,,! ,,me?od ,,by ,,:i* ,,! ,,causes ,,( 
,,! ,,pres5t ,,& ,,pa/ ,,conditions ,,( 
,,organic ,,nature ,,are ,,to ,,be      
,,discov]$4--,,! ,,orig9ation ,,( ,,liv+
 ,,be+s  ,lecture ,,iii4 7( ,,vi471     
,lectures ,to ,work+ ,m51 at ! ,museum (
 ,practical ,geology1 #ahfc1 ,on ,d>w9's
 "w3 ,orig9 ( ,species4   ,by ,?omas ,h4
 ,huxley    ,9 ! two prec$+ lectures ,i 
h endeav\r$ to indicate to y ! ext5t ( !
 subject-matt] ( ! inquiry ^u :i* we are
 engag$2 & n[1 hav+ ?us acquir$ "s      
conception ( ! ,pa/ & ,pres5t ph5om5a ( 
,organic ,nature1 ,i mu/ n[ turn to t   
:i* con/itutes ! great problem :i* we h 
set be=e ourselves2--,i mean1 ! "q ( :at
 k we h ( ! causes ( ^! ph5om5a (       
organic nature1 & h[ su* k is obta9able4
  ,"h1 on ! ?re%old ( ! inquiry1 an     
objection meets u4 ,!re are 9 ! _w a    
numb] ( extremely wor?y1 well-mean+     
p]sons1 ^: judgm5ts & op9ions are       
entitl$ to ! utmo/ respect on acc\nt (  
_! s9c]ity1 :o are ( op9ion t ,vital    
,ph5om5a1 & especially all que/ions     

relat+ to ! orig9 ( vital ph5om5a1 are  
que/ions q ap>t f ! ord9>y run (        
inquiry1 & are1 by _! v nature1 plac$   
out ( our rea*4 ,!y say t all ^! ph5om5a
 orig9at$ miracul\sly1 or 9 "s way      
totally diff]5t f ! ord9>y c\rse (      
nature1 & t !re=e !y conceive x to be   
futile1 n to say presumptu\s1 to attempt
 to inquire into !m4  ,to su* s9c]e &   
e>ne/ p]sons1 ,i w\ld only say1 t a "q (
 ?is k9d is n to be %elv$ ^u !oretical  
or speculative gr\nds4 ,y may rememb] ! 
/ory ( ! ,sophi/ :o demon/rat$ to       
,diog5es 9 ! mo/ complete & satisfactory
 mann] t he c\ld n walk2 t1 9 fact1 all 
motion 0 an impossibility2 & t ,diog5es 
refut$ him by simply gett+ up & walk+   
r\nd 8 tub4 ,s1 9 ! same way1 ! man (   
sci5ce replies to objections ( ?is k9d1 
by simply gett+ up & walk+ onw>d1 & %[+ 
:at sci5ce has done & is do+--by po9t+  
to t imm5se mass ( facts :i* h be5      
asc]ta9$ & sy/ematiz$ "u ! =ms ( ! great
 doctr9es ( ,morphology1 ( ,developm5t1 
( ,di/ribution1 & ! l4 ,he sees an      

enorm\s mass ( facts & laws relat+ to   
organic be+s1 :i* /& on ! same good s\nd
 f\ndation z e o!r natural law2 & !re=e1
 ) ?is mass ( facts & laws be=e u1      
!re=e1 see+ t1 z f> z organic matt]s h  
hi!rto be5 accessible & /udi$1 !y h %[n 
!mselves capable ( yield+ to sci5tific  
inve/igation1 we may accept ?is z pro( t
 ord] & law reign !re z well z 9 ! re/ (
 nature2 & ! man ( sci5ce says no?+ to  
objectors ( ?is sort1 b supposes t we c 
& %all walk to a k ( ! orig9 ( organic  
nature1 9 ! same way t we h walk$ to a k
 ( ! laws & pr9ciples ( ! inorganic _w4 
,b !re are objectors :o say ! same f    
ignorance & ill-w4 ,to su* ,i w\ld reply
 t ! objection comes ill f !m1 & t !    
real presumption1 ,i may almo/ say !    
real blasphemy1 9 ?is matt]1 is 9 !     
attempt to limit t inquiry into ! causes
 ( ph5om5a :i* is ! s\rce ( all human   
bless+s1 & f :i* has sprung all human   
prosp]ity & progress2 =1 aft] all1 we c 
accompli% comp>atively little2 ! limit$ 
range ( our own faculties b\nds u on e  

side1--! field ( our p[]s ( obs]vation  
is small en\gh1 & he :o endeav\rs to    
n>r[ ! sph]e ( our inquiries is only    
pursu+ a c\rse t is likely to produce ! 
greate/ h>m to 8 fell[-m54  ,b n[1      
assum+1 z we all d1 ,i hope1 t ^!       
ph5om5a are prop]ly accessible to       
inquiry1 & sett+ out ^u our se>* into ! 
causes ( ! ph5om5a ( organic nature1 or1
 at any rate1 sett+ out to discov] h[   
mu* we at pres5t "k ^u ^! ab/ruse       
matt]s1 ! "q arises z to :at is to be   
our c\rse ( proce$+1 & :at me?od we mu/ 
lay d[n = our guidance4 ,i reply to t   
"q1 t our me?od mu/ be exactly ! same z 
t :i* is pursu$ 9 any o!r sci5tific     
inquiry1 ! me?od ( sci5tific            
inve/igation be+ ! same = all ord]s (   
facts & ph5om5a :atsoev]4  ,i mu/ dwell 
a little on ?is po9t1 = ,i wi% y to     
leave ?is room ) a v cle> conviction t  
sci5tific inve/igation is n1 z _m p seem
 to suppose1 "s k9d ( mod]n black art4  
,i say t y might easily ga!r ?is        
impression f ! mann] 9 :i* _m p]sons    

speak ( sci5tific inquiry1 or talk ab\t 
inductive & d$uctive philosophy1 or !   
pr9ciples ( ! ,baconian philosophy4 ,i d
 prote/ t1 ( ! va/ numb] ( cants 9 ?is  
_w1 !re are none1 to my m9d1 s          
contemptible z ! pseudosci5tific cant   
:i* is talk$ ab\t ! ,baconian           
philosophy4  ,to he> p talk ab\t ! great
 ,*ancellor--& a v great man he c]ta9ly 
01--y w\ld ?9k t x 0 he :o _h inv5t$    
sci5ce1 & t !re 0 no su* ?+ z s\nd      
reason+ be=e ! "t ( ,que5 ,elizabe?4 ,( 
c\rse y say1 t _c possibly be true2 y   
p]ceive1 on a mom5t's reflection1 t su* 
an idea is absurdly wrong1 & yet1 s     
firmly root$ is ?is sort (              
impression1--,i _c call x an idea1 or   
conception1--! ?+ is too absurd to be   
ent]ta9$1--b s completely does x exi/ at
 ! bottom ( mo/ m5's m9ds1 t ?is has be5
 a matt] ( obs]vation ) me = _m ye>s    
pa/4 ,!re are _m m5 :o1 ?\gh kn[+       
absolutely no?+ ( ! subject ) :i* !y may
 be deal+1 wi%1 nev]!less1 to damage !  
au?or ( "s view ) :i* !y ?9k fit to     

disagree4 ,:at !y d1 !n1 is n to g &    
le>n some?+ ab\t ! subject1 :i* "o w\ld 
naturally ?9k ! be/ way ( fairly deal+ )
 x2 b !y abuse ! orig9ator ( ! view !y  
"q1 9 a g5]al mann]1 & w9d up by say+ t1
 ,aft] all1 y "k1 ! pr9ciples & me?od ( 
?is au?or are totally oppos$ to ! canons
 ( ! ,baconian philosophy4 ,!n ev]ybody 
applauds1 z a matt] ( c\rse1 & agrees t 
x mu/ be s4 ,b if y 7 to /op !m all 9 ! 
middle ( _! applause1 y w\ld probably   
f9d t nei!r ! speak] nor 8 applaud]s    
c\ld tell y h[ or 9 :at way x 0 s2 nei!r
 ! "o nor ! o!r hav+ ! slighte/ idea (  
:at !y mean :5 !y speak ( ! ,baconian   
philosophy4  ,y w und]/&1 ,i hope1 t ,i 
h n ! slighte/ desire to jo9 9 ! outcry 
aga9/ ei!r ! morals1 ! intellect1 or !  
great g5ius ( ,"l ,*ancellor ,bacon4 ,he
 0 und\bt$ly a v great man1 let p say   
:at !y w ( him2 b not)/&+ all t he did =
 philosophy1 x w\ld be entirely wrong to
 suppose t ! me?ods ( mod]n sci5tific   
inquiry orig9at$ ) him1 or ) 8 age2 !y  
orig9at$ ) ! fir/ man1 :oev] he 02 &    

inde$ exi/$ long be=e him1 = _m ( !     
ess5tial processes ( reason+ are ex]t$  
by ! high] ord] ( brutes z completely & 
effectively z by ourselves4 ,we see 9 _m
 ( ! brute creation ! ex]cise ( "o1 at  
lea/1 ( ! same p[]s ( reason+ z t :i* we
 ourselves employ4  ,! me?od ( sci5tific
 inve/igation is no?+ b ! expression ( !
 necess>y mode ( work+ ( ! human m9d4 ,x
 is simply ! mode at :i* all ph5om5a are
 reason$ ab\t1 r5d]$ precise & exact4   
,!re is no m diff]5ce1 b !re is j ! same
 k9d ( diff]5ce1 betwe5 ! m5tal         
op]ations ( a man ( sci5ce & ^? ( an    
ord9>y p]son1 z !re is betwe5 !         
op]ations & me?ods ( a bak] or ( a but*]
 weigh+ out 8 goods 9 common scales1 & !
 op]ations ( a *emi/ 9 p]=m+ a difficult
 & complex analysis by means ( 8 balance
 & f9ely-graduat$ weights4 ,x is n t !  
action ( ! scales 9 ! "o case1 & !      
balance 9 ! o!r1 diff] 9 ! pr9ciples (  
_! con/ruction or mann] ( work+2 b !    
beam ( "o is set on an inf9itely f9]    
axis ?an ! o!r1 & ( c\rse turns by !    

addition ( a mu* small] weight4  ,y w   
und]/& ?is bett]1 p]haps1 if ,i give y  
"s famili> example4 ,y h all he>d x     
repeat$1 ,i d>e say1 t m5 ( sci5ce "w by
 means ( ,induction & ,d$uction1 & t by 
! help ( ^! op]ations1 !y1 9 a sort (   
s5se1 wr+ f ,nature c]ta9 o!r ?+s1 :i*  
are call$ ,natural ,laws1 & ,causes1 & t
 out ( ^!1 by "s cunn+ skill ( _! own1  
!y build up ,hypo!ses & ,!ories4 ,& x is
 imag9$ by _m1 t ! op]ations ( ! common 
m9d c be by no means comp>$ ) ^!        
processes1 & t !y h to be acquir$ by a  
sort ( special appr5tice%ip to ! craft4 
,to he> all ^! l>ge words1 y w\ld ?9k t 
! m9d ( a man ( sci5ce mu/ be con/itut$ 
diff]5tly f t ( 8 fell[ m52 b if y w n  
be fright5$ by t]ms1 y w discov] t y are
 q wrong1 & t all ^! t]rible app>atus   
are be+ us$ by y\rselves e day & e h\r (
 y\r lives4  ,!re is a well-kn[n incid5t
 9 "o ( ,moli]e's plays1 :]e ! au?or    
makes ! h]o express unb\nd$ delight on  
be+ told t he _h be5 talk+ prose dur+ ! 
:ole ( 8 life4 ,9 ! same way1 ,i tru/1 t

 y w take com=t1 & be delight$ )        
y\rselves1 on ! discov]y t y h be5 act+ 
on ! pr9ciples ( inductive & d$uctive   
philosophy dur+ ! same p]iod4 ,probably 
!re is n "o "h :o has n 9 ! c\rse ( !   
day _h occasion to set 9 motion a       
complex tra9 ( reason+1 ( ! v same k9d1 
?\gh diff]+ ( c\rse 9 degree1 z t :i* a 
sci5tific man goes ?r\gh 9 trac+ !      
causes ( natural ph5om5a4  ,a v trivial 
circum/ance w s]ve to exemplify ?is4    
,suppose y g into a fruit]]'s %op1 want+
 an apple1--y take up "o1 &1 on bit+ x1 
y f9d x is s\r2 y look at x1 & see t x  
is h>d & gre54 ,y take up ano!r "o1 & t 
too is h>d1 gre51 & s\r4 ,! %opman (f]s 
y a ?ird2 b1 be=e bit+ x1 y exam9e x1 & 
f9d t x is h>d & gre51 & y imm$iately   
say t y w n h x1 z x mu/ be s\r1 l ^? t 
y h already tri$4  ,no?+ c be m simple  
?an t1 y ?9k2 b if y w take ! tr\ble to 
analyze & trace out into its logical    
elem5ts :at has be5 done by ! m9d1 y w  
be greatly surpris$4 ,9 ! fir/ place1 y 
h p]=m$ ! op]ation ( ,induction4 ,y f\nd

 t1 9 two exp]i5ces1 h>dness & gre5ness 
9 apples g toge!r ) s\rness4 ,x 0 s 9 ! 
fir/ case1 & x 0 confirm$ by ! second4  
,true1 x is a v small basis1 b /ill x is
 en\gh to make an induction f2 y        
g5]alize ! facts1 & y expect to f9d     
s\rness 9 apples :]e y get h>dness &    
gre5ness4 ,y f\nd ^u t a g5]al law1 t   
all h>d & gre5 apples are s\r2 & t1 s f>
 z x goes1 is a p]fect induction4 ,well1
 hav+ got y\r natural law 9 ?is way1 :5 
y are (f]$ ano!r apple :i* y f9d is h>d 
& gre51 y say1 ,all h>d & gre5 apples   
are s\r2 ?is apple is h>d & gre51 !re=e 
?is apple is s\r4 ,t tra9 ( reason+ is  
:at logicians call a syllogism1 & has   
all its v>i\s p>ts & t]ms1--its major   
premiss1 its m9or premiss1 & its        
conclusion4 ,&1 by ! help ( fur!r       
reason+1 :i*1 if drawn out1 w\ld h to be
 exhibit$ 9 two or ?ree o!r syllogisms1 
y arrive at y\r f9al det]m9ation1 ,i w n
 h t apple4 ,s t1 y see1 y h1 9 ! fir/  
place1 e/abli%$ a law by ,induction1 &  
^u t y h f\nd$ a ,d$uction1 & reason$   

out ! special conclusion ( ! p>ticul>   
case4 ,well n[1 suppose1 hav+ got y\r   
law1 t at "s "t aft]w>ds1 y are discuss+
 ! qualities ( apples ) a fri5d3 y w say
 to him1 ,x is a v curi\s ?+1--b ,i f9d 
t all h>d & gre5 apples are s\r6 ,y\r   
fri5d says to y1 ,b h[ d y "k t8 ,y at  
once reply1 ,oh1 because ,i h tri$ x ov]
 & ov] aga91 & h always f\nd !m to be s4
 ,well1 if we 7 talk+ sci5ce in/ead (   
common s5se1 we %\ld call t an          
,exp]im5tal ,v]ification4 ,&1 if /ill   
oppos$1 y g fur!r1 & say1 ,i h he>d f ! 
p 9 ,som]set%ire & ,devon%ire1 :]e a    
l>ge numb] ( apples are gr[n1 t !y h    
obs]v$ ! same ?+4 ,x is also f\nd to be 
! case 9 ,norm&y1 & 9 ,nor? ,am]ica4 ,9 
%ort1 ,i f9d x to be ! univ]sal exp]i5ce
 ( mank9d :]ev] att5tion has be5 direct$
 to ! subject4 ,:]eupon1 y\r fri5d1     
unless he is a v unreasonable man1      
agrees ) y1 & is conv9c$ t y are q "r 9 
! conclusion y h drawn4 ,he believes1   
al?\gh p]haps he does n "k he believes  
x1 t ! m ext5sive ,v]ifications are1--t 

! m frequ5tly exp]im5ts h be5 made1 &   
results ( ! same k9d arriv$ at1--t ! m  
v>i$ ! conditions "u :i* ! same results 
h be5 atta9$1 ! m c]ta9 is ! ultimate   
conclusion1 & he disputes ! "q no fur!r4
 ,he sees t ! exp]im5t has be5 tri$ "u  
all sorts ( conditions1 z to "t1 place1 
& p1 ) ! same result2 & he says ) y1    
!re=e1 t ! law y h laid d[n mu/ be a    
good "o1 & he mu/ believe x4  ,9 sci5ce 
we d ! same ?+2--! philosoph] ex]cises  
precisely ! same faculties1 ?\gh 9 a mu*
 m delicate mann]4 ,9 sci5tific inquiry 
x becomes a matt] ( duty to expose a    
suppos$ law to e possible k9d (         
v]ification1 & to take c>e1 moreov]1 t  
?is is done int5tionally1 & n left to a 
m]e accid5t1 z 9 ! case ( ! apples4 ,& 9
 sci5ce1 z 9 common life1 our confid5ce 
9 a law is 9 exact proportion to !      
abs5ce ( v>iation 9 ! result ( our      
exp]im5tal v]ifications4 ,= in/ance1 if 
y let g y\r grasp ( an article y may h 9
 y\r h&1 x w imm$iately fall to ! gr\nd4
 ,t is a v common v]ification ( "o ( !  

be/ e/abli%$ laws ( nature--t (         
gravitation4 ,! me?od by :i* m5 ( sci5ce
 e/abli% ! exi/5ce ( t law is exactly ! 
same z t by :i* we h e/abli%$ ! trivial 
proposition ab\t ! s\rness ( h>d & gre5 
apples4 ,b we believe x 9 su* an        
ext5sive1 ?or\gh1 & unhesitat+ mann]    
because ! univ]sal exp]i5ce ( mank9d    
v]ifies x1 & we c v]ify x ourselves at  
any "t2 & t is ! /ronge/ possible       
f\ndation on :i* any natural law c re/4 
,s mu* by way ( pro( t ! me?od (        
e/abli%+ laws 9 sci5ce is exactly ! same
 z t pursu$ 9 common life4 ,let u n[    
turn to ano!r matt] 7?\gh really x is b 
ano!r phase ( ! same "q71 & t is1 !     
me?od by :i*1 f ! relations ( c]ta9     
ph5om5a1 we prove t "s /& 9 ! position (
 causes t[>ds ! o!rs4  ,i want to put ! 
case cle>ly be=e y1 & ,i w !re=e %[ y   
:at ,i mean by ano!r famili> example4 ,i
 w suppose t "o ( y1 on com+ d[n 9 !    
morn+ to ! p>l\r ( y\r h\se1 f9ds t a   
tea-pot & "s spoons :i* _h be5 left 9 ! 
room on ! previ\s ev5+ are gone1--! w9d[

 is op51 & y obs]ve ! m>k ( a dirty h&  
on ! w9d[-frame1 & p]haps1 9 addition to
 t1 y notice ! impress ( a hob-nail$ %oe
 on ! gravel outside4 ,all ^! ph5om5a h 
/ruck y\r att5tion in/antly1 & be=e two 
m9utes h pass$ y say1 ,oh1 somebody has 
brok5 op5 ! w9d[1 ent]$ ! room1 & run (f
 ) ! spoons & ! tea-pot6 ,t spee* is out
 ( y\r m\? 9 a mom5t4 ,& y w probably   
add1 ,i "k !re has2 ,i am q sure ( x6 ,y
 mean to say exactly :at y "k2 b 9      
reality :at y h said has be5 !          
expression ( :at is1 9 all ess5tial     
p>ticul>s1 an ,hypo!sis4 ,y d n '"k' x  
at all2 x is no?+ b an hypo!sis rapidly 
fram$ 9 y\r own m9d6 ,& x is an hypo!sis
 f\nd$ on a long tra9 ( inductions &    
d$uctions4  ,:at are ^? inductions &    
d$uctions1 & h[ h y got at ?is hypo!sis8
 ,y h obs]v$1 9 ! fir/ place1 t ! w9d[  
is op52 b by a tra9 ( reason+ involv+ _m
 ,inductions & ,d$uctions1 y h probably 
arriv$ long be=e at ! ,g5]al ,law--& a v
 good "o x is--t w9d[s d n op5 (        
!mselves2 & y !re=e conclude t some?+   

has op5$ ! w9d[4 ,a second g5]al law t y
 h arriv$ at 9 ! same way is1 t tea-pots
 & spoons d n g out ( a w9d[            
spontane\sly1 & y are satisfi$ t1 z !y  
are n n[ :]e y left !m1 !y h be5 remov$4
 ,9 ! ?ird place1 y look at ! m>ks on ! 
w9d[-sill1 & ! %oem>ks outside1 & y say 
t 9 all previ\s exp]i5ce ! =m] k9d ( m>k
 has nev] be5 produc$ by any?+ else b ! 
h& ( a human be+2 & ! same exp]i5ce %[s 
t no o!r animal b man at pres5t we>s    
%oes ) hob-nails on !m su* z w\ld       
produce ! m>ks 9 ! gravel4 ,i d n "k1   
ev5 if we c\ld discov] any ( ^? miss+   
l9ks t are talk$ ab\t1 t !y w\ld help u 
to any o!r conclusion6 ,at any rate !   
law :i* /ates our pres5t exp]i5ce is    
/rong en\gh = my pres5t purpose4--,y    
next rea* ! conclusion1 t z ^! k9ds (   
m>ks h n be5 left by any o!r animals ?an
 m51 or are liable to be =m$ 9 any o!r  
way ?an by a man's h& & %oe1 ! m>ks 9 "q
 h be5 =m$ by a man 9 t way4 ,y h1      
fur!r1 a g5]al law1 f\nd$ on obs]vation 
& exp]i5ce1 & t1 too1 is1 ,i am sorry to

 say1 a v univ]sal & unimpea*able "o1--t
 "s m5 are ?ieves2 & y assume at once f 
all ^! premisses--& t is :at con/itutes 
y\r hypo!sis--t ! man :o made ! m>ks    
outside & on ! w9d[-sill1 op5$ ! w9d[1  
got into ! room1 & /ole y\r tea-pot &   
spoons4 ,y h n[ arriv$ at a ',v]a       
,causa'2--y h assum$ a ,cause :i* x is  
pla9 is compet5t to produce all !       
ph5om5a y h obs]v$4 ,y c expla9 all ^!  
ph5om5a only by ! hypo!sis ( a ?ief4 ,b 
t is a hypo!tical conclusion1 ( ! ju/ice
 ( :i* y h no absolute pro( at all2 x is
 only r5d]$ highly probable by a s]ies (
 inductive & d$uctive reason+s4  ,i     
suppose y\r fir/ action1 assum+ t y are 
a man ( ord9>y common s5se1 & t y h     
e/abli%$ ?is hypo!sis to y\r own        
satisfaction1 w v likely be to g (f = ! 
police1 & set !m on ! track ( ! burgl>1 
) ! view to ! recov]y ( y\r prop]ty4 ,b 
j z y are />t+ ) ?is object1 "s p]son   
comes 91 & on le>n+ :at y are ab\t1     
says1 ,my good fri5d1 y are go+ on a    
great deal too fa/4 ,h[ d y "k t ! man  

:o really made ! m>ks took ! spoons8 ,x 
might h be5 a monkey t took !m1 & ! man 
may h m]ely look$ 9 aft]w>ds4 ,y w\ld   
probably reply1 ,well1 t is all v well1 
b y see x is contr>y to all exp]i5ce ( !
 way tea-pots & spoons are ab/ract$2 s  
t1 at any rate1 y\r hypo!sis is less    
probable ?an m9e4 ,:ile y are talk+ ! ?+
 ov] 9 ?is way1 ano!r fri5d arrives1 "o 
( t good k9d ( p t ,i 0 talk+ ( a little
 :ile ago4 ,& he might say1 ,oh1 my de> 
sir1 y are c]ta9ly go+ on a great deal  
too fa/4 ,y are mo/ presumptu\s4 ,y     
admit t all ^! occurr5ces took place :5 
y 7 fa/ asleep1 at a "t :5 y c\ld n     
possibly h kn[n any?+ ab\t :at 0 tak+   
place4 ,h[ d y "k t ! laws ( ,nature are
 n susp5d$ dur+ ! night8 ,x may be t !re
 has be5 "s k9d ( sup]natural int]f]5ce 
9 ?is case4 ,9 po9t ( fact1 he decl>es t
 y\r hypo!sis is "o ( :i* y _c at all   
demon/rate ! tru?1 & t y are by no means
 sure t ! laws ( ,nature are ! same :5 y
 are asleep z :5 y are awake4  ,well1   
n[1 y _c at ! mom5t answ] t k9d (       

reason+4 ,y feel t y\r wor?y fri5d has y
 some:at at a disadvantage4 ,y w feel   
p]fectly conv9c$ 9 y\r own m9d1 h[ev]1 t
 y are q "r1 & y say to him1 ,my good   
fri5d1 ,i c only be guid$ by ! natural  
probabilities ( ! case1 & if y w be k9d 
en\gh to /& aside & p]mit me to pass1 ,i
 w g & fet* ! police4 ,well1 we w       
suppose t y\r j\rney is successful1 & t 
by good luck y meet ) a policeman2 t    
ev5tually ! burgl> is f\nd ) y\r prop]ty
 on 8 p]son1 & ! m>ks correspond to 8 h&
 & to 8 boots4 ,probably any jury w\ld  
consid] ^? facts a v good exp]im5tal    
v]ification ( y\r hypo!sis1 t\*+ ! cause
 ( ! abnormal ph5om5a obs]v$ 9 y\r      
p>l\r1 & w\ld act accord+ly4  ,n[1 9 ?is
 suppositi\s case1 ,i h tak5 ph5om5a ( a
 v common k9d1 9 ord] t y might see :at 
are ! diff]5t /eps 9 an ord9>y process (
 reason+1 if y w only take ! tr\ble to  
analyse x c>efully4 ,all ! op]ations ,i 
h describ$1 y w see1 are involv$ 9 ! m9d
 ( any man ( s5se 9 lead+ him to a      
conclusion z to ! c\rse he %\ld take 9  

ord] to make good a robb]y & puni% !    
(f5d]4 ,i say t y are l$1 9 t case1 to  
y\r conclusion by exactly ! same tra9 ( 
reason+ z t :i* a man ( sci5ce pursues  
:5 he is endeav\r+ to discov] ! orig9 & 
laws ( ! mo/ occult ph5om5a4 ,! process 
is1 & always mu/ be1 ! same2 & precisely
 ! same mode ( reason+ 0 employ$ by     
,newton & ,laplace 9 _! endeav\rs to    
discov] & def9e ! causes ( ! movem5ts ( 
! heav5ly bodies1 z y1 ) y\r own common 
s5se1 w\ld employ to detect a burgl>4 ,!
 only diff]5ce is1 t ! nature ( !       
inquiry be+ m ab/ruse1 e /ep has to be  
mo/ c>efully wat*$1 s t !re may n be a  
s+le crack or flaw 9 y\r hypo!sis4 ,a   
flaw or crack 9 _m ( ! hypo!ses ( daily 
life may be ( little or no mom5t z      
affect+ ! g5]al correctness ( !         
conclusions at :i* we may arrive2 b1 9 a
 sci5tific inquiry1 a fallacy1 great or 
small1 is always ( importance1 & is sure
 to be con/antly productive ( mis*iev\s1
 if n fatal results4  ,d n all[         
y\rselves to be misl$ by ! common notion

 t an hypo!sis is untru/wor?y simply    
because x is an hypo!sis4 ,x is (t5     
urg$1 9 respect to "s sci5tific         
conclusion1 t1 aft] all1 x is only an   
hypo!sis4 ,b :at m h we to guide u 9    
n9e-t5?s ( ! mo/ important affairs (    
daily life ?an hypo!ses1 & (t5 v        
ill-bas$ ones8 ,s t 9 sci5ce1 :]e !     
evid5ce ( an hypo!sis is subject$ to !  
mo/ rigid exam9ation1 we may rightly    
pursue ! same c\rse4 ,y may h hypo!ses &
 hypo!ses4 ,a man may say1 if he likes1 
t ! moon is made ( gre5 *eese3 t is an  
hypo!sis4 ,b ano!r man1 :o has devot$ a 
great deal ( "t & att5tion to ! subject1
 & avail$ himself ( ! mo/ p[]ful        
telescopes & ! results ( ! obs]vations (
 o!rs1 decl>es t 9 8 op9ion x is        
probably compos$ ( mat]ials v simil> to 
^? ( :i* our own e>? is made up3 & t is 
also only an hypo!sis4 ,b ,i ne$ n tell 
y t !re is an enorm\s diff]5ce 9 ! value
 ( ! two hypo!ses4 ,t "o :i* is bas$ on 
s\nd sci5tific k is sure to h a         
correspond+ value2 & t :i* is a m]e ha/y

 r&om guess is likely to h b little     
value4 ,e great /ep 9 our progress 9    
discov]+ causes has be5 made 9 exactly !
 same way z t :i* ,i h detail$ to y4 ,a 
p]son obs]v+ ! occurr5ce ( c]ta9 facts &
 ph5om5a asks1 naturally en\gh1 :at     
process1 :at k9d ( op]ation kn[n to     
occur 9 nature appli$ to ! p>ticul>     
case1 w unravel & expla9 ! my/]y8 ,h5ce 
y h ! sci5tific hypo!sis2 & its value w 
be proportionate to ! c>e & complet5ess 
) :i* its basis _h be5 te/$ & v]ifi$4 ,x
 is 9 ^! matt]s z 9 ! commone/ affairs (
 practical life3 ! guess ( ! fool w be  
folly1 :ile ! guess ( ! wise man w      
conta9 wisdom4 ,9 all cases1 y see t !  
value ( ! result dep5ds on ! pati5ce &  
fai?fulness ) :i* ! inve/igator applies 
to 8 hypo!sis e possible k9d (          
v]ification4  ,i d>e say ,i may h to    
return to ?is po9t by-&-by2 b hav+ dealt
 ?us f> ) our logical me?ods1 ,i mu/ n[ 
turn to some?+ :i*1 p]haps1 y may       
consid] m int]e/+1 or1 at any rate1 m   
tangible4 ,b 9 reality !re are b few ?+s

 t c be m important = y to und]/& ?an ! 
m5tal processes & ! means by :i* we     
obta9 sci5tific conclusions & !ories4 #a
 ,hav+ grant$ t ! inquiry is a prop] "o1
 & hav+ det]m9$ on ! nature ( ! me?ods  
we are to pursue & :i* only c lead to   
success1 ,i mu/ n[ turn to !            
consid]ation ( our k ( ! nature ( !     
processes :i* h result$ 9 ! pres5t      
condition ( organic nature4  ,"h1 let me
 say at once1 le/ "s ( y misund]/& me1 t
 ,i h extremely little to report4 ,! "q 
( h[ ! pres5t condition ( organic nature
 came ab\t1 resolves itself into two    
que/ions4 ,! fir/ is3 ,h[ has organic or
 liv+ matt] comm5c$ its exi/5ce8 ,& !   
second is3 ,h[ has x be5 p]petuat$8 ,on 
! second "q ,i %all h m to say h]eaft]4 
,b on ! fir/ "o1 :at ,i n[ h to say w be
 = ! mo/ "p ( a negative "*4  ,if y     
consid] :at k9d ( evid5ce we c h ^u ?is 
matt]1 x w resolve itself into two k9ds4
 ,we may h hi/orical evid5ce & we may h 
exp]im5tal evid5ce4 ,x is1 = example1   
conceivable1 t inasmu* z ! h>d5$ mud :i*

 =ms a consid]able portion ( ! ?ickness 
( ! e>?'s cru/ conta9s fai?ful records (
 ! pa/ =ms ( life1 & inasmu* z ^! diff] 
m & m z we g fur!r d[n1--x is possible &
 conceivable t we might come to "s      
p>ticul> b$ or /ratum :i* %\ld conta9 ! 
rema9s ( ^? creatures ) :i* organic life
 began ^u ! e>?4 ,& if we did s1 & if   
su* =ms ( organic life 7 pres]vable1 we 
%\ld h :at ,i w\ld call hi/orical       
evid5ce ( ! mode 9 :i* organic life     
began ^u ?is planet4 ,_m p]sons w tell  
y1 & inde$ y w f9d x /at$ 9 _m works on 
geology1 t ?is has be5 done1 & t we     
really possess su* a record2 !re are "s 
:o imag9e t ! e>lie/ =ms ( life ( :i* we
 h z yet discov]$ any record1 are 9 tru?
 ! =ms 9 :i* animal life began ^u !     
globe4 ,! gr\nds on :i* !y base t       
supposition are ^!3--,t if y g ?r\gh !  
enorm\s ?ickness ( ! e>?'s cru/ & get   
d[n to ! old] rocks1 ! high] v]tebrate  
animals--! quadrup$s1 birds1 &          
fi%es--cease to be f\nd2 b5ea? !m y f9d 
only ! inv]tebrate animals2 & 9 ! deepe/

 & l[e/ rocks ^? rema9s become scanti] &
 scanti]1 n 9 any v gradual progression1
 h[ev]1 until1 at l5g?1 9 :at are       
suppos$ to be ! olde/ rocks1 ! animal   
rema9s :i* are f\nd are almo/ always    
conf9$ to f\r =ms--',oldhamia'1 ^:      
precise nature is n kn[n1 :e!r plant or 
animal2 ',l+ula'1 a k9d ( mollusc2      
',trilobites'1 a cru/acean animal1 hav+ 
! same ess5tial plan ( con/ruction1 ?\gh
 diff]+ 9 _m details f a lob/] or crab2 
& ,hym5oc>is1 :i* is also a cru/acean4  
,s t y h all ! ',fauna' r$uc$1 at ?is   
p]iod1 to f\r =ms3 "o a k9d ( animal or 
plant t we "k no?+ ab\t1 & ?ree und\bt$ 
animals--two cru/aceans & "o mollusc4   
,i ?9k1 consid]+ ! organization ( ^!    
mollusca & cru/acea1 & look+ at _! v    
complex nature1 t x does inde$ require a
 v /rong imag9ation to conceive t ^! 7 !
 fir/ creat$ ( all liv+ ?+s4 ,& y mu/   
take into consid]ation ! fact t we h n !
 slighte/ pro( t ^! :i* we call ! olde/ 
b$s are really s3 ,i repeat1 we h n !   
slighte/ pro( ( x4 ,:5 y f9d 9 "s places

 t 9 an enorm\s ?ickness ( rocks !re are
 b v scanty traces ( life1 or absolutely
 none at all2 & t 9 o!r p>ts ( ! _w     
rocks ( ! v same =mation are cr[d$ ) !  
records ( liv+ =ms1 ,i ?9k x is         
impossible to place any reliance on !   
supposition1 or to feel oneself ju/ifi$ 
9 suppos+ t ^! are ! =ms 9 :i* life fir/
 comm5c$4 ,i h n "t "h to ent] ^u !     
te*nical gr\nds ^u :i* ,i am l$ to ?is  
conclusion1--t c\ld h>dly be done       
prop]ly 9 half a doz5 lectures on t "p  
alone2--,i mu/ cont5t myself ) say+ t ,i
 d n at all believe t ^! are ! olde/ =ms
 ( life4  ,i turn to ! exp]im5tal side  
to see :at evid5ce we h !re4 ,to enable 
u to say t we "k any?+ ab\t ! exp]im5tal
 orig9ation ( organization & life1 !    
inve/igator ought to be able to take    
inorganic matt]s1 su* z c>bonic acid1   
ammonia1 wat]1 & sal9es1 9 any sort (   
inorganic comb9ation1 & be able to build
 !m up into ,prote9 matt]1 & t t ,prote9
 matt] ought to beg9 to live 9 an       
organic =m4 ,t1 nobody has done z yet1 &

 ,i suspect x w be a long :ile be=e     
anybody does d x4 ,b ! ?+ is by no means
 s impossible z x looks2 = ! rese>*es ( 
mod]n *emi/ry h %[n u--,i won't say !   
road t[>ds x1 b1 if ,i may s say1 !y h  
%[n ! f+]-po/ po9t+ to ! road t may lead
 to x4  ,x is n _m ye>s ago--& y mu/    
recollect t ,organic ,*emi/ry is a "y   
sci5ce1 n above a c\ple ( g5]ations     
old1--y mu/ n expect too mu* ( x2 x is n
 _m ye>s ago s9ce x 0 said to be        
p]fectly impossible to fabricate any    
organic comp\nd2 t is to say1 any       
non-m9]al comp\nd :i* is to be f\nd 9 an
 organiz$ be+4 ,x rema9$ s = a v long   
p]iod2 b x is n[ a consid]able numb] (  
ye>s s9ce a di/+ui%$ =eign *emi/        
contriv$ to fabricate ,urea1 a sub/ance 
( a v complex "*1 :i* =ms "o ( ! wa/e   
products ( animal /ructures4 ,& ( late  
ye>s a numb] ( o!r comp\nds1 su* z      
,butyric ,acid1 & o!rs1 h be5 add$ to ! 
li/4 ,i ne$ n tell y t *emi/ry is an    
enorm\s di/ance f ! goal ,i indicate2   
all ,i wi% to po9t out to y is1 t x is  

by no means safe to say t t goal may n  
be rea*$ "o day4 ,x may be t x is       
impossible = u to produce ! conditions  
requisite to ! orig9ation ( life2 b we  
mu/ speak mode/ly ab\t ! matt]1 &       
recollect t ,sci5ce has put h] foot ^u !
 bottom r\nd ( ! ladd]4 ,truly he w\ld  
be a bold man :o w\ld v5ture to pr$ict  
:]e %e w be fifty ye>s h5ce4  ,!re is   
ano!r inquiry :i* be>s indirectly ^u ?is
 "q1 & ^u :i* ,i mu/ say a few words4 ,y
 are all ( y aw>e ( ! ph5om5a ( :at is  
call$ spontane\s g5]ation4 ,our =efa!rs1
 d[n to ! sev5te5? c5tury1 or !reab\ts1 
all imag9$1 9 p]fectly good fai?1 t     
c]ta9 vegetable & animal =ms gave bir?1 
9 ! process ( _! decomposition1 to      
insect life4 ,?us1 if y put a piece (   
meat 9 ! sun1 & all[$ x to putrefy1 !y  
conceiv$ t ! grubs :i* soon began to    
appe> 7 ! result ( ! action ( a p[] (   
spontane\s g5]ation :i* ! meat conta9$4 
,& !y c\ld give y receipts = mak+ v>i\s 
animal & vegetable prep>ations :i* w\ld 
produce p>ticul> k9ds ( animals4 ,a v   

di/+ui%$ ,italian naturali/1 nam$ ,r$i1 
took up ! "q1 at a "t :5 ev]ybody       
believ$ 9 x2 among o!rs our own great   
,h>vey1 ! discov]] ( ! circulation ( !  
blood4 ,y w con/antly f9d 8 "n quot$1   
h[ev]1 z an oppon5t ( ! doctr9e (       
spontane\s g5]ation2 b ! fact is1 & y w 
see x if y w take ! tr\ble to look into 
8 works1 ,h>vey believ$ x z pr(\ndly z  
any man ( 8 "t2 b he happ5$ to enunciate
 a v curi\s proposition--t e liv+ ?+    
came f an 'egg'2 he did n mean to use ! 
^w 9 ! s5se 9 :i* we n[ employ x1 he    
only meant to say t e liv+ ?+ orig9at$ 9
 a little r\nd$ p>ticle ( organiz$      
sub/ance2 & x is f ?is circum/ance1     
probably1 t ! notion ( ,h>vey hav+      
oppos$ ! doctr9e orig9at$4 ,!n came     
,r$i1 & he proce$$ to upset ! doctr9e 9 
a v simple mann]4 ,he m]ely cov]$ !     
piece ( meat ) "s v f9e gauze1 & !n he  
expos$ x to ! same conditions4 ,! result
 ( ?is 0 t no grubs or insects 7        
produc$2 he prov$ t ! grubs orig9at$ f !
 insects :o came & deposit$ _! eggs 9 ! 

meat1 & t !y 7 hat*$ by ! heat ( ! sun4 
,by ?is k9d ( inquiry he ?or\ghly upset 
! doctr9e ( spontane\s g5]ation1 = 8 "t 
at lea/4  ,!n came ! discov]y &         
application ( ! microscope to sci5tific 
inquiries1 :i* %[$ to naturali/s t      
besides ! organisms :i* !y already knew 
z liv+ be+s & plants1 !re 7 an imm5se   
numb] ( m9ute ?+s :i* c\ld be obta9$    
app>5tly almo/ at w f decay+ vegetable &
 animal =ms4 ,?us1 if y took "s ord9>y  
black pepp] or "s hay1 & /eep$ x 9 wat]1
 y w\ld f9d 9 ! c\rse ( a few days t !  
wat] _h become impregnat$ ) an imm5se   
numb] ( animalcules swimm+ ab\t 9 all   
directions4 ,f facts ( ?is k9d          
naturali/s 7 l$ to revive ! !ory (      
spontane\s g5]ation4 ,!y 7 head$ "h by  
an ,engli% naturali/1--,ne$ham1--&      
aft]w>ds 9 ,france by ! le>n$ ,buffon4  
,!y said t ^! ?+s 7 absolutely begott5 9
 ! wat] ( ! decay+ sub/ances out ( :i* !
 infusion 0 made4 ,x did n matt] :e!r y 
took animal or vegetable matt]1 y _h    
only to /eep x 9 wat] & expose x1 & y   

w\ld soon h pl5ty ( animalcules4 ,!y    
made an hypo!sis ab\t ?is :i* 0 a v fair
 "o4 ,!y said1 ?is matt] ( ! animal _w1 
or ( ! high] plants1 appe>s to be dead1 
b 9 reality x has a sort ( dim life ab\t
 x1 :i*1 if x is plac$ "u fair          
conditions1 w cause x to break up into !
 =ms ( ^! little animalcules1 & !y w g  
?r\gh _! lives 9 ! same way z ! animal  
or plant ( :i* !y once =m$ a "p4  ,! "q 
n[ became v hotly debat$4 ,spallanzani1 
an ,italian naturali/1 took up opposite 
views to ^? ( ,ne$ham & ,buffon1 & by   
means ( c]ta9 exp]im5ts he %[$ t x 0 q  
possible to /op ! process by boil+ !    
wat]1 & clos+ ! vessel 9 :i* x 0        
conta9$4 ,oh6 said 8 oppon5ts2 b :at d y
 "k y may be do+ :5 y heat ! air ov] !  
wat] 9 ?is way8 ,y may be de/roy+ "s    
prop]ty ( ! air requisite = ! spontane\s
 g5]ation ( ! animalcules4  ,h[ev]1     
,spallanzani's views 7 suppos$ to be ^u 
! "r side1 & ^? ( ! o!rs fell into      
discr$it2 al?\gh ! fact 0 t ,spallanzani
 _h n made good 8 views4 ,well1 !n1 !   

subject cont9u$ to be reviv$ f "t to "t1
 & exp]im5ts 7 made by sev]al p]sons2 b 
^! exp]im5ts 7 n altoge!r satisfactory4 
,x 0 f\nd t if y put an infusion 9 :i*  
animalcules w\ld appe> if x 7 expos$ to 
! air into a vessel & boil$ x1 & !n     
seal$ up ! m\? ( ! vessel1 s t no air1  
save su* z _h be5 heat$ to #bab degrees1
 c\ld rea* its cont5ts1 t !n no         
animalcules w\ld be f\nd2 b if y took ! 
same vessel & expos$ ! infusion to !    
air1 !n y w\ld get animalcules4         
,fur!rmore1 x 0 f\nd t if y connect$ !  
m\? ( ! vessel ) a r$-hot tube 9 su* a  
way t ! air w\ld h to pass ?r\gh ! tube 
be=e rea*+ ! infusion1 t !n y w\ld get  
no animalcules4 ,yet ano!r ?+ 0 notic$3 
if y took two flasks conta9+ ! same k9d 
( infusion1 & left "o entirely expos$ to
 ! air1 & 9 ! m\? ( ! o!r plac$ a ball (
 cotton wool1 s t ! air w\ld h to filt] 
itself ?r\gh x be=e rea*+ ! infusion1 t 
!n1 al?\gh y might h pl5ty ( animalcules
 9 ! fir/ flask1 y w\ld c]ta9ly obta9   
none f ! second4  ,^! exp]im5ts1 y see1 

all t5d$ t[>ds "o conclusion--t !       
infusoria 7 develop$ f little m9ute     
spores or eggs :i* 7 con/antly float+ 9 
! atmosph]e1 :i* lose _! p[] ( g]m9ation
 if subject$ to heat4 ,b "o obs]v] n[   
made ano!r exp]im5t :i* seem$ to g      
entirely ! o!r way1 & puzzl$ him        
altoge!r4 ,he took "s ( ?is boil$       
infusion t ,i h be5 speak+ (1 & by ! use
 ( a m]curial ba?--a k9d ( tr\gh us$ 9  
laboratories--he deftly inv]t$ a vessel 
conta9+ ! infusion into ! m]cury1 s t ! 
latt] rea*$ a little beyond ! level ( ! 
m\? ( ! 'inv]t$' vessel4 ,y see t he ?us
 _h a quantity ( ! infusion %ut (f f any
 possible communication ) ! out] air by 
be+ inv]t$ ^u a b$ ( m]cury4  ,he !n    
prep>$ "s pure oxyg5 & nitrog5 gases1 & 
pass$ !m by means ( a tube go+ f !      
outside ( ! vessel1 up ?r\gh ! m]cury   
into ! infusion2 s t he ?us _h x expos$ 
to a p]fectly pure atmosph]e ( ! same   
con/itu5ts z ! ext]nal air4 ,( c\rse1 he
 expect$ he w\ld get no infusorial      
animalcules at all 9 t infusion2 b1 to 8

 great dismay & discomfiture1 he f\nd he
 almo/ always did get !m4  ,fur!rmore1 x
 has be5 f\nd t exp]im5ts made 9 ! mann]
 describ$ above answ] well ) mo/        
infusions2 b t if y fill ! vessel )     
boil$ milk1 & !n /op ! neck )           
cotton-wool1 y 'w' h infusoria4 ,s t y  
see !re 7 two exp]im5ts t br\ght y to "o
 k9d ( conclusion1 & ?ree to ano!r2 :i* 
0 a mo/ unsatisfactory /ate ( ?+s to    
arrive at 9 a sci5tific inquiry4  ,"s   
few ye>s aft] ?is1 ! "q began to be v   
hotly discuss$ 9 ,france4 ,!re 0 ,m4    
,p\*et1 a pr(essor at ,r\51 a v le>n$   
man1 b c]ta9ly n a v rigid exp]im5tali/4
 ,he publi%$ a numb] ( exp]im5ts ( 8    
own1 "s ( :i* 7 v +5i\s1 to %[ t if y   
w5t to "w 9 a prop] way1 !re 0 a tru? 9 
! doctr9e ( spontane\s g5]ation4 ,well1 
x 0 "o ( ! mo/ =tunate ?+s 9 ! _w t ,m4 
,p\*et took up ?is "q1 because x induc$ 
a di/+ui%$ ,fr5* *emi/1 ,m4 ,pa/eur1 to 
take up ! "q on ! o!r side2 & he has    
c]ta9ly work$ x out 9 ! mo/ p]fect      
mann]4 ,i am glad to say1 too1 t he has 

publi%$ 8 rese>*es 9 "t to enable me to 
give y an acc\nt ( !m4 ,he v]ifi$ all ! 
exp]im5ts :i* ,i h j m5tion$ to y--& !n 
f9d+ ^? extraord9>y anomalies1 z 9 !    
case ( ! m]cury ba? & ! milk1 he set    
himself to "w to discov] _! nature4 ,9 !
 case ( milk he f\nd x to be a "q (     
temp]ature4 ,milk 9 a fre% /ate is      
slightly alkal9e2 & x is a v curi\s     
circum/ance1 b ?is v slight degree (    
alkal9ity seems to h ! effect ( pres]v+ 
! organisms :i* fall into x f ! air f   
be+ de/roy$ at a temp]ature ( #bab      
degrees1 :i* is ! boil+ po9t4 ,b if y   
raise ! temp]ature #aj degrees :5 y boil
 x1 ! milk behaves l ev]y?+ else2 & if !
 air ) :i* x comes 9 contact1 aft] be+  
boil$ at ?is temp]ature1 is pass$ ?r\gh 
a r$-hot tube1 y w n get a trace (      
organisms4  ,he !n turn$ 8 att5tion to !
 m]cury ba?1 & f\nd on exam9ation t !   
surface ( ! m]cury 0 almo/ always cov]$ 
) a v f9e du/4 ,he f\nd t ev5 ! m]cury  
itself 0 positively full ( organic      
matt]s2 t f be+ con/antly expos$ to !   

air1 x _h collect$ an imm5se numb] ( ^! 
infusorial organisms f ! air4 ,well1 "u 
^! circum/ances he felt t ! case 0 q    
cle>1 & t ! m]cury 0 n :at x _h appe>$  
to ,m4 ,s*wann to be1--a b> to !        
admission ( ^! organisms2 b t1 9        
reality1 x act$ z a res]voir f :i* !    
infusion 0 imm$iately suppli$ ) ! l>ge  
quantity t _h s puzzl$ him4  ,b n cont5t
 ) expla9+ ! exp]im5ts ( o!rs1 ,m4      
,pa/eur w5t to "w to satisfy himself    
completely4 ,he said to himself3 ,if my 
view is "r1 & if1 9 po9t ( fact1 all ^! 
appe>ances ( spontane\s g5]ation are    
altoge!r due to ! fall+ ( m9ute g]ms    
susp5d$ 9 ! atmosph]e1--:y1 ,i ought n  
only to be able to %[ ! g]ms1 b ,i ought
 to be able to cat* & s[ !m1 & produce !
 result+ organisms4 ,he1 accord+ly1     
con/ruct$ a v +5i\s app>atus to enable  
him to accompli% ?is trapp+ ( ?is g]m   
du/ 9 ! air4 ,he fix$ 9 ! w9d[ ( 8 room 
a glass tube1 9 ! c5tre ( :i* he _h     
plac$ a ball ( gun-cotton1 :i*1 z y all 
"k1 is ord9>y cotton-wool1 :i*1 f hav+  

be5 /eep$ 9 /rong acid1 is conv]t$ into 
a sub/ance ( great explosive p[]4 ,x is 
also soluble 9 alcohol & e!r4 ,"o end ( 
! glass tube 01 ( c\rse1 op5 to !       
ext]nal air2 & at ! o!r end ( x he plac$
 an aspirator1 a contrivance = caus+ a  
curr5t ( ! ext]nal air to pass ?r\gh !  
tube4 ,he kept ?is app>atus go+ =       
f\r-&-tw5ty h\rs1 & !n remov$ ! 'du/$'  
gun-cotton1 & dissolv$ x 9 alcohol &    
e!r4 ,he !n all[$ ?is to /& = a few     
h\rs1 & ! result 01 t a v f9e du/ 0     
gradually deposit$ at ! bottom ( x4 ,t  
du/1 on be+ transf]r$ to ! /age ( a     
microscope1 0 f\nd to conta9 an enorm\s 
numb] ( />* gra9s4 ,y "k t ! mat]ials ( 
our food & ! great] portion ( plants are
 compos$ ( />*1 & we are con/antly mak+ 
use ( x 9 a v>iety ( ways1 s t !re is   
always a quantity ( x susp5d$ 9 ! air4  
,x is ^! />* gra9s :i* =m _m ( ^? bright
 specks t we see danc+ 9 a ray ( light  
sometimes4 ,b besides ^!1 ,m4 ,pa/eur   
f\nd also an imm5se numb] ( o!r organic 
sub/ances su* z spores ( fungi1 :i* _h  

be5 float+ ab\t 9 ! air & _h got cag$ 9 
?is way4  ,he w5t f>!r1 & said to       
himself1 ,if ^! really are ! ?+s t give 
rise to ! appe>ance ( spontane\s        
g5]ation1 ,i ought to be able to take a 
ball ( ?is 'du/$' gun-cotton & put x    
into "o ( my vessels1 conta9+ t boil$   
infusion :i* has be5 kept away f ! air1 
& 9 :i* no infusoria are at pres5t      
develop$1 & !n1 if ,i am "r1 !          
introduction ( ?is gun-cotton w give    
rise to organisms4  ,accord+ly1 he took 
"o ( ^! vessels ( infusion1 :i* _h be5  
kept eighte5 mon?s1 )\t ! lea/ appe>ance
 ( life1 & by a mo/ +5i\s contrivance1  
he manag$ to break x op5 & introduce su*
 a ball ( gun-cotton1 )\t all[+ !       
infusion or ! cotton ball to come into  
contact ) any air b t :i* _h be5        
subject$ to a r$ heat1 & 9 tw5ty-f\r    
h\rs he _h ! satisfaction ( f9d+ all !  
indications ( :at _h be5 hi!rto call$   
spontane\s g5]ation4 ,he _h succe$$ 9   
cat*+ ! g]ms & develop+ organisms 9 !   
way he _h anticipat$4  ,x n[ /ruck him t

 ! tru? ( 8 conclusions might be        
demon/rat$ )\t all ! app>atus he _h     
employ$4 ,to d ?is1 he took "s decay+   
animal or vegetable sub/ance1 su* z     
ur9e1 :i* is an extremely decomposable  
sub/ance1 or ! juice ( yea/1 or p]haps  
"s o!r artificial prep>ation1 & fill$ a 
vessel hav+ a long tubul> neck ) x4 ,he 
!n boil$ ! liquid & b5t t long neck into
 an ,s %ape or zig-zag1 leav+ x op5 at !
 end4 ,! infusion !n gave no trace ( any
 appe>ance ( spontane\s g5]ation1 h[ev] 
long x might be left1 z all ! g]ms 9 !  
air 7 deposit$ 9 ! beg9n+ ( ! b5t neck4 
,he !n cut ! tube close to ! vessel1 &  
all[$ ! ord9>y air to h free & direct   
access2 & ! result ( t 0 ! appe>ance (  
organisms 9 x1 z soon z ! infusion _h   
be5 all[$ to /& long en\gh to all[ ( !  
gr[? ( ^? x receiv$ f ! air1 :i* 0 ab\t 
=ty-eight h\rs4 ,! result ( ,m4         
,pa/eur's exp]im5ts prov$1 !re=e1 9 !   
mo/ conclusive mann]1 t all ! appe>ances
 ( spontane\s g5]ation arose f no?+ m   
?an ! deposition ( ! g]ms ( organisms   

:i* 7 con/antly float+ 9 ! air4  ,to ?is
 conclusion1 h[ev]1 ! objection 0 made1 
t if t 7 ! cause1 !n ! air w\ld conta9  
su* an enorm\s numb] ( ^! g]ms1 t x w\ld
 be a cont9ual fog4 ,b ,m4 ,pa/eur      
repli$ t !y are n !re 9 any?+ l ! numb] 
we might suppose1 & t an exagg]at$ view 
has be5 held on t subject2 he %[$ t !   
*ances ( animal or vegetable life appe>+
 9 infusions1 dep5d entirely on !       
conditions "u :i* !y are expos$4 ,if !y 
are expos$ to ! ord9>y atmosph]e ar\nd  
u1 :y1 ( c\rse1 y may h organisms appe>+
 e>ly4 ,b1 on ! o!r h&1 if !y are expos$
 to air f a great height1 or f "s v     
quiet cell>1 y w (t5 n f9d a s+le trace 
( life4  ,s t ,m4 ,pa/eur arriv$ at la/ 
at ! cle> & def9ite result1 t all ^!    
appe>ances are l ! case ( ! worms 9 !   
piece ( meat1 :i* 0 refut$ by ,r$i1     
simply g]ms c>ri$ by ! air & deposit$ 9 
! liquids 9 :i* !y aft]w>ds appe>4 ,= my
 own "p1 ,i conceive t1 ) ! p>ticul>s ( 
,m4 ,pa/eur's exp]im5ts be=e u1 we _c   
fail to arrive at 8 conclusions2 & t !  

doctr9e ( spontane\s g5]ation has       
receiv$ a f9al 'c\p de grace'4  ,y1 (   
c\rse1 und]/& t all ?is 9 no way        
int]f]es ) ! 'possibility' ( !          
fabrication ( organic matt]s by ! direct
 me?od to :i* ,i h ref]r$1 remote z t   
possibility may be4   ,footnote #a3 ,^? 
:o wi% to /udy fully ! doctr9es ( :i* ,i
 h endeav\r$ to give "s r\gh & ready    
illu/rations1 mu/ read ,mr4 ,john ,/u>t 
,mill's ',sy/em ( ,logic'4