,,the ,,method ,,by ,,which ,,the       
,,causes ,,of ,,the ,,present ,,and     
,,past ,,conditions ,,of ,,organic      
,,nature ,,are ,,to ,,be                
,,discovered4--,,the ,,origination ,,of 
,,living ,,beings  ,lecture ,,iii4 7of  
,,vi471 ,lectures ,to ,working ,men1 at 
the ,museum of ,practical ,geology1     
#ahfc1 ,on ,darwin's work3 ,origin of   
,species4   ,by ,thomas ,h4 ,huxley     
,in the two preceding lectures ,i have  
endeavoured to indicate to you the      
extent of the subject-matter of the     
inquiry upon which we are engaged2 and  
now1 having thus acquired some          
conception of the ,past and ,present    
phenomena of ,organic ,nature1 ,i must  
now turn to that which constitutes the  
great problem which we have set before  
ourselves2--,i mean1 the question of    
what knowledge we have of the causes of 
these phenomena of organic nature1 and  
how such knowledge is obtainable4       
,here1 on the threshold of the inquiry1 
an objection meets us4 ,there are in the

 world a number of extremely worthy1    
well-meaning persons1 whose judgments   
and opinions are entitled to the utmost 
respect on account of their sincerity1  
who are of opinion that ,vital          
,phenomena1 and especially all questions
 relating to the origin of vital        
phenomena1 are questions quite apart    
from the ordinary run of inquiry1 and   
are1 by their very nature1 placed out of
 our reach4 ,they say that all these    
phenomena originated miraculously1 or in
 some way totally different from the    
ordinary course of nature1 and that     
therefore they conceive it to be futile1
 not to say presumptuous1 to attempt to 
inquire into them4  ,to such sincere and
 earnest persons1 ,i would only say1    
that a question of this kind is not to  
be shelved upon theoretical or          
speculative grounds4 ,you may remember  
the story of the ,sophist who           
demonstrated to ,diogenes in the most   
complete and satisfactory manner that he
 could not walk2 that1 in fact1 all     

motion was an impossibility2 and that   
,diogenes refuted him by simply getting 
up and walking round his tub4 ,so1 in   
the same way1 the man of science replies
 to objections of this kind1 by simply  
getting up and walking onward1 and      
showing what science has done and is    
doing--by pointing to that immense mass 
of facts which have been ascertained and
 systematized under the forms of the    
great doctrines of ,morphology1 of      
,development1 of ,distribution1 and the 
like4 ,he sees an enormous mass of facts
 and laws relating to organic beings1   
which stand on the same good sound      
foundation as every other natural law2  
and therefore1 with this mass of facts  
and laws before us1 therefore1 seeing   
that1 as far as organic matters have    
hitherto been accessible and studied1   
they have shown themselves capable of   
yielding to scientific investigation1 we
 may accept this as proof that order and
 law reign there as well as in the rest 
of nature2 and the man of science says  

nothing to objectors of this sort1 but  
supposes that we can and shall walk to a
 knowledge of the origin of organic     
nature1 in the same way that we have    
walked to a knowledge of the laws and   
principles of the inorganic world4  ,but
 there are objectors who say the same   
from ignorance and ill-will4 ,to such ,i
 would reply that the objection comes   
ill from them1 and that the real        
presumption1 ,i may almost say the real 
blasphemy1 in this matter1 is in the    
attempt to limit that inquiry into the  
causes of phenomena which is the source 
of all human blessings1 and from which  
has sprung all human prosperity and     
progress2 for1 after all1 we can        
accomplish comparatively little2 the    
limited range of our own faculties      
bounds us on every side1--the field of  
our powers of observation is small      
enough1 and he who endeavours to narrow 
the sphere of our inquiries is only     
pursuing a course that is likely to     
produce the greatest harm to his        

fellow-men4  ,but now1 assuming1 as we  
all do1 ,i hope1 that these phenomena   
are properly accessible to inquiry1 and 
setting out upon our search into the    
causes of the phenomena of organic      
nature1 or1 at any rate1 setting out to 
discover how much we at present know    
upon these abstruse matters1 the        
question arises as to what is to be our 
course of proceeding1 and what method we
 must lay down for our guidance4 ,i     
reply to that question1 that our method 
must be exactly the same as that which  
is pursued in any other scientific      
inquiry1 the method of scientific       
investigation being the same for all    
orders of facts and phenomena           
whatsoever4  ,i must dwell a little on  
this point1 for ,i wish you to leave    
this room with a very clear conviction  
that scientific investigation is not1 as
 many people seem to suppose1 some kind 
of modern black art4 ,i say that you    
might easily gather this impression from
 the manner in which many persons speak 

of scientific inquiry1 or talk about    
inductive and deductive philosophy1 or  
the principles of the ,baconian         
philosophy4 ,i do protest that1 of the  
vast number of cants in this world1     
there are none1 to my mind1 so          
contemptible as the pseudoscientific    
cant which is talked about the ,baconian
 philosophy4  ,to hear people talk about
 the great ,chancellor--and a very great
 man he certainly was1--you would think 
that it was he who had invented science1
 and that there was no such thing as    
sound reasoning before the time of      
,queen ,elizabeth4 ,of course you say1  
that cannot possibly be true2 you       
perceive1 on a moment's reflection1 that
 such an idea is absurdly wrong1 and    
yet1 so firmly rooted is this sort of   
impression1--,i cannot call it an idea1 
or conception1--the thing is too absurd 
to be entertained1--but so completely   
does it exist at the bottom of most     
men's minds1 that this has been a matter
 of observation with me for many years  

past4 ,there are many men who1 though   
knowing absolutely nothing of the       
subject with which they may be dealing1 
wish1 nevertheless1 to damage the author
 of some view with which they think fit 
to disagree4 ,what they do1 then1 is not
 to go and learn something about the    
subject1 which one would naturally think
 the best way of fairly dealing with it2
 but they abuse the originator of the   
view they question1 in a general manner1
 and wind up by saying that1 ,after all1
 you know1 the principles and method of 
this author are totally opposed to the  
canons of the ,baconian philosophy4     
,then everybody applauds1 as a matter of
 course1 and agrees that it must be so4 
,but if you were to stop them all in the
 middle of their applause1 you would    
probably find that neither the speaker  
nor his applauders could tell you how or
 in what way it was so2 neither the one 
nor the other having the slightest idea 
of what they mean when they speak of the
 ,baconian philosophy4  ,you will       

understand1 ,i hope1 that ,i have not   
the slightest desire to join in the     
outcry against either the morals1 the   
intellect1 or the great genius of ,lord 
,chancellor ,bacon4 ,he was undoubtedly 
a very great man1 let people say what   
they will of him2 but notwithstanding   
all that he did for philosophy1 it would
 be entirely wrong to suppose that the  
methods of modern scientific inquiry    
originated with him1 or with his age2   
they originated with the first man1     
whoever he was2 and indeed existed long 
before him1 for many of the essential   
processes of reasoning are exerted by   
the higher order of brutes as completely
 and effectively as by ourselves4 ,we   
see in many of the brute creation the   
exercise of one1 at least1 of the same  
powers of reasoning as that which we    
ourselves employ4  ,the method of       
scientific investigation is nothing but 
the expression of the necessary mode of 
working of the human mind4 ,it is simply
 the mode at which all phenomena are    

reasoned about1 rendered precise and    
exact4 ,there is no more difference1 but
 there is just the same kind of         
difference1 between the mental          
operations of a man of science and those
 of an ordinary person1 as there is     
between the operations and methods of a 
baker or of a butcher weighing out his  
goods in common scales1 and the         
operations of a chemist in performing a 
difficult and complex analysis by means 
of his balance and finely-graduated     
weights4 ,it is not that the action of  
the scales in the one case1 and the     
balance in the other1 differ in the     
principles of their construction or     
manner of working2 but the beam of one  
is set on an infinitely finer axis than 
the other1 and of course turns by the   
addition of a much smaller weight4  ,you
 will understand this better1 perhaps1  
if ,i give you some familiar example4   
,you have all heard it repeated1 ,i dare
 say1 that men of science work by means 
of ,induction and ,deduction1 and that  

by the help of these operations1 they1  
in a sort of sense1 wring from ,nature  
certain other things1 which are called  
,natural ,laws1 and ,causes1 and that   
out of these1 by some cunning skill of  
their own1 they build up ,hypotheses and
 ,theories4 ,and it is imagined by many1
 that the operations of the common mind 
can be by no means compared with these  
processes1 and that they have to be     
acquired by a sort of special           
apprenticeship to the craft4 ,to hear   
all these large words1 you would think  
that the mind of a man of science must  
be constituted differently from that of 
his fellow men2 but if you will not be  
frightened by terms1 you will discover  
that you are quite wrong1 and that all  
these terrible apparatus are being used 
by yourselves every day and every hour  
of your lives4  ,there is a well-known  
incident in one of ,moliere's plays1    
where the author makes the hero express 
unbounded delight on being told that he 
had been talking prose during the whole 

of his life4 ,in the same way1 ,i trust1
 that you will take comfort1 and be     
delighted with yourselves1 on the       
discovery that you have been acting on  
the principles of inductive and         
deductive philosophy during the same    
period4 ,probably there is not one here 
who has not in the course of the day had
 occasion to set in motion a complex    
train of reasoning1 of the very same    
kind1 though differing of course in     
degree1 as that which a scientific man  
goes through in tracing the causes of   
natural phenomena4  ,a very trivial     
circumstance will serve to exemplify    
this4 ,suppose you go into a fruiterer's
 shop1 wanting an apple1--you take up   
one1 and1 on biting it1 you find it is  
sour2 you look at it1 and see that it is
 hard and green4 ,you take up another   
one1 and that too is hard1 green1 and   
sour4 ,the shopman offers you a third2  
but1 before biting it1 you examine it1  
and find that it is hard and green1 and 
you immediately say that you will not   

have it1 as it must be sour1 like those 
that you have already tried4  ,nothing  
can be more simple than that1 you think2
 but if you will take the trouble to    
analyze and trace out into its logical  
elements what has been done by the mind1
 you will be greatly surprised4 ,in the 
first place1 you have performed the     
operation of ,induction4 ,you found     
that1 in two experiences1 hardness and  
greenness in apples go together with    
sourness4 ,it was so in the first case1 
and it was confirmed by the second4     
,true1 it is a very small basis1 but    
still it is enough to make an induction 
from2 you generalize the facts1 and you 
expect to find sourness in apples where 
you get hardness and greenness4 ,you    
found upon that a general law1 that all 
hard and green apples are sour2 and     
that1 so far as it goes1 is a perfect   
induction4 ,well1 having got your       
natural law in this way1 when you are   
offered another apple which you find is 
hard and green1 you say1 ,all hard and  

green apples are sour2 this apple is    
hard and green1 therefore this apple is 
sour4 ,that train of reasoning is what  
logicians call a syllogism1 and has all 
its various parts and terms1--its major 
premiss1 its minor premiss1 and its     
conclusion4 ,and1 by the help of further
 reasoning1 which1 if drawn out1 would  
have to be exhibited in two or three    
other syllogisms1 you arrive at your    
final determination1 ,i will not have   
that apple4 ,so that1 you see1 you have1
 in the first place1 established a law  
by ,induction1 and upon that you have   
founded a ,deduction1 and reasoned out  
the special conclusion of the particular
 case4 ,well now1 suppose1 having got   
your law1 that at some time afterwards1 
you are discussing the qualities of     
apples with a friend3 you will say to   
him1 ,it is a very curious thing1--but  
,i find that all hard and green apples  
are sour6 ,your friend says to you1 ,but
 how do you know that8 ,you at once     
reply1 ,oh1 because ,i have tried it    

over and over again1 and have always    
found them to be so4 ,well1 if we were  
talking science instead of common sense1
 we should call that an ,experimental   
,verification4 ,and1 if still opposed1  
you go further1 and say1 ,i have heard  
from the people in ,somersetshire and   
,devonshire1 where a large number of    
apples are grown1 that they have        
observed the same thing4 ,it is also    
found to be the case in ,normandy1 and  
in ,north ,america4 ,in short1 ,i find  
it to be the universal experience of    
mankind wherever attention has been     
directed to the subject4 ,whereupon1    
your friend1 unless he is a very        
unreasonable man1 agrees with you1 and  
is convinced that you are quite right in
 the conclusion you have drawn4 ,he     
believes1 although perhaps he does not  
know he believes it1 that the more      
extensive ,verifications are1--that the 
more frequently experiments have been   
made1 and results of the same kind      
arrived at1--that the more varied the   

conditions under which the same results 
have been attained1 the more certain is 
the ultimate conclusion1 and he disputes
 the question no further4 ,he sees that 
the experiment has been tried under all 
sorts of conditions1 as to time1 place1 
and people1 with the same result2 and he
 says with you1 therefore1 that the law 
you have laid down must be a good one1  
and he must believe it4  ,in science we 
do the same thing2--the philosopher     
exercises precisely the same faculties1 
though in a much more delicate manner4  
,in scientific inquiry it becomes a     
matter of duty to expose a supposed law 
to every possible kind of verification1 
and to take care1 moreover1 that this is
 done intentionally1 and not left to a  
mere accident1 as in the case of the    
apples4 ,and in science1 as in common   
life1 our confidence in a law is in     
exact proportion to the absence of      
variation in the result of our          
experimental verifications4 ,for        
instance1 if you let go your grasp of an

 article you may have in your hand1 it  
will immediately fall to the ground4    
,that is a very common verification of  
one of the best established laws of     
nature--that of gravitation4 ,the method
 by which men of science establish the  
existence of that law is exactly the    
same as that by which we have           
established the trivial proposition     
about the sourness of hard and green    
apples4 ,but we believe it in such an   
extensive1 thorough1 and unhesitating   
manner because the universal experience 
of mankind verifies it1 and we can      
verify it ourselves at any time2 and    
that is the strongest possible          
foundation on which any natural law can 
rest4  ,so much by way of proof that the
 method of establishing laws in science 
is exactly the same as that pursued in  
common life4 ,let us now turn to another
 matter 7though really it is but another
 phase of the same question71 and that  
is1 the method by which1 from the       
relations of certain phenomena1 we prove

 that some stand in the position of     
causes towards the others4  ,i want to  
put the case clearly before you1 and ,i 
will therefore show you what ,i mean by 
another familiar example4 ,i will       
suppose that one of you1 on coming down 
in the morning to the parlour of your   
house1 finds that a tea-pot and some    
spoons which had been left in the room  
on the previous evening are gone1--the  
window is open1 and you observe the mark
 of a dirty hand on the window-frame1   
and perhaps1 in addition to that1 you   
notice the impress of a hob-nailed shoe 
on the gravel outside4 ,all these       
phenomena have struck your attention    
instantly1 and before two minutes have  
passed you say1 ,oh1 somebody has broken
 open the window1 entered the room1 and 
run off with the spoons and the tea-pot6
 ,that speech is out of your mouth in a 
moment4 ,and you will probably add1 ,i  
know there has2 ,i am quite sure of it6 
,you mean to say exactly what you know2 
but in reality what you have said has   

been the expression of what is1 in all  
essential particulars1 an ,hypothesis4  
,you do not 'know' it at all2 it is     
nothing but an hypothesis rapidly framed
 in your own mind6 ,and it is an        
hypothesis founded on a long train of   
inductions and deductions4  ,what are   
those inductions and deductions1 and how
 have you got at this hypothesis8 ,you  
have observed1 in the first place1 that 
the window is open2 but by a train of   
reasoning involving many ,inductions and
 ,deductions1 you have probably arrived 
long before at the ,general ,law--and a 
very good one it is--that windows do not
 open of themselves2 and you therefore  
conclude that something has opened the  
window4 ,a second general law that you  
have arrived at in the same way is1 that
 tea-pots and spoons do not go out of a 
window spontaneously1 and you are       
satisfied that1 as they are not now     
where you left them1 they have been     
removed4 ,in the third place1 you look  
at the marks on the window-sill1 and the

 shoemarks outside1 and you say that in 
all previous experience the former kind 
of mark has never been produced by      
anything else but the hand of a human   
being2 and the same experience shows    
that no other animal but man at present 
wears shoes with hob-nails on them such 
as would produce the marks in the       
gravel4 ,i do not know1 even if we could
 discover any of those missing links    
that are talked about1 that they would  
help us to any other conclusion6 ,at any
 rate the law which states our present  
experience is strong enough for my      
present purpose4--,you next reach the   
conclusion1 that as these kinds of marks
 have not been left by any other animals
 than men1 or are liable to be formed in
 any other way than by a man's hand and 
shoe1 the marks in question have been   
formed by a man in that way4 ,you have1 
further1 a general law1 founded on      
observation and experience1 and that1   
too1 is1 ,i am sorry to say1 a very     
universal and unimpeachable one1--that  

some men are thieves2 and you assume at 
once from all these premisses--and that 
is what constitutes your                
hypothesis--that the man who made the   
marks outside and on the window-sill1   
opened the window1 got into the room1   
and stole your tea-pot and spoons4 ,you 
have now arrived at a ',vera            
,causa'2--you have assumed a ,cause     
which it is plain is competent to       
produce all the phenomena you have      
observed4 ,you can explain all these    
phenomena only by the hypothesis of a   
thief4 ,but that is a hypothetical      
conclusion1 of the justice of which you 
have no absolute proof at all2 it is    
only rendered highly probable by a      
series of inductive and deductive       
reasonings4  ,i suppose your first      
action1 assuming that you are a man of  
ordinary common sense1 and that you have
 established this hypothesis to your own
 satisfaction1 will very likely be to go
 off for the police1 and set them on the
 track of the burglar1 with the view to 

the recovery of your property4 ,but just
 as you are starting with this object1  
some person comes in1 and on learning   
what you are about1 says1 ,my good      
friend1 you are going on a great deal   
too fast4 ,how do you know that the man 
who really made the marks took the      
spoons8 ,it might have been a monkey    
that took them1 and the man may have    
merely looked in afterwards4 ,you would 
probably reply1 ,well1 that is all very 
well1 but you see it is contrary to all 
experience of the way tea-pots and      
spoons are abstracted2 so that1 at any  
rate1 your hypothesis is less probable  
than mine4 ,while you are talking the   
thing over in this way1 another friend  
arrives1 one of that good kind of people
 that ,i was talking of a little while  
ago4 ,and he might say1 ,oh1 my dear    
sir1 you are certainly going on a great 
deal too fast4 ,you are most            
presumptuous4 ,you admit that all these 
occurrences took place when you were    
fast asleep1 at a time when you could   

not possibly have known anything about  
what was taking place4 ,how do you know 
that the laws of ,nature are not        
suspended during the night8 ,it may be  
that there has been some kind of        
supernatural interference in this case4 
,in point of fact1 he declares that your
 hypothesis is one of which you cannot  
at all demonstrate the truth1 and that  
you are by no means sure that the laws  
of ,nature are the same when you are    
asleep as when you are awake4  ,well1   
now1 you cannot at the moment answer    
that kind of reasoning4 ,you feel that  
your worthy friend has you somewhat at a
 disadvantage4 ,you will feel perfectly 
convinced in your own mind1 however1    
that you are quite right1 and you say to
 him1 ,my good friend1 ,i can only be   
guided by the natural probabilities of  
the case1 and if you will be kind enough
 to stand aside and permit me to pass1  
,i will go and fetch the police4 ,well1 
we will suppose that your journey is    
successful1 and that by good luck you   

meet with a policeman2 that eventually  
the burglar is found with your property 
on his person1 and the marks correspond 
to his hand and to his boots4 ,probably 
any jury would consider those facts a   
very good experimental verification of  
your hypothesis1 touching the cause of  
the abnormal phenomena observed in your 
parlour1 and would act accordingly4     
,now1 in this suppositious case1 ,i have
 taken phenomena of a very common kind1 
in order that you might see what are the
 different steps in an ordinary process 
of reasoning1 if you will only take the 
trouble to analyse it carefully4 ,all   
the operations ,i have described1 you   
will see1 are involved in the mind of   
any man of sense in leading him to a    
conclusion as to the course he should   
take in order to make good a robbery and
 punish the offender4 ,i say that you   
are led1 in that case1 to your          
conclusion by exactly the same train of 
reasoning as that which a man of science
 pursues when he is endeavouring to     

discover the origin and laws of the most
 occult phenomena4 ,the process is1 and 
always must be1 the same2 and precisely 
the same mode of reasoning was employed 
by ,newton and ,laplace in their        
endeavours to discover and define the   
causes of the movements of the heavenly 
bodies1 as you1 with your own common    
sense1 would employ to detect a burglar4
 ,the only difference is1 that the      
nature of the inquiry being more        
abstruse1 every step has to be most     
carefully watched1 so that there may not
 be a single crack or flaw in your      
hypothesis4 ,a flaw or crack in many of 
the hypotheses of daily life may be of  
little or no moment as affecting the    
general correctness of the conclusions  
at which we may arrive2 but1 in a       
scientific inquiry1 a fallacy1 great or 
small1 is always of importance1 and is  
sure to be constantly productive of     
mischievous1 if not fatal results4  ,do 
not allow yourselves to be misled by the
 common notion that an hypothesis is    

untrustworthy simply because it is an   
hypothesis4 ,it is often urged1 in      
respect to some scientific conclusion1  
that1 after all1 it is only an          
hypothesis4 ,but what more have we to   
guide us in nine-tenths of the most     
important affairs of daily life than    
hypotheses1 and often very ill-based    
ones8 ,so that in science1 where the    
evidence of an hypothesis is subjected  
to the most rigid examination1 we may   
rightly pursue the same course4 ,you may
 have hypotheses and hypotheses4 ,a man 
may say1 if he likes1 that the moon is  
made of green cheese3 that is an        
hypothesis4 ,but another man1 who has   
devoted a great deal of time and        
attention to the subject1 and availed   
himself of the most powerful telescopes 
and the results of the observations of  
others1 declares that in his opinion it 
is probably composed of materials very  
similar to those of which our own earth 
is made up3 and that is also only an    
hypothesis4 ,but ,i need not tell you   

that there is an enormous difference in 
the value of the two hypotheses4 ,that  
one which is based on sound scientific  
knowledge is sure to have a             
corresponding value2 and that which is a
 mere hasty random guess is likely to   
have but little value4 ,every great step
 in our progress in discovering causes  
has been made in exactly the same way as
 that which ,i have detailed to you4 ,a 
person observing the occurrence of      
certain facts and phenomena asks1       
naturally enough1 what process1 what    
kind of operation known to occur in     
nature applied to the particular case1  
will unravel and explain the mystery8   
,hence you have the scientific          
hypothesis2 and its value will be       
proportionate to the care and           
completeness with which its basis had   
been tested and verified4 ,it is in     
these matters as in the commonest       
affairs of practical life3 the guess of 
the fool will be folly1 while the guess 
of the wise man will contain wisdom4 ,in

 all cases1 you see that the value of   
the result depends on the patience and  
faithfulness with which the investigator
 applies to his hypothesis every        
possible kind of verification4  ,i dare 
say ,i may have to return to this point 
by-and-by2 but having dealt thus far    
with our logical methods1 ,i must now   
turn to something which1 perhaps1 you   
may consider more interesting1 or1 at   
any rate1 more tangible4 ,but in reality
 there are but few things that can be   
more important for you to understand    
than the mental processes and the means 
by which we obtain scientific           
conclusions and theories4 #a ,having    
granted that the inquiry is a proper    
one1 and having determined on the nature
 of the methods we are to pursue and    
which only can lead to success1 ,i must 
now turn to the consideration of our    
knowledge of the nature of the processes
 which have resulted in the present     
condition of organic nature4  ,here1 let
 me say at once1 lest some of you       

misunderstand me1 that ,i have extremely
 little to report4 ,the question of how 
the present condition of organic nature 
came about1 resolves itself into two    
questions4 ,the first is3 ,how has      
organic or living matter commenced its  
existence8 ,and the second is3 ,how has 
it been perpetuated8 ,on the second     
question ,i shall have more to say      
hereafter4 ,but on the first one1 what  
,i now have to say will be for the most 
part of a negative character4  ,if you  
consider what kind of evidence we can   
have upon this matter1 it will resolve  
itself into two kinds4 ,we may have     
historical evidence and we may have     
experimental evidence4 ,it is1 for      
example1 conceivable1 that inasmuch as  
the hardened mud which forms a          
considerable portion of the thickness of
 the earth's crust contains faithful    
records of the past forms of life1 and  
inasmuch as these differ more and more  
as we go further down1--it is possible  
and conceivable that we might come to   

some particular bed or stratum which    
should contain the remains of those     
creatures with which organic life began 
upon the earth4 ,and if we did so1 and  
if such forms of organic life were      
preservable1 we should have what ,i     
would call historical evidence of the   
mode in which organic life began upon   
this planet4 ,many persons will tell    
you1 and indeed you will find it stated 
in many works on geology1 that this has 
been done1 and that we really possess   
such a record2 there are some who       
imagine that the earliest forms of life 
of which we have as yet discovered any  
record1 are in truth the forms in which 
animal life began upon the globe4 ,the  
grounds on which they base that         
supposition are these3--,that if you go 
through the enormous thickness of the   
earth's crust and get down to the older 
rocks1 the higher vertebrate            
animals--the quadrupeds1 birds1 and     
fishes--cease to be found2 beneath them 
you find only the invertebrate animals2 

and in the deepest and lowest rocks     
those remains become scantier and       
scantier1 not in any very gradual       
progression1 however1 until1 at length1 
in what are supposed to be the oldest   
rocks1 the animal remains which are     
found are almost always confined to four
 forms--',oldhamia'1 whose precise      
nature is not known1 whether plant or   
animal2 ',lingula'1 a kind of mollusc2  
',trilobites'1 a crustacean animal1     
having the same essential plan of       
construction1 though differing in many  
details from a lobster or crab2 and     
,hymenocaris1 which is also a           
crustacean4 ,so that you have all the   
',fauna' reduced1 at this period1 to    
four forms3 one a kind of animal or     
plant that we know nothing about1 and   
three undoubted animals--two crustaceans
 and one mollusc4  ,i think1 considering
 the organization of these mollusca and 
crustacea1 and looking at their very    
complex nature1 that it does indeed     
require a very strong imagination to    

conceive that these were the first      
created of all living things4 ,and you  
must take into consideration the fact   
that we have not the slightest proof    
that these which we call the oldest beds
 are really so3 ,i repeat1 we have not  
the slightest proof of it4 ,when you    
find in some places that in an enormous 
thickness of rocks there are but very   
scanty traces of life1 or absolutely    
none at all2 and that in other parts of 
the world rocks of the very same        
formation are crowded with the records  
of living forms1 ,i think it is         
impossible to place any reliance on the 
supposition1 or to feel oneself         
justified in supposing that these are   
the forms in which life first commenced4
 ,i have not time here to enter upon the
 technical grounds upon which ,i am led 
to this conclusion1--that could hardly  
be done properly in half a dozen        
lectures on that part alone2--,i must   
content myself with saying that ,i do   
not at all believe that these are the   

oldest forms of life4  ,i turn to the   
experimental side to see what evidence  
we have there4 ,to enable us to say that
 we know anything about the experimental
 origination of organization and life1  
the investigator ought to be able to    
take inorganic matters1 such as carbonic
 acid1 ammonia1 water1 and salines1 in  
any sort of inorganic combination1 and  
be able to build them up into ,protein  
matter1 and that that ,protein matter   
ought to begin to live in an organic    
form4 ,that1 nobody has done as yet1 and
 ,i suspect it will be a long while     
before anybody does do it4 ,but the     
thing is by no means so impossible as it
 looks2 for the researches of modern    
chemistry have shown us--,i won't say   
the road towards it1 but1 if ,i may so  
say1 they have shown the finger-post    
pointing to the road that may lead to   
it4  ,it is not many years ago--and you 
must recollect that ,organic ,chemistry 
is a young science1 not above a couple  
of generations old1--you must not expect

 too much of it2 it is not many years   
ago since it was said to be perfectly   
impossible to fabricate any organic     
compound2 that is to say1 any           
non-mineral compound which is to be     
found in an organized being4 ,it        
remained so for a very long period2 but 
it is now a considerable number of years
 since a distinguished foreign chemist  
contrived to fabricate ,urea1 a         
substance of a very complex character1  
which forms one of the waste products of
 animal structures4 ,and of late years a
 number of other compounds1 such as     
,butyric ,acid1 and others1 have been   
added to the list4 ,i need not tell you 
that chemistry is an enormous distance  
from the goal ,i indicate2 all ,i wish  
to point out to you is1 that it is by no
 means safe to say that that goal may   
not be reached one day4 ,it may be that 
it is impossible for us to produce the  
conditions requisite to the origination 
of life2 but we must speak modestly     
about the matter1 and recollect that    

,science has put her foot upon the      
bottom round of the ladder4 ,truly he   
would be a bold man who would venture to
 predict where she will be fifty years  
hence4  ,there is another inquiry which 
bears indirectly upon this question1 and
 upon which ,i must say a few words4    
,you are all of you aware of the        
phenomena of what is called spontaneous 
generation4 ,our forefathers1 down to   
the seventeenth century1 or thereabouts1
 all imagined1 in perfectly good faith1 
that certain vegetable and animal forms 
gave birth1 in the process of their     
decomposition1 to insect life4 ,thus1 if
 you put a piece of meat in the sun1 and
 allowed it to putrefy1 they conceived  
that the grubs which soon began to      
appear were the result of the action of 
a power of spontaneous generation which 
the meat contained4 ,and they could give
 you receipts for making various animal 
and vegetable preparations which would  
produce particular kinds of animals4 ,a 
very distinguished ,italian naturalist1 

named ,redi1 took up the question1 at a 
time when everybody believed in it2     
among others our own great ,harvey1 the 
discoverer of the circulation of the    
blood4 ,you will constantly find his    
name quoted1 however1 as an opponent of 
the doctrine of spontaneous generation2 
but the fact is1 and you will see it if 
you will take the trouble to look into  
his works1 ,harvey believed it as       
profoundly as any man of his time2 but  
he happened to enunciate a very curious 
proposition--that every living thing    
came from an 'egg'2 he did not mean to  
use the word in the sense in which we   
now employ it1 he only meant to say that
 every living thing originated in a     
little rounded particle of organized    
substance2 and it is from this          
circumstance1 probably1 that the notion 
of ,harvey having opposed the doctrine  
originated4 ,then came ,redi1 and he    
proceeded to upset the doctrine in a    
very simple manner4 ,he merely covered  
the piece of meat with some very fine   

gauze1 and then he exposed it to the    
same conditions4 ,the result of this was
 that no grubs or insects were produced2
 he proved that the grubs originated    
from the insects who came and deposited 
their eggs in the meat1 and that they   
were hatched by the heat of the sun4 ,by
 this kind of inquiry he thoroughly     
upset the doctrine of spontaneous       
generation1 for his time at least4      
,then came the discovery and application
 of the microscope to scientific        
inquiries1 which showed to naturalists  
that besides the organisms which they   
already knew as living beings and       
plants1 there were an immense number of 
minute things which could be obtained   
apparently almost at will from decaying 
vegetable and animal forms4 ,thus1 if   
you took some ordinary black pepper or  
some hay1 and steeped it in water1 you  
would find in the course of a few days  
that the water had become impregnated   
with an immense number of animalcules   
swimming about in all directions4 ,from 

facts of this kind naturalists were led 
to revive the theory of spontaneous     
generation4 ,they were headed here by an
 ,english naturalist1--,needham1--and   
afterwards in ,france by the learned    
,buffon4 ,they said that these things   
were absolutely begotten in the water of
 the decaying substances out of which   
the infusion was made4 ,it did not      
matter whether you took animal or       
vegetable matter1 you had only to steep 
it in water and expose it1 and you would
 soon have plenty of animalcules4 ,they 
made an hypothesis about this which was 
a very fair one4 ,they said1 this matter
 of the animal world1 or of the higher  
plants1 appears to be dead1 but in      
reality it has a sort of dim life about 
it1 which1 if it is placed under fair   
conditions1 will cause it to break up   
into the forms of these little          
animalcules1 and they will go through   
their lives in the same way as the      
animal or plant of which they once      
formed a part4  ,the question now became

 very hotly debated4 ,spallanzani1 an   
,italian naturalist1 took up opposite   
views to those of ,needham and ,buffon1 
and by means of certain experiments he  
showed that it was quite possible to    
stop the process by boiling the water1  
and closing the vessel in which it was  
contained4 ,oh6 said his opponents2 but 
what do you know you may be doing when  
you heat the air over the water in this 
way8 ,you may be destroying some        
property of the air requisite for the   
spontaneous generation of the           
animalcules4  ,however1 ,spallanzani's  
views were supposed to be upon the right
 side1 and those of the others fell into
 discredit2 although the fact was that  
,spallanzani had not made good his      
views4 ,well1 then1 the subject         
continued to be revived from time to    
time1 and experiments were made by      
several persons2 but these experiments  
were not altogether satisfactory4 ,it   
was found that if you put an infusion in
 which animalcules would appear if it   

were exposed to the air into a vessel   
and boiled it1 and then sealed up the   
mouth of the vessel1 so that no air1    
save such as had been heated to #bab    
degrees1 could reach its contents1 that 
then no animalcules would be found2 but 
if you took the same vessel and exposed 
the infusion to the air1 then you would 
get animalcules4 ,furthermore1 it was   
found that if you connected the mouth of
 the vessel with a red-hot tube in such 
a way that the air would have to pass   
through the tube before reaching the    
infusion1 that then you would get no    
animalcules4 ,yet another thing was     
noticed3 if you took two flasks         
containing the same kind of infusion1   
and left one entirely exposed to the    
air1 and in the mouth of the other      
placed a ball of cotton wool1 so that   
the air would have to filter itself     
through it before reaching the infusion1
 that then1 although you might have     
plenty of animalcules in the first      
flask1 you would certainly obtain none  

from the second4  ,these experiments1   
you see1 all tended towards one         
conclusion--that the infusoria were     
developed from little minute spores or  
eggs which were constantly floating in  
the atmosphere1 which lose their power  
of germination if subjected to heat4    
,but one observer now made another      
experiment which seemed to go entirely  
the other way1 and puzzled him          
altogether4 ,he took some of this boiled
 infusion that ,i have been speaking of1
 and by the use of a mercurial bath--a  
kind of trough used in laboratories--he 
deftly inverted a vessel containing the 
infusion into the mercury1 so that the  
latter reached a little beyond the level
 of the mouth of the 'inverted' vessel4 
,you see that he thus had a quantity of 
the infusion shut off from any possible 
communication with the outer air by     
being inverted upon a bed of mercury4   
,he then prepared some pure oxygen and  
nitrogen gases1 and passed them by means
 of a tube going from the outside of the

 vessel1 up through the mercury into the
 infusion2 so that he thus had it       
exposed to a perfectly pure atmosphere  
of the same constituents as the external
 air4 ,of course1 he expected he would  
get no infusorial animalcules at all in 
that infusion2 but1 to his great dismay 
and discomfiture1 he found he almost    
always did get them4  ,furthermore1 it  
has been found that experiments made in 
the manner described above answer well  
with most infusions2 but that if you    
fill the vessel with boiled milk1 and   
then stop the neck with cotton-wool1 you
 'will' have infusoria4 ,so that you see
 there were two experiments that brought
 you to one kind of conclusion1 and     
three to another2 which was a most      
unsatisfactory state of things to arrive
 at in a scientific inquiry4  ,some few 
years after this1 the question began to 
be very hotly discussed in ,france4     
,there was ,m4 ,pouchet1 a professor at 
,rouen1 a very learned man1 but         
certainly not a very rigid              

experimentalist4 ,he published a number 
of experiments of his own1 some of which
 were very ingenious1 to show that if   
you went to work in a proper way1 there 
was a truth in the doctrine of          
spontaneous generation4 ,well1 it was   
one of the most fortunate things in the 
world that ,m4 ,pouchet took up this    
question1 because it induced a          
distinguished ,french chemist1 ,m4      
,pasteur1 to take up the question on the
 other side2 and he has certainly worked
 it out in the most perfect manner4 ,i  
am glad to say1 too1 that he has        
published his researches in time to     
enable me to give you an account of     
them4 ,he verified all the experiments  
which ,i have just mentioned to you--and
 then finding those extraordinary       
anomalies1 as in the case of the mercury
 bath and the milk1 he set himself to   
work to discover their nature4 ,in the  
case of milk he found it to be a        
question of temperature4 ,milk in a     
fresh state is slightly alkaline2 and it

 is a very curious circumstance1 but    
this very slight degree of alkalinity   
seems to have the effect of preserving  
the organisms which fall into it from   
the air from being destroyed at a       
temperature of #bab degrees1 which is   
the boiling point4 ,but if you raise the
 temperature #aj degrees when you boil  
it1 the milk behaves like everything    
else2 and if the air with which it comes
 in contact1 after being boiled at this 
temperature1 is passed through a red-hot
 tube1 you will not get a trace of      
organisms4  ,he then turned his         
attention to the mercury bath1 and found
 on examination that the surface of the 
mercury was almost always covered with a
 very fine dust4 ,he found that even the
 mercury itself was positively full of  
organic matters2 that from being        
constantly exposed to the air1 it had   
collected an immense number of these    
infusorial organisms from the air4      
,well1 under these circumstances he felt
 that the case was quite clear1 and that

 the mercury was not what it had        
appeared to ,m4 ,schwann to be1--a bar  
to the admission of these organisms2 but
 that1 in reality1 it acted as a        
reservoir from which the infusion was   
immediately supplied with the large     
quantity that had so puzzled him4  ,but 
not content with explaining the         
experiments of others1 ,m4 ,pasteur went
 to work to satisfy himself completely4 
,he said to himself3 ,if my view is     
right1 and if1 in point of fact1 all    
these appearances of spontaneous        
generation are altogether due to the    
falling of minute germs suspended in the
 atmosphere1--why1 ,i ought not only to 
be able to show the germs1 but ,i ought 
to be able to catch and sow them1 and   
produce the resulting organisms4 ,he1   
accordingly1 constructed a very         
ingenious apparatus to enable him to    
accomplish this trapping of this germ   
dust in the air4 ,he fixed in the window
 of his room a glass tube1 in the centre
 of which he had placed a ball of       

gun-cotton1 which1 as you all know1 is  
ordinary cotton-wool1 which1 from having
 been steeped in strong acid1 is        
converted into a substance of great     
explosive power4 ,it is also soluble in 
alcohol and ether4 ,one end of the glass
 tube was1 of course1 open to the       
external air2 and at the other end of it
 he placed an aspirator1 a contrivance  
for causing a current of the external   
air to pass through the tube4 ,he kept  
this apparatus going for four-and-twenty
 hours1 and then removed the 'dusted'   
gun-cotton1 and dissolved it in alcohol 
and ether4 ,he then allowed this to     
stand for a few hours1 and the result   
was1 that a very fine dust was gradually
 deposited at the bottom of it4 ,that   
dust1 on being transferred to the stage 
of a microscope1 was found to contain an
 enormous number of starch grains4 ,you 
know that the materials of our food and 
the greater portion of plants are       
composed of starch1 and we are          
constantly making use of it in a variety

 of ways1 so that there is always a     
quantity of it suspended in the air4 ,it
 is these starch grains which form many 
of those bright specks that we see      
dancing in a ray of light sometimes4    
,but besides these1 ,m4 ,pasteur found  
also an immense number of other organic 
substances such as spores of fungi1     
which had been floating about in the air
 and had got caged in this way4  ,he    
went farther1 and said to himself1 ,if  
these really are the things that give   
rise to the appearance of spontaneous   
generation1 ,i ought to be able to take 
a ball of this 'dusted' gun-cotton and  
put it into one of my vessels1          
containing that boiled infusion which   
has been kept away from the air1 and in 
which no infusoria are at present       
developed1 and then1 if ,i am right1 the
 introduction of this gun-cotton will   
give rise to organisms4  ,accordingly1  
he took one of these vessels of         
infusion1 which had been kept eighteen  
months1 without the least appearance of 

life1 and by a most ingenious           
contrivance1 he managed to break it open
 and introduce such a ball of           
gun-cotton1 without allowing the        
infusion or the cotton ball to come into
 contact with any air but that which had
 been subjected to a red heat1 and in   
twenty-four hours he had the            
satisfaction of finding all the         
indications of what had been hitherto   
called spontaneous generation4 ,he had  
succeeded in catching the germs and     
developing organisms in the way he had  
anticipated4  ,it now struck him that   
the truth of his conclusions might be   
demonstrated without all the apparatus  
he had employed4 ,to do this1 he took   
some decaying animal or vegetable       
substance1 such as urine1 which is an   
extremely decomposable substance1 or the
 juice of yeast1 or perhaps some other  
artificial preparation1 and filled a    
vessel having a long tubular neck with  
it4 ,he then boiled the liquid and bent 
that long neck into an ,s shape or      

zig-zag1 leaving it open at the end4    
,the infusion then gave no trace of any 
appearance of spontaneous generation1   
however long it might be left1 as all   
the germs in the air were deposited in  
the beginning of the bent neck4 ,he then
 cut the tube close to the vessel1 and  
allowed the ordinary air to have free   
and direct access2 and the result of    
that was the appearance of organisms in 
it1 as soon as the infusion had been    
allowed to stand long enough to allow of
 the growth of those it received from   
the air1 which was about forty-eight    
hours4 ,the result of ,m4 ,pasteur's    
experiments proved1 therefore1 in the   
most conclusive manner1 that all the    
appearances of spontaneous generation   
arose from nothing more than the        
deposition of the germs of organisms    
which were constantly floating in the   
air4  ,to this conclusion1 however1 the 
objection was made1 that if that were   
the cause1 then the air would contain   
such an enormous number of these germs1 

that it would be a continual fog4 ,but  
,m4 ,pasteur replied that they are not  
there in anything like the number we    
might suppose1 and that an exaggerated  
view has been held on that subject2 he  
showed that the chances of animal or    
vegetable life appearing in infusions1  
depend entirely on the conditions under 
which they are exposed4 ,if they are    
exposed to the ordinary atmosphere      
around us1 why1 of course1 you may have 
organisms appearing early4 ,but1 on the 
other hand1 if they are exposed to air  
from a great height1 or from some very  
quiet cellar1 you will often not find a 
single trace of life4  ,so that ,m4     
,pasteur arrived at last at the clear   
and definite result1 that all these     
appearances are like the case of the    
worms in the piece of meat1 which was   
refuted by ,redi1 simply germs carried  
by the air and deposited in the liquids 
in which they afterwards appear4 ,for my
 own part1 ,i conceive that1 with the   
particulars of ,m4 ,pasteur's           

experiments before us1 we cannot fail to
 arrive at his conclusions2 and that the
 doctrine of spontaneous generation has 
received a final 'coup de grace'4  ,you1
 of course1 understand that all this in 
no way interferes with the 'possibility'
 of the fabrication of organic matters  
by the direct method to which ,i have   
referred1 remote as that possibility may
 be4   ,footnote #a3 ,those who wish to 
study fully the doctrines of which ,i   
have endeavoured to give some rough and 
ready illustrations1 must read ,mr4     
,john ,stuart ,mill's ',system of       
,logic'4