material from the ,google ,print        
project47           ,,biology  ,,by     
,,edmund ,,beecher ,,wilson ,,professor 
,,of ,,zoology ,,columbia ,,university  
,new ,york ,,the ,,columbia ,,university
 ,,press #aijh       ,,biology    ,a    
,,lecture ,,delivered ,,at ,,columbia   
,,university   ,,in ,,the ,,series ,,on 
,,science1 ,,philosophy ,,and ,,art     
,,november #bj1 #aijg     ,,biology     
,,by  ,,edmund ,,beecher ,,wilson       
,,professor ,,of ,,zoology ,,columbia   
,,university    ,new ,york ,,the        
,,columbia ,,university ,,press #aijh   
,,copyright1 #aijh1 by ,,the ,,columbia 
,,university ,,press4  ,set up1 and     
published ,march1 #aijh4     ,,biology  
,i must at the outset remark that among 
the many sciences that are occupied with
 the study of the living world there is 
no one that may properly lay exclusive  
claim to the name of ,biology4 ,the word
 does not1 in fact1 denote any          
particular science but is a generic term
 applied to a large group of biological 

sciences all of which alike are         
concerned with the phenomena of life4   
,to present in a single address1 even in
 rudimentary outline1 the specific      
results of these sciences is obviously  
an impossible task1 and one that ,i have
 no intention of attempting4 ,i shall   
offer no more than a kind of preface or 
introduction to those who will speak    
after me on the biological sciences of  
physiology1 botany and zoology2 and ,i  
shall confine it to what seem to me the 
most essential and characteristic of the
 general problems towards which all     
lines of biological inquiry must sooner 
or later converge4  ,it is the general  
aim of the biological sciences to learn 
something of the order of nature in the 
living world4 ,perhaps it is not amiss  
to remark that the biologist may not    
hope to solve the ultimate problems of  
life any more than the chemist and      
physicist may hope to penetrate the     
final mysteries of existence in the     
non-living world4 ,what he can do is to 

observe1 compare and experiment with    
phenomena1 to resolve more complex      
phenomena into simpler components1 and  
to this extent1 as he says1 to explain  
them2 but he knows in advance that his  
explanations will never be in the full  
sense of the word final or complete4    
,investigation can do no more than push 
forward the limits of knowledge4  ,the  
task of the biologist is a double one4  
,his more immediate effort is to inquire
 into the nature of the existing        
organism1 to ascertain in what measure  
the complex phenomena of life as they   
now appear are capable of resolution    
into simpler factors or components1 and 
to determine as far as he can what is   
the relation of these factors to other  
natural phenomena4 ,it is often         
practically convenient to consider the  
organism as presenting two different    
aspects--a structural or morphological  
one1 and a functional or                
physiological--and biologists often call
 themselves accordingly morphologists or

 physiologists4 ,morphological          
investigation has in the past largely   
followed the method of observation and  
comparison1 physiological investigation 
that of experiment2 but it is one of the
 best signs of progress that in recent  
years the fact has come clearly into    
view that morphology and physiology are 
really inseparable1 and in consequence  
the distinctions between them1 in       
respect both to subject matter and to   
method1 have largely disappeared in a   
greater community of aim4 ,morphology   
and physiology alike were profoundly    
transformed by the introduction into    
biological studies of the genetic or    
historical point of view by ,darwin1 who
 did more than any other to establish   
the fact1 suspected by many earlier     
naturalists1 that existing vital        
phenomena are the outcome of a definite 
process of evolution2 and it was he who 
first fully brought home to us how      
defective and one-sided is our view of  
the organism so long as we do not       

consider it as a product of the past4   
,it is the second and perhaps greater   
task of the biologist to study the      
organism from the historical point of   
view1 considering it as the product of a
 continuous process of evolution that   
has been in operation since life began4 
,in its widest scope this genetic       
inquiry involves not only the evolution 
of higher forms from lower ones1 but    
also the still larger question of the   
primordial relation of living things to 
the non-living world4 ,here is involved 
the possibility so strikingly expressed 
many years ago by ,tyndall in that      
eloquent passage in the ,belfast        
address1 where he declared himself      
driven by an intellectual necessity to  
cross the boundary line of the          
experimental evidence and to discern in 
non-living matter1 as he said1 the      
promise and potency of every form and   
quality of terrestrial life4 ,this      
intellectual necessity was created by a 
conviction of the continuity and        

consistency of natural phenomena1 which 
is almost inseparable from the          
scientific attitude towards nature4 ,but
 ,tyndall's words stood after all for a 
confession of faith1 not for a statement
 of fact2 and they soared far above the 
terra firma of the actual evidence4 ,at 
the present day we too may find         
ourselves logically driven to the view  
that living things first arose as a     
product of non-living matter4 ,we must  
fully recognize the extraordinary       
progress that has been made by the      
chemist in the artificial synthesis of  
compounds formerly known only as the    
direct products of living protoplasm4   
,but it must also be admitted that we   
are still wholly without evidence of the
 origin of any living thing1 at any     
period of the earth's history1 save from
 some other living thing2 and after more
 than two centuries ,redi's aphorism    
omne vivum e vivo retains to-day its    
full force4 ,it is my impression        
therefore that the time has not yet come

 when hypotheses regarding a different  
origin of life can be considered as     
practically useful4  ,if ,i have the    
temerity to ask your attention to the   
fundamental problem towards which all   
lines of biological inquiry sooner or   
later lead us it is not with the        
delusion that ,i can contribute anything
 new to the prolonged discussions and   
controversies to which it has given     
rise4 ,i desire only to indicate in what
 way it affects the practical efforts of
 biologists to gain a better            
understanding of the living organism1   
whether regarded as a group of existing 
phenomena or as a product of the        
evolutionary process2 and ,i shall speak
 of it1 not in any abstract or          
speculative way1 but from the standpoint
 of the working naturalist4 ,the problem
 of which ,i speak is that of organic   
mechanism and its relation to that of   
organic adaptation4 ,how in general are 
the phenomena of life related to those  
of the non-living world8 ,how far can we

 profitably employ the hypothesis that  
the living body is essentially an       
automaton or machine1 a configuration of
 material particles1 which1 like an     
engine or a piece of clockwork1 owes its
 mode of operation to its physical and  
chemical construction8 ,it is not open  
to doubt that the living body is a      
machine4 ,it is a complex chemical      
engine that applies the energy of the   
food-stuffs to the performance of the   
work of life4 ,but is it something more 
than a machine8 ,if we may imagine the  
physico-chemical analysis of the body to
 be carried through to the very end1 may
 we expect to find at last an unknown   
something that transcends such analysis 
and is neither a form of physical energy
 nor anything given in the physical or  
chemical configuration of the body8     
,shall we find anything corresponding to
 the usual popular conception--which was
 also along the view of                 
physiologists--that the body is animated
 by a specific vital principle1 or vital

 force1 a dominating archus that exists 
only in the realm of organic nature8 ,if
 such a principle exists1 then the      
mechanistic hypothesis fails and the    
fundamental problem of biology becomes a
 problem sui generis4  ,in its bearing  
on man's place in nature this question  
is one of the most momentous with which 
natural science has to deal1 and it has 
occupied the attention of thinking men  
in every age4 ,i cannot trace its       
history1 but it will be worth our while 
to place side by side the words of three
 of the great leaders of modern         
scientific and philosophic thought4 ,the
 saying has been attributed to          
,descartes1 ,give me matter and ,i will 
construct the world--meaning by this the
 living world as well as the non-living2
 but ,descartes specifically excepted   
the human mind4 ,i do not know whether  
the great ,french philosopher actually  
used these particular words1 but they   
express the essence of the mechanistic  
hypothesis that he adopted4 ,kant       

utterly repudiated such a conception in 
the following well known passage3 ,it is
 quite certain that we cannot become    
adequately acquainted with organized    
creatures and their hidden              
potentialities by means of the merely   
mechanical principles of nature1 much   
less can we explain them2 and this is so
 certain that we may boldly assert that 
it is absurd for man even to make such  
an attempt or to hope that a ,newton may
 one day arise who will make the        
production of a blade of grass          
comprehensible to us according to       
natural laws that have not been ordered 
by design4 ,such an insight we must     
absolutely deny to man4 ,still1 in      
another place ,kant admitted that the   
facts of comparative anatomy give us a  
ray of hope1 however faint1 that        
something may be accomplished by the aid
 of the principle of the mechanism of   
nature1 without which there can be no   
science in general4 ,it is interesting  
to turn from this to the bold and       

aggressive assertion of ,huxley3 ,living
 matter differs from other matter in    
degree and not in kind1 the microcosm   
repeats the macrocosm2 and one chain of 
causation connects the nebulous origin  
of suns and planetary systems with the  
protoplasmic foundations of life and    
organization4  ,do not expect me to     
decide where such learned doctors       
disagree2 but ,i will at this point     
venture on one comment which may sound  
the key-note of this address4 ,perhaps  
we shall find that in the long run and  
in the large sense ,kant was right2 but 
it is certain that to-day we know very  
much more about the formation of the    
living body1 whether a blade of grass or
 a man1 than did the naturalists of     
,kant's time2 and for better or for     
worse the human mind seems to be so     
constituted that it will continue its   
efforts to explain such matters1 however
 difficult they may seem to be4 ,but ,i 
return to our more specific inquiry with
 the remark that the history of         

physiology in the past two hundred years
 has been the history of a progressive  
restriction of the notion of a vital    
force or vital principle within narrower
 and narrower limits1 until at present  
it may seem to many physiologists that  
no room for it remains within the limits
 of our biological philosophy4 ,one     
after another the vital activities have 
been shown to be in greater or less     
degree explicable or comprehensible     
considered as physico-chemical          
operations of various degrees of        
complexity4 ,every physiologist will    
maintain that we cannot name one of     
these activities1 not even thought1 that
 is not carried on by a physical        
mechanism4 ,he will maintain further    
that in most cases the vital actions are
 not merely accompanied by              
physico-chemical operations but actually
 consist of them2 and he may go so far  
as definitely to maintain that we have  
no evidence that life itself can be     
regarded as anything more than their sum

 total4 ,he is able to bring forward    
cogent evidence that all modes of vital 
activity are carried on by means of     
energy that is set free in protoplasm or
 its products by means of definite      
chemical processes collectively known as
 metabolism4 ,when the matter is reduced
 to its lowest terms1 life1 as thus     
viewed1 seems to have its root in       
chemical change2 and we can understand  
how an eminent ,german physiologist     
offers us a definition or               
characterization of life that runs3 ,the
 life-process consists in the metabolism
 of proteids4 ,i ask your particular    
attention to this definition since ,i   
now wish to contrast with it another and
 very different one4  ,i shall introduce
 it to your attention by asking a very  
simple question4 ,we may admit that     
digestion1 for example1 is a purely     
chemical operation1 and one that may be 
exactly imitated outside the living body
 in a glass flask4 ,my question is1 how 
does it come to pass that an animal has 

a stomach8--and1 pursuing the inquiry1  
how does it happen that the human       
stomach is practically incapable of     
digesting cellulose1 while the stomachs 
of some lower animals1 such as the goat1
 readily digest this substance8 ,the    
earlier naturalists1 such as ,linnaeus1 
,cuvier or ,agassiz1 were ready with a  
reply which seemed so simple1 adequate  
and final that the plodding modern      
naturalist cannot repress a feeling of  
envy4 ,in their view plants and animals 
are made as they were originally        
created1 each according to its kind4    
,the biologist of to-day views the      
matter differently2 and ,i shall give   
his answer in the form in which ,i now  
and then make it to a student who may   
chance to ask why an insect has six legs
 and a spider eight1 or why a yellowbird
 is yellow and a bluebird blue4 ,the    
answer is3 ,for the same reason that the
 elephant has a trunk4 ,i trust that a  
certain rugged pedagogical virtue in    
this reply may atone for its lack of    

elegance4 ,the elephant has a trunk1 as 
the insect has six legs1 for the reason 
that such is the specific nature of the 
animal2 and we may assert with a degree 
of probability that amounts to practical
 certainty that this specific nature is 
the outcome of a definite evolutionary  
process1 the nature and causes of which 
it is our tremendous task to determine  
to such extent as we may be able4 ,but  
this does not yet touch the most        
essential side of the problem4 ,what is 
most significant is that the clumsy1    
short-necked elephant has been          
endowed--by nature1 as we say--with     
precisely such an organ1 the trunk1 as  
he needs to compensate for his lack of  
flexibility and agility in other        
respects4 ,if we are asked why the      
elephant has a trunk1 we must answer    
because the animal needs it4 ,but does  
such a reply in itself explain the fact8
 ,evidently not4 ,the question which    
science must seek to answer1 is how came
 the elephant to have a trunk2 and we do

 not properly answer it by saying that  
it has developed in the course of       
evolution4 ,it has been well said that  
even the most complete knowledge of the 
genealogy of plants and animals would   
give us no more than an ancestral       
portrait-gallery4 ,we must determine the
 causes and conditions that have        
cooperated to produce this particular   
result if our answer is to constitute a 
true scientific explanation4 ,and       
evidently he who adopts the             
machine-theory as a general             
interpretation of vital phenomena must  
make clear to us how the machine was    
built before we can admit the validity  
of his theory1 even in a single case4   
,our apparently simple question as to   
why the animal has a stomach has thus   
revealed to us the full magnitude of the
 task with which the mechanist is       
confronted2 and it has brought us to    
that part of our problem that is        
concerned with the nature and origin of 
organic adaptations4 ,without tarrying  

to attempt a definition of adaptation ,i
 will only emphasize the fact that many 
of the great naturalists1 from          
,aristotle onward1 have recognized the  
purposeful or design-like quality of    
vital phenomena as their most essential 
and fundamental characteristic4 ,herbert
 ,spencer defined life as the continuous
 adjustment of internal relations to    
external relations4 ,it is one of the   
best that has been given1 though ,i am  
not sure that ,professor ,brooks has not
 improved upon it when he says that life
 is response to the order of nature4    
,this seems a long way from the         
definition of ,verworn1 heretofore      
cited1 as the metabolism of proteids4   
,to this ,brooks opposes the telling    
epigram3 ,the essence of life is not    
protoplasm but purpose4  ,without       
attempting adequately to illustrate the 
nature of organic adaptations1 ,i will  
direct your attention to what seems to  
me one of their most striking features  
regarded from the mechanistic position4 

,this is the fact that adaptations so   
often run counter to direct or obvious  
mechanical conditions4 ,nature is       
crammed with devices to protect and     
maintain the organism against the stress
 of the environment4 ,some of these are 
given in the obvious structure of the   
organism1 such as the tendrils by means 
of which the climbing plant sustains    
itself against the action of gravity or 
the winds1 the protective shell of the  
snail1 the protective colors and shapes 
of animals1 and the like4 ,any          
structural feature that is useful       
because of its construction is a        
structural adaptation2 and when such    
adaptations are given the mechanist has 
for the most part a relatively easy task
 in his interpretation4 ,he has a far   
more difficult knot to disentangle in   
the case of the so-called functional    
adaptations1 where the organism modifies
 its activities 7and often also its     
structure7 in response to changed       
conditions4 ,the nature of these        

phenomena may be illustrated by a few   
examples so chosen as to form a         
progressive series4 ,if a spot on the   
skin be rubbed for some time the first  
result is a direct and obviously        
mechanical one2 the skin is worn away4  
,but if the rubbing be continued long   
enough1 and is not too severe1 an       
indirect effect is produced that is     
precisely the opposite of the initial   
direct one2 the skin is replaced1       
becomes thicker than before1 and a      
callus is produced that protects the    
spot from further injury4 ,the healing  
of a wound involves a similar action4   
,again1 remove one kidney or one lung   
and the remaining one will in time      
enlarge to assume1 as far as it is able1
 the functions of both4 ,if the leg of a
 salamander or a lobster be amputated1  
the wound not only heals but a new leg  
is regenerated in place of that which   
has been lost4 ,if a flatworm be cut in 
two1 the front piece grows out a new    
tail1 the hind piece a new head1 and two

 perfect worms result4 ,finally1 it has 
been found in certain cases1 including  
animals as highly organized as          
salamanders1 that if the egg be         
separated into two parts at an early    
period of development each part develops
 into a perfect embryo animal of half   
the usual size1 and a pair of twins     
results4 ,in each of these cases the    
astonishing fact is that a mechanical   
injury sets up in the organism a        
complicated adaptive response in the    
form of operations which in the end     
counteract the initial mechanical       
effect4 ,it is no doubt true that       
somewhat similar self-adjustments or    
responses may be said to take place in  
certain non-living mechanical systems1  
such as the spinning top or the         
gyroscope2 but those that occur in the  
living body are of such general         
occurrence1 of such complexity and      
variety1 and of so design-like a        
quality1 that they may fairly be        
regarded as among the most              

characteristic of the vital activities4 
,it is precisely this characteristic of 
many vital phenomena that renders their 
accurate analysis so difficult and      
complex a task2 and it is largely for   
this reason that the biological         
sciences1 as a whole1 still stand far   
behind the physical sciences1 both in   
precision and in completeness of        
analysis4  ,what is the actual working  
attitude of naturalists towards the     
general problem that ,i have endeavored 
to outline8 ,it would be a piece of     
presumption for me to speak for the body
 of working biologists1 and ,i will     
therefore speak for only one of them4   
,it is my own conviction that whatever  
be the difficulties that the mechanistic
 hypothesis has to face1 it has         
established itself as the most useful   
working hypothesis that we can at       
present employ4 ,i do not mean to assert
 that it is adequate1 or even true4 ,i  
believe only that we should make use of 
it as a working program1 because the    

history of biological research proves it
 to have been a more effective and      
fruitful means of advancing knowledge   
than the vitalistic hypothesis4 ,we     
should therefore continue to employ it  
for this purpose until it is clearly    
shown to be untenable4 ,whether we must 
in the end adopt it will depend on      
whether it proves the simplest          
hypothesis in the large sense1 the one  
most in harmony with our knowledge of   
nature in general4 ,if such is the      
outcome1 we shall be bound by a deeply  
lying instinct that is almost a law of  
our intellectual being to accept it1 as 
we have accepted the ,copernican system 
rather than the ,ptolemaic4 ,i believe  
,i am right in saying that the attitude 
,i have indicated as a more or less     
personal one is also that of the body of
 working biologists1 though there are   
some conspicuous exceptions4  ,in       
endeavoring to illustrate how this      
question actually affects research ,i   
will offer two illustrative cases1 one  

of which may indicate the fruitfulness  
of the mechanistic conception in the    
analysis of complex and apparently      
mysterious phenomena1 the other the     
nature of the difficulties that have in 
recent years led to attempts to         
re-establish the vitalistic view4 ,the  
first example is given by the so-called 
law or principle of ,mendel in heredity4
 ,the principle revealed by ,mendel's   
wonderful discovery is not shown in all 
the phenomena of heredity and is        
probably of more or less limited        
application4 ,it possesses however a    
profound significance because it gives  
almost a demonstration that a definite1 
and perhaps a relatively simple1        
mechanism must lie behind the phenomena 
of heredity in general4 ,hereditary     
characters that conform to this law     
undergo combinations1 disassociations   
and recombinations which in certain way 
suggest those that take place in        
chemical reactions2 and like the latter 
they conform to definite quantitative   

rules that are capable of arithmetical  
formulation4 ,this analogy must not be  
pressed too far2 for chemical reactions 
are individually definite and fixed1    
while those of the hereditary characters
 involve a fortuitous element of such a 
nature that the numerical result is not 
fixed or constant in the individual case
 but follows the law of probability in  
the aggregate of individuals4           
,nevertheless1 it is possible1 and has  
already become the custom1 to designate 
the hereditary organization by symbols  
or formulas that resemble those of the  
chemist in that they imply the          
quantitative results of heredity that   
follow the union of compounds of known  
composition4 ,quantitative              
prediction--not precisely accurate1 but 
in accordance with the law of           
probability--has thus become possible to
 the biological experimenter on         
heredity4 ,i will give one example of   
such a prediction made by ,professor    
,cunot in experimenting on the heredity 

of color in mice 7see the following     
table74 ,the experiment extended through
 three generations4 ,of the four        
grandparents three were pure white      
albinos1 identical in outward           
appearance1 but of different hereditary 
capacity1 while the fourth was a pure   
black mouse4 ,the first pair of         
grandparents consisted of an albino of  
gray ancestry1 ,,ag1 and one of black   
ancestry1 ,,ab4 ,the second pair        
consisted of an albino of yellow        
ancestry1 ,,ay1 and a black mouse1 ,,cb4
 ,the result of the first union1 ,,ag x 
,,ab is to produce again pure white mice
 of the composition ,,agab4 ,the second 
union1 ,,ay x ,,cb is to produce mice   
that appear pure yellow1 and have the   
formula ,,aycb4 ,what1 now1 will be the 
result of uniting the two forms thus    
produced--i4e4 ,,agab  ,,aycb8 ,cunot's 
prediction was that they should yield   
eight different kinds of mice1 of which 
four should be white1 two yellow1 one   
black and one gray4 ,the actual         

aggregate result of such unions1        
repeatedly performed1 compared with the 
theoretic expectation1 is shown in the  
foregoing table4 ,as will be seen1 the  
correspondence1 though close1 is not    
absolutely exact1 yet is near enough to 
prove the validity of the principle on  
which the prediction was based1 and we  
may be certain that had a much larger   
number of these mice been reared the    
correspondence would have been still    
closer4 ,i have purposely selected a    
somewhat complicated example1 and time  
will not admit of a full explanation of 
the manner in which this particular     
result was reached4 ,i will however     
attempt to give an indication of the    
general ,mendelian principle by means of
 which predictions of this kind are     
made4 ,this principle appears in its    
simplest form in the behavior of two    
contrasting characters of the same      
general type--for instance two colors1  
such as gray and white in mice4 ,if two 
animals1 which show respectively two    

such characters are bred together1 only 
one of the characters 7known as the     
dominant7 appears in the offspring1     
while the other 7known as the recessive7
 disappears from view4 ,in the next     
generation1 obtained by breeding these  
hybrids together1 both characters appear
 separately and in a definite ratio1    
there being in the long run three       
individuals that show the dominant      
character to one that shows the         
recessive4 ,thus1 in the case of gray   
and white mice1 the first cross is      
always gray1 while the next generation  
includes three grays to one white4 ,this
 is the fundamental ,mendelian ratio for
 a single pair of characters2 and from  
it may readily be deduced the more      
complicated combinations that appear    
when two or more pairs of characters are
 considered together4 ,such combinations
 appear in definite series1 the nature  
of which may be worked out by a simple  
method of binomial expansion4 ,by the   
use of this principle astonishingly     

accurate numerical predictions may be   
made1 even of rather complex            
combinations2 and furthermore1 new      
combinations may be1 and have been1     
artificially produced1 the number1      
character and hereditary capacity of    
which are known in advance4 ,the        
fundamental ratio for a single pair of  
characters is explained by a very simple
 assumption4 ,when a dominant and a     
recessive character are associated in a 
hybrid1 the two must undergo in some    
sense a disjunction or separation in the
 formation of the germ-cells of the     
hybrid4 ,this takes place in a quite    
definite way1 exactly half the          
germ-cells in each sex receiving the    
potentiality of the dominant character1 
the other half the potentiality of the  
recessive4 ,this is roughly expressed by
 saying that the germ-cells are no      
longer hybrid1 like the body in which   
they arise1 but bear one character or   
the other2 and although in a technical  
sense this is probably not precisely    

accurate1 it will sufficiently answer   
our purpose4 ,if1 now1 it be assumed    
that fertilization takes place          
fortuitously--that is that union is     
equally probable between germ-cells     
bearing the same character and those    
bearing opposite characters1--the       
observed numerical ratio in the         
following generation follows according  
to the law of probability4 ,thus is     
explained both the fortuitous element   
that differentiates these cases from    
exact chemical combinations1 and the    
definite numerical relations that appear
 in the aggregate of individuals4       
,grandparents ,,ag 7white7 ,,ab 7white7 
,,ay 7white7 ,,cb 7black7               
---------           -----------         
,parents     ,,agab 7white7             
,,aycb 7yellow7                         
----------------------                  
,observed    ,calculated                
,,agay                                  
,,abay     7,white7    #ha         #gf  
,,agab    ,offspring                    

---------------,,abab                   
,,agcy    7,yellow7    #cd         #ch  
,,abcy                                  
,,abcb      7,black7    #bj         #ai 
,,agcb       7,gray7    #af         #ai 
----       ----                         
#aea        #aeb   ,now1 the point that 
,i desire to emphasize is that one or   
two very simple mechanistic assumptions 
give a luminously clear explanation of  
the behavior of the hereditary          
characters according to ,mendel's law1  
and at one stroke bring order out of the
 chaos in which facts of this kind at   
first sight seem to be4 ,not less       
significant is the fact that direct     
microscopical investigation is actually 
revealing in the germ-cells a physical  
mechanism that seems adequate to explain
 the disjunction of characters on which 
,mendel's law depends2 and this         
mechanism probably gives us also at     
least a key to the long standing riddle 
of the determination and heredity of    
sex4 ,these phenomena are therefore     

becoming intelligible from the          
mechanistic point of view4 ,from any    
other they appear as an insoluble       
enigma4 ,when such progress as this is  
being made1 have we not a right to      
believe that we are employing a useful  
working hypothesis8  ,but let us now    
turn to a second example that will      
illustrate a class of phenomena which   
have thus far almost wholly eluded all  
attempts to explain them4 ,the one that 
,i select is at present one of the most 
enigmatical cases known1 namely1 the    
regeneration of the lens of the eye in  
the tadpoles of salamanders4 ,if the    
lens be removed from the eye of a young 
tadpole1 the animal proceeds to         
manufacture a new one to take its place1
 and the eye becomes as perfect as      
before4 ,that such a process should take
 place at all is remarkable enough2 but 
from a technical point of view this is  
not the extraordinary feature of the    
case4 ,what fills the embryologist with 
astonishment is the fact that the new   

lens is not formed in the same way or   
from the same material as the old one4  
,in the normal development of the       
tadpole from the egg1 as in all other   
vertebrate animals1 the lens is formed  
from the outer skin or ectoderm of the  
head4 ,in the replacement of the lens   
after removal it arises from the cells  
of the iris1 which form the edge of the 
optic cup1 and this originates in the   
embryo not from the outer skin but as an
 outgrowth from the brain4 ,as far as we
 can see1 neither the animal itself nor 
any of its ancestors can have had       
experience of such a process4 ,how1     
then1 can such a power have been        
acquired1 and how does it inhere in the 
structure of the organism8 ,if the      
process of repair be due to some kind of
 intelligent action1 as some naturalists
 have supposed1 why should not the      
higher animals and man possess a similar
 useful capacity8 ,to these questions   
biology can at present give no reply4   
,in the face of such a case the         

mechanist must simply confess himself   
for the time being brought to a         
standstill2 and there are some able     
naturalists who have in recent years    
argued that by the very nature of the   
case such phenomena are incapable of a  
rational explanation along the lines of 
a physico-chemical or mechanistic       
analysis4 ,these writers have urged1    
accordingly1 that we must postulate in  
the living organism some form of        
controlling or regulating agency which  
does not lie in its physico-chemical    
configuration and is not a form of      
physical energy--something that may be  
akin to a form of intelligence          
7conscious or unconscious71 and to which
 the physical energies are in some      
fashion subject4 ,to this supposed      
factor in the vital processes have been 
applied such terms as the entelechy     
7from ,aristotle71 or the psychoid2 and 
some writers have even employed the word
 soul in this sense--though this        
technical and limited use of the word   

should not be confounded with the more  
usual and general one with which we are 
familiar4 ,views of this kind represent 
a return1 in some measure1 to earlier   
vitalistic conceptions1 but differ from 
the latter in that they are an outcome  
of definite and exact experimental work4
 ,they are therefore often spoken of    
collectively as neo-vitalism4  ,it is   
not my purpose to enter upon a detailed 
critique of this doctrine4 ,to me it    
seems not to be science1 but either a   
kind of metaphysics or an act of faith4 
,i must own to complete inability to see
 how our scientific understanding of the
 matter is in any way advanced by       
applying such names as entelechy or     
psychoid to the unknown factors of the  
vital activities4 ,they are words that  
have been written into certain spaces   
that are otherwise blank in our record  
of knowledge1 and as far as ,i can see  
no more than this4 ,it is my impression 
that we shall do better as investigators
 of natural phenomena frankly to admit  

that they stand for matters that we do  
not yet understand1 and continue our    
efforts to make them known4 ,and have we
 any other way of doing this than by    
observation1 experiment1 comparison and 
the resolution of more complex phenomena
 into simpler components8 ,i say again1 
with all possible emphasis1 that the    
mechanistic hypothesis or machine-theory
 of living beings is not fully          
established1 that it may not be adequate
 or even true2 yet ,i can only believe  
that until every other possibility has  
realty been exhausted scientific        
biologists should hold fast to the      
working program that has created the    
sciences of biology4 ,the vitalistic    
hypothesis may be held1 and is held1 as 
a matter of faith2 but we cannot call it
 science without misuse of the word4    
,when we turn1 finally1 to the genetic  
or historical part of our task1 we find 
ourselves confronted with precisely the 
same general problem as in case of the  
existing organism4 ,biological          

investigators have long since ceased to 
regard the fact of organic evolution as 
open to serious discussion4 ,the        
transmutation of species is not an      
hypothesis or assumption1 it is a fact  
accurately observed in our laboratories2
 and the theory of evolution is only    
questioned in the same very general way 
in which all the great generalizations  
of science are held open to modification
 as knowledge advances4 ,but it is a    
very large question what has caused and 
determined evolution4 ,here1 too1 the   
fundamental problem is1 how far the     
process may be mechanically explicable  
or comprehensible1 how far it is        
susceptible of formulation in           
physico-chemical or mechanistic terms4  
,the most essential part of this problem
 relates to the origin of organic       
adaptations1 the production of the fit4 
,with ,kant1 ,cuvier and ,linnaeus      
believed this problem scientifically    
insoluble4 ,lamarck attempted to find a 
solution in his theory of the           

inheritance of the effects of use1      
disuse and other acquired characters2   
but his theory was insecurely based and 
also begged the question1 since the     
power of adaptation through which use1  
disuse and the like produce their       
effects is precisely that which must be 
explained4 ,darwin believed he had found
 a partial solution in his theory of    
natural selection1 and he was hailed by 
,haeckel as the biological ,newton who  
had set at naught the obiter dictum of  
,kant4 ,but ,darwin himself did not     
consider natural selection as an        
adequate explanation1 since he called to
 its aid the subsidiary hypotheses of   
sexual selection and the inheritance of 
acquired characters4 ,if ,i correctly   
judge1 the first of these hypotheses    
must be considered as of limited        
application if it is not seriously      
discredited1 while the second can at    
best receive the ,scotch verdict1 not   
proven4 ,in any case1 natural selection 
must fight its own battles4  ,latter day

 biologists have come to see clearly    
that the inadequacy of natural selection
 lies in its failure to explain the     
origin of the fit2 and ,darwin himself  
recognized clearly enough that it is not
 an originative or creative principle4  
,it is only a condition of survival1 and
 hence a condition of progress4 ,but    
whether we conceive with ,darwin that   
selection has acted mainly upon slight  
individual variations1 or with ,de,vries
 that it has operated with larger and   
more stable mutations1 any adequate     
general theory of evolution must explain
 the origin of the fit4 ,now1 under the 
theory of natural selection1 pure and   
simple1 adaptation or fitness has a     
merely casual or accidental character4  
,in itself the fit has no more          
significance than the unfit4 ,it is only
 one out of many possibilities of       
change1 and evolution by natural        
selection resolves itself into a series 
of lucky accidents4 ,for ,agassiz or    
,cuvier the fit is that which was       

designed to fit4 ,for natural selection1
 pure and simple1 the fit is that which 
happens to fit4 ,i1 for one1 am unable  
to find a logical flaw in this          
conception of the fit2 and perhaps we   
may be forced to accept it as           
sufficient4 ,but ,i believe that        
naturalists do not yet rest content with
 it4 ,darwin himself was repeatedly     
brought to a standstill1 not merely by  
specific difficulties in the application
 of his theory1 but also by a certain   
instinctive or temperamental            
dissatisfaction with such a general     
conclusion as the one ,i have indicated2
 and many able naturalists feel the same
 difficulty to-day4 ,whether this be    
justified or not1 it is undoubtedly the 
fact that few working naturalists feel  
convinced that the problem of organic   
evolution has been fully solved4 ,one of
 the questions with which research is   
seriously engaged is whether variations 
or mutations are indeterminate1 as      
,darwin on the whole believed1 or       

whether they may be in greater or less  
degree determinate1 proceeding along    
definite lines as if impelled by a vis a
 tergo4 ,the theory of orthogenesis1    
proposed by ,naegeli and ,eimer1 makes  
the latter assumption2 and it has found 
a considerable number of adherents among
 recent biological investigators1       
including some of our own colleagues1   
who have made important contributions to
 the investigation of this fundamental  
question4 ,it is too soon to venture a  
prediction as to the ultimate result4   
,that evolution has been orthogenetic in
 the case of certain groups1 seems to be
 well established1 but many difficulties
 stand in the way of its acceptance as a
 general principle of explanation4 ,the 
uncertainty that still hangs over this  
question and that of the heredity of    
acquired characters bears witness to the
 unsettled state of opinion regarding   
the whole problem1 and to the inadequacy
 of the attempts thus far made to find  
its consistent and adequate solution4   

,here1 too1 accordingly1 we find        
ourselves confronted with wide gaps in  
our knowledge which open the way to     
vitalistic or transcendental theories of
 development4 ,i think we should resist 
the temptation to seek such refuge4 ,it 
is more than probable that there are    
factors of evolution still unknown4 ,we 
can but seek for them4 ,nothing is more 
certain than that life and the evolution
 of life are natural phenomena4 ,we must
 approach them1 and as far as ,i can see
 must attempt to analyze them1 by the   
same methods that are employed in the   
study of other natural phenomena4 ,the  
student of nature can do no more than   
strive towards the truth4 ,when he does 
not find the whole truth there is but   
one gospel for his salvation--still to  
strive towards the truth4 ,he knows that
 each forward step on the highway of    
discovery will bring to view a new      
horizon of regions still unknown4 ,it   
will be an ill day for science when it  
can find no more fields to conquer4 ,and

 so1 if you ask whether ,i look to a day
 when we shall know the whole truth in  
regard to organic mechanism and organic 
evolution1 ,i answer3 ,no6 ,but let us  
go forward4     ,,columbia ,,university 
,,press      ,a ,series of twenty-two   
lectures descriptive in untechnical     
language of the achievements in         
,science1 ,philosophy and ,art1 and     
indicating the present status of these  
subjects as concepts of    human        
knowledge1 are being delivered at       
,columbia ,university1    during the    
academic year #aijg-aijh1 by various    
professors chosen    to represent the   
several departments of instruction4     
,,mathematics1 by ,cassius ,jackson     
,keyser1 ,adrain ,professor of          
,mathematics4     ,,physics1 by ,ernest 
,fox ,nichols1 ,professor of            
,experimental    ,physics4              
,,chemistry1 by ,charles ,f4 ,chandler1 
,professor of ,chemistry4               
,,astronomy1 by ,harold ,jacoby1        
,rutherfurd ,professor of ,astronomy4   

,,geology1 by ,james ,furman ,kemp4     
,professor of ,geology4     ,,biology1  
by ,edmund ,b4 ,wilson1 ,professor of   
,zoology4     ,,physiology1 by ,frederic
 ,s4 ,lee1 ,professor of ,physiology4   
,,botany1 by ,herbert ,maule ,richards1 
,professor of ,botany4     ,,zoology1 by
 ,henry ,e4 ,crampton1 ,professor of    
,zoology4     ,,anthropology1 by ,franz 
,boas4 ,professor of ,anthropology4     
,,archaeology1 by ,james ,rignall       
,wheeler1 ,professor of ,greek          
,archaeology and ,art4     ,,history1 by
 ,james ,harvey ,robinson1 ,professor of
 ,history4     ,,economics1 by ,henry   
,rogers ,seager1 ,professor of          
,political    ,economy4     ,,politics1 
by ,charles ,a4 ,beard1 ,adjunct        
,professor of ,politics4                
,,jurisprudence1 by ,munroe ,smith1     
,professor of ,roman ,law and           
,comparative ,jurisprudence4            
,,sociology1 by ,franklin ,henry        
,giddings1 ,professor of ,sociology4    
,,philosophy1 by ,nicholas ,murray      

,butler4 ,president of the              
,university4     ,,psychology1 by       
,robert ,s4 ,woodworth1 ,adjunct        
,professor of    ,psychology4           
,,metaphysics1 by ,frederick ,j4,e4     
,woodbridge1 ,johnsonian ,professor     
of ,philosophy4     ,,ethics1 by ,john  
,dewey1 ,professor of ,philosophy4      
,,philology1 by ,a4,v4,w4 ,jackson1     
,professor of ,indo-,iranian            
,languages4     ,,literature1 by ,harry 
,thurston ,peck1 ,anthon ,professor of  
the    ,latin ,language and ,literature4
      ,these lectures are published by  
the ,columbia ,university ,press        
separately in pamphlet form1 at the     
uniform price of twenty-five    cents1  
by mail twenty-eight cents4 ,orders will
 be taken for the    separate pamphlets1
 or for the whole series4    ,address   
,,the ,,columbia ,,university ,,press   
,columbia ,university1 ,new ,york       
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