temperature4 ,the skin of the entire    
body should be bathed frequently so that
 this function of excretion may be      
properly performed4 ,pride in one's own 
appearance forbids a dirty skin4 ,for   
those who can stand it1 a cold sponge   
bath is best4 ,soap should be used daily
 on parts exposed to dirt4 ,exercise in 
the open air is important to all who    
desire a good complexion4 ,the body     
should be kept at an even temperature by
 the use of proper underclothing4 ,wool1
 a poor conductor of heat1 should be    
used in winter1 and cotton1 which allows
 of a free escape of heat1 in summer4   
,cuts1 ,bruises1 and ,burns4--,in case  
the skin is badly broken1 it is         
necessary to prevent the entrance and   
growth of bacteria4 ,this may be done by
 washing the wound with weak antiseptic 
solutions such as #c per cent carbolic  
acid1 #c per cent lysol1 or peroxide of 

hydrogen 7full strength74 ,these        
solutions should be applied immediately4
 ,a burn or scald should be covered at  
once with a paste of baking soda1 with  
olive oil1 or with a mixture of         
limewater and linseed oil4 ,these tend  
to lessen the pain by keeping out the   
air and reducing the inflammation4      
,summary of ,changes in ,blood within   
the ,body4--,we have already seen that  
red corpuscles in the lungs lose part of
 their load of carbon dioxide that they 
have taken from the tissues1 replacing  
it with oxygen4 ,this is accompanied by 
a change of color from purple 7in blood 
which is poor in oxygen7 to that of     
bright red 7in richly oxygenated blood74
 ,other changes take place in other     
parts of the body4 ,in the walls of the 
food tube1 especially in the small      
intestine1 the blood receives its load  
of fluid food4 ,in the muscles and other
 working tissues the blood gives up food
 and oxygen1 receiving carbon dioxide   
and organic waste in return4 ,in the    

liver1 the blood gives up its sugar1 and
 the worn-out red corpuscles which break
 down are removed 7as they are in the   
spleen7 from the circulation4 ,in       
glands1 it gives up materials used by   
the gland cells in their manufacture of 
secretions4 ,in the kidneys1 it loses   
water and nitrogenous wastes 7urea74 ,in
 the skin1 it also loses some waste     
materials1 salts1 and water4       ,the 
,effect of ,alcohol on ,body ,heat4--,it
 is usually believed      that 'taking a
 drink' when cold makes one warmer4 ,but
 such      is not the case4 ,in reality 
alcohol lowers the temperature      of  
the body by dilating the blood vessels  
of the skin4 ,it      does this by means
 of its influence on the nervous system4
      ,it is1 therefore1 a mistake to   
drink alcoholic beverages      when one 
is extremely cold1 because by means of  
this more      bodily heat is allowed to
 escape4       ,because alcohol is      
quickly oxidized1 and because heat is   
produced in the process1 it was long    

believed to be of value      in         
maintaining the heat of the body4 ,a    
different view now      prevails as the 
result of much observation and          
experiment4      ,physiologists show by 
careful experiments that though the     
temperature of the body rises during    
digestion of food1 it      is lowered   
for some hours when alcohol is taken4   
,the flush      which is felt upon the  
skin after a drink of wine or spirits   
is due in part to an increase of heat in
 the body1 but also      to the         
paralyzing effect of the alcohol upon   
the capillary      walls1 allowing them 
to dilate1 and so permitting more of    
the warm blood of the interior of the   
body to reach the      surface4 ,there  
it is cooled by radiation1 and the      
general      temperature is             
lowered4--,,macy1 ,physiology4  ,effect 
of ,alcohol on ,respiration4--,alcohol  
tends to congest the membrane of the    
throat and lungs4 ,it does this by      
paralyzing the nerves which take care of

 the tiny blood vessels in the walls of 
the air tubes and air sacs4 ,the        
capillaries become full of blood1 the   
air spaces are lessened1 and breathing  
is interfered with4 ,the use of alcohol 
is believed by many physicians to       
predispose a person to tuberculosis4    
,certainly this disease attacks drinkers
 more readily than those who do not     
drink4 ,alcohol interferes with the     
respiration of the cells because it is  
oxidized very quickly within the body as
 it is quickly absorbed and sent to the 
cells4 ,so rapid is this oxidation that 
it interferes with the oxidation of     
other substances4 ,using alcohol has    
been likened to burning kerosene in a   
stove2 the operation is a dangerous one4
  ,effects of ,tobacco on               
,respiration4--,tobacco smoke contains  
the same kind of poisons as the tobacco1
 with other irritating substances added4
 ,it is extremely irritating to the     
throat2 it often causes a cough1 and    
renders it more liable to inflammation4 

,if the smoke is inhaled more deeply1   
the vaporized nicotine is still more    
readily absorbed and may thus produce   
greater irritation in the bronchi and   
lungs4 ,cigarettes are worse than other 
forms of tobacco1 for they contain the  
same poisons with others in addition4   
,effect of ,alcohol on the              
,kidneys4--,it is said that alcohol is  
one of the greatest causes of disease in
 the kidneys4 ,the forms of disease     
known as fatty degeneration of the      
kidney and ,bright's disease are both   
frequently due to this cause4 ,the      
kidneys are the most important organs   
for the removal of nitrogenous waste4   
,alcohol unites more easily with oxygen 
than most other food materials1 hence it
 takes away oxygen that would otherwise 
be used in oxidizing these foods4       
,imperfect oxidation of foods causes the
 development and retention of poisons in
 the blood which it becomes the work of 
the kidneys to remove4 ,if the kidneys  
become overworked1 disease will occur4  

,such disease is likely to make itself  
felt as rheumatism or gout1 both of     
which are believed to be due to waste   
products 7poisons7 in the blood4        
,poisons produced by ,alcohol4--,when   
too little oxygen enters the draft of   
the stove1 the wood is burned           
imperfectly1 and there are clouds of    
smoke and irritating gases4 ,so1 if     
oxygen unites with the alcohol and too  
little reaches the cells1 instead of    
carbon dioxide1 water1 and urea being   
formed1 there are other products1 some  
of which are exceedingly poisonous and  
which the kidneys handle with           
difficulty4 ,the poisons retained in the
 circulation never fail to produce their
 poisonous effects1 as shown by         
headaches1 clouded brain1 pain1 and     
weakness of the body4 ,the word         
intoxication means in a state of        
poisoning4 ,these poisons gradually     
accumulate as the alcohol takes oxygen  
from the cells4 ,the worst effects come 
last1 when the brain is too benumbed to 

judge fairly of their harm4             
,,reference ,,books                     
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,davison1 ,human   
,body and ,health4 ,american ,book      
,company4      ,gulick1 ,hygiene        
,series1 ,emergencies1 ,good ,health4   
,ginn        and ,company4      ,hough  
and ,sedgwick1 ,the ,human ,mechanism4  
,ginn and ,company4      ,macy1 ,general
 ,physiology4 ,american ,book ,company4 
,ritchie1 ,human ,physiology4 ,world    
,book ,company4     ,,xxiii4 ,,body     
,,control ,,and ,,habit ,,formation     
,problems4--,how is body control        
maintained8             7a7 ,what is the
 mechanism of direction and control8    
7b7 ,what is the method of direction and
 control8             7c7 ,what are     
habits8 ,how are they formed and how    
broken8             7d7 ,what are the   
organs of sense8 ,what are their uses8  
7e7 ,how does alcohol affect the nervous
 system8                                

,,laboratory ,,suggestions              
,demonstration4--,sensory motor         
reactions4                              
,demonstration4--,nervous system4       
,models and frog      dissections4      
,demonstration4--,neurones under        
compound microscope      7optional74    
,demonstration4--,reflex acts are       
unconscious acts3 show how              
conscious acts may become habitual4     
,home exercise in habit forming4        
,the senses4--,home exercises4--7#a7 ,to
 determine areas most      sensitive to 
touch4 7#b7 ,to determine or map out hot
 and cold      spots on an area on the  
wrist4 7#c7 ,to determine functions of  
different areas on tongue4              
,demonstration4--,show how eye defects  
are tested4       ,laboratory           
summary4--,the effects of alcohol on the
 nervous      system4   ,the ,body a    
,self-directed ,machine4--,throughout   
the preceding chapters the body has been
 likened to an engine1 which1 while     
burning its fuel1 food1 has done work4  

,if we were to carry our comparison     
further1 however1 the simile ceases4    
,for the engineer runs the engine1 while
 the bodily machine is self-directive4  
,moreover1 most of the acts we perform  
during a day's work are results of the  
automatic working of this bodily        
machine4 ,the heart pumps2 the blood    
circulates its load of food1 oxygen1 and
 wastes2 the movements of breathing are 
performed2 the thousand and one         
complicated acts that go on every day   
within the body are seemingly           
undirected4  ,illustration3 ,the central
 nervous system4  ,automatic            
,activity4--,in addition to this1       
numbers of other of our daily acts are  
not thought about4 ,if we are           
well-regulated body machines1 we get up 
in the morning1 automatically wash1     
clean our teeth1 dress1 go to the       
toilet1 get our breakfast1 walk to      
school1 even perform such complicated   
processes as that of writing1 without   
thinking about or directing the machine4

 ,in these respects we have become      
creatures of habit4 ,certain acts which 
once we might have learned consciously1 
have become automatic4  ,but once at    
school1 if we are really making good in 
our work in the classroom1 we begin a   
higher control of our bodily functions4 
,automatic control acts no longer1 and  
sensation is not the only guide--for we 
now begin to make conscious choice2 we  
weigh this matter against another1--in  
short1 we think4  ,parts of the ,nervous
 ,system4--,this wonderful              
self-directive apparatus placed within  
us1 which is in part under control of   
our will1 is known as the nervous       
system4 ,in the vertebrate animals1     
including man1 it consists of two       
divisions4 ,one includes the brain1     
spinal cord1 the cranial and spinal     
nerves1 which together make up the      
cerebro-spinal nervous system4 ,the     
other division is called the sympathetic
 nervous system and has to do with those
 bodily functions which are beyond our  

control4 ,every group of cells in the   
body that has work to do 7excepting the 
floating cells of the blood7 is directly
 influenced by these nerves4 ,our bodily
 comfort is dependent upon their        
directive work4 ,the organs which put us
 in touch with our surroundings are     
naturally at the surface of the body4   
,small collections of nerve cells1      
called ganglia1 are found in all parts  
of the body4 ,these nerve centers are   
connected1 to a greater or less degree1 
with the surface of the body by the     
nerves1 which serve as pathways between 
the end organs of touch1 sight1 taste1  
etc41 and the centers in the brain or   
spinal cord4 ,thus sensation is         
obtained4  ,sensations and              
,reactions4--,we have already seen that 
simpler forms of life perform certain   
acts because certain outside forces     
acting upon them cause them to react to 
the stimulus from without4 ,the         
one-celled animal responds to the       
presence of food1 to heat1 to oxygen1 to

 other conditions in its surroundings4  
,an earthworm is repelled by light1 is  
attracted by food4 ,all animals1        
including man1 are put in touch with    
their surroundings by what we call the  
organs of sensation4 ,the senses of man1
 besides those we commonly know as those
 of sight1 hearing1 taste1 smell1 and   
touch1 are those of temperature1        
pressure1 and pain4 ,it is obvious that 
such organs1 if they are to be of use to
 an animal1 must be at the outside of   
the body4 ,thus we find eyes and ears in
 the head1 and taste cells in the mouth1
 while other cells in the nose perceive 
odors1 and still others in the skin are 
sensitive to heat or cold1 pressure or  
pain4  ,but this is not all4 ,strangely 
enough1 we do not see with our eyes or  
taste with our taste cells4 ,these      
organs receive the sensations1 and by   
means of a complicated system of greatly
 elongated cell structures1 the message 
is sent inward1 relayed by other        
elongated cells until the sensory       

message reaches an inner station1 in the
 central nervous system4 ,we see and    
hear and smell in our brain4 ,let us    
next examine the structure of the nerve 
cells or neurons part of which serve as 
pathways for these messages4            
,illustration3 ,diagram of a neuron or  
nerve unit4  ,neurones4--,a nerve cell1 
like other cells in the body1 is a mass 
of protoplasm containing a nucleus4 ,but
 the body of the nerve cell is usually  
rather irregular in shape1 and          
distinguished from most other cells by  
possessing several delicate1 branched   
protoplasmic projections called         
dendrites4 ,one of these processes1 the 
axon1 is much longer than the others and
 ends in a muscle or organ of sensation4
 ,the axon forms the pathway over which 
nervous impulses travel to and from the 
nerve centers4  ,a nerve consists of a  
bundle of such tiny axons1 bound        
together by connective tissue4 ,as a    
nerve ganglia is a center of activity in
 the nervous system1 so a cell body is a

 center of activity which may send an   
impulse over this thin strand of        
protoplasm 7the axon7 prolonged many    
hundreds of thousands of times the      
length of the cell4 ,some neurones in   
the human body1 although visible only   
under the compound microscope1 give rise
 to axons several feet in length4       
,because some bundles of axons originate
 in organs that receive sensations and  
send those sensations to the central    
nervous system1 they are called sensory 
nerves4 ,other axons originate in the   
central nervous system and pass outward 
as nerves producing movement of muscles4
 ,these are called motor nerves4  ,the  
,brain of ,man4--,in man1 the central   
nervous system consists of a brain and  
spinal cord inclosed in a bony case4    
,from the brain1 twelve pairs of nerves 
are given off2 thirty-one pairs more    
leave the spinal cord4 ,the brain has   
three divisions4 ,the cerebrum makes up 
the largest part4 ,in this respect it   
differs from the cerebrum of the frog   

and other vertebrates4 ,it is divided   
into two lobes1 the hemispheres1 which  
are connected with each other by a broad
 band of nerve fibers4 ,the outer       
surface of the cerebrum is thrown into  
folds or convolutions which give a large
 surface1 the cell bodies of the neurons
 being found in this part of the        
cerebrum4 ,holding the cell bodies and  
fibers in place is a kind of connective 
tissue4 ,the inner part 7white in color7
 is composed largely of fibers which    
pass to other parts of the brain and    
down into the spinal cord4 ,under the   
cerebrum1 and dorsal to it1 lies the    
little brain1 or cerebellum4 ,the two   
sides of the cerebellum are connected by
 a band of nerve fibers which run around
 into the lower hindbrain or medulla4   
,this band of fibers is called the pons4
 ,the medulla is1 in structure1 part of 
the spinal cord1 and is made up largely 
of fibers running longitudinally4  ,the 
,sympathetic ,nervous                   
,system4--,connected with the central   

nervous system is that part of the      
nervous apparatus that controls the     
muscles of the digestive tract and blood
 vessels1 the secretions of gland cells1
 and all functions which have to do with
 life processes in the body4 ,this is   
called the sympathetic nervous system4  
,functions of the ,parts of the ,central
 ,nervous ,system of the ,frog4--,from  
careful study of living frogs1 birds1   
and some mammals we have learned much of
 what we know of the functions of the   
parts of the central nervous system in  
man4  ,it has been found that if the    
entire brain of a frog is destroyed and 
separated from the spinal cord1 the frog
 will continue to live1 but with a very 
peculiarly modified activity4 ,it does  
not appear to breathe1 nor does it      
swallow4 ,it will not move or croak1 but
 if acid is placed upon the skin so as  
to irritate it1 the legs make movements 
to push away and to clean off the       
irritating substance4 ,the spinal cord  
is thus shown to be a center for        

defensive movements4 ,if the cerebrum is
 separated from the rest of the nervous 
system1 the frog seems to act a little  
differently from the normal animal4 ,it 
jumps when touched1 and swims when      
placed in water4 ,it will croak when    
stroked1 or swallow if food be placed in
 its mouth4 ,but it manifests no hunger 
or fear1 and is in every sense a machine
 which will perform certain actions     
after certain stimulations4 ,its        
movements are automatic4 ,if now we     
watch the movements of a frog which has 
the brain uninjured in any way1 we find 
that it acts spontaneously4 ,it tries to
 escape when caught4 ,it feels hungry   
and seeks food4 ,it is capable of       
voluntary action4 ,it acts like a normal
 individual4  ,illustration3 ,diagram to
 show the parts of the brain and action 
of the different parts of the brain4    
,functions of the ,cerebrum4--,in       
general1 the functions of the different 
parts of the brain in man agree with    
those functions we have already observed

 in the frog4 ,the cerebrum has to do   
with conscious activity2 that is1       
thought4 ,it presides over what we call 
our thoughts1 our will1 and our         
sensations4 ,a large part of the area of
 the outer layer of the cerebrum seems  
to be given over to some one of the     
different functions of speech1 hearing1 
sight1 touch1 movements of bodily parts4
 ,the movement of the smallest part of  
the body appears to have its definite   
localized center in the cerebrum4       
,experiments have been performed on     
monkeys1 and these1 together with       
observations made on persons who had    
lost the power of movement of certain   
parts of the body1 and who1 after death1
 were found to have had diseases        
localized in certain parts of the       
cerebrum1 have given to us our knowledge
 on this subject4  ,illustration3       
,diagram of the nerve path of a simple  
reflex action4  ,reflex ,actions2 their 
,meaning4--,if through disease or for   
other reasons the cerebrum does not     

function1 no will power is exerted1 nor 
are intelligent acts performed4 ,all    
acts performed in such a state are known
 as reflex actions4 ,the involuntary    
brushing of a fly from the face1 or the 
attempt to move away from the source of 
annoyance when tickled with a feather1  
are examples of reflexes4 ,in a reflex  
act1 a person does not think before     
acting4 ,the nervous impulse comes from 
the outside to cells that are not in the
 cerebrum4 ,the message is              
short-circuited back to the surface by  
motor nerves1 without ever having       
reached the thinking centers4 ,the nerve
 cells which take charge of such acts   
are located in the cerebellum or spinal 
cord4  ,automatic ,acts4--,some acts1   
however1 are learned by conscious       
thought1 as writing1 walking1 running1  
or swimming4 ,later in life1 however1   
these activities become automatic4 ,the 
actual performance of the action is then
 taken up by the cerebellum1 medulla1   
and spinal ganglia4 ,thus the thinking  

portion of the brain is relieved of part
 of its work4  ,bundles of ,habits4--,it
 is surprising how little real thinking 
we do during a day1 for most of our acts
 are habitual4 ,habit takes care of our 
dressing1 our bathing1 our care of the  
body organs1 our methods of eating2 even
 our movements in walking and the kind  
of hand we write are matters of habit   
forming4 ,we are bundles of habits1 be  
they good ones or bad ones4  ,habit     
,formation4--,the training of the       
different areas in the cerebrum to do   
their work well is the object of        
education4 ,when we learned to write1 we
 exerted conscious effort in order to   
make the letters4 ,now the act of       
forming the letters is done without     
thought4 ,by training1 the act has      
become automatic4 ,in the beginning1 a  
process may take much thought and many  
trials before we are able to complete   
it4 ,after a little practice1 the same  
process may become almost automatic4 ,we
 have formed a habit4 ,habits are really

 acquired reflex actions4 ,they are the 
result of nature's method of training4  
,the conscious part of the brain has    
trained the cerebellum or spinal cord to
 do certain things that1 at first1 were 
taken charge of by the cerebrum4        
,importance of ,forming ,right          
,habits4--,among the habits early to be 
acquired are the habits of studying     
properly1 of concentrating the mind1 of 
learning self-control1 and1 above all1  
of contentment4 ,get the most out of the
 world about you4 ,remember that the    
immediate effect in the study of some   
subjects in school may not be great1 but
 the cultivation of correct methods of  
thinking may be of the greatest         
importance later in life4 ,the man or   
woman who has learned how to concentrate
 on a problem1 how to weigh all sides   
with an unbiased mind1 and then to      
decide on what they believe to be best  
and right are the efficient and happy   
ones of their generation4       ,the    
hell to be endured hereafter1 of which  

theology tells1      is no worse than   
the hell we make for ourselves in this  
world by habitually fashioning our      
characters in the wrong      way4 ,could
 the young but realize how soon they    
will become      mere walking bundles of
 habits1 they would give more heed to   
their conduct while in the plastic      
state4 ,we are spinning      our own    
fates1 good or evil1 and never to be    
undone4 ,every      smallest stroke of  
virtue or of vice leaves its            
never-so-little scar4 ,the drunken ,rip 
,van ,winkle1 in      ,jefferson's play1
 excuses himself for every fresh        
dereliction by saying1 ',i won't count  
this time6' ,well6 he      may not count
 it1 and a kind ,heaven may not count   
it2 but it      is being counted none   
the less4 ,down among his nerve cells   
and fibers the molecules are counting   
it1 registering and      storing it up  
to be used against him when the next    
temptation comes4 ,nothing we ever do   
is1 in strict      scientific           

literalness1 wiped out4 ,of course this 
has its      good side as well as its   
bad one4 ,as we become permanent        
drunkards by so many separate drinks1 so
 we become saints in      the moral1 and
 authorities in the practical and       
scientific1      spheres by so many     
separate acts and hours of work4 ,let no
      youth have any anxiety about the  
upshot of his education1      whatever  
the line of it may be4 ,if he keep      
faithfully busy      each hour of the   
working day1 he may safely leave the    
final      result to itself4 ,he can    
with perfect certainty count on         
waking up some fine morning1 to find    
himself one of the      competent ones  
of his generation1 in whatever pursuit  
he may      have singled out4--,,james1 
,psychology4  ,some ,rules for ,forming 
,good ,habits4--,professor ,horne gives 
several rules for making good or        
breaking bad habits4 ,they are3 ,first1 
act on every opportunity4 ,second1 make 
a strong start4 ,third1 allow no        

exception4 ,fourth1 for the bad habit   
establish a good one4 ,fifth1 summoning 
all the man within1 use effort of will4 
,why not try these out in forming some  
good habit8 ,you will find them         
effective4  ,illustration3 ,the effect  
of fatigue on nerve cells4 a1 healthy   
brain cell2 b1 fatigued brain cell4     
,necessity of ,food1 ,fresh ,air1 and   
,rest4--,the nerve cells1 like all other
 cells in the body1 are continually     
wasting away and being rebuilt4         
,oxidation of food material is more     
rapid when we do mental work4 ,the cells
 of the brain1 like muscle cells1 are   
not only capable of fatigue1 but show   
this in changes of form and of contents4
 ,food brought to them in the blood1    
plenty of fresh air1 especially when    
engaged in active brain work1 and rest  
at proper times1 are essential in       
keeping the nervous system in condition4
 ,one of the best methods of resting the
 brain cells is a change of occupation4 
,tennis1 golf1 baseball1 and other      

outdoor sports combine muscular exercise
 with brain activity of a different sort
 from that of business or school work4  
,but change of occupation will not rest 
exhausted neurones4 ,for this1 sleep is 
necessary4 ,especially is sleep an      
important factor in the health of the   
nervous system of growing children4     
,necessity of ,sleep4--,most brain cells
 attain their growth early in life4     
,changes occur1 however1 until some time
 after the school age4 ,ten hours of    
sleep should be allowed for a child1 and
 at least eight hours for an adult4 ,at 
this time1 only1 do the brain cells have
 opportunity to rest and store food and 
energy for their working period4  ,sleep
 is one way in which all cells in the   
body1 and particularly those of the     
nervous system1 get their rest4 ,the    
nervous system1 by far the most delicate
 and hardest-worked set of tissues in   
the body1 needs rest more than do other 
tissues1 for its work directing the body
 only ends with sleep or                

unconsciousness4 ,the afternoon nap1    
snatched by the brain worker1 gives him 
renewed energy for his evening's work4  
,it is not hard application to a task   
that wearies the brain2 it is continuous
 work without rest4                     
,,the ,,senses  ,touch4--,in animals    
having a hard outside covering1 such as 
certain worms1 insects1 and crustaceans1
 minute hairs1 which are sensitive to   
touch1 are found growing out from the   
body covering4 ,at the base of these    
hairs are found neurones which send     
axons inward to the central nervous     
system4  ,illustration3 ,nerves in the  
skin3 a1 nerve fiber2 b1 tactile        
papillae1 containing a tactile          
corpuscle2 c1 papillae containing blood 
vessels4 7,after ,benda47  ,organs of   
,touch4--,in man1 the nervous mechanism 
which governs touch is located in the   
folds of the dermis or in the skin4     
,special nerve endings1 called the      
tactile corpuscles1 are found there1    
each inclosed in a sheath or capsule of 

connective tissue4 ,inside is a         
complicated nerve ending1 and axons pass
 inward to the central nervous system4  
,the number of tactile corpuscles       
present in a given area of the skin     
determines the accuracy and ease with   
which objects may be known by touch4    
,if you test the different parts of the 
body1 as the back of the hand1 the neck1
 the skin of the arm1 of the back1 or   
the tip of the tongue1 with a pair of   
open dividers1 a vast difference in the 
accuracy with which the two points may  
be distinguished is noticed4 ,on the tip
 of the tongue1 the two points need only
 be separated by #a_/bd of an inch to be
 so distinguished4 ,in the small of the 
back1 a distance of #b inches may be    
reached before the dividers feel like   
two points4  ,temperature1 ,pressure1   
,pain4--,the feeling of temperature1    
pressure1 and pain is determined by     
different end organs in the skin4 ,two  
kinds of nerve fibers exist in the skin1
 which give distinct sensations of heat 

and cold4 ,these nerve endings can be   
located by careful experimentation4     
,there are also areas of nerve endings  
which are sensitive to pressure1 and    
still others1 most numerous of all1     
sensitive to pain4  ,taste              
,organs4--,the surface of the tongue is 
folded into a number of little          
projections known as papillae4 ,these   
may be more easily found on your own    
tongue if a drop of vinegar is placed on
 its broad surface4 ,in the folds1      
between these projections on the top and
 back part of the tongue1 are located   
the organs of taste4 ,these organs are  
called taste buds4  ,illustration3 ,a1  
isolated taste bud1 from whose upper    
free end project the ends of the taste  
cells2 ,b1 supporting or protecting     
cell2 ,c1 sensory cell4  ,each taste bud
 consists of a collection of            
spindle-shaped neurones1 each cell      
tipped at its outer end with a hairlike 
projection4 ,these cells send inward    
fibers to other cells1 the fibers from  

which ultimately reach the brain4 ,the  
sensory cells are surrounded by a number
 of projecting cells which are arranged 
in layers about them4 ,thus the organ in
 longitudinal section looks somewhat    
like an onion cut lengthwise4  ,how we  
,taste4--,four kinds of substances may  
be distinguished by the sense of taste4 
,these are sweet1 sour1 bitter1 and     
salt4 ,certain taste cells located near 
the back of the tongue are stimulated   
only by a bitter taste4 ,sweet          
substances are perceived by cells near  
the tip of the tongue1 sour substances  
along the sides1 and salt about equally 
all over the surface4 ,a substance must 
be dissolved in fluid in order to be    
tasted4 ,many things which we believe we
 taste are in reality perceived by the  
sense of smell4 ,such are spicy sauces  
and flavors of meats and vegetables4    
,this may easily be proved by holding   
the nose and chewing1 with closed eyes1 
several different substances1 such as an
 apple1 an onion1 and a raw potato4     

,smell4--,the sense of smell is located 
in the membrane lining the upper part of
 the nose4 ,here are found a large      
number of rod-shaped cells which are    
connected with the brain by means of the
 olfactory nerve4 ,in order to perceive 
odors1 it is necessary to have them     
diffused in the air2 hence we sniff so  
as to draw in more air over the         
olfactory cells4  ,the ,organ of        
,hearing4--,the organ of hearing is the 
ear4 ,the outer ear consists of a       
funnel-like organ composed largely of   
cartilage which is of use in collecting 
sound waves4 ,this part of the ear      
incloses the auditory canal1 which is   
closed at the inner end by a tightly    
stretched membrane1 the tympanic        
membrane or ear drum4 ,the function of  
the tympanic membrane is to receive     
sound waves1 for all sound is caused by 
vibrations in the air1 these vibrations 
being transmitted1 by the means of a    
complicated apparatus found in the      
middle ear1 to the real organ of hearing

 located in the inner ear4              
,illustration3 ,section of ear3 ,e4,m41 
auditory canal2 ,ty4,m41 tympanic       
membrane2 ,eu41 ,eustachian tube2 ,ty1  
middle ear2 ,coc41 ,a4,s4,c41 ,e4,s4,c41
 etc41 internal ear4  ,middle           
,ear4--,the middle ear in man is a      
cavity inclosed by the temporal bone1   
and separated from the outer ear by the 
tympanic membrane4 ,a little tube called
 the ,eustachian tube connects the inner
 ear with the mouth cavity4 ,by allowing
 air to enter from the mouth1 the air   
pressure is equalized on the ear drum4  
,for this reason1 we open the mouth at  
the time of a heavy concussion and thus 
prevent the rupture of the delicate     
tympanic membrane4 ,placed directly     
against the tympanic membrane and       
connecting it with the inner ear is a   
chain of three tiny bones1 the smallest 
bones of the body4 ,the outermost is    
called the hammer2 the next the anvil2  
the third the stirrup4 ,all three bones 
are so called from their resemblances in

 shape to the articles for which they   
are named4 ,these bones are held in     
place by very small muscles which are   
delicately adjusted so as to tighten or 
relax the membranes guarding the middle 
and inner ear4  ,the ,inner ,ear4--,the 
inner ear is one of the most            
complicated1 as well as one of the most 
delicate1 organs of the body4 ,deep     
within the temporal bone there are found
 two parts1 one of which is called1     
collectively1 the semicircular canal    
region1 the other the cochlea1 or organ 
of hearing4  ,it has been discovered by 
experimenting with fish1 in which the   
semicircular canal region forms the     
chief part of the ear1 that this region 
has to do with the equilibrium or       
balancing of the body4 ,we gain in part 
our knowledge of our position and       
movements in space by means of the      
semicircular canals4  ,that part of the 
ear which receives sound waves is known 
as the cochlea1 or snail shell1 because 
of its shape4 ,this very complicated    

organ is lined with sensory cells       
provided with cilia4 ,the cavity of the 
cochlea is filled with a fluid4 ,it is  
believed that somewhat as a stone thrown
 into water causes ripples to emanate   
from the spot where it strikes1 so sound
 waves are transmitted by means of the  
fluid filling the cavity to the sensory 
cells of the cochlea 7collectively known
 as the organ of ,corti7 and thence to  
the brain by means of the auditory      
nerve4  ,the ,character of              
,sound4--,when vibrations which are     
received by the ear follow each other at
 regular intervals1 the sound is said to
 be musical4 ,if the vibrations come    
irregularly1 we call the sound a noise4 
,if the vibrations come slowly1 the     
pitch of the sound is low2 if they come 
rapidly1 the pitch is high4 ,the ear is 
able to perceive as low as thirty       
vibrations per second and as high as    
almost thirty thousand4 ,the ear can be 
trained to recognize sounds which are   
unnoticed in untrained ears4            

,illustration3 ,longitudinal section    
through the eye4  ,the ,eye4--,the eye  
or organ of vision is an almost         
spherical body which fits into a socket 
of bone1 the orbit4 ,a stalklike        
structure1 the optic nerve1 connects the
 eye with the brain4 ,free movement is  
obtained by means of six little muscles 
which are attached to the outer coat1   
the eyeball1 and to the bony socket     
around the eye4  ,the wall of the       
eyeball is made up of three coats4 ,an  
outer tough white coat1 of connective   
tissue1 is called the sclerotic coat4   
,under the sclerotic coat1 in front1 the
 eye bulges outward a little4 ,here the 
outer coat is continuous with a         
transparent tough layer called the      
cornea4 ,a second coat1 the choroid1 is 
supplied with blood vessels and cells   
which bear pigments4 ,it is a part of   
this coat which we see through the      
cornea as the colored part of the eye   
7the iris74 ,in the center of the iris  
is a small circular hole 7the pupil74   

,the iris is under the control of       
muscles1 and may be adjusted to varying 
amounts of light1 the hole becoming     
larger in dim light1 and smaller in     
bright light4 ,the inmost layer of the  
eye is called the retina4 ,this is1     
perhaps1 the most delicate layer in the 
entire body4 ,despite the fact that the 
retina is less than #a_/hj of an inch in
 thickness1 there are several layers of 
cells in its composition4 ,the optic    
nerve enters the eye from behind and    
spreads out to form the surface of the  
retina4 ,its finest fibers are          
ultimately connected with numerous      
elongated cells which are stimulated by 
light4 ,the retina is dark purple in    
color1 this color being caused by a     
layer of cells next to the choroid coat4
 ,this accounts for the black appearance
 of the pupil of the eye1 when we look  
through the pupil into the darkened     
space within the eyeball4 ,the retina   
acts as the sensitized plate in the     
camera1 for on it are received the      

impressions which are transformed and   
sent to the brain as sensations of      
sight4 ,the eye1 like the camera1 has a 
lens4 ,this lens is formed of           
transparent1 elastic material4 ,it is   
found directly behind the iris and is   
attached to the choroid coat by means of
 delicate ligaments4 ,in front of the   
lens is a small cavity filled with a    
watery fluid1 the aqueous humor1 while  
behind it is the main cavity of the eye1
 filled with a transparent1 almost      
jellylike1 vitreous humor4 ,the lens    
itself is elastic4 ,this circumstance   
permits of a change of form and1 in     
consequence1 a change of focus upon the 
retina of the lens4 ,by means of this   
change in form1 or accommodation1 we are
 able to distinguish between near and   
distant objects4  ,illustration3 ,how   
far away can you read these letters8    
,measure the distance4 ,twenty feet is a
 test for the normal eye4  ,defects in  
the ,eye4--,in some eyes1 the lens is in
 focus for near objects1 but is not     

easily focused upon distant objects2    
such an eye is said to be nearsighted4  
,other eyes which do not focus clearly  
on objects near at hand are said to be  
farsighted4 ,still another eye defect is
 astigmatism1 which causes images of    
lines in a certain direction to be      
indistinct1 while images of lines       
transverse to the former are distinct4  
,many nervous troubles1 especially      
headaches1 may be due to eye strain4 ,we
 should have our eyes examined from time
 to time1 especially if we are subject  
to headaches4  ,the ,alcohol            
,question4--,it is agreed by            
investigators that in large or continued
 amounts alcohol has a narcotic effect2 
that it first dulls or paralyzes the    
nerve centers which control our         
judgment1 and later acts upon the       
so-called motor centers1 those which    
control our muscular activities4  ,the  
reason1 then1 that a man in the first   
stages of intoxication talks rapidly and
 sometimes wittily1 is because the      

centers of judgment are paralyzed4 ,this
 frees the speech centers from control  
exercised by our judgment1 with the     
resultant rapid and free flow of speech4
  ,in small amounts alcohol is believed 
by some physiologists to have always    
this same narcotic effect1 while other  
physiologists think that alcohol does   
stimulate the brain centers1 especially 
the higher centers1 to increased        
activity4 ,some scientific and          
professional men use alcohol in small   
amounts for this stimulation and report 
no seeming harm from the indulgence4    
,others1 and by far the larger number1  
agree that this stimulation from alcohol
 is only apparent and that even in the  
smallest amounts alcohol has a narcotic 
effect4  ,the ,paralyzing ,effects of   
,alcohol on the ,nervous                
,system4--,alcohol has the effect of    
temporarily paralyzing the nerve        
centers4 ,the first effect is that of   
exhilaration4 ,a man may do more work   
for a time under the stimulation of     

alcohol4 ,this stimulation1 however1 is 
of short duration and is invariably     
followed by a period of depression and  
inertia4 ,in this latter state1 a man   
will do less work than before4 ,in      
larger quantities1 alcohol has the      
effect of completely paralyzing the     
nerve centers4 ,this is seen in the case
 of a man dead drunk4 ,he falls in a    
stupor because all of the centers       
governing speech1 sight1 locomotion1    
etc41 have been temporarily paralyzed4  
,if a man takes a very large amount of  
alcohol1 even the nerve centers         
governing respiration and circulation   
may become poisoned1 and the victim will
 die4  ,effect on the ,organs of        
,special ,sense4--,professor ,forel1 one
 of the foremost ,european experts on   
the question of the effect of alcohol on
 the nervous system1 says3 ,through all 
parts of nervous activity from the      
innervation of the muscles and the      
simplest sensation to the highest       
activity of the soul the paralyzing     

effect of alcohol can be demonstrated4  
,several experimenters of undoubted     
ability have noted the paralyzing effect
 of alcohol even in small doses4 ,by the
 use of delicate instruments of         
precision1 ,ridge tested the effect of  
alcohol on the senses of smell1 vision1 
and muscular sense of weight4 ,he found 
that two drams of absolute alcohol      
produced a positive decrease in the     
sensitiveness of the nerves of feeling1 
that so small a quantity as one half    
dram of absolute alcohol diminished the 
power of vision and the muscular sense  
of weight4 ,kraepelin and ,kurz by      
experiment determined that the acuteness
 of the special senses of sight1        
hearing1 touch1 taste1 and smell was    
diminished by an ounce of alcohol1 the  
power of vision being lost to one third 
of its extent and a similar effect being
 produced on the other special senses4  
,other investigators have reached like  
conclusions4 ,there is no doubt but that
 alcohol1 even in small quantities1     

renders the organs of sense less        
sensitive and therefore less accurate4  
,illustration3 ,table to show a         
comparison of chances of illness and    
death in drinkers and non-drinkers4     
,solid black1 drinkers4 7,from ,german  
sources47  ,effect of ,alcohol on the   
,ability to ,resist ,disease4--,among   
certain classes of people the belief    
exists that alcohol in the form of      
brandy or some other drink or in patent 
medicines1 malt tonics1 and the like is 
of great importance in building up the  
body so as to resist disease or to cure 
it after disease has attacked it4       
,nothing is further from the truth4 ,in 
experiments on a large number of        
animals1 including dogs1 rabbits1 guinea
 pigs1 fowls1 and pigeons1 ,laitenen1 of
 the ,university of ,helsingsfors1 found
 that alcohol1 without exception1 made  
these animals more susceptible to       
disease than were the controls4  ,one of
 the most serious effects of alcohol is 
the lowered resistance of the body to   

disease4 ,it has been proved that a much
 larger proportion of hard drinkers die 
from infectious or contagious diseases  
than from special diseased conditions   
due to the direct action of alcohol on  
the organs of the body4 ,this lowered   
resistance is shown in increased        
liability to contract disease and       
increased severity of the disease4 ,we  
have already alluded to the findings of 
insurance companies with reference to   
the length of life--the abstainers from 
alcohol have a much better chance of a  
longer life and much less likelihood of 
infection by disease germs4  ,use of    
,alcohol in the ,treatment of           
,disease4--,in the ,london ,temperance  
,hospital alcohol was prescribed        
seventy-five times in thirty-three      
years4 ,the death rate in this hospital 
has been lower than that of most general
 hospitals4 ,sir ,william ,collins1     
after serving nineteen years as surgeon 
in this hospital1 said3--       ,in my  
experience1 speaking as a surgeon1 the  

use of alcohol      is not essential for
 successful surgery4444 ,at the ,london 
,temperance ,hospital1 where alcohol is 
very rarely      prescribed1 the        
mortality in amputation cases and in    
operation cases generally is remarkably 
low4 ,total      abstainers are better  
subjects for operation1 and recover     
more rapidly from accidents1 than those 
who habitually take      stimulants4    
,in a paper read at the ,international  
,congress on ,tuberculosis1 in ,new     
,york1 #aijf1 ,dr4 ,crothers remarked   
that alcohol as a remedy or a preventive
 medicine in the treatment of           
tuberculosis is a most dangerous drug1  
and that all preparations of sirups     
containing spirits increase1 rather than
 diminish1 the disease4  ,dr4 ,kellogg  
says3 ,the paralyzing influence of      
alcohol upon the white cells of the     
blood--a fact which is attested by all  
investigators--is alone sufficient to   
condemn the use of this drug in acute or
 chronic infections of any sort4        

,illustration3 ,effect of use of alcohol
 on memory4  ,the ,effect of ,alcohol   
upon ,intellectual ,ability4--,with     
regard to the supposed quickening of the
 mental processes ,horsley and ,sturge1 
in their recent book1 ,alcohol and the  
,human ,body1 say3       ,kraepelin     
found that the simple reaction period1  
by which      is meant the time occupied
 in making a mere response to a         
signal1 as1 for instance1 to the sudden 
appearance of a      flag1 was1 after   
the ingestion of a small quantity of    
alcohol 7#a_/d to #a_/b ounce71 slightly
 accelerated2 that there      was1 in   
fact1 a slight shortening of the time1  
as though the      brain were enabled to
 operate more quickly than before4 ,but 
he found that after a few minutes1 in   
most cases1 a slowing      of mental    
action began1 becoming more and more    
marked1 and      enduring as long as the
 alcohol was in active operation in     
the body1 i4e4 four to five hours4444   
,kraepelin found that      it was only  

more or less automatic work1 such as    
reading      aloud1 which was quickened 
by alcohol1 though even this was        
rendered less trustworthy and accurate4 
,again3 ,kraepelin      had always      
shared the popular belief that a small  
quantity      of alcohol 7one to two    
teaspoonfuls7 had an accelerating       
effect on the activity of his mind1     
enabling him to perform      test       
operations1 as the adding and           
subtracting and learning      of figures
 more quickly4 ,but when he came to     
measure with      his instruments the   
exact period and time occupied1 he      
found1 to his astonishment1 that he had 
accomplished these      mental          
operations1 not more1 but less1 quickly 
than      before4444 ,numerous further  
experiments were carried out in         
order to test this matter1 and these    
proved that alcohol      lengthens the  
time taken to perform complex mental    
processes1 while by a singular illusion 
the person      experimented upon       

imagines that his psychical actions are 
rendered more rapid4  ,illustration3    
,the effect of alcohol upon ability to  
do mental work4  ,attention--that is1   
the power of the mind to grasp and      
consider impressions obtained through   
the senses--is weakened by drink4 ,the  
ability of the mind to associate or     
combine ideas1 the faculty involved in  
sound judgment1 showed that when the    
persons had taken the amounts of alcohol
 mentioned1 the combinations of ideas or
 judgments expressed by them were       
confused1 foggy1 sentimental1 and       
general4 ,when the persons had taken no 
alcohol1 their judgments were rational1 
specific1 keen1 showing closer          
observation4       ,the words of        
,professor ,helmholtz at the celebration
 of his      seventieth birthday are    
very interesting in this connection4    
,he spoke of the ideas flashing up from 
the depths of the      unknown soul1    
that lies at the foundation of every    
truly      creative intellectual        

production1 and closed his account of   
their origin with these words3 ',the    
smallest quantity of an      alcoholic  
beverage seemed to frighten these ideas 
away4'--,,dr4 ,g4 ,,sims ,,woodhead1    
,professor of ,pathology1               
,cambridge ,university1 ,england4       
,professor ,von ,bunge 7,textbook of    
,physiological and ,pathological        
,chemistry7 of ,switzerland says that3  
,the stimulating action which alcohol   
appears to exert on      the brain      
functions is only a paralytic action4   
,the cerebral      functions which are  
first interfered with are the power of  
clear judgment and reason4 ,no man ever 
became witty by aid      of spirituous  
drinks4 ,the lively gesticulations and  
useless      exertions of intoxicated   
people are due to paralysis1--the       
restraining influences1 which prevent a 
sober man from      uselessly expending 
his strength1 being removed4  ,the      
,drink ,habit4--,the harmful effects of 
alcohol 7aside from the purely          

physiological effect upon the tissues   
and organs of the body7 are most        
terribly seen in the formation of the   
alcohol habit4 ,the first effect of     
drinking alcoholic liquors is that of   
exhilaration4 ,after the feeling of     
exhilaration is gone1 for this is a     
temporary state1 the subject feels      
depressed and less able to work than    
before he took the drink4 ,to overcome  
this feeling1 he takes another drink4   
,the result is that before long he finds
 a habit formed from which he cannot    
escape4 ,with body and mind weakened1 he
 attempts to break off the habit4 ,but  
meanwhile his will1 too1 has suffered   
from overindulgence4 ,he has become a   
victim of the drink habit6       ,the   
capital argument against alcohol1 that  
which must      eventually condemn its  
use1 is this1 that it takes away all    
the reserved control1 the power of      
mastership1 and therefore      offends  
against the splendid pride in himself or
 herself1      which is fundamental in  

every man or woman worth                
anything4--,,dr4 ,,john ,,johnson1      
quoting ,walt ,whitman4                 
,self-indulgence1 be it in gratification
 of such a simple desire as that for    
candy or the more harmful indulgence in 
tobacco or alcoholic beverages1 is      
dangerous--not only in its immediate    
effects on the tissues and organs1 but  
in its more far-reaching effects on     
habit formation4 ,each one of us is a   
bundle of appetites4 ,if we gratify     
appetites of the wrong kind1 we are     
surely laying the foundation for the    
habit of excess4 ,self-denial is a good 
thing for each of us to practice at one 
time or another1 if for no other purpose
 than to be ready to fight temptation   
when it comes4  ,the ,economic ,effect  
of ,alcoholic ,poisoning4--,in the      
struggle for existence1 it is evident   
that the man whose intellect is the     
quickest and keenest1 whose judgment is 
most sound1 is the man who is most      
likely to succeed4 ,the paralyzing      

effect of alcohol upon the nerve centers
 must place the drinker at a            
disadvantage4 ,in a hundred ways1 the   
drinker sooner or later feels the       
handicap that the habit of drink has    
imposed upon him4 ,many corporations1   
notably several of our greatest         
railroads 7the ,pennsylvania and the    
,new ,york ,central ,railroad among     
them71 refuse to employ any but         
abstainers in positions of trust4 ,few  
persons know the number of railway      
accidents due to the uncertain eye of   
some engineer who mistook his signal1 or
 the hazy inactivity of the brain of    
some train dispatcher who1 because of   
drink1 forgot to send the telegram that 
was to hold the train from wreck4 ,in   
business and in the professions1 the    
story is the same4 ,the abstainer wins  
out over the drinking man4  ,effect of  
,alcohol on ,ability to do ,work4--,in  
,physiological ,aspects of the ,liquor  
,problem1 ,professor ,hodge1 formerly of
 ,clark ,university1 describes many of  

his own experiments showing the effect  
of alcohol on animals4 ,he trained four 
selected puppies to recover a ball      
thrown across a gymnasium4 ,to two of   
the dogs he gave food mixed with doses  
of alcohol1 while the others were fed   
normally4 ,the ball was thrown #ajj feet
 as rapidly as recovered4 ,this was     
repeated #ajj times each day for        
fourteen successive days4 ,out of #adjj 
times the dogs to which alcohol had been
 given brought back the ball only #dgh  
times1 while the others secured it #ibb 
times4  ,dr4 ,parkes experimented with  
two gangs of men1 selected to be as     
nearly similar as possible1 in mowing4  
,he found that with one gang abstaining 
from alcoholic drinks and the other not1
 the abstaining gang could accomplish   
more4 ,on transposing the gangs1 the    
same results were repeatedly obtained4  
,similar results were obtained by       
,professor ,aschaffenburg of ,heidelberg
 ,university1 who found experimentally  
that men were able to do #ae per cent   

less work after taking alcohol4         
,recently many experiments along the    
same lines have been made4 ,in          
typewriting1 in typesetting1 in         
bricklaying1 or in the highest type of  
mental work the result is the same4 ,the
 quality and quantity of work done on   
days when alcohol is taken is less than 
on days when no alcohol is taken4  ,the 
,relation of ,alcohol to                
,efficiency4--,we have already seen that
 work is neither so well done nor is as 
much accomplished by drinkers as by     
non-drinkers4  ,a ,massachusetts shoe   
manufacturer told a recent writer on    
temperance that in one year his firm    
lost over #ejjj in shoes spoiled by     
drinking men1 and that he had himself   
traced these spoiled shoes to the       
workmen who1 through their use of       
alcoholic liquors1 had thus rendered    
themselves incapable4 ,this is a serious
 handicap to our modern factory system1 
and explains why so many factory towns  
and cities are strongly favoring a      

policy of ,no license in opposition to  
the saloons4  ,it is believed that the  
largest number of accidents in shops and
 mills takes place on ,monday1 because  
the alcohol that is drunk on ,sunday    
takes away the skill and attentive care 
of the workman4 ,to prove the truth of  
this opinion1 the accidents of the      
building trades in ,zurich were studied 
during a period of six years1 with the  
result shown by this table3--           
,illustration3 ,shaded1 non-alcoholic2  
black1 alcoholic1 accidents4 7,from     
,tolman1 ,hygiene for the ,worker47     
,another relation to efficiency is shown
 by the following chart4 ,during the    
week the curve of working efficiency is 
highest on ,friday and lowest on        
,monday4 ,the number of accidents were  
also least on ,friday and greatest on   
,monday4 ,lastly the assaults were      
fewest in number on ,friday and greatest
 on ,sunday and ,monday4 ,the moral is  
plain4 ,workingmen are apt to spend     
their week's wages freely on ,saturday4 

,much of this goes into drink1 and as a 
result comes crime on ,sunday because of
 the deadened moral and mental condition
 of the drinker1 and loss of efficiency 
on ,monday1 because of the poisonous    
effects of the drug4  ,illustration3    
,notice that the curve of efficiency is 
lowest on ,monday and that crimes and   
accidents are most frequent on ,sunday  
and ,monday4 ,account for this4  ,effect
 of ,alcohol upon ,duration of          
,life4--,still more serious is the      
relation of alcohol as a direct cause of
 disease 7see table74  ,it is as yet    
quite impossible1 in the ,united ,states
 at least1 to tell just how many deaths 
are brought about1 directly or          
indirectly1 by alcohol4 ,especially is  
this true in trying to determine the    
number of cases of deaths from disease  
promoted by alcohol4 ,in ,switzerland   
provision is made for learning these    
facts1 and the records of that country  
throw some light on the subject4  ,dr4  
,rudolph ,pfister made a study of the   

records of the city of ,basle for the   
years #ahib-aijf1 finding the percentage
 of deaths in which alcohol had been    
reported by the attending physician as  
one cause of death4 ,he found that #ah4a
 per cent of all deaths of men between  
#dj and #ej years of age were caused1 in
 part at least1 by alcohol1 and this at 
what should be the most active period in
 a man's life1 the time when he is most 
needed by his family and community4     
,taking all ages between #bj and #hj1 he
 found that alcohol was one cause of    
death in one man in every ten who died4 
,illustration  ,another study was made  
by a certain doctor in ,sweden1 from    
records of #ajhb deaths occurring in his
 own practice and the local hospital4   
,no case was counted as alcoholic of    
which there was the slightest doubt4 ,of
 deaths of adult men1 #ah in every #ajj 
were due1 directly or indirectly1 to    
alcoholism4 ,in middle life1 between the
 ages of #dj and #ej1 #bi2 and between  
#ej and #fj years of age1 #be4f out of  

every #ajj deaths had alcohol as one    
cause1 thus agreeing with other         
statistics we have been quoting4--,from 
the ,metropolitan1 ,vol4 ,,xxv1 ,number 
#aa4  ,illustration3 ,the proportion of 
crime due to alcohol is shown in black4 
,the ,relation of ,alcohol to           
,crime4--,a recent study of more than   
#bejj habitual users of alcohol showed  
that over #ff per cent had committed    
crime4 ,usually the crimes had been done
 in saloons or as a result of quarrels  
after drinking4 ,of another lot of      
#bc1eha criminals questioned1 #bj1jgj   
said that alcohol had led them to commit
 crime4  ,the ,relation of ,alcohol to  
,pauperism4--,we have already spoken of 
the ,jukes family4 ,these and many other
 families of a similar sort are more or 
less directly a burden upon the state4  
,alcohol is in part at least responsible
 for the condition of such families4    
,alcohol weakens the efficiency and     
moral courage1 and thus leads to        
begging1 pauperism1 petty stealing or   

worse1 and ultimately to life in some   
public institution4 ,in ,massachusetts1 
of #cbcj inmates of such institutions1  
#ff per cent were alcoholics4  ,the     
,relation of ,alcohol to                
,heredity4--,perhaps the gravest side of
 the alcohol question lies here4 ,if    
each one of us had only himself to think
 of1 the question of alcohol might not  
be so serious4 ,but drinkers may hand   
down to their unfortunate children      
tendencies toward drink as well as      
nervous diseases of various sorts2 an   
alcoholic parent may beget children who 
are epileptic1 neurotic1 or even insane4
  ,in the ,state of ,new ,york there are
 at the present time some #cj1jjj insane
 persons in public and private          
hospitals4 ,it is believed that about   
one fifth of them1 or #fjjj patients1   
owe their insanity to alcohol used      
either by themselves or by their        
parents4 ,in the asylums of the ,united 
,states there are #aej1jjj insane       
people4 ,taking the same proportions as 

before1 there are #cj1jjj persons in    
this country whom alcohol has made or   
has helped to make insane4 ,this is the 
most terrible side of the alcohol       
problem4                                
,,reference ,,reading                   
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,overton1 ,general 
,hygiene4 ,american ,book ,company4     
,the ,gulick ,hygiene ,series1          
,emergencies1 ,good ,health1 ,the       
,body at ,work1 ,control of ,body and   
,mind4 ,ginn and ,company4              
,ritchie1 ,human ,physiology4 ,world    
,book ,company4      ,hough and         
,sedgwick1 ,the ,human ,mechanism4 ,ginn
 and ,company4     ,,xxiv4 ,,man',s     
,,improvement ,,of ,,his ,,environment  
,problems4--,how may we improve our home
 conditions of living8            ,how  
may we help improve our conditions at   
school8            ,how does the city   
care for the improvement of our         
environment8              7a7 ,in       

inspection of buildings1 etc4           
7b7 ,in inspection of food supplies4    
7c7 ,in inspection of milk4             
7d7 ,in care of water supplies4         
7e7 ,in disposal of wastes4             
7f7 ,in care of public health4          
,,laboratory ,,suggestions       ,home  
exercise4--,how to ventilate my bedroom4
      ,demonstration4--,effect of use of
 duster and damp cloth        upon      
bacteria in schoolroom4      ,home      
exercise4--,luncheon dietaries4         
,home exercise4--,sanitary map of my own
 block4      ,demonstration4--,the      
bacterial content of milk of various    
grades and from different sources4      
,demonstration4--,bacterial content of  
distilled water1 rain        water1 tap 
water1 dilute sewage4      ,laboratory  
exercise4--,study of board of health    
tables to        plot curves of         
mortality from certain diseases during  
certain times of year4   ,the ,purpose  
of this ,chapter4--,in the preceding    
chapters we have traced the lives of    

both plants and animals within their own
 environment4 ,we have seen that man1 as
 well as plants and other animals1 needs
 a favorable environment in order to    
live in comfort and health4 ,it will be 
the purpose of the following pages first
 to show how we as individuals may      
better our home environment1 and        
secondly1 to see how we may aid the     
civic authorities in the betterment of  
conditions in the city in which we live4
  ,illustration3 ,how ,i should         
ventilate my bedroom4  ,home            
,conditions4--,the ,bedroom4--,we spend 
about one third of our total time in our
 bedroom4 ,this room1 therefore1        
deserves more than passing attention4   
,first of all1 it should have good      
ventilation4 ,two windows make an ideal 
condition1 especially if the windows    
receive some sun4 ,such a condition as  
this is manifestly impossible in a      
crowded city1 where too often the       
apartment bedrooms open upon narrow and 
ill-ventilated courts4 ,until           

comparatively recent time1 tenement     
houses were built so that the bedrooms  
had practically no light or air2 now1   
thanks to good tenement-house laws1 wide
 airshafts and larger windows are       
required by statute4  ,care of the      
,bedroom4--,since sunlight cannot always
 be obtained for a bedroom1 we must so  
care for and furnish the room that it   
will be difficult for germs to grow     
there4 ,bedroom furniture should be     
light and easy to clean1 the bedstead of
 iron1 the floors painted or of         
hardwood4 ,no hangings should be allowed
 at the windows to collect dust1 nor    
should carpets be allowed for the same  
reason4 ,rugs on the floor may easily be
 removed when cleaning is done4 ,the    
furniture and woodwork should be wiped  
with a damp cloth every day4 ,why a damp
 cloth8 ,in certain tenements in ,new   
,york ,city1 tuberculosis is believed to
 have been spread by people occupying   
rooms in which a previous tenant has had
 tuberculosis4 ,a new tenant should     

insist on a thorough cleaning of the    
bedrooms and removal of old wall paper  
before occupancy4  ,sunlight            
,important4--,in choosing a house in the
 country we would take a location in    
which the sunlight was abundant4 ,a     
shaded location might be too damp for   
health4 ,sunlight should enter at least 
some of the rooms4 ,in choosing an      
apartment we should have this matter in 
mind1 for1 as we know1 germs cannot long
 exist in sunlight4  ,illustration3     
,this map shows how cases of            
tuberculosis are found recurring in the 
same locality and in the same houses    
year after year4 ,each black dot is one 
case of tuberculosis4                   
,heating4--,houses in the country are   
often heated by open fires1 stoves or   
hot-air furnaces1 all of which make use 
of heated currents of air to warm the   
rooms4 ,but in the city apartments1     
usually pipes conduct steam or hot water
 from a central plant to our rooms4 ,the
 difficulty with this system is that it 

does not give us fresh air1 but warms   
over the stale air in a room4 ,steam    
causes our rooms to be too warm part of 
the time1 and not warm enough part of   
the time4 ,thus we become overheated and
 then take cold by becoming chilled4    
,steam heat is thus responsible for much
 sickness4  ,lighting4--,lighting our   
rooms is a matter of much importance4 ,a
 student lamp1 or shaded incandescent   
light1 should be used for reading4      
,shades must be provided so that the    
eyes are protected from direct light4   
,gas is a dangerous servant1 because it 
contains a very poisonous substance1    
carbon monoxide4 ,it is estimated that  
#ad per cent of the total product of the
 gas plant leaks into the streets and   
houses of the cities supplied4 ,this    
forms an unseen menace to the health in 
cities4 ,gas pipes1 and especially gas  
cocks1 should be watched carefully for  
escaping gas4 ,rubber tubing should not 
be used to conduct gas to movable gas   
lamps1 because it becomes worn and      

allows gas to escape4  ,illustration3   
,during the summer all food should be   
protected from flies4 ,why8  ,insects   
and ,foods4--,in the summer our houses  
should be provided with screens4 ,all   
food should be carefully protected from 
flies4 ,dirty dishes1 scraps of food1   
and such garbage should be quickly      
cleaned up and disposed of after a meal4
 ,insect powder 7pyrethrum7 will help   
keep out croton bugs and other          
undesirable household pests1 but        
cleanliness will do far more4 ,most     
kitchen pests1 as the roach1 simply stay
 with us because they find dirt and food
 abundant4  ,use of ,ice4--,food should 
be properly cared for at all times1 but 
especially during the summer4 ,iceboxes 
are a necessity1 especially where       
children live1 in order to keep milk    
fresh4 ,a dirty icebox is almost as bad 
as none at all1 because food will decay 
or take on unpleasant odors from other  
foods4  ,illustration3 ,the wrong and   
the right kind of garbage cans4         

,disposal of ,wastes4--,in city houses  
the disposal of human wastes is provided
 for by a city system of sewers4 ,the   
wastes from the kitchen1 the garbage1   
should be disposed of each day4 ,the    
garbage pail should be frequently       
sterilized by rinsing it with boiling   
water4 ,plenty of lye or soap should be 
used4 ,remember that flies frequent the 
uncovered garbage pail1 and that they   
may next walk on your food4 ,collection 
and disposal of garbage is the work of  
the municipality4  ,illustration3 ,the  
culture 7,a7 was exposed to the air of a
 dirty street in the crowded part of    
,manhattan4 7,b7 was exposed to the air 
of a well-cleaned and watered street in 
the uptown residence portion4 ,which    
culture has the more colonies of        
bacteria8 ,how do you account for this8 
,school ,surroundings4--,how to ,improve
 ,them4--,from five to six hours a day  
for forty weeks is spent by the average 
boy or girl in the schoolroom4 ,it is   
part of our environment and should      

therefore be considered as worthy of our
 care4 ,not only should a schoolroom be 
attractive1 but it should be clean and  
sanitary4 ,city schools1 because of     
their locations1 of the sometimes poor  
janitorial service1 and especially      
because of the selfishness and          
carelessness of children who use them1  
may be very dirty and unsanitary4 ,dirt 
and dust breed and carry bacteria4      
,plate cultures show greatly increased  
numbers of bacteria to be in the air    
when pupils are moving about1 for then  
dust1 bearing bacteria1 is stirred up   
and circulated through the air4         
,sweeping and dusting with dry brooms or
 feather dusters only stirs up the dust1
 leaving it to settle in some other     
place with its load of bacteria4        
,professor ,hodge tells of an experience
 in a school in ,worcester1 ,mass4 ,a   
health brigade was formed among the     
children1 whose duty was to clean the   
rooms every morning by wiping all       
exposed surface with a damp cloth4 ,in a

 school of #dbe pupils not a single case
 of contagious diseases appeared during 
the entire year4 ,why not try this in   
your own school8  ,unselfishness the    
,motto4--,pupils should be unselfish in 
the care of a school building4 ,papers  
and scraps dropped by some careless boy 
or girl make unpleasant the surroundings
 for hundreds of others4 ,chalk thrown  
by some mischievous boy and then tramped
 underfoot may irritate the lungs of a  
hundred innocent schoolmates4 ,colds or 
worse diseases may be spread through the
 filthy habits of some boys who spit in 
the halls or on the stairways4  ,lunch  
,time and ,lunches4--,if you bring your 
own lunch to school1 it should be clean1
 tasty1 and well balanced as a ration4  
,in most large schools well-managed     
lunch rooms are part of the school      
equipment1 and balanced lunches can be  
obtained at low cost4 ,do not make a    
lunch entirely from cold food1 if hot   
can be obtained4 ,do not eat only       
sweets4 ,ice cream is a good food1 if   

taken with something else1 but be sure  
of your ice cream4 ,hokey pokey cream1  
tested in a ,new ,york school           
laboratory1 showed the presence of many 
more colonies of bacteria than good milk
 would show4 ,above all1 be sure the    
food you buy is clean4 ,stands on the   
street1 exposed to dust and germs1 often
 sell food far from fit for human       
consumption4  ,illustration3 ,a sensible
 lunch box1 sanitary and compact4  ,if  
you eat your lunch on the street near   
your school1 remember not to scatter    
refuse4 ,paper1 bits of lunch1 and the  
like scattered on the streets around    
your school show lack of school spirit  
and lack of civic pride4 ,let us learn  
above all other things to be good       
citizens4  ,illustration3 ,dust exhausts
 on grinding wheels protect lungs of the
 workmen4  ,inspection of ,factories1   
,public ,buildings1 etc4--,it is the    
duty of a city to inspect the condition 
of all public buildings and especially  
of factories4 ,inspection should        

include1 first1 the supervision of the  
work undertaken4 ,certain trades where  
grit1 dirt1 or poison fumes are given   
off are dangerous to human health1 hence
 care for the workers becomes a         
necessity4 ,factories should also be    
inspected as to cleanliness1 the amount 
of air space per person employed1       
ventilation1 toilet facilities1 and     
proper fire protection4 ,tenement       
inspection should be thorough and should
 aim to provide safe and sanitary homes4
  ,inspection of ,food ,supplies4--,in a
 city certain regulations for the care  
of public supplies are necessary4       
,foods1 both fresh and preserved1 must  
be inspected and rendered safe for the  
thousands of people who are to use them4
 ,all raw foods exposed on stands should
 be covered so as to prevent insects or 
dust laden with bacteria from coming in 
contact with them4 ,meats must be       
inspected for diseases1 such as         
tuberculosis in beef1 or trichinosis in 
pork4 ,cold storage plants must be      

inspected to prevent the keeping of food
 until it becomes unfit for use4        
,inspection of sanitary conditions of   
factories where products are canned1 or 
bakeries where foods are prepared1 must 
be part of the work of a city in caring 
for its citizens4  ,care of ,raw        
,foods4--,each one of us may cooperate  
with the city government by remembering 
that fruits and vegetables can be       
carriers of disease1 especially if they 
are sold from exposed stalls or carts   
and handled by the passers-by4 ,all     
vegetables1 fruits1 or raw foods should 
be carefully washed before using4       
,spoiled or overripe fruit1 as well as  
meat which is decayed1 is swarming with 
bacteria and should not be used4  ,an   
interesting exercise would be the       
inspection of conditions in your own    
home block4 ,make a map showing the     
houses on the block4 ,locate all stores1
 saloons1 factories1 etc4 ,notice any   
cases of contagious disease1 marking    
this fact on the map4 ,mark all heaps of

 refuse in the street1 all uncovered    
garbage pails1 any street stands that   
sell uncovered fruit1 and any stores    
with an excessive number of flies4  ,in 
addition to food inspection1 two very   
important supplies must be rendered safe
 by a city for its citizens4 ,these are 
milk and water4  ,illustration3 ,clean  
cows in clean barns with clean milkers  
and clean milk pails means clean milk in
 the city4  ,care in ,production of     
,milk4--,milk when drawn from a healthy 
cow should be free from bacteria4 ,but  
immediately on reaching the air it may  
receive bacteria from the air1 from the 
hands of the person who milks the cows1 
from the pail1 or from the cow herself4 
,cows should1 therefore1 be milked in   
surroundings that are sanitary1 the     
milkers should wear clean garments1 put 
on over their ordinary clothes at       
milking time1 while pails and all       
utensils used should be kept clean4     
,especially the surface exposed on the  
udder from which the milk is drawn      

should be cleansed before milking4      
,most large cities now send inspectors  
to the farms from which milk is         
supplied4 ,farms that do not accept     
certain standards of cleanliness are not
 allowed to have their milk become part 
of the city supply4  ,tuberculosis and  
,milk4--,it is recognized that in some  
,european countries from #cj to #dj per 
cent of all cattle have tuberculosis4   
,many dairy herds in this country are   
also infected4 ,it is also known that   
the tubercle bacillus of cattle and man 
are much alike in form and action and   
that probably the germ from cattle would
 cause tuberculosis in man4             
,fortunately1 the tuberculosis germ does
 not grow in milk1 so that even if milk 
from tubercular cattle should get into  
our supply1 it would be diluted with the
 milk of healthy cattle4 ,in order to   
protect our milk supply from these germs
 it would be necessary to kill all      
tubercular cattle 7almost an            
impossibility7 or to pasteurize our milk

 so as to kill the germs in it4  ,other 
,disease ,germs in ,milk4--,we have     
already shown how typhoid may be spread 
through milk4 ,usually such outbreaks   
may be traced to a single case of       
typhoid1 often a person who is a typhoid
 carrier1 i4e4 one who may not suffer   
from the effects of the disease1 but who
 carries the germs in his body1         
spreading them by contact4 ,a recent    
epidemic of typhoid in ,new ,york ,city 
was traced to a single typhoid carrier  
on a farm far from the city4 ,sometimes 
the milk cans may be washed in          
contaminated water or the cows may even 
get the germs on their udders by wading 
in a polluted stream4 ,diphtheria1      
scarlet fever1 and ,asiatic cholera are 
also undoubtedly spread through milk    
supplies4 ,milk also plays a very       
important part in the high death rate   
from diarrhoeal diseases among young    
children in warm weather4 ,why8         
,illustration3 ,a diagram to show how   
typhoid may be spread in a city through 

an infected milk supply4 ,the black     
spots in the blocks mean cases of       
typhoid4 ,a1 a farm where typhoid       
exists2 the dashes in the streets       
represent the milk route4 ,b is a second
 farm which sends part of its milk to   
,a2 the milk cans from ,b are washed at 
farm ,a and sent back to ,b4 ,a few     
cases of typhoid appear along ,b's milk 
route4 ,how do you account for that8    
,grades of ,milk in a ,city             
,supply4--,milk which comes to a city   
may be roughly placed in three different
 classes4 ,the best milk1 coming from   
farms where the highest sanitary        
standards exist1 where the cows are all 
tubercular tested1 where modern         
appliances for handling and cooling the 
milk exist1 is known as certified or1 in
 ,new ,york ,city1 grade ,a milk4 ,most 
of the milk sold1 however1 is not so    
pure nor is so much care taken in       
handling it4 ,such milk1 known in ,new  
,york as grade ,b milk1 is pasteurized  
before delivery1 and is sold only in    

bottles4 ,a still lower grade of milk   
7dipped milk7 is sold direct from cans4 
,it is evident that such milk1 often    
exposed to dust and other dirt1 is unfit
 for any purpose except for cooking4 ,it
 should under no circumstances be used  
for children4 ,a regulation recently    
made by the ,new ,york ,city ,department
 of ,health states that milk sold loose 
in restaurants1 lunch-rooms1 soda       
fountains1 and hotels must be           
pasteurized4  ,care of a ,city ,milk    
,supply4--,besides caring for milk in   
its production on the farm1 proper      
transportation facilities must be       
provided4 ,much of the milk used in ,new
 ,york ,city is forty-eight hours old   
before it reaches the consumer4 ,during 
shipment it must be kept in refrigerator
 cars1 and during transit to customers  
it should be iced4 ,why8 ,all but the   
highest grade milk should be            
pasteurized4 ,why8 ,milk should be      
bottled by machinery if possible so as  
to insure no personal contact2 it should

 be kept in clean1 cool places2 and no  
milk should be sold by dipping from     
cans4 ,why is this a method of          
dispensing impure milk8  ,care of ,milk 
in the ,home4--,finally1 milk at home   
should receive the best of care4 ,it    
should be kept on ice and in covered    
bottles1 because it readily takes up the
 odors of other foods4 ,if we are not   
certain of its purity or keeping        
qualities1 it should be pasteurized at  
home4 ,why8  ,illustration3 ,new ,york  
,city is spending #cej1jjj1jjj to have a
 pure and abundant water supply4 ,this  
is the tunnel which will bring the water
 from the ,catskill ,mountains to ,new  
,york ,city4  ,water ,supplies4--,one of
 the greatest assets to the health of a 
large city is pure water4 ,by pure water
 we mean water free from all organic    
impurities1 including germs4 ,water from
 springs and deep driven wells is the   
safest water1 that from large reservoirs
 next best1 while water that has        
drainage in it1 river water for example1

 is very unsafe4  ,the waters from deep 
wells or springs if properly protected  
will contain no bacteria4 ,water taken  
from protected streams into which no    
sewage flows will have but few bacteria1
 and these will be destroyed if exposed 
to the action of the sun and the        
constant aeration 7mixing with oxygen7  
which the surface water receives in a   
large lake or reservoir4 ,but water     
taken from a river into which the sewage
 of other towns and cities flows must be
 filtered before it is fit for use4     
,illustration3 ,the city of ,lowell in  
#ahia took its water without filtering1 
i4e4 from the ,merrimack ,river at the  
point shown on the map4  ,typhoid fever 
broke out in ,north ,chelmsford and     
about two weeks later cases began to    
appear in ,lowell until a great epidemic
 occurred4 ,explain this outbreak4 ,each
 black dot is a case of typhoid4        
,typhoid fever germs live in the food   
tube1 hence the excreta of a typhoid    
patient will contain large numbers of   

germs4 ,in a city with a system of      
sewage such germs might eventually pass 
from the sewers into a river4 ,many     
cities take their water supply directly 
from rivers1 sometimes not far below    
another large town4 ,such cities must   
take many germs into their water supply4
 ,many cities1 as ,cleveland and        
,buffalo1 take their water from lakes   
into which their sewage flows4 ,others1 
as ,albany1 ,pittsburgh1 and            
,philadelphia1 take their drinking water
 directly from rivers into which sewage 
from cities above them on the river has 
flowed4 ,filtering such water by means  
of passing the water through settling   
basins and sand filters removes about   
#ih per cent of the germs4 ,the result  
of drinking unfiltered and filtered     
water in certain large cities is shown  
graphically at right4 ,in cities which  
drain their sewage into rivers and      
lakes1 the question of sewage disposal  
is a large one1 and many cities now have
 means of disposing of their sewage in  

some manner as to render it harmless to 
their neighbors4  ,illustration3 ,filter
 beds at ,albany1 ,n4 ,y4               
,illustration3 ,cases of typhoid per    
#ajj1jjj inhabitants before filtering   
water supply 7solid7 and after 7shaded7 
in ,a1 ,watertown1 ,n4 ,y42 ,b1 ,albany1
 ,n4 ,y42 ,c1 ,lawrence1 ,mass42 ,d1    
,cincinnati1 ,ohio4 ,what is the effect 
of filtering the water supply8          
,railroads are often responsible for    
carrying typhoid and spreading it4 ,it  
is said that a recent outbreak of       
typhoid in ,scranton1 ,pa41 was due to  
the fact that the excreta from a typhoid
 patient traveling in a sleeping car was
 washed by rain into a reservoir near   
which the train was passing4 ,railroads 
are thus seen to be great open sewers4  
,a sanitary car toilet is the only      
remedy4  ,illustration3 ,this chart     
shows that during a cholera epidemic in 
#ahib there were hundreds of cases of   
cholera in ,hamburg1 which used         
unfiltered water from the ,elbe1 but in 

adjoining ,altona1 where filtered water 
was used1 the cases were very few4      
,illustration3 ,stone filter beds in a  
sewage disposal plant4  ,sewage         
,disposal4--,sewage disposal is an      
important sanitary problem for any city4
 ,some cities1 like ,new ,york1 pour    
their sewage directly into rivers which 
flow into the ocean4 ,consequently much 
of the liquid which bathes the shores of
 ,manhattan ,island is dilute sewage4   
,other cities1 like ,buffalo or         
,cleveland1 send their sewage into the  
lakes from which they obtain their      
supply of drinking water4 ,still other  
cities which are on rivers are forced to
 dispose of their sewage in various     
ways4 ,some have a system of filter beds
 in which the solid wastes are acted    
upon by the bacteria of decay1 so that  
they can be collected and used as       
fertilizer4 ,others precipitate or      
condense the solid materials in the     
sewage and then dispose of it4 ,another 
method is to flow the sewage over large 

areas of land1 later using this land for
 the cultivation of crops4 ,this method 
is used by many small ,european cities4 
,illustration3 ,collecting ashes4  ,the 
,work of the ,department of ,street     
,cleaning4--,in any city a menace to the
 health of its citizens exists in the   
refuse and garbage4 ,the city streets1  
when dirty1 contain countless millions  
of germs which have come from decaying  
material1 or from people ill with       
disease4 ,in most large cities a        
department of street cleaning not only  
cares for the removal of dust from the  
streets1 but also has the removal of    
garbage1 ashes1 and other waste as a    
part of its work4 ,the disposal of solid
 wastes is a tremendous task4 ,in       
,manhattan the dry wastes are estimated 
to be #a1jjj1jjj tons a year in addition
 to about #age1jjj tons of garbage4     
,prior to #ahie in the city of ,new     
,york garbage was not separated from    
ashes2 now the law requires that garbage
 be placed in separate receptacles from 

ashes4 ,do you see why8 ,the            
street-cleaning department should be    
aided by every citizen2 rules for the   
separation of garbage1 papers1 and ashes
 should be kept4 ,garbage and ash cans  
should be covered4 ,the practice of     
upsetting ash or garbage cans is one    
which no young citizen should allow in  
his neighborhood1 for sanitary reasons4 
,the best results in summer street      
cleaning are obtained by washing or     
flushing the streets1 for thus the dirt 
containing germs is prevented from      
getting into the air4 ,the garbage is   
removed in carts1 and part of it is     
burned in huge furnaces4 ,the animal and
 plant refuse is cooked in great tanks2 
from this material the fats are         
extracted1 and the solid matter is sold 
for fertilizer4 ,ashes are used for     
filling marsh land4 ,thus the removal of
 waste matter may pay for itself in a   
large city4  ,illustration3 ,the upper  
picture shows the stables where millions
 of flies were bred2 the lower picture1 

the disinfection of manure so as to     
prevent the breeding of flies4  ,an     
,experiment in ,civic ,hygiene4--,during
 the summer of #aiac an interesting     
experiment on the relation of flies and 
filth to disease was carried on in ,new 
,york ,city by the ,bureau of ,public   
,health and ,hygiene of the ,new ,york  
,association for improving the condition
 of the poor4 ,two adjoining blocks were
 chosen in a thickly populated part of  
the ,bronx near a number of stables     
which were the sources of great numbers 
of flies4 ,in one block all houses were 
screened1 garbage pails were furnished  
with covers1 refuse was removed and the 
surroundings made as sanitary as        
possible4 ,in the adjoining block       
conditions were left unchanged4 ,during 
the summer as flies began to breed in   
the manure heaps near the stables all   
manure was disinfected4 ,thus the       
breeding of flies was checked4 ,the     
campaign of education was continued     
during the summer by means of moving    

pictures1 nurses1 boy scouts1 and school
 children who became interested4  ,at   
the end of the summer it was found that 
there had been a considerable decrease  
in the number of cases of fly-carried   
diseases and a still greater decrease in
 the total days of sickness 7especially 
of children7 in the screened and        
sanitary block4 ,the table and pictures 
speak for themselves4 ,if such a small  
experiment shows results like this1 then
 what might a general clean-up of a city
 show8  ,illustration3 ,in the upper    
picture a little girl can be seen       
dumping garbage from the fire escape4   
,she was a foreigner and knew no better4
 ,the picture below shows the result of 
such garbage disposal4  ,public         
,hygiene4--,although it is absolutely   
necessary for each individual to obey   
the laws of health if he or she wishes  
to keep well1 it has also become        
necessary1 especially in large cities1  
to have general supervision over the    
health of people living in a community4 

,this is done by means of a department  
or board of health4 ,it is the function 
of this department to care for public   
health4 ,in addition to such a body in  
cities1 supervision over the health of  
its citizens is also exercised by state 
boards of health4 ,but as yet the       
government of the ,united ,states has   
not established a ,bureau of ,health1   
important as such a bureau would be4    
,the ,functions of a ,city ,board of    
,health4--,the administration of the    
,board of ,health in ,new ,york ,city   
includes a number of divisions1 each of 
which has a different work to do4 ,each 
is in itself important1 and1 working    
together1 the entire machine provides   
ways and means for making the great city
 a safe and sanitary place in which to  
live4 ,let us take up the work of each  
division of the health board in order to
 find out how we may cooperate with     
them4  ,illustration3 ,comparison of    
cases of illness during the summer of   
#aiac in two city blocks1 one clean and 

the other dirty4 ,what are your         
conclusions8  ,the ,division of         
,infectious ,diseases4--,infectious     
diseases are chiefly spread through     
personal contact4 ,it is the duty of a  
government to prevent a person having   
such a disease from spreading it        
broadcast among his neighbors4 ,this can
 be done by quarantine or isolation of  
the person having the disease4 ,so the  
board of health at once isolates any    
case of disease which may be            
communicated from one person to another4
 ,no one save the doctor or nurse should
 enter the room of the person           
quarantined4 ,after the disease has run 
its course1 the clothing1 bedding1 etc41
 in the sick room is fumigated4 ,this is
 usually done by the board of health4   
,formaldehyde in the form of candles for
 burning or in a liquid form is a good  
disinfectant4 ,in disinfecting the room 
should be tightly closed to prevent the 
escape of the gas used1 as the object of
 the disinfection is to kill all the    

disease germs left in the room4 ,in some
 cases of infectious disease1 as scarlet
 fever1 it is found best to isolate the 
patients in a hospital used for that    
purpose4 ,examples of the most          
infectious diseases are measles1 scarlet
 fever1 whooping cough1 and diphtheria4 
,immunity4--,in the prevention of germ  
diseases we must fight the germ by      
attacking the parasites directly with   
poisons that will kill them 7such       
poisons are called germicides or        
disinfectants71 and we must strive to   
make the persons coming in contact with 
the disease unlikely to take it4 ,this  
insusceptibility or immunity may be     
either natural or acquired4 ,natural    
immunity seems to be in the constitution
 of a person1 and may be inherited4     
,immunity may be acquired by means of   
such treatment as the antitoxin         
treatment for diphtheria4 ,this         
treatment1 as the name denotes1 is a    
method of neutralizing the poison       
7toxin7 caused by the bacteria in the   

system4 ,it was discovered a few years  
ago by a ,german1 ,von ,behring1 that   
the serum of the blood of an animal     
immune to diphtheria is capable of      
neutralizing the poison produced by the 
diphtheria-causing bacteria4 ,horses are
 rendered immune by giving them the     
diphtheria toxin in gradually increasing
 doses4 ,the serum of the blood of these
 horses is then used to inoculate the   
patient suffering from or exposed to    
diphtheria1 and thus the disease is     
checked or prevented altogether by the  
antitoxin injected into the blood4 ,the 
laboratories of the board of health     
prepare this antitoxin and supply it    
fresh for public use4  ,illustration3   
,antitoxin for diphtheria prepared by   
the ,new ,york ,board of ,health4  ,it  
has been found from experience in       
hospitals that deaths from diphtheria   
are largely preventable by early use of 
antitoxin4 ,when antitoxin was used on  
the first day of the disease no deaths  
took place4 ,if not used until the      

second day1 #e deaths occurred in every 
hundred cases1 on the third day #aa     
deaths1 on the #dth day #ai deaths1 and 
on the #eth day #bj deaths out of every 
hundred cases4 ,it is therefore         
advisable1 in a suspected case of       
diphtheria1 to have antitoxin used at   
once to prevent serious results4        
,vaccination4--,smallpox was once the   
most feared disease in this country2 #ie
 per cent of all people suffered from   
it4 ,as late as #ahih1 over #ej1jjj     
persons lost their lives annually in    
,russia from this disease4 ,it is       
probably not caused by bacteria1 but by 
a tiny animal parasite4 ,smallpox has   
been brought under absolute control by  
vaccination1--the inoculation of man    
with the substance 7called virus7 which 
causes cowpox in a cow4 ,cowpox is like 
a mild form of smallpox1 and the        
introduction of this virus gives        
complete immunity to smallpox for       
several years after vaccination4 ,this  
immunity is caused by the formation of a

 germicidal substance in the blood1 due 
to the introduction of the virus4       
,another function of the board of health
 is the preparation and distribution of 
vaccine 7material containing the virus  
of cowpox74  ,rabies                    
7,hydrophobia74--,this disease1 which is
 believed to be caused by a protozoan   
parasite1 is communicated from one dog  
to another in the saliva by biting4 ,in 
a similar manner it is transferred to   
man4 ,the great ,french bacteriologist1 
,louis ,pasteur1 discovered a method of 
treating this disease so that when taken
 early at the time of the entry of the  
germ into the body of man1 the disease  
can be prevented4 ,in some large cities 
7among them ,new ,york7 the board of    
health has established a laboratory     
where free treatment is given to all    
persons bitten by dogs suspected of     
having rabies4  ,vaccination against    
,typhoid4--,typhoid fever has within the
 past five years received a new check   
from vaccination which has been         

introduced into our army and which is   
being used with good effect by the      
health departments of several large     
cities4  ,the following figures show the
 differences between number of cases and
 mortality in the army in #ahih during  
the war with ,spain and in #aiaa during 
the concentration of certain of our     
troops at ,san ,antonio1 ,texas4        
#ahih--bnd ,division1 #gth ,army ,corps1
 ,jacksonville1 ,florida4               
,june-,october1 #ahih    ,mean strength1
 #aj1gei4   ,cases of typhoid certain   
and probable1 #bfic4   ,death from      
typhoid1 #beh4   ,death from all        
diseases1 #bha4    ,manoeuver ,division1
 ,san ,antonio1 ,texas4 ,march          
#aj-;,july #aa1 #aiaa4    ,mean         
strength1 #ab1hja4   ,cases of typhoid1 
#a4   ,death from typhoid1 #j4   ,deaths
 all diseases1 #aa4  ,illustration3     
,comparison of cases of and death from  
typhoid in #ahih and #aiaa4 ,what have  
we learned about combating typhoid since
 #ahih8  ,during this period there were 

#di cases of typhoid and #ai deaths in  
the near-by city of ,san ,antonio4 ,but 
in camp1 where vaccination for typhoid  
was required1 all were practically      
immune4 ,in the army at large1 since    
typhoid vaccination has been practiced1 
#aijh-aiji1 the death rate from typhoid 
has dropped from #b4i per #ajjj to 4#jc 
per #ajjj1 a wonderful record when we   
remember that during the                
,spanish-,american ,war #hf per cent of 
the deaths in the army were from typhoid
 fever4  ,illustration3 ,the best cures 
for tuberculosis are rest1 plenty of    
fresh out-of-door air1 and wholesome    
food4  ,illustration3 ,a sanitarium for 
tuberculosis4 ,notice the outdoor       
sleeping rooms4  ,how the ,board of     
,health fights                          
,tuberculosis4--,tuberculosis1 which a  
few years ago killed fully one seventh  
of the people who died from disease in  
this country1 now kills less than one   
tenth4 ,this decrease has been largely  
brought about because of the treatment  

of the disease4 ,since it has been      
proved that tuberculosis if taken early 
enough is curable1 by quiet living1 good
 food1 and plenty of fresh air and      
light1 we find that numerous sanitaria  
have come into existence which are      
supported by private or public means4   
,at these sanitaria the patients live   
out of doors1 especially sleep in the   
air1 while they have plenty of          
nourishing food and little exercise4    
,the department of health of ,new ,york 
,city maintains a sanitarium at         
,otisville in the ,catskill ,mountains4 
,here people who are unable to provide  
means for getting away from the city are
 cared for at the city's expense and a  
large percentage of them are cured4 ,in 
this way and by tenement house laws     
which require proper air shafts and     
window ventilation in dwellings1 by laws
 against spitting in public places1 and 
in other ways1 the boards of health in  
our towns and cities are waging war on  
tuberculosis4  ,ex-,president ,roosevelt

 said1 in one of his latest messages to 
,congress3--       ,there are about     
#c1jjj1jjj people seriously ill in the  
,united ,states1 of whom #ejj1jjj are   
consumptives4 ,more than      half of   
this illness is preventable4 ,if we     
count the value      of each life lost  
at only #agjj and reckon the average    
earning lost by illness at #gjj a year  
for grown men1 we      find that the    
economic gain from mitigation of        
preventable      disease in the ,united 
,states would exceed #a1ejj1jjj1jjj a   
year4 ,this gain can be had through     
medical investigation and      practice1
 school and factory hygiene1 restriction
 of labor      by women and children1   
the education of the people in both     
public and private hygiene1 and through 
improving the      efficiency of our    
health service1 municipal1 state1 and   
national4  ,work of the ,division of    
,school and ,infant ,hygiene4--,besides 
the work of the division of infectious  
disease1 the division of sanitation1    

which regulates the general sanitary    
conditions of houses and their          
surroundings and the division of        
inspection1 which looks after the purity
 and conditions of sale and delivery of 
milk and foods1 there is another        
department which most vitally concerns  
school children4 ,this is the division  
of school and infant hygiene4 ,the work 
of this department is that of the care  
of the children of the city4 ,during the
 year #aiab1 #bgi1ggf visits were made  
to the homes of school children of the  
city of ,new ,york by inspectors and    
nurses4 ,besides this1 thousands of     
children in school were cared for and   
aided by the city4  ,adenoids4--,many   
children suffer needlessly from         
adenoids1--growths in the back of the   
nose or mouth which prevent sufficient  
oxygen being admitted to the lungs4 ,a  
child suffering from these growths is   
known as a mouth breather because the   
mouth is opened in order to get more    
air4 ,the result to the child may be a  

handicap of deafness1 chronic running of
 the nose1 nervousness1 and lack of     
power to think4 ,his body cells are     
starving for oxygen4 ,a very simple     
operation removes this growth4          
,cooperation on the part of the children
 and parents with the doctors or nurses 
of the board of health will do much in  
removing this handicap from many young  
lives4  ,eyestrain4--,another handicap  
to a boy or girl is eyestrain4          
,twenty-two per cent of the school      
children of ,massachusetts were recently
 found to have defects in vision4 ,tests
 for defective eyesight may be made at  
school easily by competent doctors1 and 
if the child or parent takes the advice 
given to correct this by procuring      
proper glasses1 a handicap on future    
success will be removed4  ,decayed      
,teeth4--,decayed teeth are another     
handicap1 cared for by this division4   
,free dental clinics have been          
established in many cities1 and if      
children will do their share1 the       

chances of their success in later life  
will be greatly aided4 ,boys and girls1 
if handicapped with poor eyes or teeth1 
do not have a fair chance in life's     
competition4 ,in a certain school in    
,new ,york ,city there were #bcf pupils 
marked ,c in their school work4 ,these  
children were examined1 and #abf were   
found to have bad teeth1 #ed defective  
vision1 and #ef other defects1 as poor  
hearing1 adenoids1 enlarged tonsils1    
etc4 ,of these children #ahe were       
treated for these various difficulties1 
and #ea did not take treatment4 ,during 
the following year's work #agf of these 
pupils improved from ,c to ,b or ,a1    
while #fj did not improve4 ,if defects  
are such a handicap in school1 then what
 would be the chances of success in life
 outside4  ,in conclusion3 this         
department of school hygiene deserves   
the earnest aid of every young citizen1 
girl or boy4 ,if each of us would       
honestly help by maintaining quarantine 
in the case of contagious disease1 by   

observing the rules of the health       
department in fumigation1 by acting upon
 advice given in case of eyestrain1 bad 
teeth1 or adenoids1 and most of all by  
observing the rules of personal hygiene 
as laid down in this book1 the city in  
which we live would1 a generation hence1
 contain stronger1 more prosperous1 and 
more efficient citizens than it does    
to-day4                                 
,,reference ,,books                     
,,elementary       ,hunter1 ,laboratory 
,problems in ,civic ,biology4 ,american 
,book ,company4      ,davison1 ,the     
,human ,body and ,health4 ,american     
,book ,company4      ,gulick ,hygiene   
,series1 ,town and ,city4 ,ginn and     
,company4      ,hough and ,sedgwick1    
,the ,human ,mechanism1 ,part ,,ii4     
,ginn and        ,company4              
,overton1 ,general ,hygiene4 ,american  
,book ,company4      ,richards1         
,sanitation in ,daily ,life4 ,whitcomb  
and ,barrows4      ,richmond and        
,wallach1 ,good ,citizenship4 ,american 

,book        ,company4      ,ritchie1   
,primer of ,sanitation4 ,world ,book    
,company4      ,sharpe1 ,laboratory     
,manual of ,biology1 pages #cbj-ccd4    
,american ,book ,company4               
,,advanced       ,allen1 ,civics and    
,health4 ,ginn and ,company4            
,chapin1 ,municipal ,sanitation in the  
,united ,states4 ,snow        and       
,farnham4      ,chapin1 ,sources and    
,modes of ,infection4 ,wiley and ,sons4 
,conn1 ,practical ,dairy ,bacteriology4 
,orange ,judd ,company4      ,hough and 
,sedgwick1 ,the ,human ,mechanism4 ,part
 ,,ii4 ,ginn and        ,company4       
,hutchinson1 ,preventable ,diseases4    
,the ,houghton1 ,mifflin                
,company4      ,morse1 ,the ,collection 
and ,disposal of ,municipal ,waste4     
,municipal ,journal and ,engineer4      
,overlock1 ,the ,working ,people1 ,their
 ,health and ,how to        ,protect    
,it4 ,mass4 ,health ,book ,publishing   
,co4      ,price1 ,handbook of          
,sanitation4 ,wiley and ,sons4          

,tolman1 ,hygiene for the ,worker4      
,american ,book ,company4               
,,reports1 ,,etc4       ,american       
,health ,magazine4      ,annual ,report 
of ,department of ,health1 ,city of ,new
 ,york 7and        other cities74       
,bulletins and ,publications of         
,committee of ,one ,hundred on          
,national ,health4      ,school         
,hygiene1 ,american ,school ,hygiene    
,association4      ,grinnell1 ,our ,army
 versus a ,bacillus4 ,national          
,geographic        ,magazine4     ,,xxv4
 ,,some ,,great ,,names ,,in ,,biology  
,if we were to attempt to group the     
names associated with the study of      
biology1 we would find that in a general
 way they were connected either with    
discoveries of a purely scientific      
nature or with the benefiting of man's  
condition by the application of the     
purely scientific discoveries4 ,the     
first group are necessary in a science  
in order that the second group may apply
 their work4 ,it was necessary for men  

like ,charles ,darwin or ,gregor ,mendel
 to prove their theories before men like
 ,luther ,burbank or any of the men now 
working in the ,department of           
,agriculture could benefit mankind by   
growing new varieties of plants4 ,the   
discovery of scientific truths must be  
achieved before the men of modern       
medicine can apply these great truths to
 the cure or prevention of disease4     
,since we are most interested in        
discoveries which touch directly upon   
human life1 the men of whom this chapter
 treats will be those who1 directly or  
indirectly1 have benefited mankind4     
,the ,discoverers of ,living            
,matter4--,the names of a number of men 
living at different periods are         
associated with our first knowledge of  
cells4 ,about the middle of the         
seventeenth century microscopes came    
into use4 ,through their use plant cells
 were first described and pictured as   
hollow boxes or cells4 ,but it was not  
until #ahch that two ,german friends1   

,schleiden and ,schwann by name1 working
 on plants and animals1 discovered that 
both of these forms of life contained a 
jellylike substance that later came to  
be called protoplasm4 ,another ,german  
named ,max ,schultz in #ahfa gave the   
name protoplasm to all living matter1   
and a little later still ,professor     
,huxley1 a famous ,englishman1 friend   
and champion of ,charles ,darwin1 called
 attention to the physical and chemical 
qualities of protoplasm so that it came 
to be known as the chemical and physical
 basis of life4  ,illustration3 ,prof4  
,tyndall's experiment to show that if   
air containing germs is kept from       
organic substances1 such substances will
 not decay4 ,the box is sterilized2     
likewise the tubes 7t7 containing       
nutrients4 ,air is allowed to enter by  
the tubes 7u71 which are so made that   
dust is prevented from entering4 ,a     
thermometer 7th7 records the            
temperature4 ,the substances in the     
tubes do not decay1 no matter how       

favorable the temperature4  ,life comes 
from ,life4--,another group of men1     
after years of patient experimentation1 
worked out the fact that life comes from
 other life4 ,in ancient times it was   
thought that life arose spontaneously2  
for example1 that fish or frogs arose   
out of the mud of the river bottoms1 and
 that insects came from the dew or      
rotting meat4 ,it was believed that     
bacteria arose spontaneously in water1  
even as late as #ahgf1 when ,professor  
,tyndall proved by experiment the       
contrary to be true4  ,as early as #afea
 ,william ,harvey1 the court physician  
of ,charles ,i of ,england1 showed that 
all life came from the egg4 ,it was much
 later1 however1 that the part played by
 the sperm and egg cell in fertilization
 was carefully worked out4 ,it is to    
,harvey1 too1 that we owe the beginnings
 of our knowledge of the circulation of 
the blood4 ,he showed that blood moved  
through tubes in the body and that the  
heart pumped it4 ,he might be called the

 father of modern physiology as well as 
the father of embryology4 ,a long list  
of names might be added to that of      
,harvey to show how gradually our       
knowledge of the working of the human   
body has been added to4 ,at the present 
time we are far from knowing all the    
functions of the various parts of the   
human engine1 as is shown by the number 
of investigators in physiology at the   
present time4 ,present-day problems have
 much to do with the care of the human  
mechanism and with its surroundings4    
,the solution of these problems will    
come from applying the sciences of      
hygiene1 preventive medicine1 and       
sanitation4  ,in the preceding chapters 
of this book we have learned something  
about our bodies and their care4 ,we    
have found that man is able within      
limitations to control his environment  
so as to make it better to live in4 ,all
 of the scientific facts that have been 
of use to man in the control of disease 
have been found out by men who have     

devoted their lives in the hope that    
their experiments and their sacrifices  
of time1 energy1 and sometimes life     
itself might make for the betterment of 
the human race4 ,such men were ,harvey1 
,jenner1 ,lister1 ,koch1 and ,pasteur4  
,illustration3 ,edward ,jenner1 the     
discoverer of vaccination4  ,edward     
,jenner and ,vaccination4--,the         
civilized world owes much to ,edward    
,jenner1 the discoverer of vaccination  
against smallpox4 ,born in ,berkeley1 a 
little town of ,gloucestershire1        
,england1 in #agdi1 as a boy he showed a
 strong liking for natural history4 ,he 
studied medicine and also gave much time
 to the working out of biological       
problems4 ,as early as #agge he began to
 associate the disease called cowpox    
with that of smallpox1 and gradually the
 idea of inoculation against this       
terrible scourge1 which killed or       
disfigured hundreds of thousands every  
year in ,england alone1 was worked out  
and applied4 ,he believed that if the   

two diseases were similar1 a person     
inoculated with the mild disease        
7cowpox7 would after a slight attack of 
this disease be immune against the more 
deadly and loathsome smallpox4 ,it was  
not until #agif that he was able to     
prove his theory1 as at first few people
 would submit to vaccination4 ,war at   
this time was being waged between       
,france and ,england1 so that the former
 country1 usually so quick to appreciate
 the value of scientific discoveries1   
was slow to give this method a trial4   
,in spite of much opposition1 however1  
by the year #ahjb1 vaccination was      
practiced in most of the civilized      
countries of the world4 ,at the present 
time the death rate in ,great ,britain1 
the home of vaccination1 is less than   
4#c to every #a1jjj1jjj living persons4 
,this shows that the disease is         
practically wiped out in ,england4 ,an  
interesting comparison with these       
figures might be made from the history  
of the disease in parts of ,russia where

 vaccination is not practiced4 ,there1  
thousands of deaths from smallpox occur 
annually4 ,during the winter of         
#aiac-aiad an epidemic of smallpox with 
more than #bej cases broke out in the   
city of ,niagara ,falls4 ,this epidemic 
appears to be due to a campaign         
conducted by people who do not believe  
in vaccination4 ,in cities and towns    
near by1 where vaccination was          
practiced1 no cases of smallpox         
occurred4 ,naturally if opposition to   
vaccination is found nowadays1 ,jenner  
had a much harder battle to fight in his
 day4 ,he also had many failures1 due to
 the imperfect methods of his time4 ,the
 full worth of his discovery was not    
fully appreciated until long after his  
death1 which occurred in #ahbc4         
,illustration3 ,louis ,pasteur4  ,louis 
,pasteur4--,the one man who1 in         
biological science1 did more than any   
other to directly benefit mankind was   
,louis ,pasteur4 ,born in #ahbb1 in the 
mountains near the border of            

northeastern ,france1 he spent the early
 part of his life as a normal boy1 fond 
of fishing and not very partial to      
study4 ,he inherited from his father1   
however1 a fine character and grim      
determination1 so that when he became   
interested in scientific pursuits he    
settled down to work with enthusiasm and
 energy4  ,at the age of twenty-five he 
became well known throughout ,france as 
a physicist4 ,shortly after this he     
became interested in the tiny plants we 
call bacteria1 and it was in the field  
of bacteriology that he became most     
famous4 ,first as professor at          
,strassburg and at ,lille1 later as     
director of scientific studies in the   
,ecole ,normale at ,paris1 he showed his
 interest in the application of his     
discoveries to human welfare4  ,in #aheg
 ,pasteur showed that fermentation was  
due to the presence of bacteria1 it     
having been thought up to this time that
 it was a purely chemical process4 ,this
 discovery led to very practical ends1  

for ,france was a great wine-producing  
country1 and with a knowledge of the    
cause of fermentation many of the       
diseases which spoiled wine were        
checked4  ,in #ahfe-ahfh ,pasteur turned
 his attention to a silkworm disease    
which threatened to wipe out the silk   
industry of ,france and ,italy4 ,he     
found that this disease was caused by   
bacteria4 ,after a careful study of the 
case he made certain recommendations    
which1 when carried out1 resulted in the
 complete overthrow of the disease and  
the saving of millions of dollars to the
 poor people of ,france and ,italy4     
,the greatest service to mankind came   
later in his life when he applied       
certain of his discoveries to the       
treatment of disease4 ,first            
experimenting upon chickens and later   
with cattle1 he proved that by making a 
virus 7poison7 from the germs which     
caused certain diseases he could reduce 
this virus to any desired strength4 ,he 
then inoculated the animals with the    

virus of reduced strength1 giving the   
inoculated animals a mild attack of the 
disease1 and found that this made them  
immune from future attacks4 ,this       
discovery1 first applied to chicken     
cholera1 laid the foundation for all    
future work in the uses of serums1      
vaccines1 and antitoxins4  ,pasteur was 
perhaps the best known through his study
 of rabies4 ,the great ,pasteur         
,institute1 founded by popular          
subscriptions from all over the world1  
has successfully treated over #bb1jjj   
cases of rabies with a death rate of    
less than #a per cent4 ,but more than   
that it has been the place where ,roux1 
a fellow worker with ,pasteur1          
discovered the antitoxin for diphtheria 
which has resulted in the saving of     
thousands of human lives4 ,here also    
have been established the principles of 
inoculation against bubonic plague1     
lockjaw1 and other germ diseases4       
,pasteur died in #ahie at the age of    
seventy-three1 the most perfect man in  

the realm of science1 a man beloved by  
his countrymen and honored by the entire
 world4  ,illustration3 ,robert ,koch4  
,robert ,koch4--,another name associated
 with the battle against disease germs  
is that of ,robert ,koch4 ,born in      
,klausthal1 ,hanover1 in #ahdc1 he later
 became a practicing physician1 and     
about #ahhj was called to ,berlin to    
become a member of the sanitary         
commission and professor in the school  
of medicine4 ,in #ahha he discovered the
 germ that causes tuberculosis and two  
years later the germ that causes        
,asiatic cholera4 ,his later work has   
been directed toward the discovery of a 
cure for tuberculosis and other germ    
diseases4 ,as yet1 however1 no certain  
cure seems to have been found4  ,lister 
and ,antiseptic ,treatment of           
,wounds4--,a third great benefactor of  
mankind was ,sir ,joseph ,lister1 an    
,englishman who was born in #ahbg4 ,as a
 professor of surgery he first applied  
antiseptics in the operating room4 ,by  

means of the use of carbolic acid or    
other antiseptics on the surface of     
wounds1 on instruments1 and on the hands
 and clothing of the operating surgeons1
 disease germs were prevented from      
taking a foothold in the wounds4 ,thus  
blood poisoning was prevented4 ,this    
single discovery has done more to       
prevent death after operations than any 
other of recent time4  ,modern ,workers 
on the ,blood4--,at the present time    
several names stand out among           
investigators on the blood4 ,paul       
,ehrlich1 a ,german born in #ahed1 is   
justly famous for his work on the blood 
and its relation to immunity from       
certain diseases4 ,his last great       
research has given to the world a       
specific against the dread disease      
syphilis4  ,another name associated with
 the blood is that of ,elias            
,metchnikoff1 a ,russian4 ,he was born  
in #ahde4 ,metchnikoff first advanced   
the belief that the colorless blood     
corpuscles1 or phagocytes1 did service  

as the sanitary police of the body4 ,he 
has found that there are several        
different kinds of colorless corpuscles1
 each having somewhat different work to 
do4 ,much of the modern work done by    
physiologists on the blood are directly 
founded on the discoveries of           
,metchnikoff4  ,illustration3 ,charles  
,darwin1 the grand old man of biology4  
,heredity and ,evolution4 ,charles      
,darwin4--,there is still another       
important line of investigation in      
biology that we have not mentioned4     
,this is the doctrine of evolution and  
the allied discoveries along the line of
 heredity4 ,the development or evolution
 of plants and animals from simpler     
forms to the many and present complex   
forms of life have a practical bearing  
on the betterment of plants and animals1
 including man himself4 ,the one name   
indelibly associated with the word      
evolution is that of ,charles ,darwin4  
,charles ,darwin was born on ,february  
#ab1 #ahji1 a son of well-to-do parents1

 in the pretty ,english village of      
,shrewsbury4 ,as a boy he was very fond 
of out-of-door life1 was a collector of 
birds' eggs1 stamps1 coins1 shells1 and 
minerals4 ,he was an ardent fisherman1  
and as a young man became an expert     
shot4 ,his studies1 those of the        
,english classical school1 were not     
altogether to his liking4 ,it is not    
strange1 perhaps1 that he was thought a 
very ordinary boy1 because his interest 
in the out-of-doors led him to neglect  
his studies4 ,later he was sent to      
,edinburgh ,university to study         
medicine4 ,here the dull lectures1      
coupled with his intense dislike for    
operations1 made him determine never to 
become a physician4 ,but all this time  
he showed his intense interest in       
natural history and took frequent part  
in the discussions at the meetings of   
one of the student zoological societies4
  ,in #ahbh his father sent him to      
,cambridge to study for the ministry4   
,his three years at the university were 

wasted so far as preparation for the    
ministry were concerned1 but they were  
invaluable in shaping his future4 ,he   
made the acquaintance of one or two     
professors who were naturalists like    
himself1 and in their company he spent  
many happy hours in roaming over the    
countryside collecting beetles and other
 insects4 ,in #ahca an event occurred   
which changed his career and made       
,darwin one of the world's greatest     
naturalists4 ,he received word through  
one of his professional friends that the
 position of naturalist on her          
,majesty's ship ,beagle was open for a  
trip around the world4 ,darwin applied  
for the position1 was accepted1 and     
shortly after started on an eventful    
five years' trip around the world4 ,he  
returned to ,england a famous naturalist
 and spent the remainder of his long and
 busy life producing books which have   
done more than those of any other writer
 to account in a satisfactory way for   
the changes of form and habits of plants

 and animals on the earth4 ,his theories
 established a foundation upon which    
plant and animal breeders were able to  
work4  ,his wonderful discovery of the  
doctrine of evolution was due not only  
to his information and experimental     
evidence1 but also to an iron           
determination and undaunted energy4 ,in 
spite of almost constant illness brought
 about by eyestrain1 he accomplished    
more than most well men have done4 ,his 
life should mean to us not so much the  
association of his name with the ,origin
 of ,species or ,plants and ,animals    
under ,domestication1 two of his most   
famous books1 but rather that of a      
patient1 courteous1 and brave gentleman 
who struggled with true ,english pluck  
against the odds of disease and the     
attacks of hostile critics4 ,he gave to 
the world the proofs of the theory on   
which we to-day base the progress of the
 world4 ,darwin lived long enough to see
 many of his critics turn about and come
 over to his beliefs4 ,he died on the   

#aith of ,april1 #ahhb1 at seventy-four 
years of age4  ,associated with         
,darwin's name we must place two other  
co-workers on heredity and evolution1   
,alfred ,russel ,wallace1 an ,englishman
 who independently and at about the same
 time reached many of the conclusions   
that ,darwin came to1 and ,august       
,weissman1 a ,german4 ,the latter showed
 that the protoplasm of the germ cells  
7eggs and sperms7 is directly handed    
down from generation to generation1 they
 being different from the other body    
cells from the very beginning4 ,in #ahhc
 a ,german named ,boveri discovered that
 the chromosomes of the egg and the     
sperm cell were at the time of          
fertilization just half in number of the
 other cells 7see page #beb7 so that a  
fertilized egg was really a whole cell  
made up of two half cells1 one from each
 parent4 ,the chromosomes within the    
nucleus1 we remember1 are believed to be
 the bearers of the hereditary qualities
 handed down from parent to child4 ,this

 discovery shows us some of the         
mechanics of heredity4  ,applications to
 ,plant and ,animal ,breeding4--,turning
 to the practical applications of the   
scientific work on the method of        
heredity1 the name of ,gregor ,mendel1  
an ,austrian monk1 stands out most      
prominently4 ,mendel lived from #ahbb   
until #ahhd4 ,his work1 of which we     
already have learned something 7see page
 #beh71 remained undiscovered until a   
few years ago4 ,the application of his  
methods to plant and animal raising are 
of the utmost importance because the    
breeder is able to separate the         
qualities he desires and breed for those
 qualities only4 ,another name we have  
mentioned with reference to plant       
breeding is ,hugo de ,vries1 the        
,dutchman who recently showed that in   
some cases plants arise as new species  
by sudden and great variations known as 
mutations4 ,and lastly1 in our own      
,california1 ,luther ,burbank1 by       
careful hybridizing1 is making lasting  

fame with his new and useful hybrid     
plants4                                 
,,references       ,conn1 ,biology4     
,silver1 ,burdett  ,co4      ,darwin1   
,life and ,letters of ,charles ,darwin4 
,appletons4      ,galton1 ,hereditary   
,genius4 ,london 7#ahib74               
,thompson1 ,heredity4 ,john ,murray1    
,london ,england4      ,wasmann1        
,problem of ,evolution4 ,kegan ,paul1   
,trench1 ,truebner and ,co41            
,london1 ,e4 ,c4                        
,,appendix           ,a ,,suggested     
,,outline ,,for ,,biology ,,beginning   
,,in ,,the ,,fall                       
,,list ,,of ,,topics                    
,,first ,,term  ,first week4 ,,why      
,,study ,,biology8 ,relation to human   
health1 hygiene4 ,relations existing    
between plants and animals4 ,relation of
 bacteria to man4 ,uses of plants and   
animals4 ,conservation of plants and    
animals4 ,relation to life of citizen in
 the city4 ,plants and animals in       
relation to their environment4 ,what is 

the environment2 light1 heat1 water1    
soil1 food1 etc4 ,what plants take out  
of the environment4 ,what animals take  
out of the environment4 ,dependence of  
plants and animals upon the factors of  
the environment4 ,laboratory3 ,study of 
a plant or an animal in the school or at
 home to determine what it takes from   
its environment4  ,second week4 ,,some  
,,relations ,,existing ,,between        
,,plants 7,,green7 ,,and ,,animals4     
,field trip planned to show that insects
 feed upon plants2 make their homes upon
 plants4 ,that flowers are pollinated by
 insects4 ,insects lay eggs upon certain
 food plants4 ,green plants make food   
for animals4 ,other relations4 7,time   
allotment4 ,one day trip1 collecting1   
etc42 two days' discussion of trip in   
all its relations47 ,make a careful     
study of the locality you wish to visit1
 have a plan that the pupils know about 
beforehand4 ,review and hygiene of      
pupil's environment1 #b days4  ,third   
week4 ,,study ,,of ,a ,,flower1 ,,parts 

,,essential ,,to ,,pollination ,,named4 
,adaptations for insect pollination     
worked out in laboratory4 ,study of bee 
or butterfly as an insect carrier of    
pollen4 ,names of parts of insect       
learned4 ,elementary knowledge of groups
 of insects seen on field trip4 ,bees1  
butterflies1 grasshoppers1 beetles1     
possibly flies and bugs4 ,drawing of a  
flower1 parts labeled4 ,drawing of an   
insect1 outline only1 parts labeled4    
,careful study of some fall flower      
fitted for insect pollination with an   
insect as pollinating agent4 ,some      
examples of cross-pollination explained4
 ,practical value of cross-pollination4 
,fourth week4 ,,living ,,plants ,,and   
,,animals ,,compared4 ,parts of plants1 
functions2 organs1 tissues1 cells4      
,demonstration cells of onion or elodea4
 ,how cells form others4 ,what living   
matter can do4 ,reproduction4 ,growth of
 pollen tube1 fertilization4            
,development of ovule into seed4        
,fruits1 how formed4 ,uses1 to man4     

,fifth week4 ,,what ,,makes ,a ,,seed   
,,grow4 ,bean seed1 a baby plant1 and   
food supply4 ,food1 what is it8 ,organic
 nutrients1 tests for starch1 protein1  
oil4 ,show their presence in seeds4     
,sixth week4 ,,need ,,for ,,foods4      
,germination of bean due to 7a7 presence
 of foods1 7b7 outside factors4 ,what is
 done with the food4 ,release of energy4
 ,examples of engine1 plants1 human     
body4 ,oxidation in body4 ,proof by     
experiment4 ,test for presence of       
,,co#b4 ,oxidation in growing plant1    
experiment4 ,respiration a general need 
for both plants and animals4  ,seventh  
week4 ,,need ,,for ,,digestion4 ,the    
corn grain4 ,parts1 growth1 food supply 
outside body of plant1 how does it get  
inside4 ,digestion1 need for4 ,test for 
grape sugar4 ,enzymes1 their function4  
,action of diastase on starch4  ,eighth 
week4 ,,what ,,plants ,,take ,,from     
,,the ,,soil1 ,,how ,,they ,,do ,,this4 
,use of root4 ,influence of gravity and 
water4 ,why8 ,absorption a function4    

,root hairs4 ,demonstration4 ,pocket    
gardens1 optional home work1 but each   
pupil must work on root hairs from      
actual specimen4 ,how root absorbs4     
,osmosis2 what substances will osmose4  
,experiments to demonstrate this4       
,ninth week4 ,,composition ,,of ,,soil4 
,what root hairs take out of soil4      
,plant needs mineral matter to make     
living matter4 ,why8 ,nitrogen          
necessary4 ,sources of nitrogen1 the    
nitrogen-fixing bacteria4 ,relation of  
this to man4 ,rotation of crops4  ,tenth
 week4 ,,how ,,green ,,plants ,,make    
,,food4 ,passage of liquids up stem4    
,demonstration4 ,structure of a green   
leaf4 ,cellular structure demonstrated4 
,microscopic demonstration of cells1    
stoma1 air spaces1 chlorophyll bodies4  
,evaporation of water from green leaf1  
regulation of transpiration4  ,eleventh 
week4 ,midterm ,examinations4 ,sun a    
source of energy4 ,effect of light on   
green plants4 ,experimental proof4      
,starch made in green leaf4 ,light and  

air necessary for starch making4 ,proof4
 ,protein making in leaf4 ,by-products  
in starch making4 ,proof4 ,respiration4 
,twelfth week4 ,,the ,,circulation ,,and
 ,,distribution ,,of ,,food ,,in ,,green
 ,,plants4 ,uses of bark1 wood1 what    
part of stem does food pass down4       
,willow twig experiment4 ,summary of    
functions of living matter in plant4    
,forestry lecture4 ,economic uses of    
green plants4 ,reports4  ,thirteenth    
week4 ,,plants ,,without ,,chlorophyll  
,,in ,,their ,,relation ,,to ,,man4     
,saprophytic fungi4 ,molds4 ,growth on  
bread or other substances4 ,conditions  
most favorable for growth4 ,favorite    
foods4 ,methods of prevention4 ,economic
 importance4  ,fourteenth week4 ,,yeasts
 ,,in ,,their ,,relation ,,to ,,man4    
,experiments to show fermentation is    
caused by yeasts4 ,experiments to show  
conditions necessary for fermentation4  
,the part played by yeasts in bread     
making1 in wine making1 in other        
industries4 ,structure of yeast         

demonstrated4 ,summary4  ,fifteenth     
week4 ,,experiments ,,to ,,show ,,where 
,,bacteria ,,may ,,be ,,found ,,and     
,,conditions ,,necessary ,,to ,,growth  
,,begun4 ,have cultures collected and   
placed in a warm room during the        
holidays4 ,suggested experiments are    
exposure to air of quiet room and room  
with persons moving1 dust of floor1     
knife blade1 etc4  ,sixteenth1          
seventeenth1 and eighteenth weeks4 ,,the
 ,,month ,,of ,,january ,,should ,,be   
,,devoted ,,to ,,the ,,study ,,of       
,,bacteria ,,in ,,their ,,general       
,,relations ,,to ,,man4 ,economically1  
both directly and indirectly4 ,especial 
emphasis placed on the nature and       
necessity of decay4 ,bacteria in        
relation to disease should also be      
emphasized4 ,the experiments to be      
performed and the topics expected to be 
covered follow4  ,,conditions           
,,favorable ,,and ,,unfavorable ,,for   
,,growth ,,of ,,bacteria4 7,use bouillon
 cultures47 ,effect of intense heat1    

sterile bouillon exposed to air1 effect 
of boiling1 effect of cold1 effect of   
antiseptics 7corrosive sublimate1       
carbolic acid1 boric acid1 formalin1    
etc471 effect of large amounts of sugar 
and salt and the relation of this to    
preserving1 etc4 ,bring out practical   
application of principles demonstrated4 
,discuss sterilization in medicine and  
surgery1 cold storage1 canning1         
sterilization1 e4g4 laundries1 etc41 use
 of antiseptics1 preserving by means of 
salt and sugar4 ,microscopic            
demonstration of bacteria4 ,methods of  
reproduction4 ,importance in causing    
organic decay1 fixation of nitrogen1    
various useful forms in cheese making1  
butter ripening1 etc4 ,harmfulness of   
bacteria as disease producers4 ,specific
 diseases discussed3 tuberculosis1      
typhoid1 infective colds1 blood         
poisoning1 etc4 ,vaccination4           
,antitoxins begun--continued after      
knowledge of human body is gained4 ,work
 of ,lister and ,pasteur4  ,nineteenth  

and twentieth weeks4 ,,review ,,and     
,,examinations4                         
,,second ,,term  ,first week4 ,,the     
,,balanced ,,aquarium4 ,carbon and      
nitrogen cycles4 ,balanced aquarium and 
hay infusion compared4  ,second week4   
,,one ,,protozoan1 ,,demonstration ,,to 
,,show ,,changes ,,in ,,shape1          
,,response ,,to ,,stimuli1 ,,summary    
,,of ,,vital ,,processes ,,in ,,cell4   
,food getting1 digestion1 assimilation1 
oxidation1 excretion1 growth1           
reproduction4 ,internal structure of    
protozoan4 ,protozoa as cause of        
disease4  ,third week4 ,,general        
,,survey ,,of ,,animal ,,kingdom4       
,survey introduced by museum trip if    
possible4 ,protozoa1 worm1 insect1 fish1
 mammal4 ,distinction between vertebrate
 and invertebrate4 ,character of        
mammalia4 ,division of labor emphasized4
 ,man's place in nature4  ,fourth week4 
,,study ,,of ,,the ,,frog4 ,relation to 
habitat1 adaptations for locomotion1    
food getting1 respiration1 comparison of

 frog and fish on latter point4 ,osmotic
 exchange of gases emphasized4 ,cell    
respiration4  ,fifth week4              
,,metamorphosis ,,of ,,frog4            
,fertilization1 cell division1 and      
differentiation emphasized4 ,touch on   
plant and animal breeding4 ,function of 
chromosomes as bearers of heredity4     
,comparison of bird's egg and mammal    
embryo4  ,sixth week4 ,,factors ,,in    
,,breeding4 #a4 ,variation4 #b4         
,selection4 #c4 ,heredity fixes         
variation4 #d4 ,hybridizing4 #e4        
,control of environment4 ,eugenics in   
relation to 7a7 crime1 7b7 disease1 7c7 
genius4 ,continuity of germ plasm4 ,work
 of ,darwin1 ,mendel1 ,de ,vries1       
,burbank4  ,seventh week4 ,a ,,brief    
,,study ,,of ,,the ,,gross ,,structure  
,,of ,,the ,,human ,,body4 ,skin1       
muscles1 bones4 ,removal of lime from   
bone by ,h,cl to show other substances  
and need for lime4 ,effect of posture1  
spinal curvature1 fractures1 sprains4   
,eighth week4 ,,need ,,for ,,food4      

,nutritive value of food4 ,use of charts
 to show foods rich in carbohydrates1   
fats1 proteins1 minerals1 water1 refuse4
 ,the relation of age1 sex1 work1 and   
environment to the food requirements4   
,what is a cheap food4 ,price list of   
common foods at present time4 ,efforts  
of government to secure a cheap food    
supply for the people4 ,digestibility of
 foods4  ,ninth week4 ,,how ,,the ,,fuel
 ,,value ,,of ,,food ,,has ,,been       
,,determined4 ,meaning of calorie4 ,the 
#ajj-;caloric portion1 its use in       
determining a daily or weekly dietary4  
,standard dietary as determined by      
,atwater4 ,comparison of standards of   
,chittenden and ,voit with those of     
,atwater4  ,tenth week4 ,,study ,,of    
,,pupil',s ,,dietary4 ,planning ideal   
meals4 ,individual dietaries for one day
 required from each pupil4 ,discussions 
and corrections4 ,the family dietary4   
,relation to cost4  ,eleventh week4     
,,digestion4 ,the digestive system in   
the frog and in man compared4 ,drawings 

of each4 ,glands and enzymes4 ,internal 
secretions and their importance4        
,demonstration of glandular tissues4    
,experiment to show digestion of starch 
in mouth4  ,twelfth week4 ,,digestion   
,,continued4 ,digestion of white of egg 
by gastric juice4 ,digestion of starch  
with pancreatic fluid4 ,functions of    
pancreatic juice4 ,microscopic          
examination of emulsion4 ,reasons for   
digestion4 ,part played by osmosis4     
,demonstration of osmosis4 ,non-osmosis 
of non-digested foods1 comparison       
between osmosable qualities of starch   
and grape sugar4  ,thirteenth week4     
,,absorption4 ,where and how foods are  
absorbed4 ,the structure of a villus    
explained4 ,course taken by foods after 
absorption4 ,function of liver4 ,blood  
making the result of absorption4        
,composition of blood1 red and colorless
 corpuscles1 plasma1 blood plates1      
antibodies4 ,microscopic drawing of     
corpuscles of frog's and man's blood4   
,fourteenth week4 ,,circulation ,,of    

,,blood4 ,the heart and lungs of frog   
demonstrated4 ,heart of man a force     
pump1 explain with use of force pump4   
,demonstration of beef's heart4         
,circulation and changes of blood in    
various parts of body4 ,work of cells   
with reference to blood made clear4     
,capillary circulation 7demonstration of
 circulation in tadpole's tail or web of
 frog's foot74  ,fifteenth week4        
,,respiration ,,and ,,excretion4        
,necessity for taking of oxygen to cells
 and removal of wastes from cells4 ,part
 played by blood and lymph4 ,mechanics  
of breathing 7use of experiments74      
,changes of air and blood in lungs      
7experiments74 ,best methods of         
ventilation 7experiments74 ,elimination 
of wastes from blood by lungs1 skin1 and
 kidneys4 ,cell respiration4  ,sixteenth
 week4 ,,hygiene ,,of ,,organs ,,of     
,,excretion1 especially care of skin4   
,the general structure and functions of 
the central nervous system4 ,sensory and
 motor nerves4 ,reflexes1 instincts1    

habits4 ,habit formation1 importance of 
right habits4 ,rules for habit          
formation4 ,habit-forming drugs and     
other agents4 ,lecture4  ,seventeenth1  
eighteenth1 nineteenth weeks4 ,,civic   
,,hygiene ,,and ,,sanitation4 ,hygiene  
of special senses1 eye and ear4 ,a well 
citizen an efficient citizen4 ,public   
health is purchasable4 ,improvement of  
environment a means of obtaining this4  
,civic hygiene and sanitation4 ,cleaning
 up neighborhood1 inquiry into home and 
street conditions4 ,fighting the fly4   
,conditions of milk and water supply4   
,relation of above to disease4 ,work of 
,board of ,health1 etc4 ,review and     
,examinations4             ,,suggested  
,,syllabus ,,for ,,course ,,beginning   
,,february #a                 ,,and     
,,ending ,,the ,,following ,,january    
,,first ,,term  ,first week4 ,,why      
,,study ,,biology8 ,relation to human   
health1 hygiene4 ,relations existing    
between plants and animals4 ,relation of
 bacteria to man4 ,uses of plants and   

animals4 ,conservation of plants and    
animals4 ,relation to life of citizen in
 this city4 ,needs of plants and        
animals3 7#a7 food1 7#b7 water1 7#c7    
air1 7#d7 proper temperature4 ,study of 
a single plant or animal in relation to 
its environment4 ,problems of city      
government3 7a7 storage1 preservation   
and distribution of foods1 7b7 water    
supply1 7c7 overcrowded tenements1 7d7  
street cleaning1 7e7 clean schools4     
,biological problems in city government4
  ,second week4 ,,interrelations        
,,between ,,plants ,,and ,,animals4     
,plants furnish food1 clothing1 shelter1
 and medicine4 ,animals use food1       
shelter4 ,man's use of plants as above4 
,man's use of animals as above4 ,plant  
and animal industries4 ,use of balanced 
aquarium as illustrative material4      
,third week4 ,,destruction ,,of ,,food  
,,and ,,other ,,things ,,by ,,mold4     
,home experiment4 ,conditions favorable 
to growth of mold4 ,food1 moisture1     
temperature4 ,destruction of commodities

 by mold3 food1 leather1 clothing4      
,fourth week1 fifth week4 ,,destruction 
,,of ,,foods ,,by ,,bacteria4           
,experiment4 ,to show where bacteria are
 found4 ,soil1 dust1 water1 milk1 hands1
 mouth4 ,use and harm of decay4         
,relation to agriculture4 ,experiment4  
,conditions favorable and unfavorable to
 growth of bacteria3 boiling1 cold1     
sugar1 salt4 ,bacteria in relation to   
disease briefly mentioned4 ,bacteria in 
industries4  ,sixth week4 ,,use ,,of    
,,stored ,,food ,,by ,,young ,,green    
,,plant3 7a7 for energy1 7b7 for        
construction of tissue4 ,experiment4    
,structure of bean seed4 ,draw to show  
outer coat1 cotyledon1 hypocotyl1 and   
plumule4 ,test for starch and sugar     
7grape74 ,test for oil1 protein1 water1 
mineral matter4 ,use of all nutrients to
 seedling4  ,seventh week4 ,,other      
,,needs ,,of ,,young ,,plants4 ,home    
experiments to show 7a7 temperature1 7b7
 amount of water most favorable to      
germination4 ,experiment4 ,to show need 

of oxygen4 ,to show that germinating    
seeds give off carbon dioxide4 ,proof of
 presence of carbon dioxide in breath4  
,the needs of a young plant compared    
with those of a boy or girl4  ,eighth   
week4 ,,digestion ,,in ,,seedling4      
,structure of corn grain4 ,experiment4  
,to show that starch is digested in a   
growing seedling 7corn74 ,experiment4   
,to show that diastase digests starch4  
,discussion of experiments4  ,ninth     
week4 ,,what ,,plants ,,take ,,from     
,,the ,,soil ,,and ,,how ,,they ,,do    
,,this4 ,use of roots4 ,proof that it   
holds plant in position1 takes in water 
and mineral matter1 and in some cases   
stores food4 ,influence of gravity and  
water4 ,labeled drawing of root hair4   
,root hair as a cell emphasized4        
,osmosis demonstrated4  ,tenth week4    
,,composition ,,of ,,the ,,soil4        
,demonstration of presence of mineral   
and organic substances in the soil4     
,what root hairs take from the soil4    
,mineral matter necessary and why4      

,importance and sources of nitrogen4    
,soil exhaustion and its prevention4    
,nitrogen-fixing bacteria4 ,review      
bacteria of decay4 ,rotation of crops4  
,eleventh week4 ,,upward ,,course ,,of  
,,materials ,,in ,,the ,,stem4          
,demonstration of pea seedlings with    
eosin to show above4 ,demonstration of  
evaporation of water from a leaf4       
,action of stomata in control of        
transpiration4 ,cellular structure of   
leaf4 ,demonstration of elodea to show  
cell4  ,twelfth week4 ,,sun ,a ,,source 
,,of ,,energy4 ,heliotropism4           
,demonstration4 ,necessity of sunlight  
for starch manufacture4 ,necessity of   
air for starch manufacture4 ,by-products
 in starch making4 ,oil manufacture in  
leaf4 ,protein manufacture in plant4    
,respiration4  ,thirteenth week4        
,,reproduction4 ,necessity for 7a7      
perpetuation1 7b7 regeneration4 ,study  
of a typical flower to show sepals1     
petals1 stamens1 pistil4 ,functions of  
each part4 ,cross and longitudinal      

sections of ovary shown and drawn4      
,emphasis on essential organs4          
,pollination1 self and cross4 7,,note4  
,at least one field trip must be planned
 for the month of ,may4 ,this trip will 
take up the following topics3 ,the      
relations between flowers and insects4  
,the food and shelter relation between  
plants and animals4 ,recognition of #e  
to #aj common trees4 ,need of           
conservation of forests4 ,an extra trip 
could well be taken to give child a     
little knowledge and love for spring    
flowers and awakening nature47          
,fourteenth week4 ,,study ,,of ,,the    
,,bee ,,or ,,butterfly ,,with           
,,reference ,,to ,,adaptations ,,for    
,,insect ,,pollination4 ,study of an    
irregular flower to show adaptations for
 insect visitors4 ,fertilization begun4 
,growth of pollen tubes4  ,fifteenth    
week4 ,,fertilization ,,completed4 ,use 
of chart to show part played by egg and 
sperm cell4 ,ultimate result the        
formation of embryo and its growth under

 favorable conditions into young plant4 
,relation of flower and fruit1 pea1 or  
bean used for this purpose4 ,development
 of fleshy fruit4 ,apple used for this  
purpose4  ,sixteenth week4 ,,maturing   
,,of ,,parts ,,and ,,storing ,,of ,,food
 ,,in ,,seed ,,and ,,fruit4 ,the devices
 for scattering the seeds and relation  
to future plants4 ,resume of processes  
of nutrition to show how materials found
 in fruit and seed are obtained by the  
plant4  ,seventeenth week4 ,,plant      
,,breeding4 ,factors3 7a7 selective     
planting1 7b7 cross-pollination1 7c7    
hybridizing4 ,heredity and variation    
begun4 ,darwin and ,burbank mentioned4  
,eighteenth and nineteenth weeks4 ,,the 
,,natural ,,resources ,,of ,,man3       
,,soil1 ,,water1 ,,plants1 ,,animals4   
,the relation of plant life to the above
 factors of the environment4 ,the       
relation of insects to plants 7forage   
and other crops7 and the relation of    
birds to insects4 ,need for conservation
 of the helpful factors in the          

environment of plants4 ,attention called
 to some native birds as insect and wood
 destroyers4  ,twentieth week4 ,,review 
,,and ,,examinations4                   
,,second ,,term  ,first week4 ,,the     
,,balanced ,,aquarium4 ,study of        
conditions producing this4 ,the role of 
green plants1 the role of animals4 ,what
 causes the balance4 ,how the balance   
may be upset4 ,the nitrogen cycle4 ,what
 it means in the world outside the      
aquarium4 ,symbiosis as opposed to      
parasitism4 ,examples4  ,second week4   
,,study ,,of ,,the ,,paramoecium4 ,study
 of a hay infusion to show how          
environment reacts upon animals4        
,relation to environment4 ,study of cell
 under microscope to show reactions4    
,structure of cell4 ,response to        
stimuli1 function of cilia1 gullet1     
nucleus1 contractile vacuoles1 food     
vacuoles1 asexual reproduction4         
,drawings to show how locomotion is     
performed1 general structure4 ,copy     
chart for fine structure4  ,third week4 

,a ,,bird',s-,,eye ,,view ,,of ,,the    
,,animal ,,kingdom4 ,one day4           
,development of a multicellular         
organism4 7,use models47 ,one day4      
,physiological division of labor4       
,tissues1 organs4 ,functions common to  
all animals4 ,illustrative material4    
,optional trip to museum for use of     
illustrative material to illustrate the 
principal characteristics of 7a7 a      
simple metazoan1 sponge1 or hydrazoan1  
7b7 a segmented worm1 7c7 a crustacean  
7,decapod71 7d7 an insect1 7e7 a mollusk
 and echinoderm1 7f7 vertebrates4       
7,differences between vertebrates and   
invertebrates47 ,the characteristics of 
the vertebrates4 ,distinguish between   
fishes1 amphibia1 reptiles1 birds1      
mammals4 ,two days for discussion4      
,man's place in the animal series1      
elementary discussion of what evolution 
means4  ,fourth week4 ,,the ,,economic  
,,importance ,,of ,,animals4 ,uses of   
animals3 7#a7 ,as food4 ,directly3 fish1
 shellfish1 birds1 domesticated mammals4

 7#b7 ,indirectly as food3 protozoa1    
crustacea4 7#c7 ,they destroy harmful   
animals and plants4 ,snakes--birds2     
birds--insects2 birds--weed seeds2      
herbivorous animals--weeds4 7#d7        
,furnish clothing1 etc4 ,pearl buttons1 
etc4 7#e7 ,animal industries1 silkworm  
culture1 etc4 7#f7 ,domesticated        
animals4       ,animals do harm3 7#a7   
,to gardens4 7#b7 ,to crops4 7#c7 ,to   
stored      food2 examples1 rats1       
insects1 etc4 7#d7 ,to forest and shade 
trees4 7#e7 ,to human life4 ,disease3   
parasitism and its                      
results1--examples1 from worms1 etc42   
disease carriers fly1      etc4         
,preventive measures4 ,methods of       
extermination4       ,references to     
,toothaker's ,commercial ,raw           
,materials4 ,use      one day for       
laboratory work from references4  ,fifth
 week4 ,,the ,,study ,,of ,a            
,,water-,,breathing ,,vertebrate4 ,two  
days4 ,the fish1 adaptations in body1   
fins1 for food getting1 for breathing4  

,structure of gills shown4 ,laboratory  
demonstration to show how water gets to 
the gills4 ,drawings4 ,outline of fish1 
gills4 ,required trip to aquarium4      
,object1 to see fish in environment4    
,one day4 ,home work at market4 ,why are
 some fish more expensive than others4  
,economic importance of fish4 ,relation 
of habits of 7a7 food getting1 7b7      
spawning to catching and extermination  
of fish4 ,two days4 ,means of preventing
 overfishing1 stocking1 fishing laws1   
artificial fertilization of eggs1       
methods4 ,development of fish egg4      
,comparison with that of frog and bird4 
,sixth week4 ,,the ,,factors            
,,underlying ,,plant ,,and ,,animal     
,,breeding4 ,study of pupils in class to
 show heredity and variation4           
,conclusion4 ,animals tend to vary and  
to be like their ancestors4 ,heredity1  
role of sex cells1 chromosomes4         
,principles of plant breeding4          
,selective planting1 hybridizing1 work  
of ,darwin1 ,mendel1 ,de ,vries1 and    

,burbank4 ,methods and results4 ,animal 
breeding1 examples given1 results4      
,improvement of man3 7#a7 by control of 
environment1 7a7 example of clean-up    
campaign1 #aiac2 7#b7 by control of     
individual1 personal hygiene1 and       
control of heredity4 ,eugenics4         
,examples from ,davenport1 ,goddard1    
etc4  ,seventh week4 ,,the ,,human      
,,machine4 ,skin1 bones and muscles1    
function of each4 ,examples and         
demonstration with skeleton4 ,organs of 
body cavity2 show manikin4 ,work done by
 cells in body4  ,eighth week4 ,,study  
,,of ,,foods to determine3 7a7 nutritive
 value4 ,exercise with food charts to   
determine foods rich in water1 starch1  
sugar1 fats1 proteins1 mineral salts1   
refuse4 ,one day4 7b7 ,nutritive value  
of foods as related to work1 age1 sex1  
environment1 cost1 and digestibility4   
,foods compared to determine what is    
really a cheap food4  ,ninth week4 ,,how
 ,,the ,,fuel ,,value ,,of ,,food ,,has 
,,been ,,determined4 ,the dietaries of  

,atwater1 ,chittenden1 and ,voit4 ,the  
#ajj-;calorie portion table and its use4
  ,tenth week4 ,,the ,,application ,,of 
,,the #ajj-;,,calorie ,,portion ,,to    
,,the ,,making ,,of ,,the ,,daily       
,,dietaries4 ,luncheon dietaries4 ,a    
balanced dietary for pupil for one day4 
,family dietaries4 ,relation to cost4   
,reasons for this4  ,eleventh week4     
,,food ,,adulterations4 ,tests4 ,drugs  
and the alcohol question4  ,twelfth     
week4 ,,digestion4 ,the alimentary canal
 of frog and of man compared4 ,drawings4
 7,one day47 ,the work of glands4 ,work 
of salivary gland4 ,enzymes1 internal   
secretions4 ,experiments to show 7a7    
digestion of starch by saliva1 7b7      
digestion of proteins by gastric or     
pancreatic juice1 7c7 emulsification of 
fats in the presence of an alkaline     
medium4 ,functions of other digestive   
glands4 ,movements of stomach and       
intestine discussed and explained4      
,thirteenth week4 ,,absorption4 ,how it 
takes place1 where it takes place4      

,passage of foods into blood1 function  
of liver1 glycogen4  ,fourteenth week4  
,,the ,,blood ,,and ,,its ,,circulation4
 ,composition and functions of plasma1  
red corpuscles1 colorless corpuscles1   
blood plates1 antibodies4 ,the lymph and
 work of tissues4 ,the blood and its    
method of distribution4 ,heart a force  
pump4 ,demonstration4 ,arteries1        
capillaries 7demonstration71 veins4     
,hygiene of exercise4  ,fifteenth week4 
,,what ,,respiration ,,does ,,for ,,the 
,,body4 ,the apparatus used4 ,changes of
 blood within lungs1 changes of air     
within lungs4 ,demonstration4 ,cell     
respiration4 ,the mechanics of          
respiration4 ,demonstration4            
,ventilation1 need for1 explain proper  
ventilation4 ,demonstration4 ,hygiene of
 fresh air and proper breathing4        
,dusting1 sweeping1 etc4  ,sixteenth    
week4 ,,excretion1 ,,organs ,,of4 ,skin 
and kidneys1 regulation of body heat4   
,colds and fevers4 ,proper care of skin1
 hygiene4 ,summary of blood changes in  

body4 ,explanation of same4             
,seventeenth week4 ,,body ,,control     
,,and ,,habit ,,formation4 ,nervous     
system1 nerve control4 ,the neuron      
theory1 brain psychology explained in   
brief4 ,habits and habit formation4     
,hygiene of sense organs4  ,eighteenth  
and nineteenth weeks4 ,,civic ,,hygiene 
,,and ,,sanitation4 ,,the ,,improvement 
,,of ,,one',s ,,environment4 ,civic     
conditions discussed4 ,water1 milk1 food
 supplies4 ,relation to disease4 ,how   
safeguarded4 ,how help improve          
conditions in city4  ,twentieth week4   
,,review ,,and ,,examinations4          
,,hygiene ,,outline        7,this       
outline may be introduced with ,plant   
,biology1 or1      better1 may come as  
application of the work in ,second-term 
,biology47   ,,the ,,environment4       
,changes for betterment under control4  
,how a city boy may improve his         
environment3 by proper clothing1 proper 
food and preparation of food1 by care in
 home life2 by sanitary conditions in   

neighborhood and in home4  ,,review ,,of
 ,,activities ,,of ,,cell4              
,irritability1 food taking1             
assimilation1 oxidation1 excretion1     
reproduction4 ,similarity of functions  
of plant and animal cells4 ,all cells   
perform these functions4 ,some cells    
perform functions especially well1 e4g4 
contracting muscle cells4 ,all cells    
need food and oxygen4 ,some must have   
this carried to them4 ,a system of tubes
 carries blood which carries food and   
oxygen4 ,food must be prepared to get   
into the blood4 ,digestive system3      
mouth1 teeth1 stomach1 intestines1      
glands1 and digestive juices4 ,uses of  
above in preparing food to pass into the
 blood4 ,absorption of food into the    
blood4 ,how oxygen gets to the cells4   
,nose1 throat1 windpipe1 lungs2 blood   
goes to lungs and carries away oxygen4  
,excretion4 ,cells give up wastes to    
blood and these wastes taken out of     
blood by kidneys and other glands and   
passed out of body4 ,sweat1 urine1      

carbon dioxide4  ,,certain ,,kinds ,,of 
,,work ,,performed ,,by ,,certain       
,,kinds ,,of ,,cells4 ,advantage of     
this4 ,cells of movement4 ,muscles1     
tissues4 ,bones as levers necessary for 
some movements4 ,this especially true   
for legs and arms4 ,skeleton also       
necessary for protection of internal    
organs and support of body4 ,making of  
special things in the body1 e4g4        
digestive juices given to certain cells 
called gland cells4 ,working together or
 coordination of different organs       
provided for by nervous system4 ,this is
 composed of cells which are highly     
irritable or sensitive4 ,collections of 
these nerve cells give us the power of  
feeling or sensation and of thinking4   
,,dietetics4 ,diet influenced by age1   
weight1 occupation1 temperature or      
climate1 cheapness of food1             
digestibility4  ,,nutrients4 ,list of   
nutrients found in seeds and fruits1    
also other common foods4 ,need of       
nutrients for human body4 ,nitrogenous  

foods1 examples4 ,a mixed diet best4    
,,digestion ,,and ,,indigestion4 ,what  
is digestion8 ,where does it take place8
 ,causes of indigestion4 ,eating too    
rapidly and not chewing food4 ,eating   
foods hard to digest4 ,overeating4      
,eating between meals4 ,hard exercise   
immediately before or after eating4     
,,constipation4 ,a condition in which   
the bowels do not move at least once    
every day4 ,dangers of constipation4    
,poisonous materials may be absorbed1   
causing lack of inclination to work1    
headache4 ,importance of regular habits 
of emptying the bowels4 ,each one must  
try to get at the cause of constipation 
in his own case4 ,causes of             
constipation4 ,lack of exercise1        
improper food1 not drinking enough      
water1 lack of laxative food1 as fruits2
 lack of sleep1 lack of regular habits4 
,remedies4 ,avoid use of drugs4 ,half   
hour before breakfast a glass of hot    
water1 exercise of abdominal muscles1   
laxative foods1 form habit of moving    

bowels after breakfast4  ,,hygiene ,,of 
,,circulation ,,and ,,absorption4 ,how  
digested foods get to the cells4        
,absorption4 ,definition4 ,the passing  
of the digested food into the blood4    
,how accomplished4 ,blood vessels4 ,in  
walls of stomach and food tube4         
,membrane of cells separating food from 
blood4 ,food passes by osmosis through  
the membrane and by osmosis through the 
thin walls of the blood vessels4        
,,circulation ,,of ,,foods4 ,blood      
contains foods1 oxygen1 and waste       
materials4 ,heart pumps the blood1 blood
 vessels subdivide until very small and 
thin1 so food1 etc41 passes from them to
 cells4 ,hygiene of the heart4          
,,transpiration ,,and ,,excretion4      
,skin1 function in excretion4 ,bathing4 
,care of skin4 ,hot baths4 ,bathe at    
least twice a week4 ,cold baths1 how    
taken4 ,bathtub not a necessity4 ,effect
 of latter on educating skin to react4  
,relation to catching cold4  ,,care ,,of
 ,,scalp ,,and ,,nails4 ,scalp should be

 washed weekly4 ,if dandruff present1   
wash often enough to keep clean4        
,baldness often results from dandruff4  
,finger nails cut even with end of      
fingers and cleaned daily with scrub    
brush4  ,,hygiene ,,of ,,respiration4   
,definition of respiration4 ,object of  
respiration4 7,connection between       
circulation and respiration47 ,necessity
 of oxygen4 ,organs of respiration4     
,lungs most important4 ,deep breath1    
function4 ,ventilation1 reasons for4    
,mouth breathing4 ,results4 ,lessened   
mental power1 nasal catarrh1 colds      
easily caught4  ,,plants ,,harmful ,,to 
,,man4 ,poison ivy and mushrooms4       
,treatment4 ,poisoning4 ,send for       
physician4 ,cause vomiting by 7#a7      
finger1 7#b7 mustard and water4 7,,note4
 ,an unconscious person should not be   
given anything by the mouth unless he   
can swallow47 ,relation of yeasts and   
bacteria to man4 ,fermentation a cause  
of indigestion4 ,relation to candy1     
sirups1 sour stomach1 formation of gas  

causes pain4  ,,bacteria ,,of ,,mouth   
,,and ,,alimentary ,,canal4 ,entrance of
 bacteria by mouth and nose4 ,nose3 cold
 in the head1 grippe1 catarrh4 ,mouth3  
decay of teeth1 tonsillitis1 diphtheria4
 ,germs pass from one person to another1
 no one originates germs in himself4    
,precautions against receiving and      
transferring germs4 ,common drinking    
cups1 towels1 coins1 lead pencils1      
moistening fingers to turn pages in book
 or to count roll of bills4             
,tuberculosis germs4 ,entrance by mouth1
 lungs favorite place1 may be any part  
of body4 ,dust of air1 sweeping streets1
 watering a necessity4 ,spitting in     
streets and in public buildings4 ,germs 
of typhoid fever4 ,entrance3 water1     
milk1 fresh uncooked vegetables1        
oysters4 ,thrive in small intestines4   
,preventable4 ,typhoid epidemics1       
methods of prevention of typhoid4       
,conditions favorable for growth of     
specific disease germs4 ,work of ,boards
 of ,health4  ,home sanitary conditions1

 sunlight1 air1 curtains and blinds1    
open windows4 ,live out of doors as much
 as possible4 ,cleanliness4 ,bare walls 
well scrubbed better than carpets and   
rugs4 ,lace curtains1 iron bedsteads1   
one thickness of paper on walls4 ,open  
plumbing1 dry cellars1 all garbage      
promptly removed4  ,this outline is     
largely the work of ,dr4 ,l4 ,j4 ,mason 
and ,dr4 ,c4 ,h4 ,morse of the          
department of biology of the ,de ,witt  
,clinton ,high ,school4                 
,,weights1 ,,measures1 ,,and            
,,temperatures   ,as the metric system  
of weights and measures and the         
,centigrade measurement of temperatures 
are employed in scientific work1 the    
following tables showing the ,english   
equivalents of those in most frequent   
use are given for the convenience of    
those not already familiar with these   
standards4 ,the values given are        
approximate only1 but will answer for   
all practical purposes4                 
,,weight      ,kilogram   kg4  #b-a_/e  

pounds                                  
---------------------------------       
#ae-a_/b grains                         
avoirdupois4                   #a_/bh of
 an ounce   ,gram       gm4             
avoirdupois4                            
-----------------------------------     
,,capacity                              
-----------------------------------     
#fa cubic inches1                    or 
a little more                    than #a
 quart1   ,liter       l4   ,u4 ,s4     
measure4                                
---------------------------------       
,cubic           cc4  #a_/af of a       
centimeter        cubic inch4           
,,measures ,,of ,,length      ,,metric  
,,english ,,equivalents                 
--------------------------------        
,kilometer km4 #b_/c of a mile4         
--------------------------------        
,meter      m4 #ci inches4              
--------------------------------        
,decimeter dm4 #d inches4               
--------------------------------        

,centimetercm4 #b_/e of an inch4        
--------------------------------        
,millimetermm4 #a_/be of an inch4       
,the next table gives the ,fahrenheit   
equivalent for every tenth degree       
,centigrade from absolute zero to the   
boiling point of water4 ,to find the    
corresponding ,f4 for any degree ,c41   
multiply the given ,c4 temperature by   
nine1 divide by five1 and add           
thirty-two4 ,conversely1 to change ,f4  
to ,c4 equivalent1 subtract thirty-two1 
multiply by five1 and divide by nine4   
,,cent4  ,,fahr4   -------------    #ajj
    #bab     #ij    #aid     #hj    #agf
     #gj    #aeh     #fj    #adj     #ej
    #abb     #dj    #ajd     #cj     #hf
     #bj     #fh     #aj     #ej      #j
     #cb    -#aj     #ad    -#bj     -#d
    -#cj    -#bb    -#dj    -#dj    -#ej
    -#eh   -#ajj   -#adh   -------------
   ,absolute zero   -#bgc   -#dei       
,,laboratory ,,equipment  ,the following
 articles comprise a simple equipment   
for a laboratory class of ten4 ,the     

equipment for larger classes is         
proportionately less in price4 ,the     
following articles may be obtained from 
any reliable dealer in laboratory       
supplies1 such as the ,bausch and ,lomb 
,optical ,company of ,rochester1 ,n4,y41
 or the ,kny-,scheerer ,company1 #djd1  
#daj ,west #bgth ,street1 ,new ,york    
,city3--      #a balance1 ,harvard trip 
style1 with weights on carrier4     #a  
bell jar1 about #cfe mm4 high by #afe   
mm4 in diameter4    #aj wide mouth 7salt
 mouth7 bottles1 with corks to fit4     
#aj #be c4c4 dropping bottles for       
iodine1 etc4    #be #bej c4c4           
glass-stoppered bottles for stock       
solutions4   #ajj test tubes1 assorted  
sizes1 principally #f x #c_/d4    #ej   
test tubes on base 7excellent for       
demonstrations74     #b graduated       
cylinders1 one to #ajj c4c41 one to #ejj
 c4c4     #a package filter paper #cjj  
mm4 in diameter4    #aj flasks1         
,erlenmeyer form1 #ejj c4c4 capacity4   
#b glass funnels1 one #ej1 one #aej mm4 

in diameter4    #cj ,petri dishes1 #ajj 
mm4 in diameter1 #aj mm4 in depth4      
#aj feet glass tubing1 soft1 sizes #b1  
#c1 #d1 #e1 #f1 assorted4     #a        
aquarium jar1 #aj liters capacity4      
#b specimen jars1 glass tops1 of about  
#a liter capacity4    #aj hand          
magnifiers1 vulcanite or tripod form4   
#b compound demonstration microscopes or
 #a more expensive compound             
microscope4   #cjj insect pins1         
,klaeger1 #c sizes assorted4    #aj feet
 rubber tubing to fit glass tubing1 size
 #c_/h inch4     #a chemical thermometer
 graduated to #ajj deg4 ,c4    #ae agate
 ware or tin trays about #cej mm4 long  
by #ajj wide4     #a gal4 #ie per cent  
alcohol4 7,do not use denatured         
alcohol47     #a set gram weights1 #a   
mg4 to #ajj g4     #a razor1 for cutting
 sections4     #a box rubber bands1     
assorted sizes4     #a support stand    
with rings4     #b books test paper1 red
 and blue4    #aj ,syracuse watch       
glasses4     #a steam sterilizer 7tin   

will do74     #a spool fine copper wire4
     #a test tube rack4     #e test tube
 brushes4    #aj pairs scissors4    #aj 
pairs forceps4    #bj needles in        
handles4    #aj scalpels4    #ab mason  
jars1 pints4    #ab mason jars1 quarts4 
#a alcohol lamp4     #a gross slides4   
#ajj cover slips ,no4 #b4     #a mortar 
and pestle4     #b bulb pipettes4     #a
 liter formol4     #a oz4 iodine cryst4 
#a oz4 potassium iodide4     #f oz4     
nitric acid4     #f oz4 ammonium        
hydrate4     #f oz4 benzole or xylol4   
#f oz4 chloroform4   #a_/b lb4 copper   
sulphate4   #a_/b lb4 sodium hydroxide4 
#a_/b lb4 rochelle salts4     #f oz4    
glycerine4  ,the materials for          
,pasteur's solution and ,sach's nutrient
 solution can best be obtained from a   
druggist at the time needed and in very 
small and accurately measured           
quantities4  ,the agar or gelatine      
cultures in ,petri dishes may be        
obtained from the local ,board of       
,health or from any good druggist4      

,these cultures are not difficult to    
make1 but take a number of hours'       
consecutive work1 often difficult for   
the average teacher to obtain4 ,full    
directions how to prepare these cultures
 will be found in ,hunter's ,laboratory 
,problems in ,civic ,biology4           
,,index  7,illustrations are indicated  
by page numerals in bold-faced type47   
,absorption1 definition1 #bgj2     of   
digested foods1 #cjh1 #cji4             
,accommodation of eye1 #cfa4            
,acetanilid1 #bie4   ,action of the     
heart1 #cai4   ,adaptations1 #bd2     in
 bee1 #cf2     in birds1 #ahi2     in   
fish1 #bcb2     in frog1 #bda2     in   
mammalia1 #aib4   ,adenoids1 #cdj1 #cie4
   ,adulteration in foods1 #bhh4   ,air1
 and bacteria1 #ade2     composition of1
 #bj2     fresh1 #ccg2     needed in    
germination1 #ff2     necessary in      
starch making1 #ia2     passages in     
lungs1 #ccj2     use to plants and      
animals1 #ba4   ,albumin1 #fb4          
,alcohol1 a food1 #bhi2     a poison1   

#bia4     and ability to resist disease1
 #cfc2     and ability to work1 #cfh2   
and body heat1 #cde2     and crime1     
#cga1 #cgb2     and digestion1 #caa2    
and duration of life1 #cgj2     and     
efficiency1 #cfi2     and heredity1     
#cgb2     and intellectual ability1     
#cfd2     and kidneys1 #cdf2     and    
living matter1 #bia2     and memory1    
#cfe2     and mental ability1 #cff2     
and nervous system1 #cfb2     and organs
 of special sense1 #cfb2     and        
pauperism1 #cga2     and resistance1    
#cbg2     and respiration1 #cdf2     and
 the blood1 #cbg2     and treatment of  
disease1 #cfd2     effect on            
circulation1 #cbg2     effect on eye1   
#cfa2     effect on liver1 #cab2        
produces poisons1 #cdg4   ,algae1 #agf4 
,alfalfa plant1 #aea4   ,alimentary     
canal1 #big4   ,alkali1 #cjf4           
,alkalinity1 #bih4   ,alligator1 #bcj4  
,ambergris1 #bje4   ,ammonium hydrate1  
#fa4   ,amoeba1 #agj1 #ahb1 #ccb4       
,amphibia1 #ahf1 #ahg2     as food1     

#bjb4   ,anal fin of fish1 #bcc4        
,angiosperms1 #agf4   ,animals1 as      
disease carriers1 #bbg2     breeding of1
 #bei2     domesticated1 #bfj2          
functions of1 #dh1 #ahj2     need       
plants1 #cd2     oils of1 #bje2         
parasitic1 #bbg2     series1 #ahb2      
that prey upon man1 #bcj2     use to    
man1 #ag2     use to plants1 #cd4       
,annual rings1 #ih4   ,anopheles1 #bag1 
#bah4   ,anosia plexippus1 #cb4         
,anther1 #cf4   ,antibodies1 uses of1   
#caf4   ,antiseptics1 #aeg4             
,antitoxin1 #aeg1 #cia4   ,anura1 #ahh4 
,anvil1 #cei4   ,aorta1 #cbj4           
,apoplexy1 #cbh4   ,appendages of the   
fish1 #bcc4   ,appendicular skeleton1   
#bfh4   ,appendix1 #cji4   ,apples1 #ef1
 #abd4   ,aqueous humor1 #cfa4          
,arachnida1 #ahe4   ,arteries1 #cah2    
structure of1 #cbc4   ,arthropods1 #ahe4
   ,artificial1 cross-pollination1 #df2 
propagation of fishes1 #bdj2            
respiration1 #cdj2     selection1 #bec4 
,asexual reproduction1 #agd4            

,assimilation in plants1 #ajc4          
,attention1 effect of alcohol1 #cfd4    
,audubon1 #baa4   ,auricle of human     
heart1 #cai2     of fish heart1 #bcf4   
,automatic activity1 #cdh1 #ced4        
,axial skeleton1 #bfh4     ,bacillus1   
#adb4   ,bacteria1 #acd2     and        
fermentation1 #aej2     cause decay1    
#adi2     cause disease1 #aea2          
effect on food1 #add2     growth of1    
#ade2     isolating a pure culture1     
#adb2     nitrogen fixing1 #hj1 #ha1    
#aea1 #aeb2     of decay1 #add2         
relation to man1 #af2     size and form1
 #adb1 #adc2     useful1 #aej2     where
 found1 #aci1 #ada4   ,bacteriology1    
#af4   ,bad posture1 #bgj4   ,balanced1 
aquarium1 #aei1 #afj2     diet1 #bhe4   
,barbels of fish1 #bcd4   ,barberry     
embryo1 #ajc4   ,bark1 use of1 #ih4     
,barrier1 natural1 #be4   ,bast1 #ig4   
,beans1 as food1 #fb4   ,beans1 peas1   
#ee4   ,beans1 seedlings1 #fc4          
,bedroom1 care of1 #cgd4   ,bee1        
adaptations1 #cf2     head of1 #ch2     

mouth parts1 #ch4   ,beer and wine      
making1 #acg4   ,benedict's test1 #fh4  
,benzoic acid1 #adh4   ,beverages and   
condiments1 #abd4   ,biceps1 #bfi4      
,bichloride of mercury1 #adh4   ,bile1  
functions of1 #cjf1 #cjg4   ,biology1   
definition1 #ae2     relation to        
society1 #ah4   ,birds1 #ahi2     as    
food1 #bjb2     classification1 #aia2   
development1 #bdf2     eat insects1     
#bji2     eat weed seeds1 #baj2         
embryo1 #bdf1 #bdg4   ,bismuth1 #cjd4   
,bison1 #aib4   ,black ,death1 #bbg4    
,blade of leaf1 #he4   ,blastula1 #agg4 
,blood1 amount and distribution1 #cah2  
changes in lungs1 #ccj2     circulation 
of man1 #cah2     clotting1 #cad2       
composition1 #cad2     effect of        
alcohol1 #cbg2     function1 #cac2      
plates1 #cae2     poisoning1 #aef2      
temperature1 #cah2     vessel of skin1  
#cdd4   ,blubber1 #bje4   ,blue crab1   
#aii4   ,board of health1 functions1    
#chi4   ,body1 a machine1 #cdh2         
cavity1 #bgj2     heat and alcohol1     

#cde2     of fish1 #bcb4   ,bony fish1  
#ahg4   ,boracic acid1 #adh4   ,borax1  
#adh4   ,brain1 of fish1 #bcg2     of   
man1 #cea4   ,bread1 making1 #aci2      
mold1 #acc4   ,bream1 #bcc4             
,breathing1 #ccc2     and tight         
clothing1 #cci2     hygienic habits1    
#cch2     in leaf1 #ic2     of fish1    
#bcd2     of frog1 #bdb2     of         
vertebrates1 #bcb2     rate of1 #ccd4   
,breeding of animals1 #bei4   ,bright's 
disease1 #cdf4   ,bronchi1 #ccj4        
,bronchial tubes1 #ccj4   ,bruises1     
#cde4   ,bryophytes1 #agf4   ,bubonic   
plague1 #bbg4   ,budding1 #bee1 #bef4   
,bumblebees1 #cg4   ,burbank1 ,luther1  
#djf4   ,burns1 treatment of1 #cde4     
,butter and eggs1 #ch1 #ci4             
,calorie1 portion1 #bhf2                
requirement1 #bhb4   ,calyx1 #ce4       
,cambium layer1 #ih4   ,canning1 #ade4  
,cannon1 ,prof41 #cjd4   ,capillaries1  
#cah1 #cbc2     circulation in1 #cbb2   
of fish1 #bcf4   ,carbohydrates1 #fj1   
#bgc4   ,carbolic acid1 #adi4   ,carbon 

and oxygen cycle1 #afa4   ,carbon       
dioxide1 test for1 #fd4   ,care of milk 
supply1 #chj1 #chc4   ,carnivorous1     
#bcj4   ,caudal fin of fish1 #bcc4      
,cause of dyspepsia1 #caj4   ,cells1    
#ej2     as units1 #aga2     division1  
#ea2     mucous1 #bii2     of pond scum1
 #agc2     reproduction of1 #ej2        
respiration1 #ccb2     tissue1 #agi2    
work of1 #bgj4   ,cephalothorax1 #ahe4  
,cerebellum1 #ceb4   ,cerebro-spinal    
nervous system1 #cej4   ,cerebrum1 #cea4
   ,cestodes1 #bbg4   ,changes1 of blood
 in lungs1 #ccj2     of air in lungs1   
#cca4   ,characters1 determiners of1    
#beh4   ,chelonia1 #ahh4   ,chemical1   
compounds1 #bj2     elements1 #bj2      
of human body1 #ba4   ,chestnut canker1 
#aca4   ,china1 deforestation in1 #ajh4 
,chittenden table1 #caa4   ,chloral1    
#bic4   ,chlorophyll bodies1 #ej1 #ij4  
,chloroplasts1 #ij4   ,chromosomes1 #ej2
     and heredity1 #bea4   ,chrysalis1  
#cc4   ,cilia1 #aga4   ,circulation1    
effect of alcohol1 #cbg2     effect of  

exercise1 #cbf2     effect of tobacco1  
#cbh2     in fish1 frog1 man1 #cba1     
#cbb2     in stem1 #ii1 #ajj1 #aja2     
of blood of man1 #cah2     of fish1     
#bcf2     of frog1 #bdc2     portal1    
#cbb2     pulmonary1 #cbj2     systemic1
 #cbj4   ,city's need for trees1 #aae4  
,civic hygiene1 #chh4   ,clams1 #bjj4   
,classification1 of birds1 #aia2     of 
plants1 #agf4   ,cloaca of frog1 #bdc4  
,clothing1 #bjc4   ,clotting of blood1  
#cad4   ,coal1 #fd4   ,cobra1 #bcj4     
,cocaine1 #bic4   ,coccus bacteria1     
#adb4   ,cochineal and lac1 #bjh4       
,cochlea1 #cei4   ,codling moth1 #bae4  
,coelenterates1 #ahc4   ,cold-blooded   
animals1 #cah2     effect of1 #bc4      
,cold storage1 #adg4   ,colds and       
fevers1 #cdc4   ,coleoptera1 #cb4       
,collecting ashes1 #chg4   ,colonies of 
bacteria1 #ada2     of trilliums1 #age4 
,colorless corpuscles1 #cac2            
structure1 #cae2     function1 #caf4    
,common foods contain nutrients1 #bge4  
,comparison1 of food tube of frog and   

man1 #big2     of mold1 yeast and       
bacteria1 #adc2     of starch making and
 milling1 #ib4   ,complemental air1     
#ccd4   ,complex one-celled animals1    
#aga4   ,composition1 of milk1 #bgc1    
#bhj2     of plasma1 #cac2     of soil1 
#gg4   ,compound eyes of bumblebee1 #cg1
 #ch4   ,conservation1 of food fish1    
#bci2     of fur-bearing animals1 #bjd2 
of our natural resources1 #ag4          
,constipation1 #caj4   ,constrictor     
killing a mouse1 #bac4   ,contagious    
diseases1 #aeb4   ,convolutions1 #ceb4  
,corn1 #abj1 #aba2     germinated grain 
cut lengthwise1 #fi2     long section of
 ear1 #fg2     structure of grain1 #ff4 
,cornfield1 #dd4   ,corolla1 #ce4       
,corpuscles1 colorless and red1 #cac4   
,cost of food and diet1 #bha1 #bhc2     
of parasitism1 #bfc4   ,cotton1 #abe2   
boll weevil1 #abf1 #abg1 #bad4          
,cotyledons1 #ei2     food in1 #fj4     
,crab1 #aii4   ,crayfish1 #ahd4         
,crocodile1 #bcj4   ,crocodilia1 #ahi4  
,crustacea1 #ahe4   ,culex1 #bah1 #bah4 

,culture medium1 #adj4   ,cuts and      
bruises1 treatment1 #cbf1 #cde4         
,daily calorie requirement1 #bhb2       
fuel needs of body1 #bhd4   ,dandelion1 
whorled leaves1 #ij4   ,darwin1         
,charles1 #dj1 #djd4   ,darwin and      
natural selection1 #bec4   ,deaths1     
table1 #cab4   ,decay caused by         
bacteria1 #adi4   ,decayed teeth1 #cif4 
,defects in eye1 #cfa4   ,deforestation 
in ,china1 #ajh4   ,dendrites1 #cea4    
,department of ,agriculture1 work of1   
#bee4   ,department of street cleaning1 
#chg4   ,determiners1 #bea2     of      
character1 #beh4   ,development1 of     
apple1 #ef2     of bird1 #bdf2     of   
egg1 #agh2     of trout1 #bch2     of   
mammal1 #bdg2     of salmon1 #bda2      
of simple animal1 #agg4   ,diagram of   
frog's tongue1 #bdb2     of gills of    
fish1 #bce2     of neuron1 #cea2     of 
wall small intestine1 #cjg4             
,diaphragm1 #bgj1 #big4   ,diastase1    
#aja1 #cjj2     action on starch1 #fi4  
,diet1 and cost of food1 #bha2     and  

digestibility1 #bha2     balanced1 #bhe2
     relation of age1 #bhj2     relation
 of environment to1 #bhj2     relation  
to sex1 #bhj2     relation of work to1  
#bgg2     the best1 #bhd4   ,dietary1   
the best1 #bhb4   ,digested food1       
absorption of1 #cjh4   ,digestibility   
and diet1 #bha4   ,digestion1 #fh1 #ajj1
 #aha2     effect of alcohol1 #caa2     
definition of1 #bgj2     in stem1 #ii2  
in stomach1 #cjd2     of starch1 #bii2  
purpose of1 #fi1 #bif4   ,digestive     
system of fish1 #bce4   ,digestive tract
 of frog and man1 #big4   ,diphtheria1  
#aeb4   ,dipnoi1 #ahg1 #bcf4   ,diptera1
 #ca4   ,discoverers of living matter1  
#cih4   ,disease1 and alcohol1 #cab2    
and bacteria1 #aea2     carriers1       
animals1 #bbf2     carriers1 flies1     
#bbb2     carriers1 insects1 #bbe2      
caused by bacteria1 #aeb2     caused by 
protozoa1 #agb2     effect of alcohol1  
#cbg2     of nose and throat1 #cdj2     
protozoan1 #bba4   ,disinfectants1 #adh4
   ,division of labor1 #agh1 #bfg4      

,dog1 skeleton1 #ahe4   ,domesticated   
animals1 #bjc1 #bfj4   ,dominant        
characters1 #beh4   ,dormant1 #bb4      
,dorsal1 #ahf2     fin1 #bcc4   ,drugs1 
use and abuse1 #bid4   ,duff1 #aac4     
,dyspepsia1 cause and prevention1 #caj4 
,ear1 section1 #cei4   ,echinoderms1    
#ahd4   ,economic value of green plants1
 #aag2     importance of spawning habits
 of fishes1 #bci4   ,ectoderm1 #agg4    
,effect of light on leaves1 #hh4        
,efficiency of a week1 #cgj4   ,egg1    
#agg1 #bdf4   ,egg-laying habits of     
fishes1 #bch4   ,ehrlich1 ,paul1 #djc4  
,elasmobranchs1 #ahg4   ,elements1      
chemical1 #bj1 #ba4   ,elodea1 #di1 #ej4
   ,embryo1 #eh1 #ei1 #ajc2     of bird1
 #bdg2     of mammal1 #bdg4   ,emulsion1
 #cjf4   ,endoderm1 #agg4               
,endoskeleton1 definition1 #bcg4        
,endosperm1 #fg4   ,enemies of forests1 
#aac1 #aad4   ,energy1 #fd2     of a    
tree1 #id2     source of1 #hh4          
,english sparrow1 #bab4   ,environment1 
#ai1 #ai2     care and improvement of1  

#bf2     changes in1 #be2     determines
 kind of plants and animals1 #bc1 #bc1  
#bd2     normal1 #bh2     of man1 #bf1  
#bff2     natural1 #be2     relation to 
diet1 #bhj2     what plants and animals 
take from1 #ba4   ,enzymes1 #fh1 #aja1  
#bih4   ,epicotyl1 #ei4   ,epidermis1   
#hf4   ,epithelial layer1 #cjh4         
,epithelium1 #agi4   ,erosion1          
prevention of1 #ajf1 #ajh2     at       
,sayre1 ,pa41 #ajf4   ,essential organs1
 #cf4   ,esophagus1 #cjb4   ,eugenics1  
#bfa4   ,eustachian tubes1 #cjj1 #cei4  
,euthenics1 #bfd4   ,evaporation1 #ii2  
of water1 #he1 #hf1 #hg4   ,evolution1  
#aid1 #aie4   ,excretion1 #aha1 #bgj1   
#ccb2     organs of1 #cdj2     in       
plants1 #ajc4   ,exercise and           
circulation1 #cbf2     and health1 #cci4
   ,exoskeleton1 #ahe1 #bcg4            
,extermination of birds1 #baa4   ,eye1  
compound1 #cj2     defects in1 #cfa2    
section of1 #cfj4   ,eyestrain1 #cie4   
,factory inspection1 #cgi4   ,fallowing1
 #hb4   ,fatigue1 #cbf2     and nerve   

cells1 #cef4   ,fats and oils1 #fj1     
#bgc4   ,fehling's solution1 #fh1 #bii4 
,fermentation1 #ace1 #acf1 #aej4        
,fertilization1 of fish eggs1 #bdj2     
of flower1 #ed4   ,fibers1 vegetable1   
#abg4   ,fibrin1 #cae4   ,fibrinogen1   
#cae4   ,fig insect1 #dc4   ,filament1  
#cf4   ,filter beds at ,albany1 ,n4 ,y41
 #che4   ,fins1 #bcc4   ,fishes1 #ahf2  
artificial propagation1 #bdj2     as    
food1 #bja2     body of1 #bcb2          
breathing1 #bcd2     circulation1 #bcf1 
#cba2     digestive system1 #bce2       
egg-laying habits1 #bch2     food       
getting1 #bcd2     food of1 #bcg2       
gills1 #bcd2     heart1 #bcf2           
migration1 #bch2     nervous system1    
#bcg2     skeleton1 #bcg2     senses1   
#bcc2     swim bladder1 #bcf4           
,fission1 #agj4   ,flagella of bacteria1
 #adb4   ,flatworms1 #ahc4   ,flax1     
#abh4   ,flea1 #bbe4   ,floral envelope1
 #ce4   ,flower1 fertilization of1 #ed2 
lengthwise section1 #ce2     use and    
structure1 #ce4   ,fluid1 #aha4   ,fly1 

a disease carrier1 #bbb2     foot of1   
#bbc2     life history1 #bbb2           
typhoid1 #bbc4   ,foods1 absorption of1 
#cji2     adulteration1 #bhh2           
amphibia as1 #bjb2     birds as1 #bjb2  
cost of1 #bhc2     fish as1 #bja2       
fruits and seeds1 #aai2     getting of  
fish1 #bcd2     in cotyledons1 #fj2     
inorganic1 #bgd2     inspection1 #chj2  
is alcohol a food1 #bhi2     leaves1    
#aag1 #aah2     making in green leaf1   
#ic2     mammals as1 #bjb2     of animal
 origin1 #bgi2     of bacteria1 #add2   
of fishes1 #bcg2     of insects1 #cc2   
of plant origin1 #bgh2     of starfish1 
#baf2     reptiles as1 #bjb2     roots  
as1 #aai2     stems as1 #aah2           
taking1 #aha2     tube of frog1 #bdc2   
values1 tables1 #bgf2     waste in      
kitchen1 #bhg2     why we need1 #bgb4   
,foraminifera1 #ahb4   ,forestry1 #aac4 
,forest destruction1 #aab1 #aac2        
fires1 #aab2     of ,north ,carolina1   
#aje2     other uses1 #aji2             
protecting1 #aad2     regions of ,united

 ,states1 #aji4   ,formaldehyde1 #adh4  
,formation of habits1 #ced4   ,four     
o'clock embryo1 #ajc4   ,fresh air1     
#ccg4   ,frog1 adaptations for life1    
#bda2     and man1 digestive tract1     
#big2     breathing1 #bdb2              
circulation1 #bdc1 #cbb2     development
 of1 #bdd2     diagram of tongue1 #bdb2 
food tube1 #bdc2     glands1 #bdc2      
locomotion of1 #bda2     long section1  
#bdc2     metamorphosis1 #bde2          
nervous system1 #ceb2     sense organs1 
#bdb4   ,fruit1 a typical1 #ee4   ,fruit
 of locust1 #ee4   ,fruits and seeds as 
foods1 #aai4   ,fruits1 how scattered1  
#ef4   ,fuel1 daily needs1 #bhd4   ,fuel
 values of nutrients1 #bgg4             
,functions1 of all animals1 #ahj2     of
 an animal1 #dh2     of bile1 #cjg2     
of blood1 #cac2     of cerebrum1 #cec2  
of colorless corpuscle1 #caf2     of    
lymph1 #cag2     of parts of plant1 #dh2
     of red corpuscle1 #cad4   ,fungi1  
#acj1 #agf2     moldlike1 #ace2     of  
our homes1 #acb4   ,fur-bearing animals1

 #bjd4     ,gall bladder1 #cjf2         
insects1 #bjh4   ,gallflies1 #dc4       
,ganoids1 #ahf1 #ahg4   ,garbage cans1  
#cgg4   ,garden fruits1 #abc4   ,gastric
 glands1 #cjc2     of frog1 #bdc4       
,gastric juice1 #cjc4   ,gastrula1 #agg1
 #agh4   ,genus1 #age4   ,geranium1 #de4
   ,german forest1 #aad4   ,germ cells1 
#bea4   ,germination1 of bean1 #fc2     
of pollen1 #ed4   ,gills of fish1 #bcd2 
rakers1 #agb1 #bcd4   ,glands1 #big1    
#bih1 #bii2     gastric1 #cjc2          
lymph1 #cbd2     of frog1 #bdc2         
salivary1 #bii4   ,glomerulus1 #cda4    
,glottis of frog1 #bdc4   ,glycogen1    
#cjg4   ,gonorrhea1 #aef4   ,grafting1  
#bef4   ,grains1 #abb4   ,grape sugar1  
test for1 #fh4   ,gravity1 influence on 
root1 #gb4   ,green plants1 economic    
value1 #aag2     give off oxygen1 #ie2  
harmful1 #abg2     make starch1 #ij1    
#ib4   ,groups of plants1 #agd4         
,guano1 #hb4   ,guard cells1 #hh4       
,gullet1 #big1 #cjj1 #cja1 #cjb1 #cjc2  
of frog1 #bdc4   ,gymnosperms1 #agf4    

,gypsy moth1 #bae4     ,habits1 #ced4   
,habitat of protozoa1 #agb4   ,habit    
formation1 #ced4   ,haemoglobin1 #cad1  
#ccj4   ,hammer1 #cei4   ,hard palate1  
#cja4   ,harm done by insects1 #cd1     
#bbe4   ,harmful green plants1 #abg2    
preservatives1 #adh4   ,hay infusion1   
#afc1 #afd4   ,head of a bee1 #ch4      
,heart a force pump1 #cbj2     diagram1 
#cai2     in action1 #cai2     internal 
structure1 #cai2     of fish1 #bcf2     
size1 position1 #cah4   ,heat1 and      
bacteria1 #ade2     effect of1 #bb2     
output1 #bhe4   ,heating the house1     
#cge4   ,hemiptera1 #cb4   ,hen's egg1  
#bdf4   ,herbivorous animals1 #bac4     
,heredity1 and evolution1 #djd2         
bearers of1 #bea2     definition1 #bdi2 
relation of alcohol to1 #cgb4   ,hervey1
 ,william1 #cii4   ,hibernate1 #bb4     
,hides1 #bje4   ,hilum1 #ei4   ,honey   
and wax1 #bjg4   ,hookworm1 #ahc1 #bbh1 
#bbi4   ,horse1 ancestor of1 #aic1 #bfj4
   ,how food is swallowed1 #cjb4        
,human blood1 #cad4   ,human body1 a    

machine1 #bfg2     composition of1 #ba4 
,human physiology1 definition1 #ae4     
,humming bird1 #dc4   ,humus1 #gi4      
,hundred calorie portions1 #bhf4        
,huxley1 #cih4   ,hybridizing1 #bed4    
,hybrids1 #bed4   ,hydra1 #agi4         
,hydrochloric acid1 #cjc4   ,hydrogen of
 water1 #bj1 #bj4   ,hydrophobia1 #cib4 
,hygiene1 #bg2     of breathing1 #cch2  
of skin1 #cdd2     of mouth1 #cjb2      
of muscles and bones1 #bfh2     outline1
 #dae2     personal1 #bfa4   ,hypocotyl1
 #ei4   ,hymenoptera1 #cj4              
,ichneumon fly1 #bjh4   ,illness of     
drinkers1 #cfc4   ,imperfect flowers1   
#dd1 #de4   ,immunity1 #aeg1 #cij4      
,improvement1 by selection1 #bec2     of
 man1 #bfa4   ,impure water1 #bhi4      
,incisors1 #cja4   ,infectious diseases1
 #bg1 #cfc1 #cij4   ,infusoria1 #ahb4   
,inner ear1 #cei4   ,inoculation1 #aeg4 
,inorganic soil1 #gg2     foods1 #bgd4  
,insects1 #ahe2     and foods1 #cgf2    
as disease carriers1 #bbe2     as       
pollinating agents1 #cf2     damage done

 by1 #cd1 #bad2     diagram of1 #bi2    
food of1 #cc2     of the house1 #baf2   
orders of1 #cj4   ,inspection1 of       
factories1 #cgi2     of raw food1 #chj4 
,instincts1 #aie4   ,internal           
secretions1 #cag4   ,intestinal fluid1  
#cjf2     glands1 #cjh4   ,intestine1   
large1 #cji4   ,invertebrates1 #ahe4    
,iris1 #cfj4   ,isolation1 #cij4        
,jenner1 ,edward1 #djj4   ,jimson weed1 
#abh4   ,jukes1 #bfa4     ,kidney bean1 
#ei1 #fc4   ,kidneys1 #aha2     human1  
#cda2     of frog1 #bdc4   ,kinetic     
energy1 #bfg4   ,knots1 #aab4   ,koch1  
,robert1 #djc4     ,labor1 division of1 
#agh4   ,laboratory equipment1 #dah4    
,lacteals1 #cji1 #cbd4   ,lactic acid1  
#aej4   ,lactometer1 #bhh4   ,ladybug1  
#bji4   ,large intestine1 #cji2     of  
frog1 #bdc4   ,larva of milkweed        
butterfly1 #cb4   ,latent energy1 #bfg4 
,lateral line1 #bcd4   ,leaves1 as food1
 #aag2     evaporation of water from1   
#he2     cell structure of1 #he2        
mosaic1 #ij2     respiration1 #if2      

section1 #di2     skeleton of1 #he2     
structure1 #he1 #hf4   ,length measures1
 #dag4   ,leopard frog1 #ahh4           
,lepidoptera1 #cj4   ,levers1 #bfi4     
,life comes from life1 #cii4   ,life    
cycle1 #ajd2     of plants1 #ajc4       
,life history of malarial parasite1     
#bag4   ,ligaments1 #bfh4   ,ligature1  
applying1 #cbf4   ,light1 a condition of
 environment1 #ba1 #bb2     and         
bacteria1 #ade2     effect of1 #bb2     
necessary for starch making1 #ia4       
,lighting the home1 #cgf4   ,lily1      
narrow leaves1 #ij4   ,limewater test1  
#fd4   ,lister1 ,sir ,joseph1 #djc4     
,liver1 #cjf2     a storehouse1 #cjg2   
effect of alcohol on1 #cab2     of frog1
 #bdc4   ,living matter and alcohol1    
#bia2     plant and animal compared1    
#dg2     things1 needs of1 #bff2        
things1 varying sizes of1 #ea4          
,lizard1 #ahh4   ,lobster1 #aih4        
,locomotion1 #aha2     of frog1 #bda4   
,lowell1 typhoid area1 #chd4   ,lumber  
transporting1 #aaj-aaa4   ,lungs1 air   

passages1 #ccj2     changes of blood in1
 #ccj4   ,lymph1 function1 #cag2        
glands and vessels1 #cbd1 #cbe4         
,lysol1 #adh4     ,mac,nichol1 ,dr4 ,t4 
,alexander1 #cbg4   ,macronucleus1 #afi4
   ,malaria1 cause1 #bag4   ,malarial   
mosquito1 #bah4   ,malarial parasite1   
life history1 #bag4   ,mammal           
development1 #bdg2     embryo1 #bdg4    
,mammals1 #aia2     adaptations1 #aib2  
as food1 #bjb2     classification1 #aib4
   ,mammary glands1 #aia4   ,man1       
animals that prey upon1 #bcj2     and   
his environment1 #bff2     circulation  
of blood1 #cah2     improvement of1     
#bfa2     in his environment1 #bf2      
mouth cavity1 #cjj2     place in nature1
 #aie2     races of1 #aif2     stomach1 
#cjc4   ,manufacture of fats1 #ic4      
,measures1 #dag4   ,mechanics of        
respiration1 #ccb1 #ccc4   ,membrane1   
mucous1 #bii4   ,mendel1 ,gregor1 #beg1 
#djf4   ,mesenteric glands1 #cji4       
,mesentery1 #big4   ,mesoderm1 #agg4    
,metamorphosis of frog1 #bdd1 #bde4     

,metchnikoff1 #caf4   ,methods1 of      
cutting timber1 #aaa2     of breathing  
in vertebrates1 #bcb4   ,micronucleus1  
#afi4   ,micropyle1 #ei4   ,middle ear1 
#cei4   ,migration of fishes1 #bch4     
,milk1 and tuberculosis1 #cha2          
composition of1 #bgc1 #bhj2     germs   
in1 #cha2     grades of1 #cha2     under
 microscope1 #aej1 #cje4   ,milkweed1   
butterfly1 #cb1 #cc4   ,milling and     
starch making1 #ib4   ,mink1 #bje4      
,mixed diet1 #bhd4   ,moisture1 #bd1    
#gh4   ,mollusca1 #ahe4   ,mollusk1     
#ahe4   ,mold1 #acc1 #acd1 #ace2        
yeast and bacteria1 #adc4   ,morning    
glory embryo1 #ajc4   ,mosquito1        
malarial1 #bah2     yellow fever1 #bai4 
,moss plant1 #agg4   ,mother of pearl1  
#bjf4   ,motor nerves1 #cea4   ,mouth   
cavity in man1 #cjj1 #cjj4   ,mouth     
parts of bee1 #ch4   ,mucous membrane1  
#bii4   ,mucus cells1 #bii4   ,muscles  
and bones1 hygiene1 #bfh4   ,mutations1 
#bec1 #djf4   ,mutual aid between       
flowers and   insects1 #da4   ,mycelium1

 #acc4   ,myriapoda1 #ahe4     ,natural 
environment1 #be2     selection1 #bec4  
,nectar1 #ce4   ,need1 of food1 #bgb2   
of sleep1 #cef2     of ventilation1     
#cce4   ,needs of living things1 #bff4  
,nerve cells and fatigue1 #cef2         
vasomotor1 #cbe4   ,nervous control1    
#aha2     of heart1 #cbe2     of        
respiration1 #ccd2     of sweat glands1 
#cdc4   ,nervous system1 #bga1 #cdi2    
of frog1 #ceb4   ,neuron1 diagram1 #cea4
   ,newt1 #ahg4   ,nicotine1 #bic4      
,nictitating membrane of frog1 #bdb4    
,nitrates1 #hj4   ,nitric acid1 #fa4    
,nitrogen1 #hj2     cycle1 #afb2        
fixing bacteria1 #hj1 #ha1 #aea2     of 
air1 #bj4   ,nodules1 #ha4   ,normal    
heat output1 #bhe4   ,nose and throat1  
diseases1 #cdj4   ,nucleus1 #ej4        
,nutrients1 #bgc1 #bgd2     fuel values1
 #bgg2     in common foods1 #bge4       
,object of a field trip1 #bh4   ,oils1  
test for1 #fa4   ,operculum1 #bcd4      
,ophidia1 #ahi4   ,orbit of eye1 #cfj4  
,orchard fruits1 #abd4   ,organic       

matter1 #fd4   ,organic nutrients1 #fj4 
,organisms1 #dg4   ,organs1 #dg1 #dh1   
#ahj2     of ,corti1 #cfj2     of       
excretion1 #cdj2     of hearing1 #ceh2  
of respiration1 #ccj2     of taste1     
#ceh2     of touch1 #ceg4   ,orthoptera1
 #cj4   ,osmosis1 definition1 #ge2      
experiment1 #ajj2     physiological     
importance1 #gg4   ,ostrich1 #aia4      
,outline of courses1 #djg-dad4          
,ovaries of frog1 #bdc4   ,ovary1 #cf4  
,ovules1 #ed4   ,oxidation1 #fd2     in 
our bodies1 #fe4   ,oxygen cycle1 #afa2 
given off by green plants1 #ie2     of  
air1 #bj2     of water1 #bj4   ,oyster1 
#aii1 #bjj4     ,packard 7zoologist71   
#cc4   ,palate1 hard and soft1 #cja4    
,palisade tissue1 #hf4   ,pancreas1     
#cje2     of frog1 #bdc2     work of1   
#cje4   ,papillae1 #cja4   ,pappus1 #eg4
   ,paramoecium1 #afg1 #afh1 #afi2      
needs of1 #bff2     response to stimuli1
 #afg4   ,parasites1 #aca4   ,parasitic 
animals cause disease1 #bbg4            
,parasitism1 cost and remedy1 #bfc4     

,parotid1 #bii4   ,pasteur1 ,louis1     
#dja4   ,pasteurization1 #adf4   ,pea   
pod1 #ee4   ,pearls1 #bjf4   ,pectoral  
fin1 #bcc4   ,pelvic fin1 #bcc4         
,pepsin1 #cjc4   ,peptic gland1 #cjd4   
,perfumes1 #bje4   ,pericardium1 #cai4  
,peristaltic waves1 #cjc4   ,personal   
hygiene1 #bfa4   ,perspiration1 #cdc4   
,petals1 #ce4   ,petri dishes1 #adj4    
,phagocytes1 #caf4   ,pharynx1 #cja4    
,phenolphthalein1 #hj4   ,phosphoric    
acid1 #hb4   ,photosynthesis1 #ib1 #ic4 
,physiology of mold1 #acc4   ,pistil1   
#cf4   ,pith1 #ig4   ,placentae of      
mammal1 #bdg4   ,plankton1 #bce4        
,plants1 animals depend on1 #cd2     and
 animals1 mutually helpful1 #ah2        
classification1 #agf2     food for      
insects1 #cc2     as food makers1 #hh2  
function of parts1 #dh2     groups1     
#agd2     need minerals1 #hj2     need  
of nitrogen1 #hj1 #hb2     processes1   
#ajc2     reproduction1 #agc4   ,plasma1
 #cac4   ,plasmodium malariae1 #ahb1    
#bag4   ,pleura1 #ccb4   ,pleurococcus1 

#aff4   ,plumule1 #ei4   ,pneumonia1    
#ccf4   ,pocket garden1 #gc4   ,poison1 
alcohol1 #bia2     ivy1 #abh2           
produced by alcohol1 #cdg4   ,polar     
bear1 #bjd4   ,pollen1 #cf2             
germination of1 #ec1 #ed4               
,pollination1 #cf1 #dj2     cross and   
self1 #dj2     wind1 #dd4   ,pond scum1 
#agc4   ,pons1 #ceb4   ,porifera1 #ahb4 
,portal circulation1 #cji1 #cbb4        
,portions1 hundred calorie1 #bhf4       
,potato beetle1 #bad4   ,potato beetle1 
embryo1 #ajc4   ,premolars1 #cjb4       
,preservatives1 #adg4   ,prevention of  
dyspepsia1 #caj2     of molds1 #acd4    
,proboscis1 #cj4   ,prolegs1 #cb4       
,pronuba1 #db1 #dc4   ,protecting       
forests1 #aad4   ,proteins1 #fj1 #bgc2  
making1 #ic2     test for1 #fa4         
,protoplasm1 #ej2     what it can do1   
#eb4   ,protozoa1 #agb1 #ahb1 #bje4     
,protozoan diseases1 #bba4              
,pteridophytes1 #agf4   ,ptomaines1     
#add1 #adg4   ,ptyalin1 #cjj4   ,public 
hygiene1 #chi4   ,pulmonary circulation1

 #cbj4   ,pulse1 cause1 #cbc4   ,pupa of
 milkweed butterfly1 #cc4   ,pupil of   
eye1 #cfj4   ,pure food laws1 #bhh4     
,purpose of digestion1 #fi1 #bif4       
,pyloric caeca1 #bce4     ,quarantine1  
#bg1 #cij4     ,rabies1 #cib4   ,races  
of man1 #aif4   ,radiolaria1 #ahb4      
,radiolarian skeleton1 #ahb4            
,recessive characters1 #beh4   ,rectum1 
#big4   ,red corpuscles1 #cac1 #cad4    
,reflex actions1 #cec4   ,regulation of 
heat of body1 #cdc4   ,relation1 of age 
to diet1 #bhj2     of alcohol to crime1 
#cga2     of alcohol to heredity1 #cgb2 
of alcohol to pauperism1 #cga2     of   
animals to man1 #ag2     of bacteria to 
free nitrogen1 #ha2     of bacteria to  
man1 #af2     of biology to society1    
#ah2     of cost of food to diet1 #bha2 
of digestibility to diet1 #bha2     of  
environment to diet1 #bhj2     of green 
plants and animals1 #ae1 #afa1 #afb2    
of sex to diet1 #bhj2     of work to    
diet1 #bgg2     of yeasts to man1 #ace4 
,rennin1 #cjc4   ,reproduction1 #ajc1   

#aha2     importance of1 #eb2     in    
seed plants1 #agc1 #agd2     of cells1  
#ej2     of ,paramoecium1 #afi4         
,reptiles1 #ahf4   ,reptilia1 #ahh4     
,reserve air1 #ccd4   ,residual air1    
#ccd4   ,respiration1 #ff1 #aha2     and
 alcohol1 #cdf2     and nervous control1
 #ccd2     and tobacco1 #cdf2           
mechanics of1 #ccb1 #ccc2     necessity 
for1 #cbi2     organs of1 #ccj2     of  
cells1 #ccb2     of leaves1 #if4        
,retina1 #cfj4   ,rhizoids1 #acc4       
,rhizopoda1 #ahb4   ,rice field1 #abc4  
,ringworm1 #acd4   ,roaches1 #baf4      
,rock fern1 #age4   ,rockweed1 #agf4    
,roots as food1 #aai2     as food       
storage1 #hc2     downward growth of1   
#gb2     fine structure1 #gc2     give  
out acid1 #gi1 #hj2     hairs1 #gd1 #ge2
     influence of gravity1 #gb2         
influence of moisture1 #gc2     passage 
of soil water1 #gf2     pressure1 #aja2 
system1 primary1 secondary1 tertiary    
roots1 #gb2     uses of1 #ga4           
,rotation of crops1 #ha4   ,roundworms1 

#ahc1 #bbh4   ,rules of habit formation1
 #cef4   ,russian thistle1 #abi4        
,saliva1 #fi1 #bii4   ,salivary glands1 
#bii2     glands of frog1 #bdc4         
,salmon1 #bja1 #bda4   ,sand shark1     
#ahf4   ,sandworm1 #ahd4   ,sanitarium  
for tuberculosis1 #cid4   ,sanitation1  
#bg4   ,saprophytes1 #aca4              
,scavengers1 #aej4   ,schleiden and     
,schwann1 #cih4   ,schultz1 ,max1 #cih4 
,sclerotic coat1 #cfj4   ,sea anemones1 
#ahc4   ,secretion1 #bii1 #cjf4         
,secretions1 internal1 #cag4   ,section1
 of ear1 #cei2     of timber1 #aaa4     
,sedgwick1 ,william ,t41 #cab4   ,seed1 
#ed2     how scattered1 #ef2     plants1
 reproduction1 #agd2     why it grows1  
#eh4   ,seedlings of bean1 #fc4         
,segmented worms1 #ahc4   ,selection1   
artificial1 #bec2     natural1 #bec4    
,selective planting1 #bed4              
,semicircular canal1 #cei4              
,sensations1 #cej4   ,sense organs1     
#aha2     of fish1 #bcc2     of frog1   
#bdb4   ,senses1 #ceg4   ,sensory       

nerves1 #cea4   ,sepals1 #ce4   ,series1
 animal1 #ahb4   ,serum1 #cad4   ,sewage
 disposal1 #chf4   ,sex1 relation to    
diet1 #bhj4   ,shelf fungi1 #acb4       
,sieve tubes1 #ig4   ,simple animal1    
development1 #agg4   ,simplest plants1  
#aff4   ,skeleton1 of dog1 #ahe2     of 
fish1 #bcg2     of leaf1 #he2     of    
man1 #bfh4   ,skin1 #bfh2     hygiene   
of1 #cdd4   ,skunk1 #bje4   ,sleep1 need
 of1 #cef4   ,small intestine1 #cjg1    
#cjh4   ,smell1 sense of1 #ceh4         
,snail1 #ahe4   ,snakes1 #ahi2     food 
of1 #bab4   ,soft palate1 #cja4   ,soil1
 composition of1 #gg2     how water is  
held in1 #gg1 #gh4   ,sound1 character  
of1 #cfj4   ,sour bread1 #aci4   ,soy   
beans1 #aeb4   ,sparrow1 #bdf4          
,spawning habits1 economic importance1  
#bci4   ,species1 #age1 #aid4   ,sperm1 
#agg4   ,spermaries of frog1 #bdc4      
,spermatophytes1 #agf4   ,spinal cord of
 fish1 #bcg4   ,spiracles1 #bi4         
,spirillum1 #adb4   ,sponge1 #ahj1 #ahb1
 #ahc1 #bjf4   ,spore1 #aca1 #agc2      

plants1 #agd4   ,sporozoa1 #ahb4        
,sprengel1 ,conrad1 #dj4   ,squash bug1 
#bae4   ,stables1 clean and filthy1     
#chh4   ,stamens1 #cf4   ,starch1 action
 of diastase1 #fi2     digestion1 #bii2 
grains1 #fj2     in bean1 #fa2     made 
by green leaves1 #ij1 #ib2     test for1
 #fa4   ,starch making and milling1 #ib4
   ,starfish1 #ahd2     food of1 #baf4  
,stegomyia1 #bba4   ,stems1 as food1    
#aah2     passage of fluids up1 #hd2    
structure of1 #ig4   ,sterilization1    
#ade4   ,sterilizer1 #adj4   ,stigma1   
#cf4   ,stimulants1 #bhi4   ,stirrup1   
#cei4   ,stomata1 #hf1 #hh4   ,stomach1 
#big2     digestive experiments1 #cjd2  
of frog1 #bdc2     of man1 #cjc4        
,street cleaning department1 #chg4      
,structure1 colorless corpuscles1 #cae2 
of leaf1 #he2     of red corpuscle1     
#cad2     of root1 #gc2     of root     
hairs1 #gd4   ,sturgeon1 #ahf4   ,style1
 #cf4   ,sublingual glands1 #bii4       
,submaxillary glands1 #bii4             
,suffocation1 #cdj4   ,sulphur1 #adi4   

,sun1 source of energy1 #hh4   ,sundew1 
#ajb4   ,sunlight in home1 #cgd4        
,sweat glands1 #cdb4   ,sweeping and    
dusting1 #ccf4   ,swim bladder of fish1 
#bcf4   ,symbiosis1 #afc4   ,sympathetic
 nerves1 #ceb2     nervous system1 #cjd1
 #cej4   ,syphilis1 #aeb1 #aef4         
,systemic circulation1 #cbj4     ,table 
of cost of food1 #bgf1 #bhc4   ,tactile 
corpuscles1 #ceg4   ,taenia solium1     
#bbg4   ,tapeworm1 #bbg4   ,taproot1    
cross section1 #gd4   ,taste buds1 #cja1
 #ceh4   ,teeth1 #cja4   ,teleosts1     
#ahg4   ,temperature1 #dag2     of      
blood1 #cah4   ,tern1 #aij4   ,testa1   
#ei4   ,test1 for carbon dioxide1 #fd2  
nutrients1 #fa1 #fh4   ,thallophytes1   
#agf4   ,thoracic duct1 #cbd4   ,tidal  
air1 #ccd4   ,timber1 methods of        
cutting1 #aaa4   ,tissue cells1 #di1    
#agi4   ,toad1 use of1 #bji4   ,tobacco 
and circulation1 #cbh2     and          
respiration1 #cdf2     users of1 #bic4  
,tortoise1 #ahh4   ,touch1 #ceg4        
,tourniquet1 #cbf4   ,toxin1 #aeb1 #caf4

   ,trachea1 #ahe4   ,transpiration1    
#he1 #hg4   ,transportation of lumber1  
#aaj1 #aaa4   ,treatment of cuts and    
bruises1 #cbf4   ,trees1 need of city1  
#aae2     preventing erosion1 #ajh2     
regulate water supply1 #aje2     value  
of1 #aje4   ,trichina1 #bbh4            
,trichinosis1 #bbh4   ,trillium1 #age4  
,trout1 development1 #bch4              
,trypanosomes1 #bba4   ,tuberculosis1   
#aeb1 #aec2     and milk1 #cha2     how 
to fight1 #cic1 #cid4   ,tussock moth1  
#bae4   ,twig1 section of1 #ih4         
,tympanic membrane1 #ceh4   ,tympanum of
 frog1 #bdb4   ,tyndall box1 #cii4      
,typhoid1 #bbd1 #che2     and diarrhoea1
 #bjj4   ,typhoid fever1 #aeb1 #aee1    
#chb4     ,unit characters1 #beh4       
,ureter1 #cdb4   ,urethra1 #cdb4        
,urine1 #cda4   ,urodela1 #ahh4   ,uses1
 of animals1 #aih2     of antibodies1   
#caf2     of green plants1 #aag2     of 
ice1 #cgg2     of nutrients1 #bgd2      
of protozoa1 #agb4   ,uterus of a       
mammal1 #bdg4     ,vaccination1 #aeg1   

#bba1 #cia4   ,vacuoles1 contracting1   
#afh4   ,value1 of insects1 #bjh2     of
 trees1 #aje4   ,valves1 #ahe1 #cai2    
in vein1 #cbd4   ,variation1 #bej4      
,vasomotor nerves1 #cbe4   ,vegetable   
fibers and oils1 #abg4   ,veins1 #cah2  
function and structure1 #cbc2           
valves1 #cbd4   ,venae cavae1 #cbb4     
,ventilation1 #cce1 #cch4   ,ventricle1 
#cai2     of fish heart1 #bcf4   ,venus 
fly trap1 #ajb4   ,vermiform appendix1  
#cji4   ,vertebral column1 #ahf4        
,vertebrates1 breathing of1 #bcb4       
,villi1 #cjh4   ,virginia creeper1 #abh4
   ,virus1 #cib4   ,vitreous humor1     
#cfa4   ,vorticella1 #aga1 #agh4        
,vries1 ,hugo de1 #bec1 #djf4           
,warner1 ,chas4 ,dudley1 #baa4   ,waste 
of food1 #bhg4   ,water1 #bge2          
composition of1 #bj2     impure1 #bhi2  
supply1 #chc4   ,weed1 #dh1 #abh4       
,weights1 #dag4   ,wheat crop1 #aba1    
#abb4   ,wild orchid1 #dj4   ,windpipe1 
#cjj1 #cja4   ,wood1 uses of1 #aaj4     
,work of cells1 #bgj2     of ,department

 of ,agriculture1 #bee2     relation to 
diet1 #bgg4   ,worms1 #ahc4     ,yeasts1
 #acf1 #ach1 #aci2     relation to man1 
#ace4   ,yellow fever mosquito1 #bai4   
,yucca1 #db1 #dc4     ,zygospore1 #agd4 
,transcriber's ,notes3  ,punctuation1   
use of hyphens1 and accent marks were   
standardized4 ,obsolete and alternative 
spellings were left unchanged4 ,spelling
 of 'paramoecium' and 'paramoecia' were 
left unchanged4  ,braces are used to    
indicate subscripted numbers in chemical
 formulas1 e4g4 ,,co#b4 ,pipes 77 are   
used to designate bold numbers in the   
index4  ,footnotes were moved to the end
 of the paragraph in which the anchor   
occurs4 ,footnote anchors #f and #g     
refer to the same footnote1 as do       
anchors #cg and #ch4  ,greek letters in 
the chart in ,chapter ,,xx are spelled  
within brackets3 alpha and beta4  ,the  
following changes were made for         
consistency within the text3            
'zoological' to 'zoological'            
'diarrhea' to 'diarrhoea'  ,other       

changes3    'proteid' to 'protein' in   
the header of the table in ,chapter ,v  
'do' added to header to ,chapter ,,vii  
444 how do green plants make food8444   
',s arpe' to ',sharpe' in the ,reference
 ,books list at the end of     ,chapter 
,,xiv   'yoke' to 'yolk' 444 7which is  
the yolk or yellow portion7 444   'does'
 to 'do' 444 ,both 444 do the same thing
 444   'page #bjg' to 'page #cjg1' in   
reference to lacteals4   'centers' to   
'center's' 444 the nervous center's     
controlling the blood 444   'scapels' to
 'scalpels' in the appendix list of     
laboratory equipment   'and' added to   
'444 ,pasteur's solution and ,sach's    
nutrient solution 444'   ',scavangers'  
to ',scavengers' in the index