,transcriber's notes3    ,in this       
transcription1 italic text is denoted by
 99asterisks99 and bold  text by equal  
signs4 ,subscripts are indicated by     
underscores 7e4g4  99a99#a and 99b99#a  
in ,fig4#e caption7 and superscripts by 
7e4g4 99a99#a4 in  ,fig4 #i caption74   
,page footnotes 7renumbered in          
consecutive order7 are now located      
immediately below the relevant          
paragraphs4    ,the rare spelling typos 
noted in the original text have been    
corrected  silently 7e4g4               
invividual--individual1                 
hyberbola--hyperbola7 but  inconsistent 
use of the ligature _/ae 7e4g4          
palontology_/palaeontology71            
inconsistent use of alternative         
spellings 7e4g4 learned_/learnt71 and   
occasional inconsistencies of           
hyphenation have been left as in the    
original4 ,minor punctuation typos have 
been corrected silently 7e4g4  index    
entries with missing commas74 ,the      
abbreviation viz4 appears in  both roman

 and italic font4    ,formatting of     
entries in the ,table of ,contents does 
not accurately  match that of the       
corresponding headings in the text1     
particularly the  heading ,pt4,i-,b-#c  
which contains an extraneous 4    ,in   
,figure #ab caption1 multiple ditto     
marks have been replaced by the         
relevant text for greater clarity4      
,,the ,,science ,,and ,,philosophy      
,,of ,,the ,,organism                   
,,agents                ,america        
,the ,macmillan ,company                
#fd  #ff ,fifth ,avenue1 ,new ,york     
,australasia    ,the ,oxford ,university
 ,press1 ,melbourne                     
,canada         ,the ,macmillan ,company
 of ,canada1 ,ltd4                      
#bg ,richmond ,street ,west1 ,toronto   
,india          ,macmillan  ,company1   
,ltd4                                   
,macmillan ,building1 ,bombay           
#cji ,bow ,bazaar ,street1 ,calcutta    
,,the                                   
,,science ,,and ,,philosophy            

,,of ,,the ,,organism                   
,,the ,,gifford ,,lectures ,,delivered  
,,before                         ,,the  
,,university ,,of ,,aberdeen            
,,in ,,the ,,year #aijg                 
,,by                            ,,hans  
,,driesch1 ,ph4,d4                      
,,heidelberg                            
,,london                                
,,adam ,,and ,,charles ,,black          
#aijh                             99,all
 rights reserved99          ,,preface   
,this work is not a text-book of        
theoretical biology2 it is a systematic 
presentment of those biological topics  
which bear upon the true  philosophy of 
nature4 ,the book is written in a       
decidedly subjective  manner1 and it    
seems to me that this is just what      
8,gifford ,lectures0  ought to be4 ,they
 ought never to lose1 or even try to    
lose1 their  decidedly personal         
character4    ,my appointment as        
,gifford ,lecturer1 the news of which   
reached me in  ,february #aijf1 came    

just at the right moment in the progress
 of my  theoretical studies4 ,i had     
always tried to improve my previous     
books by  adding notes or altering the  
arrangement2 ,i also had left a good    
deal of  things unpublished1 and thus ,i
 often hoped that ,i might have occasion
  to arrange for a new1 improved1 and   
enlarged edition of those books4  ,this 
work then is the realisation of my      
hopes2 it is1 in its way1 a  definitive 
statement of all that ,i have to say    
about the ,organic4    ,the first volume
 of this work1 containing the lectures  
for #aijg--though  the division into    
8lectures0 has not been                 
preserved--consists of ,parts  ,i4 and  
,,ii4 of ,section ,a1 8,the ,chief      
,results of ,analytical ,biology40  ,it 
gives in ,part ,i4 a shortened1 revised1
 and1 as ,i hope1 improved  account of  
what was published in my 99,analytische 
,theorie der organischen                
,entwickelung99 7#ahid71 99,die         
,localisation morphogenetischer         

,vorgnge2  ein ,beweis ,vitalistischen  
,geschehens99 7#ahii71 and 99,die       
organischen  ,regulationen99 7#aija71   
though for the professed biologist the  
two  last-named books are by no means   
superseded by the new work4 ,part ,,ii4 
has never been published in any         
systematic form before1 though there are
  many remarks on ,systematics1         
,darwinism1 etc41 in my previous papers4
    ,the second volume--to be published 
in the autumn1 after the delivery of    
the #aijh lectures--will begin with the 
third and concluding part of the        
scientific section1 which is a very     
carefully revised and rearranged  second
 edition of my book1 99,die 8,seele0 als
 elementarer ,naturfactor99  7#aijc74   
,the greater part of this volume1       
however1 will be devoted to the         
8,philosophy of the ,organism10 99i4e499
 ,section ,b1 which1 in my opinion1     
includes the most important parts of the
 work4    ,some apology is needed for my
 presuming to write in ,english4 ,i was 

led to do so by the conviction1 mistaken
 perhaps1 that the process of           
translation would rob the lectures of   
that individual and personal  character 
which1 as ,i said before1 seems to me so
 much to be desired4 ,i  wished nothing 
to come between me and my audience4 ,i  
accordingly wrote  my manuscript in     
,english1 and then submitted it to      
linguistic revision  by such skilled aid
 as ,i was able to procure at           
,heidelberg4 ,my reviser  tells me that 
if the result of his labours leaves much
 to be desired1  it is not to be        
wondered at1 but that1 being neither a  
biologist nor a  philosopher1 he has    
done his best to make me presentable to 
the ,english  reader4 ,if he has failed 
in his troublesome task1 ,i know that it
 is not  for want of care and attention1
 and ,i desire here to record my sense  
of  indebtedness to him4 ,he wishes to  
remain anonymous1 but ,i am permitted   
to say that1 though resident in a       
foreign university1 he is of ,scottish  

name and ,english birth4    ,my         
gratitude to my friends at ,aberdeen1 in
 particular to ,professor and  ,mrs4 ,j4
 ,a4 ,thomson1 for their hospitality and
 great kindness towards me  cannot be   
expressed here2 they all know that they 
succeeded in making me  feel quite at   
home with them4    ,i am very much      
obliged to my publishers1 ,messrs4 ,a4  
and ,c4 ,black1 for  their readiness to 
fulfil all my wishes with respect to    
publication4      ,the lectures         
contained in this book were written in  
,english by a  ,german and delivered at 
a ,scottish university4 ,almost all of  
the ideas  discussed in it were first   
conceived during the author's long      
residence  in ,southern ,italy4 ,thus   
this book may be witness to the truth   
which1  ,i hope1 will be universally    
recognised in the near future--that all 
culture1 moral and intellectual and     
aesthetic1 is not limited by the  bounds
 of nationality4      ,,hans ,,driesch4 
,heidelberg1 99#bnd ,january #aijh994   

,,contents ,,of ,,the ,,first ,,volume  
,,the ,,programme                       
,,page    ,on ,lord ,gifford's          
,conception of 8,science0               
#a    ,natural ,sciences and 8,natural  
,theology0                              
#c    ,our ,philosophical ,basis        
#e    ,on ,certain ,characteristics of  
,biology as a ,science                  
#i    ,the ,three ,different ,types of  
,knowledge about ,nature                
#ac    ,general ,plan of these ,lectures
                                     #ae
    ,general ,character of the ,organic 
,form                              #ai  
,,section ,a4--,,the ,,chief ,,results  
,,of ,,analytical ,,biology      ,,part 
,i4--,,the ,,individual ,,organism      
,,with ,,regard ,,to ,,form ,,and       
,,metabolism      99,a499 ,,elementary  
,,morphogenesis--        ,evolutio and  
,epigenesis in the old ,sense           
#be      ,the ,cell                     
#bg      ,the ,egg3 its ,maturation and 
,fertilisation                          

#ca      ,the ,first ,developmental     
,processes of ,echinus                  
#cc      ,comparative ,embryology       
#dd      ,the ,first ,steps of          
,analytical ,morphogenesis              
#de      ,the ,limits of ,pure          
,description in ,science                
#ej      99,b499 ,,experimental ,,and   
,,theoretical ,,morphogenesis--      #a4
 ,,the ,,foundations ,,of ,,the         
,,physiology ,,of ,,development4        
8,,evolutio0 ,,and 8,,epigenesis0       
#eb        ,the ,theory of ,weismann    
#eb      ,experimental ,morphology      
#ef      ,the ,work of ,wilhelm ,roux   
#eh      ,the ,experiments on the ,egg  
of the ,sea-urchin                      
#ei      ,on the ,intimate ,structure of
 the ,protoplasm of the ,germ           
#fe      ,on some ,specificities of     
,organisation in ,certain ,germs        
#gj      ,general ,results of the ,first
 ,period of 8,entwickelungsmechanik0    
#ga      ,some ,new ,results concerning 
,restitutions                           

#gd      #b4 ,,analytical ,,theory ,,of 
,,morphogenesis                         
#gf        4 ,,the ,,distribution ,,of  
,,morphogenic ,,potencies               
#gf          ,prospective ,value and    
,prospective ,potency                   
#gf        ,the ,potencies of the       
,blastomeres                            
#gi        ,the ,potencies of           
,elementary ,organs in ,general         
#hj        ,explicit and ,implicit      
,potencies3 ,primary and ,secondary     
,potencies                              
#hc        ,the ,morphogenetic ,function
 of ,maturation in the ,light of        
,recent ,discoveries                    
#he        ,the ,intimate ,structure of 
,protoplasm3 ,further ,remarks          
#hh        ,the ,neutrality of the      
,concept of 8,potency0                  
#hi        4 ,,the 8,,means0 ,,of       
,,morphogenesis                         
#hi        4 ,the ,internal ,elementary 
,means of ,morphogenesis                
#ij          ,some ,remarks on the      

,importance of ,surface ,tension in     
,morphogenesis                          
#ia        ,on ,growth                  
#ic        ,on ,cell-division           
#id        4 ,the ,external ,means of   
,morphogenesis                          
#ie          ,the ,discoveries of       
,herbst                                 
#if        4 ,,the ,,formative ,,causes 
,,or ,,stimuli                          
#ii          ,the ,definition of ,cause 
#ii        ,some ,instances of          
,formative and ,directive ,stimuli      
#ajb        4 ,,the ,,morphogenetic     
,,harmonies                             
#ajg        4 ,,on ,,restitutions       
#aaj          ,a few ,remarks on        
,secondary ,potencies and on ,secondary 
,morphogenetic ,regulations in ,general 
#aaj        ,the ,stimuli of            
,restitutions                           
#aac      #c4 ,,the ,,problem ,,of      
,,morphogenetic ,,localisation3 ,,the   
,,theory ,,of ,,the                     
,,harmonious-,,equipotential            

,,system--,,first       ,,proof ,,of    
,,the ,,autonomy ,,of ,,life            
#aah        ,the ,general ,problem      
#aah      ,the ,morphogenetic 8,system0 
#aai      ,the                          
8,harmonious-equipotential ,system0     
#abb      ,instances of                 
8,harmonious-equipotential ,systems0    
#abf      ,the ,problem of the ,factor  
99,e99                                  
#acb      ,no ,explanation offered by   
8,means0 or 8,formative ,stimuli0       
#acb      ,no ,explanation offered by a 
,chemical ,theory of ,morphogenesis     
#acd      ,no ,machine ,possible ,inside
 the ,harmonious ,systems               
#ach      ,the ,autonomy of             
,morphogenesis proved                   
#adb      8,entelechy0                  
#adc      ,some ,general ,remarks on    
,vitalism                               
#ade      ,the ,logic of our ,first     
,proof of ,vitalism                     
#adf      #d4 ,,on ,,certain ,,other    
,,features ,,of ,,morphogenesis         

,,advocating       ,,its ,,autonomy     
#aej        ,harmonious-equipotential   
,systems formed by ,wandering ,cells    
#aea      ,on ,certain ,combined ,types 
of ,morphogenetic ,systems              
#aec      ,the 8,morphaesthesia0 of     
,noll                                   
#aeg      ,restitutions of the ,second  
,order                                  
#aeh      ,on the 8,equifinality0 of    
,restitutions                           
#aei      ,remarks on                   
8,retro-,differentiation0               
#afc      99,c499 ,,adaptation--        
,,introductory ,,remarks ,,on           
,,regulations ,,in ,,general            
#afe      #a4 ,,morphological           
,,adaptation                            
#afh        ,the ,limits of the ,concept
 of ,adaptation                         
#afh      ,adaptations to ,functional   
,changes from ,without                  
#agb      ,true ,functional ,adaptation 
#agf      ,theoretical ,conclusions     
#agi      #b4 ,,physiological           

,,adaptation                            
#ahd        ,specific ,adaptedness      
99not99 8,adaptation0                   
#ahf      ,primary and ,secondary       
,adaptations in ,physiology             
#ahh      ,on ,certain ,pre-requisites  
of ,adaptations in ,general             
#ahi      ,on ,certain ,groups of       
,primary ,physiological ,adaptations    
#aij        ,general ,remarks on        
,irritability                           
#aij      ,the ,regulation of ,heat     
,production                             
#aic      ,primary ,regulations in the  
,transport of ,materials and            
,certain ,phenomena of ,osmotic         
,pressure                         #aid  
,chromatic ,regulations in ,algae       
#aig      ,metabolic ,regulations       
#aih        ,immunity the only ,type of 
a ,secondary ,physiological             
,adaptation                             
#bjd      ,no ,general ,positive ,result
 from this ,chapter                     
#bji      ,a few ,remarks on the ,limits

 of ,regulability                       
#bab      99,d499 ,,inheritance4        
,,second ,,proof ,,of ,,the ,,autonomy  
,,of ,,life--        ,the ,material     
,continuity in ,inheritance             
#bad      ,on ,certain ,theories which  
,seek to ,compare ,inheritance to       
,memory #baf      ,the                  
,complex-,equipotential ,system and its 
,rle in ,inheritance    #bai      ,the  
,second ,proof of ,life-,autonomy4      
,entelechy at the ,bottom        of     
,inheritance                            
#bbd      ,the ,significance of the     
,material ,continuity in ,inheritance   
#bbg      ,the ,experimental ,facts     
about ,inheritance                      
#bbh      ,the ,rle of the ,nucleus in  
,inheritance                            
#bcc      ,variation and ,mutation      
#bcg      99,,conclusions ,,from ,,the  
,,first ,,main ,,part ,,of ,,these      
,,lectures99          #bdj              
,,part ,,ii4--,,systematics ,,and       
,,history      99,a499 ,,the            

,,principles ,,of ,,systematics--       
,rational ,systematics                  
#bdc      ,biological ,systematics      
#bdf      99,b499 ,,the ,,theory ,,of   
,,descent--      #a4 ,,generalities     
#bej        ,the ,covert ,presumption of
 all ,theories of ,descent              
#bec      ,the ,small ,value of ,pure   
,phylogeny                              
#bee      ,history and ,systematics     
#beg      #b4 ,,the ,,principles ,,of   
,,darwinism                             
#bfj        ,natural ,selection         
#bfa      ,fluctuating ,variation the   
,alleged ,cause of ,organic ,diversity  
#bfd      ,darwinism ,fails all along   
the ,line                               
#bfi      #c4 ,,the ,,principles ,,of   
,,lamarckism                            
#bga        ,adaptation as the          
,starting-,point                        
#bgb      ,the ,active ,storing of      
,contingent ,variations as a            
,hypothetic ,principle                  
#bgc      ,criticism of the             

8,inheritance of ,acquired ,characters0 
assumed by ,lamarckism                  
#bge      ,other ,principles ,wanted    
#bha      ,criticism of the ,hypothesis 
of ,storing and ,handing ,down          
,contingent ,variations                 
#bhb      #d4 ,,the ,,real ,,results    
,,and ,,the ,,unsolved ,,problems ,,of  
,,transformism     #bij      #e4 ,,the  
,,logical ,,value ,,of ,,the ,,organic  
,,form ,,according ,,to ,,the           
,,different ,,transformistic ,,theories 
#bic        ,the ,organic ,form and     
,entelechy                              
#bid      99,c499 ,,the ,,logic ,,of    
,,history                               
#big      #a4 ,,the ,,possible ,,aspects
 ,,of ,,history                         
#bii      #b4 ,,phylogenetic            
,,possibilities                         
#cjd      #c4 ,,the ,,history ,,of      
,,mankind                               
#cjf        ,cumulations in ,human      
,history                                
#cjh      ,human ,history not an        

8,evolution0                            
#caa      ,the ,problem of the 8,single0
 as such                                
#cae      99,,conclusions ,,about       
,,systematics ,,and ,,history ,,in      
,,general99            #cbb             
,,the ,,programme      ,,on ,,lord      
,,gifford',s ,,conception ,,of          
8,,science0    ,this is the first time  
that a biologist has occupied this      
place2 the  first time that a biologist 
is to try to carry out the intentions of
 the  noble and high-minded man to whom 
this lectureship owes its foundation4   
,on such an occasion it seems to be not 
undesirable to inquire what ,lord       
,gifford's own opinions about natural   
science may have been1 what place  in   
the whole scheme of human knowledge he  
may have attributed to those  branches  
of it which have become almost the      
centre of men's intellectual  interest4 
,and1 indeed1 on studying ,lord         
,gifford's bequest with the object of   
finding in it some reference to the     

natural sciences1 one easily notes  that
 he has assigned to them a very high    
place compared with the other  sciences1
 at least in one respect3 with regard to
 their methods4    ,there is a highly   
interesting passage in his will which   
leaves no doubt  about our question4    
,after having formally declared the     
foundation of  this lectureship 8for    
,promoting1 ,advancing1 ,teaching and   
,diffusing  the study of ,natural       
,theology in the widest sense of that   
term10 and  after having arranged about 
the special features of the lectures1 he
  continues3 8,i wish the lecturers to  
treat their subject as a strictly       
natural science1 the greatest of all    
possible sciences1 indeed1 in one       
sense1 the only science1 that of        
,infinite ,being4444 ,i wish it         
considered  just as astronomy or        
chemistry is40    ,of course1 it is not 
possible to understand these words of   
,lord  ,gifford's will in a quite       
literal sense4 ,if1 provisionally1 we   

call  8natural theology0 the ultimate   
conclusions which may be drawn from a   
study of nature in connection with all  
other results of human sciences1  there 
cannot be any doubt that these          
conclusions will be of a rather         
different character from the results    
obtained in1 say1 the special field  of 
scientific chemistry4 ,but1             
nevertheless1 there are1 ,i think1 two  
points of contact between the wider and 
the narrower field of knowledge1  and   
both of them relate to method4 ,lord    
,gifford's own phrase1 8,infinite       
,being10 shows us one of these          
meeting-points4 ,in opposition to       
history  of any form1 natural sciences  
aim at discovering such truths as are   
independent of special time and of      
special space1 such truths as are       
8ideas0 in the sense of ,plato2 and such
 eternal results1 indeed1 always  stand 
in close relation to the ultimate       
results of human knowledge  in general4 
,but besides that there is still another

 feature which  may be common both to   
8natural theology0 and to the special   
natural  sciences1 and which is most    
fully developed in the latter3 freedom  
from  prepossessions4 ,this1 at least1  
is an ideal of all natural sciences2  ,i
 may say it is 99the99 ideal of them4   
,that it was this feature which  ,lord  
,gifford had in view in his comparison  
becomes clear when we read  in his will 
that the lectures on natural theology   
are to be delivered  8without reference 
to or reliance upon any supposed special
 exceptional  or so-called miraculous   
revelation40    ,so we might say that   
both in their logical and their moral   
methods1  natural sciences are to be the
 prototype of 8,natural ,theology0 in   
,lord  ,gifford's sense4      ,,natural 
,,sciences ,,and 8,,natural ,,theology0 
,but now let us study in a more         
systematic manner the possible relations
  of the natural sciences to natural    
theology as a science4    ,how is it    
possible for a natural scientist to     

contribute to the science  of the       
highest and ultimate subject of human   
knowledge8    ,almost all natural       
sciences have a sort of navet in their  
own spheres2  they all stand on the     
ground of what has been called a nave   
realism1  as long as they are1 so to    
say1 at home4 ,that in no way prejudices
  their own progress1 but it seems to   
stand in the way of establishing        
contact with any higher form of human   
knowledge than themselves4  ,one may be 
a first-rate organic chemist even when  
looking upon the  atoms as small        
billiard balls1 and one may make        
brilliant discoveries  about the        
behaviour of animals even when regarding
 them in the most  anthropomorphic      
manner--granted that one is a good      
observer2 but it  can hardly be admitted
 that our chemist would do much to      
advance the  theory of matter1 or our   
biologist to solve the problem of the   
relations  between body and mind4    ,it
 is only by the aid of philosophy1 or ,i

 would rather say by keeping  in        
constant touch with it1 that natural    
sciences are able to acquire  any       
significance for what might be called   
99the99 science of nature in the  most  
simple form4 ,unhappily the term        
8natural philosophy0 is restricted  in  
,english to theoretical physics4 ,this  
is not without a high degree of         
justification1 for theoretical physics  
has indeed lost its navet and  become a 
philosophy of nature2 but it            
nevertheless is very unfortunate  that  
this use of the term 8natural           
philosophy0 is established in  this     
country1 as we now have no proper       
general term descriptive of a  natural  
science that is in permanent relation to
 philosophy1 a natural  science which   
does not use a single concept without   
justifying it  epistemologically1       
99i4e499 what in ,german1 for instance1 
would simply be  called                 
8,naturphilosophie40    ,let us call it 
philosophy of nature2 then we may say   

that only by  becoming a true philosophy
 of nature are natural sciences of all  
sorts  able to contribute to the highest
 questions which man's spirit of        
inquiry can suggest4    ,these highest  
questions themselves are the outcome of 
the combination  of the highest results 
of all branches of philosophy1 just as  
our  philosophy of nature originated in 
the discussion of the results of  all   
the separate natural sciences4 ,are     
those highest questions not  only to be 
asked1 are they to be also solved8 ,to  
be solved in a way  which does not      
exceed the limits of philosophy as the  
domain of actual  understanding8    ,the
 beginning of a long series of studies  
is not the right place to  decide this  
important question2 and so1 for the     
present certainly1  8natural theology0  
must remain a problem4 ,in other words3 
it must  remain an open question at the 
beginning of our studies1 whether after 
all there can be any final general      
answer1 free from contradictions1       

applicable to the totality of questions 
asked by all the branches of            
philosophy4    ,but let us not be       
disturbed by this problematic entrance  
to our studies4  ,let us follow biology 
on its own path2 let us study its       
transition from  a 8nave0 science to a  
real branch of the philosophy of nature4
 ,in this  way we perhaps shall be able 
to understand what its part may be in   
solving what can be solved4    ,that is 
to be our subject4      ,,our           
,,philosophical ,,basis    ,we call     
99nature99 what is given to us in space4
    ,of course we are not obliged in    
these lectures to discuss the           
psychological and epistemological       
problems of space with its three        
dimensions1 nor are we obliged to       
develop a general theory of reality  and
 its different aspects4 ,a few          
epistemological points will be          
considered later at proper times1 and   
always in connection with results  of   
theoretical biology4    ,at present it  

must suffice to say that our general    
philosophical point  of view will be    
idealistic1 in the critical meaning of  
the word4 ,the  universe1 and within the
 universe nature1 in the sense just     
defined1  is my phenomenon4 ,that is    
what ,i know4 ,i know nothing more1     
either  positively or negatively2 that  
is to say1 ,i do not know that the world
  is 99only my99 phenomenon1 but1 on the
 other hand1 ,i know nothing about  its 
8absolute reality40 ,and more1 ,i am not
 even able to describe in  intelligible 
words what 8absolute reality0 might     
mean4 ,i am fully  entitled to state3   
the universe 99is99 as truly as ,i      
am--though in  a somewhat different     
sense of 8being0--and ,i 99am99 as truly
 as the  universe is2 but ,i am not     
entitled to state anything beyond these 
two corresponding phrases4 ,you know    
that1 in the history of ,european       
philosophy at least1 ,bishop ,berkeley  
was the first clearly to outline  the   
field of idealism4    ,but my           

phenomenon--the world1 especially       
nature--consists of elements  of two    
different kinds3 some of them are merely
 passive1 some of them  contain a       
peculiar sort of activity in themselves4
 ,the first are  generally called       
sensations1 but perhaps would be better 
called elements  or presentations2 the  
others are forms of construction1 and1  
indeed1  there is an active element     
embraced in them in this sense1 that    
they  allow1 by their free combination1 
the discovery of principles which  are  
not to be denied1 which must be         
affirmed1 whenever their meaning  is    
understood4 ,you know that ,i am        
speaking here of what are generally     
called categories and synthetic         
judgments 99a priori991 and that it was 
,kant who1 on the foundations laid by   
,locke1 ,hume1 and ,leibnitz1 first     
gave the outlines of what may be called 
the real system of critical  philosophy4
 ,indeed1 our method will be to a great 
extent ,kantian1 though  with certain   

exceptions2 it is to be strictly        
idealistic1 and will not  in the        
,kantian way operate with things in     
themselves2 and it regards  the         
so-called 8synthetic judgment 99a       
priori990 and the problem of the        
relation between categorical principles 
and experience in a somewhat  different 
manner4 ,we think it best to define the 
much disputed concept  899a priori990 as
 8independent of the 99amount99 of      
experience02 that is  to say1 all       
categories and categorical principles   
are brought to my  consciousness by that
 fundamental event which is called      
experience1 and  therefore are not      
independent of it1 but they are not     
inferences from  experience1 as are     
so-called empirical laws4 ,we almost    
might say that we  only have to be      
reminded of those principles by         
experience1 and1 indeed1  we should not1
 ,i think1 go very far wrong in saying  
that the ,socratic  doctrine1 that all  
knowledge is recollection1 holds good as

 far as  categories and categorical     
principles are in question4    ,but     
enough at present about our general     
philosophy4    ,as to the philosophy of 
nature1 there can be no doubt that1 on  
the basis  of principles like those we  
have shortly sketched1 its ultimate aim 
must  be to co-ordinate everything in   
nature with terms and principles of the 
categorical style4 ,the philosophy of   
nature thus becomes a system2 a  system 
of which the general type is afforded by
 the innate constructive  power of the  
,ego4 ,in this sense the ,kantian dictum
 remains true1 that  the ,ego prescribes
 its own laws to nature1 though1 of     
course1 8nature10  that is1 what is     
given in space1 must be such as to      
permit that sort of  8prescription40    
,one often hears that all sciences1     
including the science of sciences1      
philosophy1 have to find out what is    
true4 ,what1 then1 may be called  8true0
 by an idealistic philosopher1 for whom 
the old realistic formula  of the       

conformity between knowledge and the    
object cannot have any  meaning8        
,besides its ordinary application to    
simple facts or to simple  judgments1   
where the word truth only means absence 
of illusion or no  false statement1     
truth can be claimed for a philosophical
 doctrine or  for a system of such      
doctrines only in the sense that there  
are no  contradictions amongst the parts
 of the doctrine or of the system       
themselves1 and that there are no       
features in them which impel our        
categorical ,ego to further analysis4   
,those of you who attended ,professor   
,ward's lectures on 8,naturalism and    
,agnosticism10 or who have read his     
excellent book on that subject1 will    
know what the aims of a theory of matter
 are4 ,you will also be aware  that1 at 
present1 there does not exist any theory
 of matter which can  claim to be       
8true02 there are contradictions in     
every theory of matter1  and1 moreover1 
there are always some points where we   

are obliged to ask  for further         
information and receive no answer4      
,experience here has not  yet aroused   
all the categorical functions which are 
needed in order to  form one unity out  
of what seem to be incompatibilities at 
the present  day4 ,why is that8 ,maybe  
because experience is not yet complete  
in this  field1 but maybe also because  
the whole subject is so complicated     
that it takes much time to attach       
categorical functions to what is        
experienced4    ,but it is not our      
object here to deal either with         
epistemology proper  or with ontology3 a
 full analysis of biological facts is   
our problem4  ,why1 then1 all these     
introductions8 why all these            
philosophical sketches  in fields of    
knowledge which have quite another      
relation to philosophy  than biology    
has8 ,biology1 ,i hear some one say1 is 
simply and solely  an empirical science2
 in some sense it is nothing but applied
 physics  and chemistry1 perhaps applied

 mechanics4 ,there are no fundamental   
principles in biology which could bring 
it in any close contact with            
philosophy4 ,even the one and only      
principle which might seem to be  an    
innate principle of our experience about
 life1 the principle of  evolution1 is  
only a combination of more simple       
factors of the physical  and chemical   
type4    ,it will be my essential       
endeavour to convince you1 in the course
 of  these lectures1 that such an aspect
 of the science of biology is wrong2    
that biology is an elemental natural    
science in the true sense of the  word4 
,but if biology is an elemental science1
 then1 and only then1 it stands  in     
close relations to epistemology and     
ontology--in the same relations  to     
them1 indeed1 as every natural science  
does which deals with true  elements of 
nature1 and which is willing to abandon 
nave realism and  contribute its share  
to the whole of human knowledge4        
,and1 therefore1 a philosophical sketch 

is not out of place at the  beginning of
 lectures on the ,philosophy of the     
,organism4 ,we may be  forced1 we1      
indeed1 shall be forced1 to remain for  
some time on the  ground of realistic   
empiricism1 for biology has to deal with
 very  complicated experiences2 but     
there will be a moment in our progress  
when  we shall enter the realm of the   
elemental ontological concepts1 and  in 
that very moment our study of life will 
have become a part of real  philosophy4 
,it was not without good reasons1       
therefore1 that ,i shortly  sketched1 as
 a sort of introduction to my lectures1 
the general point of  view which we     
shall take with regard to philosophical 
questions1 and to  questions of the     
philosophy of nature in particular4     
,,on ,,certain ,,characteristics ,,of   
,,biology ,,as ,a ,,science    ,biology 
is the science of life4 ,practically1   
all of you know what a  living being is1
 and therefore it is not necessary to   
formulate a  definition of life1 which1 

at the beginning of our studies1 would  
be  either provisional and incomplete1  
or else dogmatic4 ,in some respects1    
indeed1 a definition should rather be   
the end of a science than its  opening4 
,we shall study the phenomena of living 
organisms analytically1 by the  aid of  
experiment2 our principal object will be
 to find out laws in  these phenomena2  
such laws will then be further analysed1
 and precisely  at that point we shall  
leave the realm of natural science      
proper4    ,our science is the highest  
of all natural sciences1 for it embraces
 as  its final object the actions of    
man1 at least in so far as actions also 
are phenomena observable on living      
bodies4    ,but biology is also the most
 difficult of all natural sciences1 not 
only from the complexity of the         
phenomena1 which it studies1 but in     
particular for another reason which is  
seldom properly emphasised1 and         
therefore will well repay us for a few  
words devoted to it4    ,except so far  

as the 8elements0 of chemistry come into
 account1 the  experimenter in the      
inorganic fields of nature is not       
hampered by the  specificity of         
composite objects3 he makes all the     
combinations he  wants4 ,he is always   
able to have at his disposal red rays of
 a desired  wave length when and where  
he wants1 or to have1 at a given time   
and  place1 the precise amount of any   
organic compound which he wishes to     
examine4 ,and he forces electricity and 
electromagnetism to obey his  will1 at  
least with regard to space1 time1 and   
intensity of their  appearance4    ,the 
biologist is not able to 8make0 life1 as
 the physicist has made red  rays or    
electromagnetism1 or as the chemist has 
made a certain compound  of carbon4 ,the
 biologist is almost always in that     
strange plight in  which the physicist  
would be if he always had to go to      
volcanoes in  order to study the        
conductivity of heat1 or if he had to   
wait for  thunderstorms in order to     

study electricity4 ,the biologist is    
dependent  on the specificity of living 
objects as they occur in nature4    ,a  
few instances may show you what great   
inconveniences may hence arise  to      
impede practical biological research4   
,we later on shall have to deal  with   
experiments on very young embryos3 parts
 of the germ will have  to be destroyed 
in order to study what will happen with 
the rest4 ,now  almost all germs are    
surrounded by a membrane2 this membrane 
has to be  detached before any operation
 is possible4 ,but what are we to do if 
it  is not possible to remove the       
membrane without killing the embryo8 ,or
  what if1 as for instance in many      
marine animals1 the membrane may be     
removed but the germs are killed by     
contact with sea-water8 ,in both  cases 
no experiments at all will be possible  
on a sort of germ which  otherwise1 for 
some special circumstances of its       
organisation1 might  have given results 
of importance4 ,these results become    

impossible for  only a practical1 for a 
very secondary reason2 but enough3 they 
are  impossible1 and they might have    
thrown light on problems which now  must
 remain problems4 ,quite the same thing 
may occur in experiments  on physiology 
proper or functional physiology3 one    
kind of animals  survives the operation1
 the other kind does not1 and therefore1
 for  merely extrinsic reasons1 the     
investigations have to be restricted to 
the first1 though the second might have 
given more important results4  ,and thus
 the biological experimenter always     
finds himself in a sort of  dependence  
on his subjects1 which can hardly be    
called pleasant4 ,to a  great extent the
 comparatively slow advance of          
biological sciences is  due to this very
 fact3 the unalterable specific nature  
of biological  material4    ,but there  
is still another feature of biology     
dependent on the same  fact4 ,if a      
science is tied down to specific objects
 in every path it  takes1 it first1 of  

course1 has to know all about those     
objects1 and  that requires nothing else
 but plain description4 ,we now         
understand why  pure description1 in the
 most simple sense of the word1 takes up
 such an  enormous part of every        
text-book of biological science4 ,it is 
not only  morphology1 the science of    
form1 that is most actively concerned   
with  description2 physiology also1 in  
its present state1 is pure description  
of what the functions of the different  
parts of the body of animals and  plants
 actually 99are991 at least for about   
nine-tenths of its range4 ,it  seems to 
me important to press this point very   
emphatically1 since we  often hear that 
physiology is from the very beginning a 
much higher sort  of knowledge than     
morphology1 inasmuch as it is rational4 
,that is not at  all true of the        
beginning of physiology3 what the       
functions of the liver  or of the root  
are has simply to be described just as  
the organisation  of the brain or of the

 leaf1 and it makes no difference       
logically that  one species of          
description has to use the experimental 
method1 while the  other has not4 ,the  
experiment which only discovers what    
happens here or  what happens there1    
possesses no kind of logical superiority
 over pure  description at all4    ,but 
there will be another occasion in our   
lectures to deal more fully  with the   
logic of experiment and with the        
differences of descriptive  knowledge   
and real rational science4      ,,the   
,,three ,,different ,,types ,,of        
,,knowledge ,,about ,,nature    ,natural
 sciences cannot originate before the   
given phenomena of nature  have been    
investigated in at least a superficial  
and provisional manner1  by and for the 
practical needs of man4 ,but as soon as 
true science  begins in any limited     
field1 dealing1 let us say1 with animals
 or with  minerals1 or with the         
properties of bodies1 it at once finds  
itself  confronted by two very different

 kinds of problems1 both of them--like  
all 8problems0--created in the last     
resort by the logical organisation  of  
the human mind1 or1 to speak still more 
correctly1 of the ,ego4    ,in any      
branch of knowledge which practical     
necessities have separated  from others1
 and which science now tries to study   
methodically1 there  occur general      
sequences in phenomena1 general orders  
of events4 ,this  uniformity is revealed
 only gradually1 but as soon as it has  
shown  itself1 even in the least degree1
 the investigator seizes upon it4 ,he   
now devotes himself chiefly1 or even    
exclusively1 to the generalities in  the
 sequences of all changes4 ,he is       
convinced that there must be a sort  of 
most general and at the same time of    
most universal connection about  all    
occurrences4 ,this most universal       
connection has to be found out2 at      
least it will be the ideal that always  
will accompany the inquiring mind       
during its researches4 ,the 8law of     

nature0 is the ideal ,i am speaking     
about1 an ideal which is nothing less   
than one of the postulates of the       
possibility of science at all4    ,using
 for our purposes a word which has been 
already introduced into  terminology by 
the philosopher ,windelband1 though in a
 somewhat  different sense1 we shall    
call that part of every branch of       
natural  sciences which regards the     
establishment of a law of nature as its 
ideal1 8nomothetic10 99i4e499           
8law-giving40    ,but while every       
natural science has its nomothetic side1
 it also has  another half of a very    
different kind4 ,this second half of    
every natural  science does not care for
 the same general1 the same universal1  
which  is shown to us in every event in 
a different and specified kind3 it  is  
diversity1 it is specification1 that    
constitutes the subject of  its         
interest4 ,its aim is to find a         
sufficient reason for the types of      
diversities1 for the types of           

specifications4 ,so in chemistry there  
has been found a systematic order in the
 long series of the compounds  and of   
the elements2 crystallography also has  
its different systems of  crystals1 and 
so on4    ,we have already employed the 
word by which we shall designate this   
second half of every natural science3 it
 is the 8systematic0 side of  science4  
,nomothetic work on the one side and    
systematics on the other do1 in  fact1  
appear in every natural science1 and    
besides them there are no  other main   
parts4 ,but 8science0 as a whole stands 
apart from another  aspect of reality   
which is called 8history40 ,history     
deals with  particulars1 with particular
 events at such and such a place1 whilst
  science always abstracts from the     
particular1 even in its systematic      
half4#a    #a ,windelband 799,geschichte
 und ,naturwissenschaft991 #c ,auflage1 
#aijd7  gives the name 8nomothetic0 to  
the whole of our 8science0 and calls the
  method of history 8idiographic40 ,we  

thought it better to establish three    
fundamental types of all possible       
branches of knowledge4      ,,general   
,,plan ,,of ,,these ,,lectures          
,turning now to a sort of short outline 
of what is to be discussed  in the whole
 of our future lectures1 this summer and
 next1 it seems  clear1 without further 
analysis1 that biology as a science has 
its  nomothetic and its systematic part 
also2 respiration and assimilation1  for
 instance1 have proved to be types of   
natural laws among living  phenomena1   
and that there is a 8system0 of animals 
and plants is too  commonly known to    
require further explanation here4       
,therefore we might  study first        
biological laws1 and after that         
biological systematics1 and  in the     
third place perhaps biological history4 
,but that would hardly  correspond to   
the philosophical aims of our lectures3 
our chief object  is not biology as a   
regular science1 as treated in          
text-books and in  ordinary university  

lectures2 our chief object is the       
,philosophy of the  ,organism1 as aided 
and supported by scientific biology4    
,therefore a  general acquaintance with 
biology must be assumed in these        
lectures1 and  the biological materials 
must be arranged according to their     
bearing on  further1 that is on         
philosophical1 analysis4    ,that will  
be done1 not1 of course1 to the extent  
of my regarding every  one of my        
audience as a competent biologist2 on   
the contrary1 ,i shall  explain most    
fully all points of biology proper1 and 
even of the most  simple and descriptive
 kind of biology1 which serve as bases  
for  philosophical analysis4 ,but ,i    
shall do so only if they indeed do serve
  as such bases4 ,all our biology will  
be not for its own sake1 but for the    
sake of philosophy4    ,whilst regarding
 the whole of the biological material   
with such aims1  it seems to me best to 
arrange the properly scientific material
 which  is to be the basis of my        

discussions1 not along the lines which  
biology  as an independent science would
 select1#b but to start from the three  
different kinds of fundamental phenomena
 which living bodies offer to           
investigation1 and to attach all        
systematics exclusively to one of them4 
,for there will not be very much for    
philosophy to learn from biological     
systematics at present4    #b ,see ,j4  
,arth4 ,thomson1 99,the ,science of     
,life991 ,london1 #ahii4    ,life is    
unknown to us except in association with
 bodies3 we only know  living bodies and
 call them organisms4 ,it is the final  
object of all  biology to tell us what  
it ultimately means to say that a body  
is  8living10 and in what sorts of      
relation body and life stand one to the 
other4    ,but at present it is enough  
to understand the terms 8body0 and      
8living0  in the ordinary and popular   
sense4    ,regarding living bodies in   
this unpretentious manner1 and          
recollecting  what the principal        

characters are of all bodies we know as 
living ones1  we easily find that there 
are three features which are never      
wanting  wherever life in bodies occurs4
 ,all living bodies are specific as to  
form--they 8have0 a specific form1 as we
 are accustomed to say4 ,all  living    
bodies also exhibit metabolism2 that is 
to say1 they stand in a  relation of    
interchange of materials with the       
surrounding medium1 they  take in and   
give out materials1 but their form can  
remain unchanged  during these          
processes4 ,and1 in the last place1 we  
can say that all  living bodies move2   
though this faculty is more commonly    
known among  animals only1 even         
elementary science teaches the student  
that it also  belongs to plants4        
,therefore we may ask for 8laws of      
nature0 in biology about form1 about    
metabolism1 and about movements4 ,in    
fact1 it is according to this scheme    
that we shall arrange the materials of  
the biological part of our  lectures1   

though1 as we cannot regard the three   
divisions as equally  important in their
 bearing on our ultimate purposes1 we   
shall not treat  them quite on equal    
terms4 ,it will appear that1 at least in
 the present  state of science1 the     
problems of organic form and of organic 
movement  have come into much closer    
relation to philosophical analysis than 
have  most of the empirical data on     
metabolism4    ,it is 99form99          
particularly which can be said to occupy
 the very centre  of biological         
interest2 at least it furnishes the     
foundation of all  biology4 ,therefore  
we shall begin our scientific studies   
with a full and  thorough analysis of   
form4 ,the science of living forms1     
later on1 will  afford us a key to study
 metabolism proper with the greatest    
advantage  for our philosophical aims1  
and therefore the physiology of what is 
usually called the vegetative functions 
will be to us a sort of appendix  to our
 chapters on form2 only the theory of a 

problematic 8living  substance0 and of  
assimilation in the most general meaning
 of the word  will be reserved for the  
philosophical part2 for very good       
reasons1  as ,i hope to show4 ,but our  
chapters on the living forms will have  
yet  another appendix besides the survey
 of the physiology of metabolism4       
,biological systematics almost wholly   
rests on form1 on 8morphology02 and     
what hitherto has been done on the      
metabolical side of their problems1     
consists of a few fragments1 which are  
far from being an equivalent to  the    
morphological system2 though1 of course 
it must be granted that1  logically1    
systematics1 in our general meaning of  
the word1 as the sum  of problems about 
the typically different and the         
specific1 may be  studied on the basis  
of each one of the principal            
characteristics of  living bodies1 not  
only on that of their forms4 ,therefore1
 systematics  is to be the second       
appendix to the chief part of our       

studies in  morphology1 and systematics1
 in its turn1 will later on lead us to  
a short sketch of the historical side of
 biology1 to the theory of  evolution in
 its different forms1 and to the logic  
of history in general4    ,so far will  
our programme be carried out during this
 summer4 ,next year  the theory of      
movements will conclude our merely      
scientific analysis1  and the remaining 
part of the course next summer will be  
devoted to the  philosophy of living    
nature4 ,i hope that nobody will be able
 to accuse  our philosophy of resting on
 unsound foundations4 ,but those of you1
 on  the other hand1 who would be apt to
 regard our scientific chapters as a    
little too long compared with their     
philosophical results1 may be asked  to 
consider that a small clock-tower of a  
village church is generally  less       
pretentious but more durable than the   
campanile of ,san ,marco has  been4     
,indeed1 these lectures will afford more
 8facts0 to my hearers1 than  ,gifford  

,lectures probably have done1 as a rule4
 ,but how could that  be otherwise on   
the part of a naturalist8 ,scientific   
facts are the  material that the        
philosophy of nature has to work with1  
but these  facts1 unfortunately1 are not
 as commonly known as historical facts1 
for instance1 generally are2 and they   
must be known1 in order that a          
philosophy of the organism may be of any
 value at all1 that it may be  more than
 a mere entertainment4    ,goethe once  
said1 that even in so-called facts there
 is more 8theory0  than is usually      
granted2 he apparently was thinking of  
what might be  called the ultimate or   
the typical facts in science4 ,it is    
with such  typical or ultimate facts1 of
 course1 that we must become acquainted 
if  our future philosophy is to be of   
profit to us4    ,certainly1 there would
 be nothing to prevent us from arranging
 our  materials in a manner exactly the 
reverse of that which we shall adopt2   
we could begin with a general principle 

about the organic1 and could  try to    
deduce all its special features from    
that principle1 and such a  way perhaps 
would seem to be the more fascinating   
method of argument4  ,but though logical
 it would not be psychological1 and     
therefore would  be rather unnatural4   
,and thus our 99most99 general principle
 about the  organic will not come on the
 scene before the eighteenth of these   
twenty  lectures1 although it is not a  
mere inference or deduction from the    
former lectures3 it will be a           
culmination of the whole1 and we shall  
appreciate its value the better the more
 we know what that whole really  is4    
,,general ,,character ,,of ,,the        
,,organic ,,form    ,our programme of   
this year1 it was said1 is to be devoted
 wholly  to organic forms1 though one of
 its appendixes1 dealing with some      
characteristics of the physiology of    
metabolism1 will lead us on to a  few   
other phenomena4 ,what then are the     
essentials of a living form1 as         

commonly understood even without a      
special study of biology8    ,living    
bodies are not simple geometrical forms1
 not1 like crystals1  merely a typical  
arrangement of surfaces in space1 to be 
reduced  theoretically1 perhaps1 to an  
arrangement of molecules4 ,living bodies
  are typically combined forms2 that is 
to say1 they consist of simpler  parts  
of different characters1 which have a   
special arrangement with  regard to one 
another2 these parts have a typical form
 of their own and  may again be         
combinations of more simple different   
parts4 ,but besides  that1 living bodies
 have not always the same typically     
combined form  during the whole of their
 life3 they become more complicated as  
they  grow older2 they all begin from   
one starting point1 which has little    
form at all1 viz41 the egg4 ,so the     
living form may be called a 8genetic    
form10 or a form considered as a        
process1 and therefore 99morphogenesis99
  is the proper and adequate term for   

the science which deals with the  laws  
of organic forms in general2 or1 if you 
prefer not to use the  same word both   
for a science and for the subjects of   
that science1 the  99physiology of      
morphogenesis994    ,now there are      
different branches of the physiology of 
morphogenesis or  physiology of form4   
,we may study1 and indeed we at first   
shall study1  what are the laws of the  
morphogenetic processes leading from the
 egg  to the adult3 that may be properly
 called physiology of development4  ,but
 living forms are not only able to      
originate in one unchangeable  way3 they
 may restore themselves1 if disturbed1  
and thus we get the  physiology of      
restoration or restitution as a second  
branch of the  science of morphogenesis4
 ,we shall draw very important data1    
some of the  foundations indeed of our  
philosophical discussions1 from the     
study of  such restitutions4 ,besides   
that1 it is to them that our survey of  
the  problems of the physiology of      

metabolism is to be appended4    ,living
 forms not only originate from the egg  
and are able to restore  themselves1    
they also may give origin to other      
forms1 guaranteeing in  this way the    
continuity of life4 ,the physiology of  
heredity therefore  appears as the      
counterpart to those branches of the    
physiology of form  which deal with     
individual form and its restitutions4   
,and our discussion  on heredity may be 
followed by our second appendix to this 
chief section  on form1 an appendix     
regarding the outlines of systematics1  
evolution  and history4    ,theoretical 
considerations on biology generally     
start1 or at least1  used to start1 from
 the evolution theory1 discussing all   
other problems  of the physiology of    
form by the way only1 as things of      
secondary  importance4 ,you see from our
 programme1 that we shall go just the   
opposite way3 evolution will come last  
of all1 and will be treated  shortly2   
but the morphogenesis of the individual 

will be treated very  fully1 and very   
carefully indeed4    ,why then this     
deviation from what is the common       
practice8 ,because we do  not know very 
much about evolution at all1 because in 
this field we are  just at the very     
beginning of what deserves the name of  
exact knowledge4  ,but concerning       
individual morphogenesis we really know1
 even at present1  if not very much1 at 
least something1 and that we know in a  
fairly exact  form1 aided by the results
 of experiments4    ,and it will not be 
without its reward1 if we restrict our  
aims in such a  manner1 if we prefer to 
deal more fully with a series of        
problems1 which  may seem at the first  
glance to be of less interest than      
others4 ,after a  few lectures we shall 
find already that we may decide one very
 important  question about life merely  
by an analysis of individual form       
production1  and without any regard to  
problematic and doubtful parts of       
biology3  that we may decide the        

question1 whether 8life0 is only a      
combination  of chemical and physical   
events1 or whether it has its elemental 
laws1  laws of its own4    ,but to      
prepare the road that is to lead to such
 results we first have  to restrict our 
aims once more1 and therefore the next  
lecture of this  course1 which          
eventually is to touch almost every     
concept of philosophy  proper1 will     
begin with the pure description of the  
individual  development of the common   
sea-urchin4          ,,section ,a       
,,the ,,chief ,,results ,,of            
,,analytical ,,biology          ,,part  
,i    ,,the ,,individual ,,organism     
,,with ,,regard ,,to ,,form ,,and       
,,metabolism    99,a499 ,,elementary    
,,morphogenesis      ,,evolutio ,,and   
,,epigenesis ,,in ,,the ,,old ,,sense   
,the organism is a specific body1 built 
up by a typical combination  of specific
 and different parts4 ,it is implied in 
the words of this  definition1 that the 
organism is different1 not only from    

crystals1 as  was mentioned in the last 
lecture1 but also from all combinations 
of  crystals1 such as those called      
dendrites and others1 which consist of a
  typical arrangement of identical      
units1 the nature of their combination  
depending on the forces of every single 
one of their parts4 ,for this  reason   
dendrites1 in spite of the typical      
features in their combination1  must be 
called aggregates2 but the organism is  
not an aggregate even  from the most    
superficial point of view4    ,we have  
said before1 what must have been        
familiar to you already1 that  the      
organism is not always the same in its  
individual life1 that it  has its       
development1 leading from simpler to    
more complicated forms of  combination  
of parts2 there is a 8production of     
visible manifoldness0  carried out      
during development1 to describe the     
chief character of that  process in the 
words of ,wilhelm ,roux4 ,we leave it an
 open question in  our present merely   

descriptive analysis1 whether there was 
already a  8manifoldness10 in an        
invisible state1 before development1 or 
whether  the phrase 8production of      
manifoldness0 is to be understood in an 
absolute sense4    ,it has not always   
been granted in the history of biology1 
and of  embryology especially1 that     
production of visible manifoldness is   
the  chief feature of what is called an 
organism's embryology or ontogeny3  the 
eighteenth century is full of determined
 scientific battles over the  question4 
,one school1 with ,albert von ,haller   
and ,bonnet as its leading  men1        
maintained the view that there was no   
production of different parts  at all in
 development1 this process being a mere 
8evolutio10 that is1  a growth of parts 
already existing from the beginning1    
yes1 from the  very beginning of life2  
whilst the other school1 with ,c4 ,f4   
,wolff and  ,blumenbach at its head1    
supported the opposite doctrine of      
so-called  8epigenesis10 which has been 

proved to be the right one4    ,to some 
extent these differences of opinion were
 only the outcome of the  rather        
imperfect state of the optical          
instruments of that period4 ,but  there 
were also deeper reasons beyond mere    
difficulties of description2  there were
 theoretical convictions underlying     
them4 ,it is 99impossible991  said the  
one party1 that there is any real       
production of new parts2  there 99must99
 be such a production1 said the other4  
,we ourselves shall have to deal with   
these questions of the theory of        
organic development2 but at present our 
object is narrower1 and merely          
descriptive4 ,it certainly is of great  
importance to understand most  clearly  
that there actually 99is99 a 8production
 of visible manifoldness0  during       
ontogenesis in the descriptive sense2   
the knowledge of the fact  of this      
process must be the very foundation of  
all studies on the theory  of           
development in any case1 and therefore  

we shall devote this whole  lecture to  
studies in merely descriptive           
embryology4    ,but descriptive         
embryology1 even if it is to serve      
merely as an  instance of the           
universality of the fact of epigenesis1 
can only be  studied successfully with  
reference to a concrete case4 ,we select
 the  development of the common         
sea-urchin 799,echinus                  
microtuberculatus997 as  such a case1   
and we are the more entitled to select  
this organism rather  than another1     
because most of the analytical          
experimental work1 carried  out in the  
interests of a real theory of           
development1 has been done  on the germs
 of this animal4 ,therefore1 to know at 
least the outlines  of the individual   
embryology of the ,echinus may indeed be
 called the  99conditio sine qua non99  
for a real understanding of what is to  
follow4      ,,the ,,cell#c    #c ,e4   
,b4 ,wilson1 99,the ,cell in            
,development and ,inheritance991 ,new   

,york1  ,macmillan1 #ahif4    ,you are  
aware that all organisms consist of     
organs and that each of  their organs   
has a different function3 the brain1 the
 liver1 the eyes1  the hands are types  
of organs in animals1 as are the leaves 
and the  pistils in plants4    ,you are 
also aware that1 except in the lowest   
organisms1 the so-called  ,protista1 all
 organs are built up of cells4 ,that is 
a simple fact of  observation1 and ,i   
therefore cannot agree with the common  
habit of  giving to this plain fact the 
title of cell-8theory40 ,there is       
nothing  theoretical in it2 and1 on the 
other hand1 all attempts to conceive    
the organism as a mere aggregate of     
cells have proved to be wrong4 ,it  is  
99the whole99 that uses the cells1 as we
 shall see later on1 or that  may not   
use them3 thus there is nothing like a  
8cell-theory10 even in a  deeper meaning
 of the word4    ,the cell may have the 
most different forms3 take a cell of the
 skin1 of  a muscle1 of a gland1 of the 

wood in plants as typical examples4 ,but
 in  every case two parts may be        
distinguished in a cell3 an outside     
part1  the protoplasm1 and an inside    
part1 the nucleus1 to leave out of      
special  account several others1 which1 
by the way1 may only be protoplasmatic  
modifications4    ,protoplasm is a mere 
name for what is not the nucleus2 in any
 case it is  not a homogeneous chemical 
compound2 it consists of many such      
compounds  and has a sort of            
architecture2 all organic functions are 
based upon  its metabolism4 ,the nucleus
 has a very typical structure1 which    
stands  in a close relation to its      
behaviour during the most characteristic
  morphological period of the cell3     
during its division4 ,let us devote a   
few words to a consideration of this    
division and the part the nucleus  plays
 in it2 it will directly bear on future 
theoretical considerations  about       
development4    ,there is a certain     
substance in every nucleus of a cell    

which stains  most markedly1 whenever   
cells are treated with pigments3 the    
name  of 8chromatin0 has been given to  
it4 ,the chromatin always gives the     
reaction of an acid1 while protoplasm is
 basic2 besides that it seems to  be a  
centre of oxidation4 ,now1 when a       
division of a cell is to occur1  the    
chromatin1 which had been diffusely     
distributed before1 in the form  of     
small grains1 arranges itself into a    
long and very much twisted  thread4     
,this thread breaks1 as it were by      
sections1 into almost equal  parts1     
typical in number for each species1 and 
each of these parts is  split at full   
length4 ,a certain number of pairs of   
small threads1 the  so-called           
8chromosomes10 are the ultimate result  
of this process1 which  intentionally   
has been described a little             
schematically1 the breaking  and the    
splitting in fact going on              
simultaneously or occasionally even  in 
reverse order4 ,while what we have      

described is performing in the  nucleus1
 there have happened some typical       
modifications in protoplasm1  and then1 
by an interaction of protoplasmatic and 
nuclear factors1 the  first step in the 
actual division of the cell begins4 ,of 
each pair of  the small threads of      
chromatin one constituent is moved to   
one side of  the cell1 one to the other2
 two daughter-nuclei are formed in this 
way2  the protoplasm itself at the same 
time forms a circular furrow between    
them2 the furrow gets deeper and deeper2
 at last it cuts the cell in  two1 and  
the division of the cell is             
accomplished4    ,not only is the growth
 of the already typically formed        
organism carried  out by a series of    
cell-divisions1 but also development    
proper in our  sense1 as a 8production  
of visible manifoldness10 is realised to
 a great  extent by the aid of such     
divisions1 which therefore may indeed be
 said  to be of very fundamental        
importance 7,fig4 #a74    ,illustration3

 ,fig4 #a4--;,diagram of ,cell-,division
 799after99 ,boveri74    99a499 ,resting
 cell2 the chromatin distributed in the 
form of small  granules inside the      
nucleus4 ,outside the nucleus is the    
8centrosome10  not mentioned in the     
text4    99b499 ,beginning of division2 
the chromatin arranged in the form of a 
long  thread4 ,centrosome divided in    
two4    99c499 ,the thread of chromatin 
cut into four parts1 the 8chromosomes40 
99d499 ,the four parts of the chromatin 
arranged symmetrically between the      
centrosomes and the star-like 8spheres40
    99e499 ,each of the chromosomes     
split at full length4    99f499         
,beginning of division of protoplasm2   
the two parts of each  chromosome       
separated4    99g499 ,end of            
cell-division4    ,each cell-division   
which promotes growth is followed by the
  enlargement of the two daughter-cells 
which result from it2 these two         
daughter-elements attain the exact size 
of the mother-cell before  division1 and

 as soon as this size is reached a new  
division begins3  so the growth of the  
whole is in the main the result of the  
growth of  the elements4 ,cell-divisions
 during real organ-formation may behave 
differently1 as will be described at a  
proper occasion4      ,,the ,,egg3 ,,its
 ,,maturation ,,and ,,fertilisation     
,we know that all the organs of an      
animal or plant consist of cells1 and   
we know what acts a cell can perform4   
,now there is one very important  organ 
in all living beings1 which is devoted  
to reproduction4 ,this  organ1 the      
so-called ovary in animals1 is also     
built up of cells1  and its single cells
 are called the eggs2 the eggs          
originated by  cell-division1 and       
cell-division is to lead from them to   
the new adult4    ,but1 with a very few 
exceptions1 the egg in the ovary is not 
able to  accomplish its functions1      
unless certain typical events have      
occurred1  some of which are of a merely
 preparatory kind1 whilst the others are

  the actual stimulus for development4  
,the preparatory ones are generally     
known under the name of 8maturation40   
,the egg must be 8mature10 in order that
 it may begin development1 or  even that
 it may be stimulated to it4 ,maturation
 consists of a rather  complicated      
series of phenomena3 later on we shall  
have occasion to  mention1 at least     
shortly1 what happens in the protoplasm 
during its  course2 as to the nuclear   
changes during maturation it may be     
enough  for our purposes to say1 that   
there occur certain processes among the 
chromosomes1 which lead to an extension 
of half of them in the form  of two very
 small cells1 the 8directive cells0 or  
8directive or polar  bodies10 as they   
have been somewhat cautiously called4   
,the ripe or mature egg is capable of   
being fertilised4    ,before turning to 
this important fact1 which1 by the way1 
will bring us  to our specially chosen  
type1 the ,echinus1 a few words may be  
devoted to  the phenomenon of           

8parthenogenesis10 that is to say1 the  
possibility  of development without     
fertilisation1 since owing to the       
brilliant  discoveries of the ,american 
physiologist1 ,jacques ,loeb1 this topic
 forms  one of the centres of biological
 interest at present4 ,it has long been 
known that the eggs of certain bees1    
lice1 crayfishes1 and other animals  and
 also plants1 are capable of development
 without fertilisation at  all4 ,now    
,richard ,hertwig and ,t4 ,h4 ,morgan   
already had shown1 that at  least       
nuclear division may occur in the eggs  
of other forms--in the egg  of the      
sea-urchin for instance--when these eggs
 are exposed to some  chemical injuries4
 ,but ,loeb#d succeeded in obtaining a  
full development  by treating the eggs  
of echinoderms with chloride of         
magnesium2 thus  artificial             
parthenogenesis had been discovered4    
,later researches have  shown that      
artificial parthenogenesis may occur in 
all classes of the  animal kingdom and  

may be provoked by all sorts of chemical
 or physical  means4 ,we do not know at 
present in what the proper stimulus     
consists  that must be supposed here to 
take the place of fertilisation2 it     
seems1  of course1 highly probable that 
it is always the same in the last       
resort4#e    #d 99,amer4 ,journ4        
,physiol499 vols4 iii4 and iv4 #aijj4   
#e ,according to ,delage 799,arch4      
,zool4 exp4991 #c sr4 #aj1 #aijb71 it is
  indifferent for the realisation of    
artificial parthenogenesis1 whether  but
 one1 or both1 or neither of the 8polar 
bodies0 has been formed4 ,but  the egg  
must be in the first stages of          
maturation to the extent that the       
8nuclear membrane0 must be already      
dissolved4    ,but enough about         
processes1 which at present are of a    
highly scientific1  but hardly of any   
philosophic interest4    ,by            
fertilisation proper we understand the  
joining of the male element1  the       
spermatozoon or the spermia1 with the   

female element1 the egg4 ,like  the egg1
 the spermatozoon is but a cell1 though 
the two differ very much  from one      
another in the relation between their   
protoplasm and nucleus3  in all eggs it 
is the protoplasm which is comparatively
 very large1 if  held together with     
somatic cells1 in the spermatozoon it is
 the nucleus4  ,a large amount of       
reserve material1 destined for the      
growth of the  future being1 is the     
chief cause of the size of the          
egg-protoplasm4 ,the  egg is quite or   
almost devoid of the faculty of         
movement1 while on the  contrary1       
movement is the most typical feature of 
the spermia4 ,its whole  organisation is
 adapted to movement in the most        
characteristic manner3  indeed1 most    
spermatozoa resemble a swimming         
infusorium1 of the type  of ,flagellata1
 a so-called head and a moving tail are 
their two chief  constituents2 the head 
is formed almost entirely of nuclear    
substance4    ,it seems that in most    

cases the spermatozoa swim around at    
random and  that their union with the   
eggs is assured only by their enormous  
number2  only in a few cases in plants  
have there been discovered special      
stimuli  of a chemical nature1 which    
attract the spermia to the egg4    ,but 
we cannot enter here more fully into the
 physiology of  fertilisation1 and shall
 only remark that its real significance 
is by no  means clear4#f    #f ,the     
older theories1 attributing to          
fertilisation 7or to  8conjugation10    
99i4e499 its equivalent in ,protozoa71  
some sort of  8renovation0 or           
8rejuvenescence0 of the race1 have been 
almost  completely given up4 7,see      
,calkins1 99,arch4 fr                   
,entwickelungsmechanik991  xv4 #aijb74  
,r4 ,hertwig recently has advocated the 
view1 that abnormal  relations between  
the amounts of nuclear and of           
protoplasmatic material  are rectified  
in some way by those processes4         
,teleologically1 sexual  reproduction   

has been considered as a means of       
variability 7,weismann71  but also as a 
means of preserving the type6      ,,the
 ,,first ,,development ,,process ,,of   
,,echinus    ,turning now definitively  
to the special kind of organism1 chosen 
of our  type1 the common sea-urchin1 we 
properly begin with a few words about   
the absolute size of its eggs and       
spermatozoa4 ,all of you are familiar   
with the eggs of birds and possibly of  
frogs2 these are abnormally  large eggs1
 on account of the very high amount of  
reserve material they  contain4 ,the    
almost spherical egg of our ,echinus    
only measures about a  tenth of a       
millimetre in diameter2 and the head of 
the spermatozoon has  a volume which is 
only the four-hundred-thousandth part of
 the volume  of the egg6 ,the egg is    
about on the extreme limit of what can  
be seen  without optical instruments2 it
 is visible as a small white point4 ,but
  the number of eggs produced by a      
single female is enormous and may       

amount to hundreds of thousands2 this is
 one of the properties which  render the
 eggs of ,echinus so very suitable for  
experimental research2  you can obtain  
them whenever and in any quantity you   
like2 and1  moreover1 they happen to be 
very clear and transparent1 even in     
later  stages1 and to bear all kinds of 
operations well4    ,the spermia enters 
the egg1 and it does so in the open     
water--another  of the experimental     
advantages of our type4 ,only one       
spermia enters  the egg in normal cases1
 and only its head goes in1 the tail is 
left  outside4 ,the moment that the head
 has penetrated the protoplasm of the   
egg a thin membrane is formed by the    
latter4 ,this membrane is very soft  at 
first1 becoming much stronger later on2 
it is very important for all            
experimental work1 that by shaking the  
egg in the first minutes of its         
existence the membrane can easily be    
destroyed without any damage to the  egg
 itself4    ,and now occurs the chief   

phenomenon of fertilisation3 the nucleus
 of  the spermatozoon unites with the   
nucleus of the egg4 ,when speaking of   
maturation1 we mentioned that half of   
the chromatin was thrown out of  the egg
 by that process3 now this half is      
brought in again1 but comes  from       
another individual4    ,it is from this 
phenomenon of nuclear union as the main 
character of  fertilisation that almost 
all theories of heredity assume their   
right to  regard the nuclei of the      
sexual cells as the true 8seat0 of      
inheritance4  ,later on we shall have   
occasion to discuss this hypothesis from
 the  point of view of logic and fact4  
,after the complete union of what are   
called the male and the female          
8pronuclei10 the egg begins its         
development2 and this development1 in   
its first steps1 is simply pure         
cell-division4 ,we know already the     
chief  points of this process1 and need 
only add to what has been described1    
that in the whole first series of the   

cell-divisions of the egg1 or1  to use  
the technical term1 in the whole process
 of the 8cleavage0 or  8segmentation0 of
 it1 there is never any growth of the   
daughter-elements  after each division1 
such as we know to occur after all      
cell-divisions  of later embryological  
stages4 ,so it happens1 that during     
cleavage the  embryonic cells become    
smaller and smaller1 until a certain    
limit is  reached2 the sum of the       
volumes of all the cleavage cells       
together is  equal to the volume of the 
egg4    ,but our future studies will    
require a more thorough knowledge of the
  cleavage of our ,echinus2 the         
experimental data we shall have to      
describe  later on could hardly be      
properly understood without such        
knowledge4  ,the first division plane1  
or1 as we shall say1 the first cleavage 
plane1 divides the eggs into equal      
parts2 the second lies at right  angles 
to the first and again divides equally3 
we now have a ring of  four cells4 ,the 

third cleavage plane stands at right    
angles to the  first two2 it may be     
called an equatorial plane1 if we       
compare the egg  with a globe2 it also  
divides equally1 and so we now find two 
rings1  each consisting of four cells1  
and one above the other4 ,but now the   
cell-divisions cease to be equal1 at    
least in one part of the egg3 the  next 
division1 which leads from the eight- to
 the sixteen-cell stage of  cleavage1   
forms four rings1 of four cells each1   
out of the two rings of  the eight-cell 
stage4 ,only in one half of the germ1 in
 which we shall  call the upper one1 or 
which we might call1 in comparison with 
a globe1  the northern hemisphere1 are  
cells of equal size to be found2 in the 
lower half of the egg four very small   
cells have been formed at one  8pole0 of
 the whole germ4 ,we call these cells   
the 8micromeres10 that  is1 the 8small  
parts10 on the analogy of the term      
8blastomeres10 that  is1 parts of the   
germ1 which is applied to all the       

cleavage cells in  general4 ,the place  
occupied by the micromeres is of great  
importance  to the germ as a whole3 the 
first formation of real organs will     
start  from this point later on4 ,it is 
sufficient thus fully to have studied   
the cleavage of our ,echinus up to this 
stage3 the later cleavage stages  may be
 mentioned more shortly4 ,all the       
following divisions are into  equal     
parts2 there are no other micromeres    
formed1 though1 of course1  the cells   
derived from the micromeres of the      
sixteen-cell stage always  remain       
smaller than the rest4 ,all the         
divisions are tangential2 radial        
cleavages never occur1 and therefore the
 process of cleavage ends at  last in   
the formation of one layer of cells1    
which forms the surface  of a sphere2 it
 is especially by the rounding-up of    
each blastomere1  after its individual  
appearance1 that this real surface layer
 of cells  is formed1 but1 of course1   
the condition1 that no radial divisions 

occur1 is the most important one in its 
formation4 ,when #hjh blastomeres  have 
come into existence the process of      
cleavage is finished2 a sphere  with a  
wall of cells and an empty interior is  
the result4 ,that only #hjh  cells are  
formed1 and not1 as might be expected1  
#ajbd1 is due to the  fact that the     
micromeres divide less often than the   
other elements2 but  speaking roughly1  
of course1 we may say that there are ten
 steps of  cleavage-divisions in our    
form2 #ajbd being equal to #baj4    ,we 
have learned that the first process of  
development1 the cleavage1 is  carried  
out by simple cell-division4 ,a few     
cases are known1 in which  cell-division
 during cleavage is accompanied by a    
specific migration of  parts of the     
protoplasm in the interior of the       
blastomeres1 especially  in the first   
two or first four2 but in almost all    
instances cleavage  is as simple a      
process of mere division as it is in our
 sea-urchin4  ,now the second step in   

development1 at least in our form1 is a 
typical  histological performance3 it   
gives a new histological feature to all 
of the blastomeres3 they acquire small  
cilia on their outer side and  with     
these cilia the young germ is able to   
swim about after it has left  its       
membrane4 ,the germ may be called a     
8blastula0 at this stage1 as it  was    
first called by ,haeckel1 whose useful  
denominations of the first  embryonic   
stages may conveniently be applied1 even
 if one does not agree  with most1 or   
perhaps almost all1 of his speculations 
7,fig4 #b74    ,illustration3 ,fig4     
#b4--;,early ,development of ,echinus1  
the ,common  ,sea-urchin4    99a499 ,two
 cells4    99b499 ,four cells4    99c499
 ,eight cells1 arranged in two rings of 
four1 above one another4    99d499      
,sixteen cells1 four 8micromeres0 formed
 at the 8vegetative0 pole4    99e499    
,optical section of the 8blastula10 a   
hollow sphere consisting of  about one  
thousand cells1 each of them with a     

small cilium4    ,it is important to    
notice that the formation of the        
8blastula0 from the  last cleavage stage
 is certainly a process of organisation1
 and may also  be called a              
differentiation with regard to that     
stage4 ,but there is in  the blastula no
 trace of one 99part99 of the germ      
becoming different with  respect to     
others of its parts4 ,if development    
were to go on in this  direction alone1 
high organisatory complications might   
occur3 but there  would always be only  
one sort of cells1 arranged in a sphere2
 there  would be only one kind of what  
is called 8tissue40    ,but in fact     
development very soon loads to true     
differences of the  parts of the germ   
with respect to one another1 and the    
next step of the  process will enable us
 to apply different denominations to the
 different  parts of the embryo4    ,at 
one pole of the swimming blastula1      
exactly at the point where the          
descendants of the micromeres are       

situated1 about fifty cells lose        
contact with their neighbours and leave 
the surface of the globe1 being  driven 
into the interior space of it4 ,not very
 much is known about the  exact manner  
in which these changes of cellular      
arrangement are carried  out1 whether   
the cells are passively pressed by their
 neighbours1 or  whether1 perhaps1 in a 
more active manner1 they change their   
surface  conditions2 therefore1 as in   
most ontogenetic processes1 the         
description  had best be made cautiously
 in fairly neutral or figurative words4 
,the cells which in the above manner    
have entered the interior of the        
blastula are to be the foundation of    
important parts of the future  organism2
 they are to form its connective tissue1
 many of its muscles1  and the skeleton4
 8,mesenchyme10 99i4e499 8what has been 
infused into the  other parts10 is the  
technical name usually applied to these 
cells4  ,we now have to learn their     
definite arrangement4 ,at first they lie

  as a sort of heap inside the cell wall
 of the blastula1 inside the            
8blastoderm10 99i4e499 skin of the germ4
 ,but soon they move from one  another1 
to form a ring round the pole at which  
they entered1 and on  this ring a       
process takes place which has a very    
important bearing upon  the whole type  
of the organisation of the germ4 ,you   
will have noticed  that hitherto the    
germ with regard to its symmetry has    
been a monaxial  or radial formation2   
the cleavage stages and the blastula    
with its  mesenchyme were forms with two
 different poles1 lying at the ends of  
one  single line1 and round this line   
everything was arranged concentrically4 
,but now what is called 8bilateral      
symmetry0 is established2 the           
mesenchyme ring assumes a structure     
which can be symmetrically divided  only
 by one plane1 but divided in such a    
way1 that one-half of it is the  mirror 
image of the other4 ,a figure shows best
 what has occurred1 and  you will notice

 7,fig4 #c7 two masses of cells in this 
figure1 which have  the forms of        
spherical triangles3 it is in the midst 
of these triangles  that the skeleton of
 the larva 99originates994 ,the germ had
 an upper and  a lower side before3 it  
now has got an upper and lower1 front   
and back1  99right and left99 half2 it  
now has acquired that symmetry of       
organisation  which our own body has2 at
 least it has got it as far as its      
mesenchyme  is concerned4               
,illustration3 ,fig4 #c4--;,formation of
 ,mesenchyme in ,echinus4    99a499     
,outlines of blastula1 side-view2       
mesenchyme forms a heap of cells  at the
 8vegetative0 pole4    99a99#a4 ,heap of
 mesenchyme-cells from above4    99b499 
,mesenchyme-cells arranged in a ring    
round the vegetative pole4    99c499    
,mesenchyme-cells arranged in a         
bilateral-symmetrical figure2  primordia
 of skeleton in the midst of two        
spherical triangles4    ,we leave the   
mesenchyme for a while and study another

 kind of  organogenesis4 ,at the very   
same pole of the germ where the         
mesenchyme  cells originated there is a 
long and narrow tube of cell growing in1
  and this tube1 getting longer and     
longer1 after a few hours of growth     
touches the opposite pole of the larva4 
,the growth of this cellular tube  marks
 the beginning of the formation of the  
intestine1 with all that  is to be      
derived from it4 ,the larva now is no   
longer a blastula1 but  receives the    
name of 8gastrula0 in ,haeckel's        
terminology2 it is built  up of the     
three 8germ-layers0 in this stage4 ,the 
remaining part of the  blastoderm is    
called 8ectoderm10 or outer layer2 the  
newly-formed tube1  8endoderm10 or inner
 layer2 while the third layer is the    
8mesenchyme0  already known to us4      
,the endoderm itself is a radial        
structure at first1 as was the whole    
germ in a former stage1 but soon its    
free end bends and moves against  one of
 the sides of the ectoderm1 against that

 side of it where the two  triangles of 
the mesenchyme are to be found also4    
,thus the endoderm  has acquired        
bilateral symmetry just as the          
mesenchyme before1 and  as in this stage
 the ectoderm also assumes a bilateral  
symmetry  in its form1 corresponding    
with the symmetrical relations in the   
endoderm and the mesenchyme1 we now may 
call the whole of our larva a           
bilateral-symmetrical organisation4     
,it cannot be our task to follow all the
 points of organogenesis of  ,echinus in
 detail4 ,it must suffice to state      
briefly that ere long a  second portion 
of the mesenchyme is formed in the      
larva1 starting from  the free end of   
its intestine tube2 that the formation  
of the so-called  8coelum0 occurs by a  
sort of splitting off from this same    
original  organ2 and that the intestine 
itself is divided into three parts of   
different size and aspect by two        
circular sections4    ,but we must not1 
,i think1 dismiss the formation of the  

skeleton so  quickly4 ,i told you       
already that the skeleton has its first 
origin in  the midst of the two         
triangular cell-masses of the           
mesenchyme2 but what  are the steps     
before it attains its typical and       
complicated structure8  ,at the         
beginning a very small tetrahedron1     
consisting of carbonate of  calcium1 is 
formed in each of the triangles2 the    
four edges of the  tetrahedron are      
produced into thin rods1 and by means of
 a different  organogenesis along each  
of these rods the typical formation of  
the  skeleton proceeds4 ,but the manner 
in which it is carried out is very      
strange and peculiar4 ,about thirty of  
the mesenchyme cells are occupied  in   
the formation of skeleton substance on  
each side of the larva4 ,they  wander   
through the interior space of the       
gastrula--which at this stage  is not   
filled with sea water but with a sort of
 gelatinous material--and  wander in    
such a manner that they always come to  

the right places1 where  a part of the  
skeleton is to be formed2 they form it  
by a process of  secretion1 quite       
unknown in detail2 one of them forms one
 part1 one the  other1 but what they    
form altogether1 is one whole4    ,when 
the formation of the skeleton is        
accomplished1 the typical larva  of our 
,echinus is built up2 it is called the  
8pluteus0 7,fig4 #d74 ,though  it is far
 from being the perfect adult animal1 it
 has an independent  life of its own2 it
 feeds and moves about and does not go  
through any  important changes of form  
for weeks4 ,but after a certain period  
of  this species of independent life as 
a 8larva10 the changes of form it       
undergoes again are most fundamental3 it
 must be transformed into the  adult    
sea-urchin1 as all of you know4 ,there  
are hundreds and hundreds  of single    
operations of organogenesis to be       
accomplished before that  end is        
reached2 and perhaps the strangest of   
all these operations is a  certain sort 

of growth1 by which the symmetry of the 
animal1 at least  in certain of its     
parts--not in all of them--is changed   
again from  bilateral to radial1 just   
the opposite of what happened in the    
very  early stages4    ,illustration3   
,fig4 #d4--,larval ,development of      
,echinus4    99,a499 ,the gastrula4     
99,b499 ,later stage1                   
bilateral-symmetrical4 ,intestine begins
 to divide  into three parts4    99,c499
 ,pluteus larva4 ,s  ,skeleton4 ,i      
,intestine4    ,but we cannot follow the
 embryology of our ,echinus further     
here2 and  indeed we are the less       
obliged to do so1 since in all our      
experimental  work we shall have to deal
 with it only as far as to the pluteus  
larva4  ,it is impossible under ordinary
 conditions to rear the germs up to the 
adult stages in captivity4    ,you now1 
,i hope1 will have a general idea at    
least of the processes  of which the    
individual development of an animal     
consists4 ,of course  the specific      

features leading from the egg to the    
adult are different  in each specific   
case1 and1 in order to make this point  
as clear as  possible1 ,i shall now add 
to our description a few words about    
what may  be called a comparative       
descriptive embryology4                 
,,comparative ,,embryology    ,even the 
cleavage may present rather different   
aspects4 ,there may be a  compact       
blastula1 not one surrounded by only one
 layer of cells as in  ,echinus2 or     
bilaterality may be established as early
 as the cleavage  stage--as in many     
worms and in ascidians--and not so late 
as in ,echinus4  ,the formation of the  
germ layers may go on in a different    
order and  under very different         
conditions3 a rather close relative of  
our ,echinus1  for instance1 the        
starfish1 forms first the endoderm and  
afterwards  the mesenchyme4 ,in many    
cases there is no tube of cells forming 
the  8endoderm10 but a flat layer of    
cells is the first foundation of all the

  intestinal organs3 so it is in all    
birds and in the cuttlefish4 ,and1  as  
all of you know1 of course1 there are   
very many animal forms which  have no   
proper 8larval0 stage3 there is one in  
the frog1 the well-known  8tadpole10 but
 the birds and mammals have no larvae2  
that is to say1  there is no special    
stage in the ontogeny of these forms    
which leads an  independent life for a  
certain time1 as if it were a species by
 itself1  but all the ontogenetical     
stages are properly 8embryonic0--the    
germ is  always an 8embryo0 until it    
becomes the perfect young organism4 ,and
 you  also know that not all skeletons  
consist of carbonate of calcium1 but1   
that there are skeletons of silicates1  
as in ,radiolaria1 and of horny         
substance1 as in many sponges4 ,and1    
indeed1 if we were to glance at the     
development of plants also1 the         
differences would seem to us probably   
so great that all the similarities would
 seem to disappear4    ,but there are   

similarities1 nevertheless1 in all      
development1 and we  shall now proceed  
to examine what they are4 ,as a matter  
of fact1 it was  especially for their   
sake that we studied the ontogeny of a  
special  form in such detail2 one always
 sees generalities better if one knows  
the specific features of at least one   
case4 ,what then are the features  of   
most general and far-reaching           
importance1 which may be abstracted     
from the individual history of our      
sea-urchin1 checked always by the       
teachings of other ontogenies1 including
 those of plants8      ,,the ,,first    
,,steps ,,of ,,analytical               
,,morphogenesis    ,if we look back upon
 the long fight of the schools of       
embryologists in  the eighteenth century
 about the question whether individual  
development  was to be regarded as a    
real production of visible manifoldness 
or as  a simple growth of visibly       
pre-existing manifoldness1 whether it   
was  8epigenesis0 or 8evolutio10 there  

can be no doubt1 if we rely on all  the 
investigations of the last hundred and  
fifty years1 that1 taken in  the        
descriptive sense1 the theory of        
epigenesis is right4 ,descriptively     
speaking there 99is99 a production of   
visible manifoldness in the course  of  
embryology3 that is our first and main  
result4 ,any one possessed of  an       
average microscope may any day convince 
himself personally that it is  true4    
,in fact1 true epigenesis1 in the       
descriptive sense of the term1 does     
exist4 ,one thing is formed 8after0 the 
other2 there is not a mere  8unfolding0 
of what existed already1 though in a    
smaller form2 there is  no 8evolutio0 in
 the old meaning of the word4    ,the   
word 8evolution0 in ,english usually    
serves to denote the theory of  descent1
 that is of a real relationship of all  
organisms4 ,of course we  are not       
thinking here of this modern and        
specifically ,english meaning of  the   
,latin word 99evolutio994 ,in its       

ancient sense it means to a certain     
degree just the opposite2 it says that  
there is no formation of anything  new1 
no transformation1 but simply growth1   
and this is promoted not for  the race  
but for the individual4 ,keeping well in
 mind these historical  differences in  
the meaning of the word 8evolutio10 no  
mistakes1 it seems  to me1 can occur    
from its use4 ,we now shall try to      
obtain a few more  particular results   
from our descriptive study of           
morphogenesis1 which  are nevertheless  
of a general bearing1 being real        
characteristics of  organic individual  
development1 and which1 though not      
calculated of  themselves to further the
 problem1 will in any case serve to     
prepare for  a more profound study of   
it4    ,the totality of the line of     
morphogenetic facts can easily be       
resolved  into a great number of        
distinct processes4 ,we propose to call 
these  8elementary morphogenetic        
processes02 the turning in of the       

endoderm  and its division into three   
typical parts are examples of them4 ,if 
we  give the name 8elementary organs0 to
 the distinct parts of every stage  of  
ontogeny which are uniform in themselves
 and are each the result of  one        
elementary process in our sense1 we are 
entitled to say that each  embryological
 stage consists of a certain number of  
elementary organs4  ,the mesenchyme     
ring1 the coelum1 the middle-intestine1 
are instances of  such organs4 ,it is   
important to notice well that the word  
elementary is  always understood here   
with regard to visible morphogenesis    
proper and  does not apply to what may  
be called elementary in the             
physiological  sense4 ,an elementary    
process in our sense is a very distinct 
act of  form-building1 and an elementary
 organ is the result of every one of    
such acts4    ,the elementary organs are
 typical with regard to their position  
and with  regard to their histological  
properties4 ,in many cases they are of a

  very clearly different histological   
type1 as for instance1 the cells of  the
 three so-called germ-layers2 and in    
other cases1 though apparently  almost  
identical histologically1 they can be   
proved to be different  by their        
different power of resisting injuries or
 by other means4 ,but  there are not as 
many different types of histological    
structure as there  are typically placed
 organs3 on the contrary there are many 
elementary  organs of the same type in  
different typical parts of the organism1
 as  all of you know to be the case with
 nerves and muscles4 ,it will not be    
without importance for our future theory
 of development1 carefully to  notice   
this fact1 that specialisation in the   
99position99 of embryonic  parts is more
 strict than in their histology4    ,but
 elementary organs are not only typical 
in position and histology1  they are    
typical also with regard to their form  
and their relative size4  ,it agrees    
with what has been said about histology 

being independent of  typical position1 
that there may be a number of organs in 
an embryonic  stage1 all in their most  
typical positions1 which though all     
possessing  the same histology1 may have
 different forms or different sizes or  
both3 the single bones of the skeleton  
of vertebrates or of adult  echinoderms 
are the very best instances of this most
 important feature  of organogenesis4   
,if we look back from elementary organs 
to elementary  processes1 the           
specialisation of the size of those     
organs may also be  said to be the      
consequence of a typical duration of the
 elementary  morphogenetic process      
leading to them4#g    #g ,the phrase    
899ceteris paribus990 has to be added of
 course1 as the  duration of each single
 elementary morphogenetic process is    
liable to  vary with the temperature and
 many other conditions of the medium4   
,i hardly need to say1 that the         
histology1 form1 and size of elementary 
organs are equally an expression of     

their present or future  physiological  
function4 ,at least they prepare for    
this function by a  specific sort of    
metabolism which sets in very early4    
,the whole sequence of individual       
morphogenesis has been divided by some  
embryologists into two different        
periods2 there is a first period1       
during which the foundations of the     
organisation of the 8type0 are  laid    
down1 and a second period1 during which 
the histo-physiological  specifications 
are modelled out 7von ,baer1 ,gtte1     
,roux74 ,such a  discrimination is      
certainly justified1 if not taken too   
strictly2 but  its practical application
 would encounter certain difficulties in
 many  larval forms1 and also1 of       
course1 in all plants4    ,our mention  
of plants leads us to the last of our   
analytical results4 ,if  an animal germ 
proceeds in its development from a stage
 99d99 to the stage  99g991 passing     
through 99e99 and 99f991 we may say that
 the whole of 99d99 has  become the     

whole of 99f991 but we cannot say that  
there is a certain part  of 99f99 which 
is 99d991 we cannot say that 99f99 is   
99d99  99a994 ,but in plants  we can3   
the stage 99f99 is indeed equal to 99a99
  99b99  99c99  99d99  99e99   99a99    
,transcriber's note3 probable typo for  
99f99 in vegetable organisms2  all      
earlier stages are actually visible as  
parts of the last one4 ,the  great      
embryologist1 ,carl ,ernst von ,baer1   
most clearly appreciated these          
analytical differences between animal   
and vegetable morphogenesis4 ,they      
become a little less marked if we       
remember that plants1 in a certain      
respect1 are not simple individuals but 
colonies1 and that among the  corals1   
hydroids1 bryozoa1 and ascidia1 we find 
analogies to plants in  the animal      
kingdom2 but nevertheless the           
differences we have stated are  not     
extinguished by such reasoning4 ,it     
seems almost wholly due to the          
occurrence of so many foldings and      

bendings and migrations of cells and    
complexes of cells in animal            
morphogenesis1 that an earlier stage of 
their development seems 99lost99 in the 
later one2 those processes are  almost  
entirely wanting in plants1 even if we  
study their very first  ontogenetic     
stages4 ,if we say that almost all      
production of surfaces  goes on outside 
in plants1 inside in animals1 we shall  
have adequately  described the          
difference4 ,and this feature again     
leads to the further  diversity between 
animals and plants which is best        
expressed by calling  the former        
8closed10 the latter 8open0 forms3      
animals reach a point  where they are   
finished1 plants never are finished1 at 
least in most  cases4    ,i hope you    
will allow that ,i have tried to draw   
from descriptive and  comparative       
embryology as many general analytical   
results as are  possibly to be obtained4
 ,it is not my fault if there are not   
any  more1 nor is it my fault if the    

results reached are not of the most     
satisfactory character4 ,you may say    
that these results perhaps enable  you  
to see a little more clearly and        
markedly than before a few of the       
characters of development1 but that you 
have not really learnt anything  new4   
,your disappointment--my own            
disappointment--in our analysis is due  
to the use of pure description and      
comparison as scientific methods4       
,,the ,,limits ,,of ,,pure ,,description
 ,,in ,,science    ,we have analysed our
 descriptions as far as we could1 and   
now we must  confess that what we have  
found cannot be the last thing knowable 
about individual morphogenesis4 ,there  
must be something deeper to be          
discovered3 we only have been on the    
surface of the phenomena1 we  now want  
to get to the very bottom of them4 ,why 
then occurs all that  folding1 and      
bending1 and histogenesis1 and all the  
other processes we  have described8     
,there must be something that drives    

them out1 so to say4    ,there is a very
 famous dictum in the 99,treatise on    
,mechanics99 by the  late ,gustav       
,kirchhoff1 that it is the task of      
mechanics to describe  completely and in
 the most simple manner all the motions 
that occur in  nature4 ,these words1    
which may appear problematic even in    
mechanics1  have had a really pernicious
 influence on biology4 ,people were     
extremely  pleased with them4           
8#8,describing'--that is just what we   
always have  done10 they said2 8now we  
see that we have done just what was     
right2  a famous physicist has told us  
so40 ,they did not see that ,kirchhoff  
had added the words 8completely and in  
the most simple manner02 and  moreover1 
they did not consider that ,kirchhoff   
never regarded it as the  ultimate aim  
of physics to describe thunderstorms or 
volcanic eruptions  or denudations2 yet 
it only is with such 8descriptions0 that
 biological  descriptions of 99given99  
bodies and processes are to be compared6

    ,physicists always have used both   
experiment and hypothetical             
construction--,kirchhoff himself did so 
in the most gifted manner4 ,with  these 
aids they have gone through the whole of
 the phenomena1 and what  they found to 
be ultimate and truly elemental1 that   
alone may they  be said to have         
8described02 but they have 8explained0  
by the aid of  elementalities what      
proved to be not elemental in itself4#h 
#h ,we shall not avoid in these lectures
 the word 8explain0--so much  out of    
fashion nowadays4 ,to 8explain0 means to
 subsume under known  concepts1 or      
rules1 or laws1 or principles1 whether  
the laws or concepts  themselves be     
8explained0 or not4 ,explaining1        
therefore1 is always  relative3 what is 
elemental1 of course1 is only to be     
described1 or  rather to be stated4     
,it is the 99method99 of the            
physicists--not their results--that     
morphogenesis has to apply in order to  
make progress2 and this method  we shall

 begin to apply in our next lectures4   
,physiology proper has  never been so   
short-sighted and self-satisfied as not 
to learn from  other sciences1 from     
which indeed there was very much to be  
learned2 but  morphology has3 the bare  
describing and comparing of descriptions
 has  been its only aim for about forty 
years or more1 and lines of descent of  
a very problematic character were its   
only general results4 ,it was not  seen 
that science had to begin1 not with     
problematic events of the past1  but    
with what actually happens before our   
eyes4    ,but before saying any more    
about the exact rational and            
experimental  method in morphology1     
which indeed may be regarded as a new   
method1  since its prevalence in the    
eighteenth century had been really      
forgotten1 we first shall have to       
analyse shortly some general attempts   
to understand morphogenesis by means of 
hypothetic construction  exclusively4   
,such attempts have become very         

important as points of  issue for really
 exact research1 and1 moreover1 they    
deserve attention1  because they prove  
that their authors at least had not     
quite forgotten  that there were still  
other problems to be solved in          
morphology than  only phylogenetical    
ones4          99,b499 ,,experimental   
,,and ,,theoretical ,,morphogenesis     
#a4 ,,the ,,foundations ,,of ,,the      
,,physiology ,,of ,,development4        
8,,evolutio0 ,,and  8,,epigenesis0      
,,the ,,theory ,,of ,,weismann    ,of   
all the purely hypothetic theories on   
morphogenesis that of ,august           
,weismann#i can claim to have had the   
greatest influence1 and to  be at the   
same time the most logical and the most 
elaborated4 ,the  8germ-plasma0 theory  
of the ,german author is generally      
considered as  being a theory of        
heredity1 and that is true inasmuch as  
problems of  inheritance proper have    
been the starting-point of all his      
hypothetic  speculations1 and also form 

in some respect the most valuable part  
of them4 ,but1 rightly understood1      
,weismann's theory consists of two      
independent parts1 which relate to      
morphogenesis and to heredity           
separately1 and it is only the first    
which we shall have to take into        
consideration at present2 what is       
generally known as the doctrine of the  
8continuity of the germ-plasm0 will be  
discussed in a later chapter4    #i     
99,das ,keimplasma991 ,jena1 #ahib4     
,weismann assumes that a very           
complicated organised structure1 below  
the limits of visibility even with the  
highest optical powers1 is the          
foundation of all morphogenetic         
processes1 in such a way that1 whilst   
part of this structure is handed over   
from generation to generation as  the   
basis of heredity1 another part of it is
 disintegrated during the  individual   
development1 and directs development by 
being disintegrated4  ,the expression1  
8part0 of the structure1 first calls for

 some  explanation4 ,weismann supposes  
several examples1 several copies1 as it 
were1 of his structure to be present in 
the germ cells1 and it is to  these     
copies that the word 8part0 has been    
applied by us3 at least one  copy has to
 be disintegrated during ontogeny4      
,the morphogenetic structure is assumed 
to be present in the nucleus  of the    
germ cells1 and ,weismann supposes the  
disintegration of his  hypothetic       
structure to be accomplished by nuclear 
division4 ,by the  cleavage of the egg1 
the most 99fundamental99 parts of it are
 separated  one from the other4 ,the    
word 8fundamental0 must be understood as
  applying not to proper elements or    
complexes of elements of the            
organisation1 but to the chief relations
 of symmetry2 the first  cleavage1 for  
instance1 may separate the right and the
 left part of  the structure1 the second
 one its upper and lower parts1 and     
after the  third or equatorial cleavage 
all the principal eighths of our minute 

organisation are divided off3 for the   
minute organisation1 it must now  be    
added1 had been supposed to be built up 
differently in the three  directions of 
space1 just as the adult organism is4   
,weismann concedes it  to be absolutely 
unknown in what manner the proper       
relation between the  parts of the      
disintegrated fundamental morphogenetic 
structure and the  real processes of    
morphogenesis is realised2 enough that  
there may be  imagined such a relation4 
,at the end of organogenesis the        
structure is assumed to have been       
broken up into its elements1 and these  
elements1 which may be chemical         
compounds1 determine the fate of the    
single cells of the adult organism4     
,here let us pause for a moment4 ,there 
cannot be any doubt that  ,weismann's   
theory resembles to a very high degree  
the old 8evolutio0  doctrines of the    
eighteenth century1 except that it is a 
little less  crude4 ,the chick itself is
 not supposed to be present in the hen's

 egg  before development1 and ontogeny  
is not regarded as a mere growth of     
that chick in miniature1 but what really
 is supposed to be present in  the egg  
is nevertheless a something that in all 
its parts corresponds  to all the parts 
of the chick1 only under a somewhat     
different  aspect1 while all the        
relations of the parts of the one       
correspond  to the relations of the     
parts of the other4 ,indeed1 only on    
such an  hypothesis of a fairly fixed   
and rigid relation between the parts of 
the morphogenetic structure could it be 
possible for the disintegration  of the 
structure to go on1 not by parts of     
organisation1 but by parts  of symmetry2
 which1 indeed1 is a very strange1 but  
not an illogical1  feature of           
,weismann's doctrine4    ,weismann is   
absolutely convinced that there must be 
a theory of  8evolutio10 in the old     
sense of the word1 to account for the   
ontogenetic  facts2 that 8epigenesis0   
has its place only in descriptive       

embryology1  where1 indeed1 as we know1 
manifoldness in the 99visible99 sense is
  produced1 but that epigenesis can     
never form the foundation of a real     
morphogenetic 99theory993 theoretically 
one pre-existing manifoldness is        
transformed into the other4 ,an         
epigenetic theory would lead right      
beyond  natural science1 ,weismann      
thinks1 as in fact1 all such theories1  
if  fully worked out1 have carried their
 authors to vitalistic views4 ,but      
vitalism is regarded by him as dethroned
 for ever4    ,under these circumstances
 we have a good right1 it seems to me1  
to speak  of a 99dogmatic99 basis of    
,weismann's theory of development4      
,but to complete the outlines of the    
theory itself3 ,weismann was  well aware
 that there were some grave difficulties
 attaching to his  statements3 all the  
facts of so-called adventitious         
morphogenesis in  plants1 of            
regeneration in animals1 proved that the
 morphogenetic  organisation could not  

be fully disintegrated during ontogeny4 
,but these  difficulties were not       
absolute3 they could be overcome3       
indeed1 ,weismann  assumes1 that in     
certain specific cases--and he regarded 
all cases of  restoration of a destroyed
 organisation as due to specific        
properties  of the subjects1 originated 
by roundabout variations and natural    
selection--that in specific cases1      
specific arrangements of minute parts   
were formed during the process of       
disintegration1 and were surrendered  to
 specific cells during development1 from
 which regeneration or  adventitious    
budding could originate if required4    
8,plasma of reserve0  was the name      
bestowed on these hypothetic            
arrangements4    ,almost independently  
another ,german author1 ,wilhelm        
,roux1#aj has  advocated a theoretical  
view of morphogenesis which very closely
  resembles the hypothesis of ,weismann4
 ,according to ,roux a minute  ultimate 
structure is present in the nucleus of  

the germ and directs  development by    
being divided into its parts during the 
series of nuclear  divisions4    #aj    
99,die ,bedeutung der                   
,kernteilungsfiguren991 ,leipzig1 #ahhc4
    ,but in spite of this similarity of 
the outset1 we enter an altogether      
different field of biological           
investigation on mentioning ,roux's     
name3  we are leaving hypothetic        
construction1 at least in its           
absoluteness1  and are entering the     
realms of scientific experiment in      
morphology4      ,,experimental         
,,morphology    ,i have told you already
 in the last lecture that1 while in the 
eighteenth century individual           
morphogenesis had formed the centre of  
biological interest and been studied    
experimentally in a thoroughly  adequate
 manner1 that interest gradually        
diminished1 until at last  the          
physiology of form as an exact separate 
science was almost wholly  forgotten4   
,at least that was the state of affairs 

as regards zoological  biology2         
botanists1 it must be granted1 have     
never lost the historical  continuity to
 such a degree2 botany has never ceased 
to be regarded  as one science and never
 was broken up into parts as zoology    
was4  ,zoological physiology and        
zoological morphology indeed were for   
many  years in a relationship to one    
another not very much closer than the   
relation between philology and          
chemistry4    ,there were always a few  
men1 of course1 who strove against the  
current4  ,the late ,wilhelm ,his1#aa   
instance1 described the embryology of   
the  chick in an original manner1 in    
order to find out the mechanical        
relations of embryonic parts1 by which  
passive deformation1 as an  integrating 
part of morphogenesis1 might be induced4
 ,he also most  clearly stated the      
ultimate aim of embryology to be the    
mathematical  derivation of the adult   
form from the distribution of growth in 
the  germ4 ,to ,alexander ,goette#ab we 

owe another set of analytical           
considerations about ontogeny4 ,newport1
 as early as #ahej1 and in  later years 
,pflger and ,rauber1 carried out        
experiments on the eggs  of the frog1   
which may truly be called anticipatory  
of what was to  follow4 ,but it was     
,wilhelm ,roux1#ac now professor of     
anatomy at  ,halle1 who entered the     
field with a thoroughly elaborated      
programme1  who knew not only how to    
state the problem analytically1 but also
  how to attack it1 fully convinced of  
the importance of what he did4          
8,entwickelungsmechanik10--mechanics of 
development--he called the 8new  branch 
of anatomical science0 of which he tried
 to lay the foundations4    #aa         
99,unsere ,krperform991 ,leipzig1 #ahge4
    #ab 99,die ,entwickelungsgeschichte 
der ,unke991 ,leipzig1 #ahge4    #ac    
99,gesammelte ,abhandlungen991 ,leipzig1
 #ahie4 ,most important  theoretical    
papers3--99,zeitschr4 ,biolog499 #ba1   
#ahhe2 99,die  ,entwickelungsmechanik   

der ,organismen991 ,wien1 #ahij2        
99,vortrge und  ,aufstze ber            
,entwickelungsmechanik991 ,heft i41     
,leipzig1 #aije4    ,i cannot let this  
occasion pass without emphasising in the
 most decided  manner how highly in my  
opinion ,roux's services to the         
systematic  exploration of morphogenesis
 must be esteemed4 ,i feel the more     
obliged  to do so1 because later on ,i  
shall have to contradict not only many  
of his positive statements but also most
 of his theoretical views4 ,he  himself 
has lately given up much of what he most
 strongly advocated only  ten years ago4
 ,but ,roux's place in the history of   
biological science can  never be        
altered1 let science take what path it  
will4    ,it is not the place here to   
develop the logic of experiment2 least  
of  all is it necessary in the country  
of ,john ,stuart ,mill4 ,all of you know
  that experiment1 by its method of     
isolating the single constituents  of   
complicated phenomena1 is the principal 

aid in the discovery of  so-called      
causal relations4 ,let us try then to   
see what causal  relations ,wilhelm     
,roux established with the aid of       
morphogenetic  experiment4      ,,the   
,,work ,,of ,,wilhelm ,,roux    ,we know
 already that an hypothesis about the   
foundation of individual  development   
was his starting-point4 ,like ,weismann 
he supposed that  there exists a very   
complicated structure in the germ1 and  
that nuclear  division leads to the     
disintegration of that structure4 ,he   
next tried to  bring forward what might 
be called a number of indicia supporting
 his  view4    ,a close relation had    
been found to exist in many cases       
between the  direction of the first     
cleavage furrows of the germ and the    
direction  of the chief planes of       
symmetry in the adult3 the first        
cleavage1 for  instance1 very often     
corresponds to the median plane1 or     
stands at right  angles to it4 ,and in  
other instances1 such as have been      

worked out into  the doctrine of        
so-called 8cell-lineages10 typical      
cleavage cells were  found to correspond
 to typical organs4 ,was not that a     
strong support  for a theory which      
regarded cellular division as the       
principal means  of differentiation8 ,it
 is true1 the close relations between   
cleavage  and symmetry did not exist in 
every case1 but then there had always   
happened some specific experimental     
disturbances1 99e4g499 influences of  an
 abnormal direction of gravity on       
account of a turning over of the  egg1  
and it was easy to reconcile such cases 
with the generally accepted  theory on  
the assumption of what was called       
8anachronism0 of cleavage4    ,but ,roux
 was not satisfied with mere indicia1 he
 wanted a proof1 and  with this         
intention he carried out an experiment  
which has become  very celebrated4#ad   
,with a hot needle he killed one of the 
first two  blastomeres of the frog's egg
 after the full accomplishment of its   

first  cleavage1 and then watched the   
development of the surviving cell4 ,a   
typical half-embryo was seen to         
emerge--an organism indeed1 which was as
  much a half as if a fully formed      
embryo of a certain stage had been cut  
in two by a razor4 ,it was especially in
 the anterior part of the embryo  that  
its 8halfness0 could most clearly be    
demonstrated4    #ad 99,virchow's       
,archiv499 #aad1 #ahhh4    ,that seemed 
to be a proof of ,weismann's and ,roux's
 theory of  development1 a proof of the 
hypothesis that there is a very         
complicated  structure which promotes   
ontogeny by its disintegration1 carried 
out  during the cell divisions of       
embryology by the aid of the process of 
nuclear division1 the so-called         
8karyokinesis40    ,to the dispassionate
 observer it will appear1 ,i suppose1   
that the  conclusions drawn by ,roux    
from his experiment go a little beyond  
their  legitimate length4 ,certainly    
some sort of 8evolutio0 is proved by    

rearing half the frog from half the egg4
 ,but is anything proved1 is  there     
anything discovered at all about the    
nucleus8 ,it was only on  account of the
 common opinion about the part it played
 in morphogenesis  that the nucleus had 
been taken into consideration4          
,things soon became still more          
ambiguous4      ,,the ,,experiments ,,on
 ,,the ,,egg ,,of ,,the ,,sea-,,urchin  
,roux's results were published for the  
first time in #ahhh2 three years  later 
,i tried to repeat his fundamental      
experiment on another subject  and by a 
somewhat different method4 ,it was known
 from the cytological  researches of the
 brothers ,hertwig and ,boveri that the 
eggs of the  common sea-urchin          
799,echinus microtuberculatus997 are    
able to stand well  all sorts of rough  
treatment1 and that1 in particular1 when
 broken into  pieces by shaking1 their  
fragments will survive and continue to  
segment4  ,i took advantage of these    
facts for my purposes4 ,i shook the     

germs  rather violently during their    
two-cell stage1 and in several instances
 ,i  succeeded in killing one of the    
blastomeres1 while the other one was not
  damaged1 or in separating the two     
blastomeres from one another4#ae    #ae 
99,zeitschr4 wiss4 ,zool499 #ec1 #ahia4 
,let us now follow the development of   
the isolated surviving cell4 ,it  went  
through cleavage just as it would have  
done in contact with its  sister-cell1  
and there occurred cleavage stages which
 were just half  of the normal ones4    
,the stage1 for instance1 which         
corresponded to the  normal sixteen-cell
 stage1 and which1 of course1 in my     
subjects was  built up of eight elements
 only1 showed two micromeres1 two       
macromeres  and four cells of medium    
size1 exactly as if a normal            
sixteen-cell stage  had been cut in two2
 and the form of the whole was that of a
 hemisphere4  ,so far there was no      
divergence from ,roux's results4    ,the
 development of our ,echinus proceeds   

rather rapidly1 the cleavage  being     
accomplished in about fifteen hours4 ,i 
now noticed on the evening  of the first
 day of the experiment1 when the        
half-germ was composed of  about two    
hundred elements1 that the margin of the
 hemispherical germ  bent together a    
little1 as if it were about to form a   
whole sphere  of smaller size1 and1     
indeed1 the next morning a 99whole99    
diminutive  blastula was swimming about4
 ,i was so much convinced that ,i should
 get  ,roux's morphogenetical result in 
all its features that1 even in spite of 
this whole blastula1 ,i now expected    
that the next morning would reveal  to  
me the half-organisation of my subject  
once more2 the intestine1 ,i  supposed1 
might come out quite on one side of it1 
as a half-tube1 and  the mesenchyme ring
 might be a half one also4    ,but      
things turned out as they were bound to 
do and not as ,i had  expected2 there   
was a typically 99whole99 gastrula on my
 dish the next  morning1 differing only 

by its small size from a normal one2 and
 this  99small but whole99 gastrula was 
followed by a whole and typical small   
pluteus-larva 7,fig4 #e74               
,illustration3 ,fig4 #e4--;,illustration
 of ,experiments on ,echinus4    99a99#a
 and 99b99#a4 ,normal gastrula and      
normal pluteus4    99a99#b and 99b99#b4 
8,half0-gastrula and 8half0-pluteus1    
that 99ought99 to result  from one of   
the first two blastomeres1 when         
isolated1 according to the  theory of   
8evolutio40    99a99#c and 99b99#c4 ,the
 small 99but whole99 gastrula and       
pluteus that actually  99do99 result4   
,that was just the opposite of ,roux's  
result3 one of the first two            
blastomeres had undergone a             
half-cleavage as in his case1 but then  
it  had become a whole organism by a    
simple process of rearrangement of its  
material1 without anything that         
resembled regeneration1 in the sense of 
a completion by budding from a wound4   
,if one blastomere of the two-cell stage

 was thus capable of performing  the    
morphogenetical process in its totality1
 it became1 of course1  99impossible99  
to allow that nuclear division had      
separated any sort of  8germ-plasm0 into
 two different halves1 and not even the 
protoplasm of  the egg could be said to 
have been divided by the first cleavage 
furrow  into unequal parts1 as the      
postulate of the strict theory of       
so-called  8evolutio0 had been4 ,this   
was a very important result1 sufficient 
alone to overthrow at once the theory of
 ontogenetical 8evolutio10  the         
8,mosaiktheorie0 as it had been         
called--not by ,roux himself1 but       
according to his views--in its          
exclusiveness4    ,after first widening 
the circle of my observations by showing
 that  one of the first four blastomeres
 is capable of performing a whole       
organogenesis1 and that three of the    
first four blastomeres together  result 
in an absolutely perfect organism1 ,i   
went on to follow up  separately one of 

the two fundamental problems which had  
been suggested  by my first experiment3 
was there anything more to find out     
about  the importance or unimportance of
 the single 99nuclear99 divisions in    
morphogenesis8#af    #af 99,zeitschr4   
wiss4 ,zool499 #ee1 #ahib4    ,by       
raising the temperature of the medium or
 by diluting the sea-water to  a certain
 degree it proved at first to be        
possible to alter in a rather           
fundamental way the type of the         
cleavage-stages without any damage to   
the resulting organism4 ,there may be no
 micromeres at the sixteen-cell  stage1 
or they may appear as early as in the   
stage of eight cells2  no matter1 the   
larva is bound to be typical4 ,so it    
certainly is not  necessary for all the 
cleavages to occur just in their normal 
order4    ,but of greater importance for
 our purposes was what followed4 ,i     
succeeded in pressing the eggs of       
,echinus between two glass plates1      
rather tightly1 but without killing     

them2 the eggs became deformed to       
comparatively flat plates of a large    
diameter4 ,now in these eggs all        
nuclear division occurred at right      
angles to the direction of pressure1    
that is to say1 in the direction of the 
plates1 as long as the pressure  lasted2
 but the divisions began to occur at    
right angles to their former  direction1
 as soon as the pressure ceased4 ,by    
letting the pressure be  at work for    
different times ,i therefore1 of course1
 had it quite in my  power to obtain    
cleavage types just as ,i wanted to get 
them4 ,if1 for  instance1 ,i kept the   
eggs under pressure until the eight-cell
 stage was  complete1 ,i got a plate of 
eight cells one beside the other1       
instead of  two rings1 of four cells    
each1 one above the other1 as in the    
normal  case2 but the next cell division
 occurred at right angles to the former 
ones1 and a sixteen-cell stage1 of two  
plates of eight cells each1 one  above  
the other1 was the result4 ,if the      

pressure continued until the            
sixteen-cell stage was reached1 sixteen 
cells lay together in one plate1  and   
two plates of sixteen cells each1 one   
above the other1 were the  result of the
 next cleavage4    ,we are not1 however1
 studying these things for cytological1 
but for  morphogenetical purposes1 and  
for these the cleavage phenomenon itself
  is less important than the            
organogenetic result of it3 all our     
subjects  resulted in 99absolutely      
normal99 organisms4 ,now1 it is clear1  
that the  spatial relations of the      
different nuclear divisions to each     
other are  anything but normal1 in the  
eggs subjected to the pressure          
experiments2  that1 so to say1 every    
nucleus has got quite different         
neighbours if  compared with the        
8normal0 case4 ,if that makes no        
difference1 then  there 99cannot99 exist
 any close relation between the single  
nuclear  divisions and organogenesis at 
all1 and the conclusion we have drawn   

more provisionally from the whole       
development of isolated blastomeres  has
 been extended and proved in the most   
perfect manner4 ,there ought to  result 
a morphogenetic chaos according to the  
theory of real 8evolutio0  carried out  
by nuclear division1 if the positions of
 the single nuclei  were fundamentally  
changed with regard to one another      
7,fig4 #f74 ,but now  there resulted not
 chaos1 but the normal organisation3    
therefore it was  disproved in the      
strictest way that nuclear divisions    
have any bearing  on the origin of      
organisation2 at least as far as the    
divisions during  cleavage come into    
account4    ,illustration3 ,fig4        
#f4--,pressure-experiments on ,echinus4 
99a99#a and 99b99#a4 ,two normal        
cleavage stages1 consisting of eight and
  sixteen cells4    99a99#b and 99b99#b4
 ,corresponding stages modified by      
exerting pressure  until the eight-cell 
stage was finished4 ,see text4    ,on   
the egg of the frog 7,o4 ,hertwig71 and 

on the egg of annelids 7,e4 ,b4         
,wilson71 my pressure experiments have  
been carried out with the same          
result4#ag    #ag ,in the pressure      
experiments ,i had altered the relative 
position of  the nuclei 99in origine994 
,in later years ,i succeeded in         
disturbing the  arrangement of the fully
 formed cells of the eight-cell stage1  
and in  getting normal larv in spite of 
that in many cases4 ,but as this series 
of experiments is not free from certain 
complications--which in part  will be   
understood later on 7see page #gc7--;it 
must suffice here to have  mentioned    
them4 7,for further information see my  
paper in 99,archiv4 f4                  
,entwickelungsmechanik991 xiv41 #aijb1  
page #ejj47      ,,on ,,the ,,intimate  
,,structure ,,of ,,the ,,protoplasm ,,of
 ,,the ,,germ    ,nuclear division1 as  
we have seen1 cannot be the basis of    
organogenesis1  and all we know about   
the whole development of isolated       
blastomeres  seems to show that there   

exists nothing responsible for          
differentiation  in the protoplasm      
either4    ,but would that be possible8 
,it cannot appear possible on a more    
profound  consideration of the nature of
 morphogenesis1 it seems to me3 as the  
untypical agents of the medium cannot be
 responsible in any way for  the origin 
of a form combination which is most     
typical and specific1  there must be    
somewhere in the egg itself a certain   
factor which is  responsible at least   
for the general orientation and symmetry
 of it4  ,considerations of this kind   
led me1 as early as #ahic1ah to urge the
  hypothesis that there existed1 that   
there 99must99 exist1 a sort of         
intimate structure in the egg1 including
 polarity and bilaterality as  the chief
 features of its symmetry1 a structure  
which belongs to every  smallest element
 of the egg1 and which might be imagined
 by analogy  under the form of          
elementary magnets4#ai ,this hypothetic 
structure  could have its seat in the   

protoplasm only4 ,in the egg of         
echinoderms it  would be capable of such
 a quick rearrangement after being      
disturbed1  that it could not be        
observed but only inferred logically2   
there might1  however1 be cases in which
 its real discovery would be possible4  
,indeed  ,roux's frog-experiment seems  
to be a case where it is found to be at 
work3 at least it seems very probable to
 assume that ,roux obtained half  of a  
frog's embryo because the protoplasm of 
the isolated blastomere had  preserved  
the 8halfness0 of its intimate          
structure1 and had not been  able to    
form a small whole out of it4    #ah    
99,mitteil4 ,neapel4 #aa1 #ahic499      
#ai ,but the elementary magnets would   
have to be bilateral6    ,of course it  
was my principal object to verify this  
hypothesis1 and  such verification      
became possible in a set of experiments 
which my  friend ,t4 ,h4 ,morgan and    
myself carried out together1#bj in      
#ahie1 on  the eggs of ctenophores1 a   

sort of pelagic animals1 somewhat       
resembling  the jelly-fish1 but of a    
rather different inner organisation4    
,the  zoologist ,chun had found even    
before ,roux's analytical studies1 that 
isolated blastomeres of the ctenophore  
egg behave like parts of the  whole and 
result in a half-organisation like the  
frog's germ does4 ,chun  had not laid   
much stress on his discovery1 which now1
 of course1 from  the new points of     
view1 became a very important one4 ,we  
first repeated  ,chun's experiment and  
obtained his results1 with the sole     
exception  that there was a tendency of 
the endoderm of the half-larva of ,bero 
to become more than 8half40 ,but that   
was not what we chiefly wanted to       
study4 ,we succeeded in cutting away a  
certain mass of the protoplasm  of the  
ctenophore egg just before it began to  
cleave1 without damaging  its nuclear   
material in any way3 in all cases1 where
 the cut was  performed at the side1    
there resulted a certain type of larvae 

from  our experiments which showed      
exactly the same sort of defects as were
  present in larvae developed from one  
of the first two blastomeres alone4     
#bj 99,arch4 ,entw4 ,mech499 #b1 #ahie4 
,the hypothesis of the morphogenetic    
importance of 99protoplasm99 had thus   
been proved4 ,in our experiments there  
was all of the nuclear material1  but   
there were defects on one side of the   
protoplasm of the egg2 and the  defects 
in the adult were found to correspond to
 these defects in the  protoplasm4      
,and now ,o4 ,schultze and ,morgan      
succeeded in performing some experiments
  which directly proved the hypothesis  
of the part played by protoplasm  in the
 subject employed by ,roux1 99viz4991   
the frog's egg4 ,the first of  these    
investigators managed to rear two whole 
frog embryos of small  size1 if he      
slightly pressed the two-cell stage of  
that form between  two plates of glass  
and turned it over2 and ,morgan1#ba     
after having  killed one of the first   

two blastomeres1 as was done in the     
original  experiment of ,roux1 was able 
to bring the surviving one to a half or 
to a whole development according as it  
was undisturbed or turned4  ,there      
cannot be any doubt that in both of     
these cases1 it is the  possibility of a
 rearrangement of protoplasm1 offered by
 the turning  over1 which allows the    
isolated blastomere to develop as a     
whole4 ,the  regulation of the frog's   
egg1 with regard to its becoming whole1 
may be  called facultative1 whilst the  
same regulation of the egg of ,echinus  
is obligatory4 ,it is not without       
interest to note that the first two     
blastomeres of the common newt1 99i4e499
 of a form which belongs to the  other  
class of ,amphibia1 after a separation  
of 99any99 kind1 99always99  develop as 
wholes1 their faculty of regulation     
being obligatory1 like  that of         
,echinus4    #ba 99,anat4 ,anz499 #aj1  
#ahie4    ,whole or partial development 
may thus be dependent on the power of   

regulation contained in the intimate    
polar-bilateral structure of the        
protoplasm4 ,where this is so1 the      
regulation and the differences in       
development are both connected with the 
chief relations of symmetry4  ,the      
development becomes a half or a quarter 
of the normal because  there is only    
one-half or one-quarter of a certain    
structure present1  one-half or         
one-quarter with regard to the very     
wholeness of this  structure2 the       
development is whole1 in spite of       
disturbances1 if  the intimate structure
 became whole first4 ,we may describe   
the  8wholeness10 8halfness10 or        
8quarterness0 of our hypothetic         
structure  in a mathematical way1 by    
using three axes1 at right angles to one
  another1 as the base of orientation4  
,to each of these1 99x991 99y991 and    
99z991 a certain specific state with    
regard to the symmetrical relations     
corresponds2 thence it follows that1 if 
there are wanting all those  parts of   

the intimate structure which are        
determined1 say1 by a negative  value of
 99y991 by minus 99y991 then there is   
wanting half of the intimate  structure2
 and this halfness of the intimate      
structure is followed by  the halfness  
of organogenesis1 the dependence of the 
latter on the  intimate structure being 
established4 ,but if regulation has     
restored1  on a smaller scale1 the whole
 of the arrangement according to all    
values  of 99x991 99y99 and 99z991      
development also can take place         
completely 7,fig4 #g74    ,illustration3
 ,fig4 #g4--;,diagram illustrating the  
intimate ,regulation of  ,protoplasm    
from 8,half0 to 8,whole40    ,the large 
circle represents the original structure
 of the egg4 ,in all  cases where       
cleavage-cells of the two-cell stage are
 isolated this  original structure is   
only present as 8half0 in the beginning1
 say  only on the right 799y997 side4   
,development then becomes 8half10 if the
  intimate structure remains half2 but  

it becomes 8whole0 7on a smaller  scale7
 if a new whole-structure 7small        
circle67 is formed by regulatory        
processes4    ,i am quite aware that    
such a discussion is rather empty and   
purely  formal1 nevertheless it is by no
 means without value1 for it shows  most
 clearly the differences between what we
 have called the intimate  structure of 
germs1 responsible only for the general 
symmetry of  themselves and of their    
isolated parts1 and another sort of     
possible  structure of the              
egg-protoplasm which we now shall have  
to consider1 and  which1 at the first   
glance1 seems to form a serious         
difficulty to our  statements1 as far at
 least as they claim to be of general   
importance4  ,the study of this other   
sort of germinal structure at the same  
time will  lead us a step farther in our
 historical sketch of the first years of
  8,entwickelungsmechanik0 and will     
bring this sketch to its end4      ,,on 
,,some ,,specificities ,,of             

,,organisation ,,in ,,certain ,,germs   
,it was known already about #ahij1 from 
the careful study of what has  been     
called 8cell-lineage10 that in the eggs 
of several families of  the animal      
kingdom the origin of certain organs may
 be traced back to  individual cells of 
cleavage1 having a typical histological 
character  of their own4 ,in ,america   
especially such researches have been    
carried  out with the utmost minuteness1
 ,e4 ,b4 ,wilson's study of the         
cell-lineage  of the ,annelid           
99,nereis99 being the first of them4 ,if
 it were true that  nuclear division is 
of no determining influence upon the    
ontogenetic  fate of the blastomeres1   
only peculiarities of the different     
parts of  the protoplasm could account  
for such relations of special cleavage  
cells to special organs4 ,i advocated   
this view as early as in #ahid1  and it 
was proved two years later by ,crampton1
 a pupil of ,wilson's1  in some very    
fine experiments performed on the germ  

of a certain  mollusc4#bb ,the egg of   
this form contains a special sort of    
protoplasm  near its vegetative pole1   
and this part of it is separated at each
  of the first two segmentations by a   
sort of pseudo-cleavage1 leading  to    
stages of three and five separated      
masses instead of two and four1  the    
supernumerary mass being the so-called  
8yolk-sac0 and possessing  no nuclear   
elements 7,fig4 #h74 ,crampton removed  
this yolk-sac at the  two-cell stage1   
and he found that the cleavage of the   
germs thus  operated upon was normal    
except with regard to the size and      
histological  appearance of one cell1   
and that the larvae originating from    
these  germs were complete in every     
respect except in their mesenchyme1     
which  was wanting4 ,a special part of  
the protoplasm of the egg had thus been 
brought into relation with quite a      
special part of organisation1 99and     
that special part of the protoplasm     
contained no nucleus994    #bb 99,arch4 

,entw4 ,mech499 #c1 #ahif4              
,illustration3 ,fig4 #h4--,the ,mollusc 
,dentalium 799after99 ,e4 ,b4 ,wilson74 
99a499 ,the egg1 consisting of three    
different kinds of protoplasmatic       
material4    99b499 ,first              
cleavage-stage4 ,there are two cells and
 one 8pseudo-cell10  the yolk-sac1 which
 contains no nucleus4 ,this was removed 
in ,crampton's  experiment4             
,,general ,,results ,,of ,,the ,,first  
,,period ,,of 8,,entwickelungsmechanik0 
,this experiment of ,crampton's1        
afterwards confirmed by ,wilson himself1
  may be said to have closed the first  
period of the new science of  physiology
 of form1 a period devoted almost       
exclusively to the problem  whether the 
theory of nuclear division or1 in a     
wider sense1 whether the  theory of a   
strict 8evolutio0 as the basis of       
organogenesis was true or  not4    ,it  
was shown1 as we have seen1 that the    
theory of the 8qualitatively  unequal   
nuclear division0 78qualitativ-ungleiche

 ,kernteilung0 in ,german7  certainly   
was not true1 and that there also was no
 strict 8evolutio0  in protoplasm4      
,hence ,weismann's theory was clearly   
disproved4 ,there  certainly is a good  
deal of real 8epigenesis0 in ontogeny1 a
 good deal  of 8production of           
manifoldness10 not only with regard to  
visibility but  in a more profound      
meaning4 ,but some sort of pre-formation
 had also  been proved to exist1 and    
this pre-formation1 or1 if you like1    
this  restricted evolution1 was found to
 be of two different kinds4 ,first an   
intimate organisation of the protoplasm1
 spoken of as its polarity and          
bilaterality1 was discovered1 and this  
had to be postulated for every  kind of 
germs1 even when it was overshadowed by 
immediate obligatory  regulation after  
disturbances4 ,besides that there were  
cases in which  a real specificity of   
special parts of the germ existed1 a    
relation of  these special parts to     
special organs3 but this sort of        

specification  also was shown to belong 
to the protoplasm4    ,it follows from  
all we have mentioned about the         
organisation of  protoplasm and its     
bearing on morphogenesis1 that the eggs 
of different  animals may behave rather 
differently1 in this respect1 and that  
the eggs indeed may be classified       
according to the degree of their        
organisation4 ,though we must leave a   
detailed discussion of these  topics to 
morphology proper1 we yet shall try     
shortly to summarise  what has been     
ascertained about them in the different 
classes of the  animal kingdom4 ,a full 
regulation of the 99intimate99 structure
 of  isolated blastomeres to a new      
whole1 has been proved to exist in the  
highest degree in the eggs of all       
echinoderms1 medusae1 nemertines1       
,amphioxus1 fishes1 and in one class of 
the ,amphibia 7the 99,urodela9972  it is
 facultative only among the other class 
of ,amphibia1 the 99,anura991  and seems
 to be only partly developed or to be   

wanting altogether among  ctenophora1   
ascidia1 annelids1 and mollusca4        
,peculiarities in the  organisation of  
99specific parts99 of protoplasm have   
been proved to occur  in more cases than
 at first had been assumed2 they exist  
even in the  echinoderm egg1 as         
experiments of the last few years have  
shown2 even  here a sort of             
specification exists at the vegetative  
pole of the egg1  though it is liable to
 a certain kind of regulation2 the same 
is true in  medusae1 nemertines1 etc42  
but among molluscs1 ascidians1 and      
annelids  no regulation about the       
specific organisation of the germ in    
cleavage  has been found in any case4   
,the differences in the degree of       
regulability of the intimate germinal   
structure may easily be reduced to      
simple differences in the physical      
consistency of their protoplasm4#bc ,but
 all differences in specific            
organisation must remain as they are for
 the present2 it will be one of  the    

aims of the future theory of development
 to trace these differences  also to a  
common source4    #bc ,it deserves      
notice in this connection1 that in some 
cases the  protoplasm of parts of a germ
 has been found to be more regulable in 
the earliest stages1 when it is very    
fluid1 than later1 when it is more      
stiff4    ,that such an endeavour will  
probably be not without success1 is     
clear1  ,i should think1 from the mere  
fact that differences with regard to    
germinal specific pre-formation do not  
agree in any way with the  systematic   
position of the animals exhibiting them2
 for1 strange as it  would be if there  
were two utterly different kinds of     
morphogenesis1 it  would be still more  
strange if there were differences in    
morphogenesis  which were totally       
unconnected with systematic             
relationship3 the  ctenophores behaving 
differently from the medusae1 and       
,amphioxus  differently from ascidians4 
,,some ,,new ,,results ,,concerning     

,,restitutions    ,we now might close   
this chapter1 which has chiefly dealt   
with the  disproof of a certain sort of 
ontogenetic theories1 and therefore  has
 been almost negative in its character1 
did it not seem desirable  to add at    
least a few words about the later       
discoveries relating to  morphogenetic  
restorations of the adult4 ,we have     
learnt that ,weismann  created his      
concept of 8reserve plasma0 to account  
for what little  he knew about          
8restitutions03 that is1 about the      
restoration of lost  parts3 he only knew
 regeneration proper in animals and the 
formation of  adventitious buds in      
plants4 ,it is common to both of these  
phenomena  that they take their origin  
from typically localised points of the  
body  in every case2 each time they     
occur a certain well-defined part of the
  body is charged with the restoration  
of the lost parts4 ,to explain  such    
cases ,weismann's hypothesis was quite  
adequate1 at least in a  logical sense4 

,but at present1 as we shall discuss    
more fully in another  chapter1 we know 
of some very widespread forms of        
restitution1 in which  what is to be    
done for a replacement of the lost is   
not entrusted to  99one99 typical part  
of the body in every case1 but in which 
the whole  of the morphogenetic action  
to be performed is transferred in its   
99single99 parts to the 99single99 parts
 of the body which is accomplishing     
restoration3 each of its parts has to   
take an individual share in the  process
 of restoration1 effecting what is      
properly called a certain kind  of      
8re-differentiation0                    
78,umdifferenzierung071 and this share  
varies  according to the relative       
position of the part in each case4      
,later on  these statements will appear 
in more correct form than at present1   
and  then it will become clear that we  
are fully entitled to emphasise at the  
end of our criticism of ,weismann's     
theory1 that his hypothesis relating  to

 restorations can be no more true than  
his theory of development  proper was   
found to be4    ,and now we shall pass  
on to our positive work4    ,we shall   
try to sketch the outlines of what might
 properly be called an  99analytical    
theory of morphogenesis992 that is1 to  
explain the sum of our  knowledge about 
organic form-production1 gained by      
experiment and by  logical analysis1 in 
the form of a real system1 in which each
 part will  be1 or at least will try to 
be1 in its proper place and in relation 
with  every other part4 ,our analytical 
work will give us ample opportunity of  
mentioning many important topics of     
so-called general physiology also1      
irrespective of morphogenesis as such4  
,but morphogenesis is always to  be the 
centre and starting-point of our        
analysis4 ,as ,i myself approach  the   
subject as a zoologist1 animal          
morphogenesis1 as before1 will be the   
principal subject of what is to follow4 
#b4 ,,analytical ,,theory ,,of          

,,morphogenesis#bd    #bd ,compare my   
99,analytische ,theorie der organischen 
,entwickelung991  ,leipzig1 #ahid1 and  
my reviews in 99,ergebnisse der         
,anatomie und                           
,entwickelungsgeschichte991 vols4 viii4 
xi4 xiv41 #ahii-aije4 ,a shorter  review
 is given in 99,ergebnisse der          
,physiologie991 vol4 v41 #aijf4 ,the    
full  literature will be found in these 
reviews4    4 ,,the ,,distribution ,,of 
,,morphogenetic ,,potencies             
99,prospective ,value and ,prospective  
,potency99    ,wilhelm ,roux did not    
fail to see that the questions of the   
locality and  the time of all           
morphogenetic differentiations had to be
 solved first1  before any problem of   
causality proper could be attacked4     
,from this  point of view he carried out
 his fundamental experiments4    ,it is 
only in terminology that we differ from 
his views1 if we prefer  to call our    
introductory chapter an analysis of the 
distribution of  morphogenetic          

potencies4 ,the result will be of course
 rather different  from what ,roux      
expected it would be4    ,let us begin  
by laying down two fundamental concepts4
 ,suppose we have  here a definite      
embryo in a definite state of           
development1 say a  blastula1 or a      
gastrula1 or some sort of larva1 then we
 are entitled  to study any special     
element of any special elementary organ 
of this  germ with respect to what is   
actually to develop out of this very    
element in the future actual course of  
this development1 whether it be         
undisturbed or disturbed in any way2 it 
is1 so to say1 the actual1 99the  real  
fate99 of our element1 that we take in  
account4 ,i have proposed to  call this 
real fate of each embryonic part in this
 very definite line  of morphogenesis   
its 99prospective value99 78prospective 
,bedeutung0 in  ,german74 ,the          
fundamental question of the first       
chapter of our analytical  theory of    
development may now be stated as        

follows3 ,is the prospective  value of  
each part of any state of the           
morphogenetic line constant1  99i4e499  
is it unchangeable1 can it be nothing   
but one2 or is it variable1  may it     
change according to different           
circumstances8    ,we first introduce a 
second concept3 the term 99prospective  
potency99  78prospective ,potenz0 in    
,german7 of each embryonic element4 ,the
 term  8prospective morphogenetic       
potency0 is to signify the 99possible   
fate99 of each of those elements4 ,with 
the aid of our two artificial  concepts 
we are now able to formulate our        
introductory question thus3  ,is the    
prospective potency of each embryonic   
part fully given by  its prospective    
value in a certain definite case2 is it1
 so to say1  identical with it1 or does 
the prospective potency contain more    
than the  prospective value of an       
element in a certain case reveals8      
,we know already from our historical    
sketch that the latter is true3 that    

the actual fate of a part need not be   
identical with its possible fate1  at   
least in many cases2 that the potency of
 the first four blastomeres  of the egg 
of the sea-urchin1 for instance1 has a  
far wider range than  is shown by what  
each of them actually performs in even  
this ontogeny4  ,there are more         
morphogenetic possibilities contained in
 each embryonic  part than are actually 
realised in a special morphogenetic     
case4    ,as the most important special 
morphogenetic case is1 of course1 the   
so-called 8normal0 one1 we can also     
express our formula in terms of  special
 reference to it3 there are more        
morphogenetic possibilities in  each    
part than the observation of the normal 
development can reveal4  ,thus we have  
at once justified the application of    
analytical experiment  to morphogenesis1
 and have stated its most important     
results4    ,as the introductory        
experiments about                       
8,entwickelungsmechanik0 have shown     

already that the prospective potency of 
embryonic parts1 at least in  certain   
cases1 99can99 exceed their prospective 
value--that1 at least in  certain cases1
 it can be different from it--the       
concept of prospective  potency at the  
very beginning of our studies puts      
itself in the centre  of analytical     
interest1 leaving to the concept of     
prospective value the  second place     
only4 ,for that each embryonic part     
actually has a certain  prospective     
value1 a specified actual fate in every 
single case of  ontogeny1 is clear from 
itself and does not affirm more than the
 reality  of morphogenetic cases in     
general2 but that the prospective value 
of the  elements may change1 that there 
is a morphogenetic power in them1 which 
contains more than actuality2 in other  
words1 that the term 8prospective       
potency0 has not only a logical but a   
factual interest3 all these points      
amount to a statement not only of the   
most fundamental introductory  results  

but also of the actual 99problems99 of  
the physiology of form4    ,if at each  
point of the germ something else 99can99
 be formed than  actually is formed1 why
 then does there happen in each case    
just what  happens and nothing else8 ,in
 these words indeed we may state the    
chief  problem of our science1 at least 
after the fundamental relation of  the  
superiority of prospective potency to   
prospective value has been  generally   
shown4    ,we consequently may shortly  
formulate our first problem as the      
question  of the distribution of the    
prospective morphogenetic potencies in  
the  germ4 ,now this general question   
involves a number of particular ones4   
,up to what stage1 if at all1 is there  
an absolutely equal distribution  of the
 potencies over all the elements of the 
germ8 ,when such an equal  distribution 
has ceased to exist at a certain stage1 
what are then the  relations between the
 parts of different potency8 ,how1 on   
the other  hand1 does a newly arisen1   

more specialised sort of potency behave 
with  regard to the original general    
potency1 and what about the distribution
  of the more restricted potency8    ,i 
know very well that all such questions  
will seem to you a little  formal1 and1 
so to say1 academical at the outset4 ,we
 shall not fail to  attach to them very 
concrete meanings4    99,the ,potencies 
of the ,blastomeres99    ,at first we   
turn back to our experiments on the egg 
of the sea-urchin  as a type of the germ
 in the very earliest stages4 ,we know  
already that  each of the first two1 or 
each of the first four1 or three of the 
first  four blastomeres together may    
produce a whole organism4 ,we may add   
that  the swimming blastula1 consisting 
of about one thousand cells1 when cut   
in two quite at random1 in a plane      
coincident with1 or at least passing    
near1 its polar axis1 may form two fully
 developed organisms out of its         
halves4#be ,we may formulate this result
 in the words3 the prospective  potency 

of the single cells of a blastula of    
,echinus is the same for  all of them2  
their prospective value is as far as    
possible from being  constant4    #be   
,if the plane of section passes near the
 equator of the germ1 two  whole larvae 
may be formed also1 but in the majority 
of cases the  8animal0 half does not go 
beyond the blastula4 ,the specific      
features of  the organisation of the    
protoplasm come into account here4 ,see 
also page  #fe1 note #a4    ,but we may 
say even a little more3 what actually   
will happen in each of  the blastula    
cells in any special case of development
 experimentally  determined depends on  
the position of that cell in the whole1 
if the  8whole0 is put into relation    
with any fixed system of co-ordinates2  
or  more shortly1 8the prospective value
 of any blastula cell is a function  of 
its position in the whole40    ,i know  
from former experience that this        
statement wants a few words of          
explanation4 ,the word 8function0 is    

employed here in the most general1      
mathematical sense1 simply to express   
that the prospective value1  the actual 
fate of a cell1 will change1 whenever   
its position in the  whole is           
different4#bf ,the 8whole0 may be       
related to any three axes  drawn through
 the normal undisturbed egg1 on the     
hypothesis that there  exists a primary 
polarity and bilaterality of the germ2  
the axes which  determine this sort of  
symmetry may1 of course1 conveniently be
 taken as  co-ordinates2 but that is not
 necessary4    #bf ,a change of the     
position of the cell is of course       
effected by each  variation of the      
direction of the cut1 which is purely a 
matter of  chance4    99,the ,potencies 
of ,elementary ,organs in ,general99    
,before dealing with other very young   
germs1 ,i think it advisable to         
describe first an experiment which is   
carried out at a later stage of  our    
well-known form4 ,this experiment will  
easily lead to a few new  concepts1     

which we shall want later on1 and will  
serve1 on the other  hand1 as a basis of
 explanation for some results1 obtained 
from the  youngest germs of some other  
animal species1 which otherwise would   
seem  to be rather irreconcilable with  
what our ,echinus teaches us4    ,you   
know1 from the second lecture1 what a   
gastrula of our sea-urchin  is4 ,if you 
bisect this gastrula1 when it is        
completely formed1 or  still better1 if 
you bisect the gastrula of the starfish1
 either along  the axis or at right     
angles to it1 you get complete little   
organisms  developed from the parts3 the
 ectoderm is formed in the typical      
manner  in the parts1 and so is the     
endoderm2 everything is proportionate   
and  only smaller than in the normal    
case4 ,so we have at once the important 
results1 that1 as in the blastula1 so in
 the ectoderm and in the  endoderm of   
our ,echinus or of the starfish1 the    
prospective potencies  are the same for 
every single element3 both in the       

ectoderm and in  the endoderm the       
prospective value of each cell is a     
8function of its  position0 7,fig4 #i74 
,illustration3 ,fig4 #i4--,the          
,starfish1 99,asterias994    99a99#a4   
,normal gastrula2 may be bisected along 
the main axis or at right  angles to it 
7see dotted lines74    99a99#b4 ,normal 
larva1 899,bipinnaria9940    99b99#a4   
,small but whole gastrula that results  
by a process of regulation  from the    
parts of a bisected gastrula4           
99b99#b4 ,small 99but whole99           
899,bipinnaria9910 developed out of     
99b99#a4    ,but a further experiment   
has been made on our gastrula4 ,if at   
the moment  when the material of the    
future intestine is most distinctly     
marked in  the blastoderm1 but not yet  
grown into a tube1 if at this moment the
  upper half of the larva is separated  
from the lower by an equatorial         
section1 you will get a complete larva  
only from that part which bears  the    
8,anlage0 of the endoderm1 while the    

other half will proceed in              
morphogenesis very well but will form   
only ectodermal organs4 ,by another     
sort of experiment1 which we cannot     
fully explain here1 it has been  shown  
that the endoderm if isolated is also   
only able to form such  organs as are   
normally derived from it4    ,and so we 
may summarise both our last results by  
saying3 though  ectoderm and endoderm   
have their potencies equally distributed
 amongst  their respective cells1 they  
possess different potencies compared one
  with the other4 ,and the same relation
 is found to hold for all cases of  what
 we call elementary organs3 they are    
8equipotential10 as we may say1  in     
themselves1 but of different potencies  
compared with each other4    99,explicit
 and ,implicit ,potencies3 ,primary and 
,secondary ,potencies99    ,we shall    
first give to our concept of            
8prospective potency0 a few words  of   
further analytical explanation with the 
help of our newly obtained  knowledge4  

,it is clear from what we have stated   
that the prospective potencies of  the  
ectoderm and of the endoderm1 and we may
 add1 of every elementary  organ in     
relation to every other1 differ between 
themselves and also in  comparison with 
the blastoderm1 from which they have    
originated4 ,but the  diversity of the  
endoderm with respect to the ectoderm is
 not of the  same kind as its diversity 
in respect to the blastoderm4 ,the      
potency  of the endoderm and that of the
 ectoderm are both specialised in their 
typical manner1 but compared with the   
potency of the blastoderm they  may be  
said not only to be specialised but also
 to be 99restricted993 the  potency of  
the blastoderm embraces the whole1 that 
of the so-called  germ-layer embraces   
only part of the whole2 and this species
 of  restriction becomes clearer and    
clearer the further ontogeny advances3  
at the end of it in the 8ultimate       
elementary organs0 there is no          
prospective potency whatever4    ,a few 

new terms will serve to state a little  
more accurately what  happens4 ,of      
course1 with regard to all morphogenesis
 which goes on  99immediately99 from the
 blastoderm1 the potency of the         
blastoderm is  restricted as much as are
 the potencies of the germ layers4 ,we  
shall  call this sort of immediate      
potency 99explicit991 and then we see at
  once that1 with regard to their       
explicit potencies1 there are only      
differences among the prospective       
potencies of the elementary organs2  but
 with respect to the 99implicit99       
potency of any of these organs1 that  is
 with respect to their potency as       
embracing the faculties of all their    
derivations1 there are also not only    
differences but true morphogenetic      
restrictions lying at the very          
foundations of all embryology4    ,but  
now those of you who are familiar with  
morphogenetic facts will  object to me1 
that what we have stated about all sorts
 of restrictions  in ontogeny is not    

true1 and you will censure me for having
 overlooked  regeneration1 adventitious 
budding1 and so on4 ,to some extent the 
criticism would be right1 but ,i am not 
going to recant2 ,i shall only          
introduce another new concept4 ,we are  
dealing only with 99primary99  potencies
 in our present considerations1 99i4e499
 with potencies which  lie at the root  
of true embryology1 not with those      
serving to regulate  disturbances of the
 organisation4 ,it is true1 we have in  
some way  disturbed the development of  
our sea-urchin's egg in order to study  
it2 more than that1 it would have been  
impossible to study it at all  without  
some sort of disturbance1 without some  
sort of operation4  ,but1 nevertheless1 
no potencies of what may properly be    
called the  99secondary99 or restitutive
 type have been aroused by our          
operations2  nothing happened except on 
the usual lines of organogenesis4 ,it is
  true1 some sort of regulation         
occurred1 but that is included among the

  factors of ontogeny proper4    ,we    
shall afterwards study more fully and   
from a more general point of  view this 
very important feature of 8primary      
regulation0 in its contrast  to         
8secondary regulation0 phenomena4 ,at   
present it must be enough to  say that  
in speaking of the restriction of the   
implicit potencies in  form-building we 
refer only to potencies of the primary  
type1 which  contain within themselves  
some properties of a 7primary7          
regulative  character4    99,the        
,morphogenetic ,function of ,maturation 
in the ,light of ,recent  ,discoveries99
    ,turning again to more concrete     
matters1 we shall first try1 with the   
knowledge acquired of the potencies of  
the blastoderm and the so-called  germ  
layers of ,echinus1 to understand       
certain rather complicated  results     
which the experimental morphogenetic    
study of other animal  forms has taught 
us4 ,we know from our historical sketch 
that there are  some very important     

aberrations from the type1 to which the 
,echinus  germ belongs1#bg 99i4e499 the 
type with an equal distribution of the  
potencies over all the blastomeres4 ,we 
know not only that in cases where  a    
regulation of the intimate structure of 
the protoplasm fails to occur  a partial
 development of isolated cells will take
 place1 but that there  may even be a   
typical disposition of typical cells for
 the formation of  typical organs only1 
without any regulability4    #bg ,the   
reader will remember 7see page #fe1 note
 #a71 that even the germ  of ,echinus is
 not quite equipotential along its main 
axis1 but it is  equipotential in the   
strictest sense around this axis4 ,the  
germs of  certain medusae seem to be    
equipotential in every respect1 even in 
their  cleavage stages4    ,let us first
 consider the last case1 of which the   
egg of mollusca is a  good type3 here   
there is no equal distribution of       
potencies whatever1  the cleavage-cells 
of this germ are a sort of real 8mosaic0

 with regard  to their morphogenetic    
potentialities4 ,is this difference     
between the  germ of the echinoderms and
 the molluscs to remain where it is1 and
  not to be elucidated any further8     
,then there would be rather important   
differences among the germs of different
 animals1 at least with regard  to the  
degree of the specification of their    
cleavage cells1 or if we  ascribe       
differences among the blastomeres to the
 organisation of the  fertilised egg    
ready for cleavage1 there would be      
differences in the  morphogenetic       
organisation of the egg-protoplasm3 some
 eggs would be  more typically          
specialised at the very beginning of    
morphogenesis than  others4    ,in the  
first years of the study of             
8,entwickelungsmechanik0 ,i pointed out 
that it must never be forgotten that the
 egg itself is the result of            
organogenesis4 ,if1 therefore1 there are
 real mosaic-like specifications  in    
some eggs at the beginning of cleavage1 

or during it1 there may  perhaps have   
been an 99earlier99 stage in the        
individual history of  the egg which did
 not show such specifications of the    
morphogenetic  structure4 ,two ,american
 authors share the merit of having      
proved  this hypothesis4 ,conklin       
showed1 several years ago1 that certain 
intracellular migrations and            
rearrangements of material do happen in 
the first stages of ovogenesis in       
certain cases1 but it is to ,e4 ,b4     
,wilson#bh that science owes a proper   
and definitive elucidation of the  whole
 subject4 ,wilson's researches1 pursued 
not only by descriptive  methods1#bi but
 also by means of analytical experiment1
 led him to the  highly important       
discovery that the eggs of several forms
 7nemertines1  molluscs71 which after   
maturation show the mosaic type of      
specification  in their protoplasm to a 
more or less high degree1 fail to show  
any  kind of specification in the       
distribution of their potencies before  

maturation has occurred4 ,in the mollusc
 egg a certain degree of  specification 
is shown already before maturation1 but 
nothing to be  compared with what       
happens afterwards2 in the egg of       
nemertines there is  no specification at
 all in the unripe egg4    #bh 99,journ4
 ,exp4 ,zool499 #a1 #aijd4    #bi ,great
 caution must be taken in attributing   
any specific  morphogenetic part to     
differently coloured or constructed     
materials1  which may be observed in the
 egg-protoplasm in certain cases4 ,they 
may  play such a part1 but in other     
cases they certainly do not 7see ,lyon1 
99,arch4 ,entw4 ,mech499 #bc1 #aijg74   
,the final decision always depends on   
experiment4    ,maturation thus becomes 
a part of ontogeny itself2 it is not    
with  fertilisation that morphogenesis  
begins1 there is a sort of ontogeny     
anterior to fertilisation4    ,these    
words constitute a summary of ,wilson's 
researches4 ,taken together  with the   
general results obtained about the      

potencies of the blastula  and the      
gastrula of ,echinus1 they reduce what  
appeared to be differences  of degree or
 even of kind in the specification of   
the egg-protoplasm 99to  mere           
differences in the time of the beginning
 of real morphogenesis994  ,what occurs 
in some eggs1 as in those of ,echinus1  
at the time of the  definite formation  
of the germ layers1 leading to a        
specification and  restriction of their 
prospective potencies1 may happen very  
much earlier  in other eggs4 ,but there 
exists in 99every99 sort of egg an      
99earliest99  stage1 in which all parts 
of its protoplasm are equal as to their 
prospectivity1 and in which there are no
 potential diversities or  restrictions 
of any kind4    ,so much for differences
 in the 99real material99 organisation  
of the germ  and their bearing on       
inequipotentialities of the cleavage    
cells4    99,the ,intimate ,structure of
 ,protoplasm3 ,further ,remarks99       
,where a typical half- or               

quarter-development from isolated       
blastomeres  happens to occur1 we know  
already that the impossibility of a     
regulation  of the 99intimate           
polar-bilateral99 structure may account 
for it4 ,as this  impossibility of      
regulation probably rests on rather     
simple physical  conditions#cj it may   
properly be stated that equal           
distribution of  potencies is not       
wanting but is only overshadowed here4  
,in this respect  there exists a logical
 difference of fundamental importance   
between  those cases of so-called       
8partial0 or better1 8fragmental0       
development  of isolated blastomeres in 
which a certain embryonic organ is      
wanting  on account of its specific     
morphogenetic material being absent1 and
  those cases in which the 8fragmental0 
embryo lacks complete 8halves0 or       
8quarters0 with regard to general       
symmetry on account of the symmetry  of 
its intimate structure being irregularly
 disturbed4 ,this logical  difference   

has not always received the attention   
which it undoubtedly  deserves4 ,our    
hypothetical intimate structure in      
itself is1 of course1  also a result of 
factors concerned in ovogenesis4 ,only  
in one case do  we actually know        
anything about its origin3 ,roux has    
shown that in the  frog it is the       
accidental path of the fertilising      
spermatozoon in the  egg which1 together
 with the polar axis1 normally          
determines the plane  of bilateral      
symmetry2 but this symmetry may be      
overcome and replaced  by another1 if   
gravity is forced to act in an abnormal 
manner upon the  protoplasm2 the latter 
showing parts of different specific     
gravity in  the eggs of all ,amphibia4  
#cj ,it seems that these physical       
conditions also--besides the real       
specifications in the organisation of   
the egg--may be different before  and   
after maturation or 7in other cases7    
fertilisation4 7,see ,driesch1          
99,archiv f4 ,entwickelungsmechanik991  

#g1 p4 #ih2 and ,brachet1 99ibid499 #bb1
 p4  #cbe47    99,the ,neutrality of the
 ,concept of 8,potency099    ,now we may
 close our rather long chapter on the   
distribution of  potencies in the germ2 
it has been made long1 because it will  
prove to  be very important for further 
analytical discussion2 and its          
importance1  in great measure1 is due to
 its freedom from prepossessions4       
,indeed1  the concept of prospective    
potency does not prejudice anything2 we 
have said1 it is true1 that limitations 
of potencies may be due to  the presence
 of specific parts of organisation in   
some cases2 that1  at least1 they may be
 connected therewith2 but we have not   
determined  at all what a prospective   
potency really is1 what the term really 
is  to signify4 ,it may seem that such a
 state of things gives an air of        
emptiness to our discussions1 that it   
leaves uncertain what is the most       
important4 ,but1 ,i think1 our way of   
argument1 which tries to reach the      

problems of greatest importance by      
degrees1 though it may be slow1 could   
hardly be called wrong and misleading4  
4 ,,the 8,,means0 ,,of ,,morphogenesis  
,we now proceed to an analysis of what  
may properly be called the 99means99  of
 morphogenesis1 the word 8means0 being  
preferable to the more usual  one       
8conditions0 in this connection1 as the 
latter would not cover the  whole field4
 ,it is in quite an unpretentious and   
merely descriptive  sense that the      
expression 8means0 should be understood 
at present2 what  is usually called     
8conditions0 is part of the             
morphogenetic means in our  sense4    4 
99,the ,internal ,elementary ,means of  
,morphogenesis99    ,we know that all   
morphogenesis1 typical or atypical1     
primary or  secondary1 goes on by one   
morphogenetic elementary process        
following the  other4 ,now the very     
foundation of these elementary processes
 themselves  lies in the elementary     
functions of the organism as far as they

 result  in the formation of stable     
visible products4 ,therefore the        
elementary  functions of the organism   
may properly be called the internal     
8means0 of  morphogenesis4    ,secretion
 and migration are among such functions2
 the former happening  by the aid of    
chemical change or by physical          
separation1 the latter by  the aid of   
changes in surface tension4 ,but hardly 
anything more concrete  has been made   
out about these or similar points at    
present4    ,we therefore make no claim 
to offer a complete system of the       
internal  elementary means of           
morphogenesis4 ,we shall only select    
from the whole  a few topics of         
remarkable morphogenetic interest1 and  
say a few words  about each4    ,but1   
first of all1 let us observe that the   
elementary means of  morphogenesis are  
far from being morphogenesis themselves4
 ,the word  8means0 itself implies as   
much4 ,it would be possible to          
understand each  of these single acts in

 morphogenesis as well as anything1 and 
yet to be  as far from understanding the
 whole as ever4 ,all means of           
morphogenesis  are only to be considered
 as the most general frame of events    
within  which morphogenesis occurs4     
99,some ,remarks on the ,importance of  
,surface ,tension in                    
,morphogenesis499--,there are a few     
purely physical phenomena which have  a 
special importance in organic           
morphology1 all of them connected  with 
capillarity or surface tension4         
,soap-lather is a very familiar  thing  
to all of you3 you know that the        
soap-solution is arranged here  in very 
thin planes separated by spaces         
containing air3 it was first  proved by 
,berthold#ca that the arrangement of    
cells in organic tissues  follows the   
same type as does the arrangement of the
 single bubbles of  a soap-lather1 and  
,btschli#cb added to this the discovery 
that the  minute structure of the       
protoplasm itself is that of a foam     

also4 ,of  course it is not one fluid   
and one gas which make up the           
constituents  of the structure in the   
organisms1 as is the case in the        
well-known  inorganic foams1 but two    
fluids1 which do not mix with one       
another4 ,one  general law holds for all
 arrangements of this kind3 the         
so-called law  of least surfaces1       
expressed by the words that the sum of  
all surfaces  existing is a minimum2 and
 it again is a consequence of this law1 
if  discussed mathematically1 that four 
lines will always meet in one point  and
 three planes in one line4 ,this        
feature1 together with a certain law    
about the relation of the angles meeting
 in one line to the size of the         
bubbles1 is realised most clearly in    
many structures of organic tissues1  and
 makes it highly probable1 at least in  
some cases1 that capillarity  is at work
 here4 ,in other cases1 as for instance 
in many plants1 a kind  of outside      
pressure1 the so-called tissue tension1 

may account for the  arrangement in     
surfaces 99minimae areae994 ,cleavage   
stages are perhaps  the very best type  
in which our physical law is expressed3 
and here  it may be said to have quite a
 simple application whenever all of the 
blastomeres are of the same physical    
kind1 whilst some complications  appear 
in germs with a specialised organisation
 and1 therefore1  with differences in   
the protoplasm of their single          
blastomeres4 ,in  such instances we may 
say that the physical law holds as far  
as the  conditions of the system permit1
 these conditions ordinarily consisting 
in a sort of non-homogeneity of the     
surfaces4    #ca 99,studien ber         
,protoplasmamechanik991 ,leipzig1 #ahhf4
    #cb 99,unters4 b4 mikroskopische    
,schume und das ,protoplasma991         
,leipzig1  #ahib4    ,it seems1 from the
 researches of ,dreyer1#cc that the     
formation of  organic skeletons may also
 be governed by the physically          
conditioned  arrangement of             

protoplasmatic or cellular elements1 and
 some phenomena  of migration and       
rearrangement among cleavage cells1 as  
described by  ,roux1 probably also      
belong here4    #cc 99,jena4            
,zeitschr499 #bf1 #ahib4    ,but let us 
never forget that the laws of surface   
tension only give  us the most general  
type of an arrangement of elements in   
all these  cases1 nothing else4 ,a      
physical law never accounts for the     
,specific6  ,capillarity gives us not   
the least clue to it4 ,as the organic   
substance1  at least in many cases1 is a
 fluid1 it must of course follow the    
general  laws of hydrostatics and       
hydrodynamics1 but life itself is as    
little  touched by its fluid-like or    
foam-like properties as it is by the    
fact  that living bodies have a certain 
weight and mass4    ,all indeed that has
 been described may be said to belong1  
in the  broadest meaning of the word1 to
 what is called by ,roux 8correlation of
  masses10 though this author originally

 intended to express by this term  only 
some sorts of passive pressure and      
deformation amongst embryonic  parts as 
discovered especially by ,his4    ,we   
must be cautious in admitting that any  
organic feature has been  explained1    
even in the most general way1 by the    
action of physical  forces4 ,what at    
first seems to be the result of         
mechanical pressure may  afterwards be  
found to be an active process of growth1
 and what at first  seems to be a full  
effect of capillarity among homogeneous 
elements may  afterwards be shown to    
depend on specialised metabolic         
conditions of the  surfaces as its      
principal cause4#cd    #cd ,according to
 ,zur ,strassen's results the early     
embryology of  99,ascaris99 proceeds    
almost exclusively by cellular          
surface-changes3 the  most typical      
morphogenetic processes are carried out 
by the aid of this  8means40 ,as a      
whole1 the embryology of 99,ascaris99   
stands quite apart and  presents a great

 number of unsolved problems2           
unfortunately1 the germ of  this form   
has not been accessible to experiment   
hitherto4    ,there are other physical  
phenomena too1 which assist             
morphogenesis2  osmotic pressure for    
instance1 which is also well known to   
operate in  many purely physiological   
processes4 ,but all these processes are 
only  means of the organism1 and can    
never do more than furnish the general  
type of events4 ,they do not constitute 
life2 they are 99used99 by life2  let it
 remain an open question1 for the       
present1 how the phenomenon of  8life0  
is to be regarded in general4#ce    #ce 
,rhumbler has recently published a      
general survey of all attempts to       
8explain0 life1 and morphogenesis in    
particular1 in a physico-chemical  way  
78,aus dem ,lckengebiet zwischen        
organismischer und anorganismischer     
,natur10 99,ergeb4 ,anat4 u4            
,entw4-gesch499 #ae1 #aijf74 ,this      
99very  pessimistic99 survey is the more

 valuable as it is written by a         
convinced  8mechanist40    99,on        
,growth994--,among the internal         
morphogenetical means which are of  a   
so-called physiological character1 that 
is1 which nobody claims to  understand  
physically at present1 there is in the  
first place 99growth991  which must be  
regarded as a very essential one4       
,analytically we must carefully         
discriminate between the increase in the
  size of the cavities of an organism by
 a passive extension of their  surfaces 
and the proper growth of the individual 
cells1 which again  may be due either to
 mere extension or to real assimilation4
 ,osmotic  pressure1 of course1 plays an
 important part both in the growth of   
the  body-cavities and in simple        
cellular extension4 ,we repeat the      
caution  against believing too much to  
be explained by this phenomenon3 it is  
the  organism which by the secretion of 
osmotic substances in the cavities or   
the protoplasm of the cells prepares the

 ground for growth even of this  osmotic
 sort4 ,the real cellular growth which  
proceeds on the basis of  assimilation  
cannot1 of course1 be accounted for by  
osmotic events1 not  even in its most   
general type4    ,ontogenetical growth  
generally sets in1 both in animals and  
in plants1  after the chief lines of    
organisation are laid out2 it is only   
the  formation of the definite          
histological structures which usually   
runs  parallel to it4    99,on          
,cell-division499--,we have already said
 a good deal about the  importance of   
cell-division in ontogeny3 it           
accompanies very many of the  processes 
of organisation in all living beings4   
,but even then1 there are  the          
,protozoa1 in the morphogenesis of which
 it does not occur at all1  and there   
have also become known many cases of    
morphogenesis in higher  animals1 mostly
 of the type of regulation1 in which    
cellular division  is almost or wholly  
wanting4 ,therefore1 cellular division  

cannot be  the true reason of           
differentiation1 but is only a process1 
which  though necessary in some cases1  
cannot be essential to it4 ,it must be  
conceded1 ,i believe1 that the same     
conclusion can be drawn from all our    
experiments on very young stages of the 
germ4    ,the investigations of the last
 few years have made it quite clear that
  even in organisms with a high power of
 morphogenetic regulation it is  always 
the form of the whole1 but not the      
individual cell1 which is  subjected to 
the regulation processes4 ,starting from
 certain results  obtained by ,t4 ,h4   
,morgan1 ,i was able to show that in all
 the small but  whole larvae1 reared    
from isolated blastomeres1 the size of  
the cells  remains normal1 only their   
number being reduced2 and ,boveri has   
shown  most clearly that it is always   
the size of the nucleus--more correctly1
  the mass of the chromatin--which      
determines how large a cell of a        
certain histological kind is to be4 ,in 

this view1 the cell appears even  more  
as a sort of material used by the       
organism as supplied1 just as  workmen  
can build the most different buildings  
with stones of a given  size4      4    
99,the ,external ,means of              
,morphogenesis99    ,we now know what   
internal means of morphogenesis are1 and
 so we may  glance at some of the most  
important 8outer means0 or 8conditions0 
of  organisation4    ,like the adult1   
the germ also requires a certain amount 
of heat1 oxygen1  and1 when it grows up 
in the sea1 salinity in the medium4 ,for
 the germ1  as for the adult1 there     
exists not only a minimum but also a    
maximum  limit of all the necessary     
factors of the medium2 the same factor  
which  at a certain intensity promotes  
development1 disturbs it from a certain 
other intensity upwards4    ,within the 
limits of this minimum and this maximum 
of every outside  agent there generally 
is an increase in the rate of           
development  corresponding to the       

increase of intensity of the agent4 ,the
  acceleration of development by heat   
has been shown to follow the law of  the
 acceleration of chemical processes by a
 rise of temperature2 that  seems to    
prove that certain chemical processes go
 on during the course  of morphogenesis4
    ,almost all that has been           
investigated of the part played by the  
external  conditions of development has 
little bearing on specific morphogenesis
  proper1 and therefore may be left out 
of account here3 we must1 however1  lay 
great stress on the general fact that   
there 99is99 a very close  dependence of
 morphogenesis on the outside factors1  
lest we should be  accused afterwards of
 having overlooked it4    ,of course all
 8external0 means or conditions of      
morphogenesis can  actually relate to   
morphogenetic processes only by becoming
 in some way  8internal10 but we        
unfortunately have no knowledge whatever
 how this  happens4 ,we at present are  
only able to ascertain what must        

necessarily  be accomplished in the     
medium1 in order that normal            
morphogenesis may go  on1 and we can    
only suppose that there exist certain   
specific internal  general states1      
indispensable for organogenesis but     
inaccessible to  present modes of       
investigation4#cf    #cf ,compare the   
analytical discussions of ,klebs1 to    
whom we owe a great  series of important
 discoveries in the field of            
morphogenetic 8means0  in botany4       
799,willkrliche ,entwickelungsnderungen 
bei ,pflanzen991 ,jena1  #aijc2 see also
 99,biol4 ,centralblatt991 vol4 xxiv41  
#aijd1 and my reply to  ,klebs1         
99ibid499 #bc1 #aijc47    99,the        
,discoveries of ,herbst499--,there are  
but few points in the doctrine  of the  
external means or conditions of         
organogenesis which have a  more special
 bearing on the specification of proper 
form1 and which  therefore require to be
 described here a little more fully4    
,all  these researches1 which have been 

carried out almost exclusively by       
,herbst1#cg relate to the effect of the 
chemical components of sea-water  upon  
the development of the sea-urchin4 ,if  
we select the most important  of        
,herbst's results1 we must in the first 
place say a few words on  the part taken
 by lime or calcium1 not only in        
establishing specific  features of form1
 but in rendering individual            
morphogenesis possible at  all4 ,herbst 
has found that in sea-water which is    
deprived of calcium the  cleavage cells 
and many tissue cells also completely   
lose contact with  each other3 cleavage 
goes on quite well1 but after each      
single division  the elements are       
separated2 at the end of the process you
 find the #hjh  cells of the germ       
together at the bottom of the dish1 all 
swimming about  like infusoria4 ,there  
seems to be some influence of the       
calcium salts  upon the physical state  
of the surfaces of the blastomeres4     
#cg 99,arch4 ,entw4 ,mech499 #ag1 #aijd4

    ,it is not without interest to note 
that this discovery has an important    
bearing on the technical side of all    
experiments dealing with the  isolation 
of blastomeres4 ,since the separation of
 the single cleavage  elements ceases as
 soon as the germs are brought back from
 the mixture  without lime into normal  
sea-water1 it of course is possible to  
separate  them up to any stage which it 
is desired to study1 and to keep them   
together afterwards4 ,thus1 if for      
instance you want to study the          
development of isolated cells of the    
eight-cell stage1 you will leave  the   
egg in the artificial mixture containing
 no calcium until the  third cleavage1  
which leads from the four- to the       
eight-cell stage1 is  finished4 ,the    
single eight cells brought back to      
normal sea-water at  this point will    
give you the eight embryos you want4    
,all researches  upon the development of
 isolated blastomeres since the time of 
,herbst's  discovery have been carried  

out by this method1 and it would have   
been  quite impossible by the old method
 of shaking to pursue the study into    
such minute detail as actually has been 
done4 ,it may be added that  calcium1   
besides its cell-uniting action1 is also
 of primary importance  in the formation
 of the skeleton4    ,among all the     
other very numerous studies of ,herbst  
we need only mention  that potassium is 
necessary for the typical growth of the 
intestine1  just as this element has    
been found necessary for normal growth  
in  plants1 and that there must be the  
ion ,,so#d1 or in other terms1  sulphur 
salts present in the water1 in order    
that the germs may acquire  their       
pigments and their bilateral symmetry4  
,this is indeed a very  important       
result1 though it cannot be said to be  
properly understood4 ,it  is a fact that
 in water without sulphates the larvae  
of ,echinus retain  the radial symmetry 
they have had in the very earliest      
stages1 and may  even preserve that     

symmetry on being brought back to normal
 sea-water if  they have spent about    
twenty-four hours in the artificial     
mixture4    ,we may now leave the       
subject of ,herbst's attempts to        
discover the  morphogenetic function of 
the single constituents of normal       
sea-water1  and may devote a few words  
to the other branch of his              
investigations1  those dealing with the 
morphogenetic effects of substances     
which are not  present in the water of  
the sea1 but have been added to it      
artificially4  ,here1 among many other  
achievements1 ,herbst has made the most 
important discovery that all salts of   
lithium effect radical changes  in      
development4#ch ,i cannot describe fully
 here how the so-called  8lithium larva0
 originates2 let me only mention that   
its endoderm is  formed outside instead 
of inside1 that it is far too large1    
that there  is a spherical mass between 
the ectodermal and the endodermal part  
of  the germ1 that a radial symmetry is 

established in place of the normal      
bilateralism1 that no skeleton exists1  
and that the mesenchyme cells  are      
placed in a quite abnormal position4    
,all these features1 though  abnormal1  
are typical of the development in       
lithium4 ,the larvae present  no really 
pathological appearance at all1 and1    
therefore1 it may indeed  be said that  
lithium salts are able to change        
fundamentally the whole  course of      
morphogenesis4 ,it detracts nothing from
 the importance of  these discoveries   
that1 at present1 they stand quite      
isolated3 only with  lithium salts has  
,herbst obtained such strange results1  
and only upon  the eggs of echinids1 not
 even upon those of asterids1 do lithium
 salts  act in this way4    #ch         
99,zeitschr4 wiss4 ,zool499 #ee1 #aijb2 
and 99,mitt4 ,neapel499 #aa1 #aijc4     
4 ,,the ,,formative ,,causes ,,or       
,,stimuli    99,the ,definition of      
,cause99    ,we cannot begin the study  
of the 8causes0 of the differentiation  

of  form without a few words of         
explanation about the terminology which 
we  shall apply4 ,causality is the most 
disputed of all categories2 many  modern
 scientists1 particularly in physics1   
try to avoid the concept of  cause      
altogether1 and to replace it by mere   
functional dependence in  the           
mathematical meaning of the term4 ,they 
claim to express completely  by an      
equation all that is discoverable about 
any sort of phenomena  constantly       
connected4    ,i cannot convince myself 
that such a very restricted view is the 
right  one3 it is very cautious1 no     
doubt1 but it is incomplete1 for we     
99have99  the concept of the acting     
8cause0 in our ,ego and are 99forced99  
to search  for applications of it in    
,nature4 ,on the other hand1 it does not
 at all  escape me that there are many  
difficulties1 or rather ambiguities1 in 
applying it4    ,we may call the 8cause0
 of any event1 the sum total of all the 
constellations of facts which must be   

completed in order that the event  may  
occur2 it is in this meaning1 for       
instance1 that the first principle  of  
energetics applies the term in the words
 99causa aequat effectum994  ,but1 by   
using the word only in this very general
 sense1 we deprive  ourselves of many   
conveniences in the further and more    
particular study  of ,nature4 ,would it 
be better to say that the 8cause0 of any
 event is  the very last change which1  
after all the constellations necessary  
for  its start are accomplished1 must   
still take place in order that the      
event may actually occur8 ,let us see   
what would follow from such a use  of   
the word causality4 ,we here have an    
animal germ in a certain stage1  say a  
larva of ,echinus1 which is just about  
to form the intestine2 all  the internal
 conditions are fulfilled1 and there is 
also a certain  temperature1 a certain  
salinity1 and so on1 but there is no    
oxygen in  the water3 the intestine2 of 
course1 will not grow in such a state of

  things1 but it soon will when oxygen  
is allowed to enter the dish4  ,is1     
therefore1 oxygen the cause of the      
formation of the intestine of  echinus8 
,nobody1 ,i think1 would care to say so4
 ,by such reasoning1  indeed1 the       
temperature1 or sodium1 might be called 
the 8cause0 of  any special process of  
morphogenesis4 ,it1 therefore1 seems to 
be of  little use to give the name of   
cause to that factor of any necessary   
constellation of events which           
accidentally happens to be the last that
  is realised4 ,but what is to be done  
then8    ,might we not say that the     
cause of any morphogenetic process is   
that  typical property1 or quality1 or  
change1 on which its specific character 
depends1 on which depends for example1  
the fact that now it is the  intestine  
which appears1 while at another time it 
is the lens of the  eye8 ,we might very 
well1 but we already have our term for  
this sort  of cause1 which is nothing   
else than our prospective potency       

applied  to that elementary organ from  
which the new process takes its origin4 
,the prospective potency indeed is the  
truly immanent cause of every           
specification affecting single          
organogenetic processes4 ,but we want   
something more than this4    ,we may    
find what we want by considering that   
each single elementary  process or      
development not only has its            
specification1 but also has  its        
specific and typical place in the       
whole--its locality4 ,therefore  we     
shall call the 8cause0 of a single      
morphogenetic process1 that  occurrence 
on which depends its 99localisation991  
whether its specific  character also    
partly depends on this 8cause0 or       
not4#ci    #ci ,in certain cases part of
 the specific feature of the process in 
question may also depend on the 8cause0 
which is localising it1 99e4g499  in the
 galls of plants4    ,this definition of
 8cause0 in morphology may be           
artificial2 in any  case it is clear4   

,and at the same time the concepts of   
the prospective  potency and of the     
8means0 of organogenesis now acquire a  
clear and  definite meaning3 potency is 
the real basis of the specific character
  of every act in morphogenesis1 and    
8means10 including conditions1 are  the 
sum of all external and internal general
 circumstances which must be  present in
 order that morphogenetic processes may 
go on1 without being  responsible for   
their specificity or localisation4      
,it is implied in these definitions of  
cause and potency1 that the former      
almost always will be of that general   
type which usually is called a  stimulus
 or 8,auslsung10 to use the             
untranslatable ,german word4 ,there is  
no quantitative correspondence between  
our 8cause0 and the morphogenetic       
effect4    99,some ,instances of        
,formative and ,directive ,stimuli99    
,again it is to ,herbst that we owe not 
only a very thorough logical  analysis  
of what he calls 8formative and         

directive stimuli0#dj but also  some    
important discoveries on this subject4  
,we cannot do more here than  barely    
mention some of the most characteristic 
facts4    #dj ,herbst1 8,ueber die      
,bedeutung die ,reizphysiologie fr die  
kausale  ,auffassung von ,vorgngen in   
der tierischen ,ontogenese0 799,biol4   
,centralblatt991 vols4 xiv41 #ahid1 and 
xv41 #ahie72 99,formative ,reize in der 
tierischen ,ontogenese991 ,leipzig1     
#aija4 ,these important papers must be  
studied by every one who wishes to      
become familiar with the subject4 ,the  
present state of science is reviewed in 
my articles in the 99,ergebnisse  der   
,anatomie und                           
,entwickelungsgeschichte991 vols4 xi4   
and xiv41 #aijb and  #aije4    ,amongst 
plants it has long been known that the  
direction of light or of  gravity may   
determine where roots or branches or    
other morphogenetic  formations are to  
arise2 in hydroids also we know that    
these factors  of the medium may be at  

work#da as morphogenetic causes1 though 
most  of the typical architecture of    
hydroid colonies certainly is due to    
internal causes1 as is also much of the 
organisation in plants4    #da ,compare 
the important papers by ,j4 ,loeb1      
99,untersuchungen zur  physiologischen  
,morphologie der ,tiere991 ,wrzburg1    
#ahia-b4    ,light and gravity are      
external formative causes2 beside that  
they are  merely 8localisers40 ,but     
there also are some external formative  
stimuli1  on which depends not only the 
place of the effect1 but also part of   
its  specification4 ,the galls of plants
 are the most typical organogenetic     
results of such stimuli4 ,the potencies 
of the plant and the specific  kind of  
the stimulus equally contribute to their
 specification2 for  several kinds of   
galls may originate on one sort of      
leaves4    ,scarcely any exterior       
formative stimuli are responsible for   
animal  organisation2 and one would     
hardly be wrong in saying that this     

morphogenetic independence in animals is
 due to their comparatively             
far-reaching functional independence of 
those external agents which  have any   
sort of direction4 ,but many            
organogenetic relations are known  to   
exist between the single parts of animal
 germs1 each of these parts  being in   
some respect external to every other2   
and1 indeed1 it might  have been        
expected already 99a priori991 that such
 formative relations  between the parts 
of an animal embryo must exist1 after   
all we have  learned about the chief    
lines of early embryology4 ,if          
differentiation  does not go on after   
the scheme of ,weismann1 that is1 if it 
is not  carried out by true 8evolutio0  
from within1 how could it be effected   
except from without8 ,indeed1 every     
embryonic part may in some respect be  a
 possible cause for morphogenetic       
events1 which are to occur on every     
other part3 it is here that the very    
roots of epigenesis are to be found4    

,heliotropism and geotropism are among  
the well-known physiological  functions 
of plants3 the roots are seen to bend   
away from the light and  towards the    
ground2 the branches behave just in the 
opposite way4 ,it now  has been supposed
 by ,herbst that such 8directive        
stimuli0 may also be  at work among the 
growing or wandering parts of the       
embryo1 that their  growth or their     
migration may be determined by the      
typical character of  other parts1 and  
that real morphogenetic characters can  
be the result of  some such relation2 a 
sort of 8chemotropism0 or 8chemotaxis0  
may be at  work here4 ,herbst himself   
has discussed theoretically several     
cases of  organogenesis in which the    
action of directive stimuli is very     
probable4  ,what has become actually    
known by experiment is not very much at 
present3 the mesenchyme cells of        
,echinus are directed in their migration
  by specified places in the ectoderm1  
the pigment cells of the yolk-sac  of   

the fish fundulus are attracted by its  
blood vessels1 and nerves  may be forced
 to turn into little tubes containing   
brain substance2  but of course only the
 first two instances have any bearing on
 typical  morphogenesis4    ,the first  
case of an 8internal formative stimulus0
 in the proper sense1  that is1 of one  
embryonic part causing another to       
appear1 was discovered  by ,herbst      
himself4 ,the arms of the so-called     
pluteus of the sea-urchin  are in       
formative dependence on the skeleton--no
 skeleton1 no arms2 so  many skeleton   
primordia1#db in abnormal cases1 so many
 arms2 abnormal  position of the        
skeleton1 abnormal position of the arms3
 these three  experimental observations 
form the proof of this morphogenetic    
relation4    #db ,i use the word        
8primordia0 for the ,german 8,anlage02  
it is better  than the word 8rudiment10 
as the latter may also serve to signify 
the very last stage of a certain        
formation that is disappearing          

7phylogenetically74    ,it may be simple
 mechanical contact1 or it may be some  
chemical  influence that really         
constitutes the 8stimulus0 in this case2
  certainly1 there exists a close and   
very specific relation of the           
localisation of one part of the embryo  
to another4 ,things are much the  same  
in another case1 which1 after having    
been hypothetically stated  by ,herbst  
on the basis of pathological data1 was  
proved experimentally  by ,spemann4 ,the
 lens of the eye of certain ,amphibia is
 formed of their  skin in response to a 
formative stimulus proceeding from the  
so-called  primary optic vesicle4 ,if   
this vesicle fails to touch the skin1 no
 lens  appears2 and1 on the other hand1 
the lens may appear in quite abnormal   
parts of the skin if they come into     
contact with the optic vesicle after    
transplantation4    ,but formative      
dependence of parts may also be of      
different types4    ,we owe to ,herbst  
the important discovery that the eyes of

 crayfishes1  after being cut off1 will 
be regenerated in the proper way1 if the
 optic  ganglion is present1 but that an
 antenna will arise in their place  if  
this ganglion has also been removed4    
,there must in this case be  some       
unknown influence of the formative kind 
on which depends1 if not  regeneration  
itself1 at least its special character4 
,in other cases there seems to be an    
influence of the central nervous  system
 on the regenerative power in general4  
,amphibia1 for instance1  are said to   
regenerate neither their legs 7,wolff71 
nor their tail  7,godlewski71 if the    
nervous communications have been        
disturbed4 ,but  in other animals there 
is no such influence2 and in yet others1
 as  for instance1 in ,planarians1 it   
must seem doubtful at present whether   
the morphogenetic influence of the      
nervous system upon processes of        
restoration is more than indirect2 the  
movements of the animal1 which  become  
very much reduced by the extirpation of 

the ganglia1 being one of  the main     
conditions of a good regeneration4      
,of course1 all we have said about the  
importance of special materials  in the 
ripe germ1 as bearing on specifically   
localised organisations1  might be      
discussed again in our present chapter1 
and our intimate  polar-bilateral       
structure of germs may also be regarded 
as embracing  formative stimuli1 at any 
rate as far as the actual poles of this 
structure are concerned4 ,this again    
would bring us to the problem of        
so-called 8polarity0 in general1 and to 
the 8inversion0 of polarity1  that is to
 a phenomenon well known in plants and  
in many hydroids and  worms1 viz41 that 
morphogenetic processes1 especially of  
the type of  restitutions1 occur        
differently1 according as their point of
 origin  represents1 so to speak1 the   
positive or the negative1 the terminal  
or  the basal end of an axis1 but that  
under certain conditions the reverse    
may also be the case4 ,but a fuller     

discussion of these important facts     
would lead us deeper and deeper into the
 science of morphogenesis  proper1      
without being of much use for our future
 considerations4    ,and so we may close
 this section#dc on formative stimuli or
 8causes0  of morphogenesis by shortly  
adding1 more on account of its factual  
than of its logical interest1 that the  
phenomenon of the determination  of     
sex1#dd according to the latest         
researches1 seems to depend on          
cytological events occurring in the very
 earliest embryonic stages1  say even   
before ontogeny1 and not on formative   
stimuli proper#de3 it  seems1 indeed1 as
 if the sexual products themselves would
 account for  the sex of the individual 
produced by them1 particularly if there 
were  differences in their chromatin4#df
    #dc ,a full analysis of the subject 
would not only have to deal with        
formative stimuli as inaugurating       
morphogenetic processes1 but also with  
those stimuli which terminate or stop   

the single acts of morphogenesis4  ,but 
little is actually known about this     
topic1 and therefore the reader  must   
refer to my other publications4 ,i will 
only say here1 that the end  of each    
single morphogenetic act may either be  
determined at the very  beginning or    
occur as an actual stopping of a process
 which otherwise  would go on for ever  
and ever2 in the first case some        
terminating  factors are included in the
 very nature of the morphogenetic act   
itself4    #dd ,a full account of the   
present state of the subject will be    
found in  ,morgan's 99,experimental     
,zoology991 ,new ,york1 #aijg4    #de   
,but there certainly exist many         
formative relations between the real    
sexual organs and the so-called         
secondary sexual characters4 ,herbst has
  given a full analytical discussion of 
all that is known on this subject2  but 
the facts are much more complicated than
 is generally supposed1 and  do not lend
 themselves therefore to short          

description4 ,see also ,foges1          
99,pflger's ,arch499 #ic1 #aijb4    #df 
,it seems that in some cases            
799,dinophilus991 certain ,arthropods7  
the sexual products are invariably      
determined as 8arrenogennetic0  or as   
8thelygennetic0 7,wilson1 99,journ4     
,exp4 ,zool499 ii4 and iii4  #aije-f71  
whilst in others 7,amphibia7 the state  
of maturation or  8super0-maturation    
determines the sex of the future        
organism 7,r4  ,hertwig1 99,verh4 ,d4   
,zool4 ,ges499 #aije-g74      4 ,,the   
,,morphogenetic ,,harmonies    ,let us  
now turn again to considerations of a   
more abstract kind3 we have  become     
acquainted with some morphogenetic      
interactions among the parts  of a      
developing embryo2 and1 indeed1 we can  
be sure that there exist far  more of   
such interactions than we know at       
present4    ,but it is far from being   
true that the development of each       
embryonic  part depends on the existence
 or development of every other one4     

,on the contrary1 it is a very important
 and fundamental feature  of            
organogenesis that it occurs in separate
 lines1 that is to  say1 in lines of    
processes which may start from a common 
root1 but  which are absolutely         
independent of one another in their     
manner of  differentiation4 ,roux has   
coined the term 8self-differentiation0  
to  denote this phenomenon1 and we admit
 that this term may be conveniently     
used for the purpose1 if only it can be 
kept in mind that its sense is  always  
relative1 and that it is also negative4 
,suppose a part1 99,a991  shows the     
phenomenon of self-differentiation3 this
 means that the  further development of 
99,a99 is not dependent on certain other
 parts1  99,b991 99,c991 and 99,d992 it 
does 99not99 mean at all that 99,a99 has
 not been  formatively dependent on some
 other parts1 99,e99 or 99,f99 at the   
time of  its first appearance1 nor does 
it imply that there might not be many   
formative actions among the constituents

 of 99,a99 itself4    ,we indeed are    
entitled to say that the ectoderm of    
,echinus shows  8self-differentiation0  
with regard to the endoderm2 it acquires
 its  mouth1 for instance1 as has been  
shown by experiment1 even in cases      
where no intestine is present at all    
7,fig4 #aj72 but ectoderm and  endoderm 
both are formatively dependent on the   
intimate and the material  organisation 
of the blastoderm4 ,it further seems    
from the most recent  experiments that  
the nerves and the muscles of the       
vertebrates are  independent of each    
other in their differentiation1 but that
 their fate  is probably determined by  
formative processes in the very earliest
  stages of ontogeny4    ,illustration3 
,fig4 #aj4--,pluteus-larva of           
,sphaerechinus4    ,the ,intestine 7i7  
is developed outside instead of inside  
7by means of  raising the temperature72 
but the mouth 7r7 is formed in its      
normal  place4 ,s  ,skeleton4    ,the   
phenomenon of self-differentiation1     

properly understood1 now may  help to   
the discovery of one most general       
character of all development4  ,if the  
phenomenon of self-differentiation      
really occurs in ontogeny  in its most  
different aspects1 and if1 on the other 
hand1 in spite  of this relative        
morphogenetic independence of embryonic 
parts1 the  resulting organism is one   
whole in organisation and in function1  
some  sort of 99harmony of              
constellation991 as it may properly be  
styled1 must  be said to be one of the  
most fundamental characters of all      
production  of individual form4 ,in     
establishing this harmony we do nothing 
more  than describe exactly what        
happens3 the harmony is shown by the    
fact  that there is a whole organism at 
the end1 in spite of the relative       
independence of the single events       
leading to it4    ,but still another    
sort of harmony is revealed in          
morphogenesis1 by an  analysis of the   
general conditions of the formative     

actions themselves4  ,in order that     
these actions may go on properly the    
possibility must be  guaranteed that the
 formative causes may always find       
something upon  which to act1 and that  
those parts which contain the potencies 
for the  next ontogenetic stage may     
properly receive the stimuli awaking    
these  potencies3 otherwise there would 
be no typical production of form at     
all4 ,this1 the second species of       
harmonious relations to be described in 
ontogeny1 may be called 99causal        
harmony992 the term simply expresses the
  unfailing relative condition of       
formative causes and cause-recipients4  
,finally1 in 99functional harmony99 we  
have an expression descriptive  of the  
unity of organic function1 and so we may
 state1 as the latest  result of our    
analytical theory of development up to  
this point1 that  individual            
morphogenesis is marked by a 99threefold
 harmony99 among its  parts4      4 ,,on
 ,,restitutions#dg    #dg ,driesch1     

99,die organischen ,regulationen991     
,leipzig1 #aija2 ,morgan1               
99,regeneration991 ,new ,york1 #aija4   
,at this stage we leave for a while our 
analytical studies of ontogeny  proper4 
,we must not forget that typical        
ontogenesis is not the only form  in    
which morphogenesis can occur3 the      
organic form is able to restore         
disturbances of its organisation1 and it
 certainly is to be regarded as  one of 
the chief problems of analytical        
morphogenesis to discover the  specific 
and real stimulus which calls forth the 
restoring processes4  ,for simply to say
 that the disturbance is the cause of   
the restoration  would be to evade the  
problem instead of attacking it4 ,but   
there are  still some other problems    
peculiar to the doctrine of             
restitutions4    99,a few ,remarks on   
,secondary ,potencies and on ,secondary 
,morphogenetic  ,regulations in         
,general99    ,we have only briefly     
mentioned in a previous chapter that    

there  exist many kinds of potencies of 
what we call the secondary or truly     
restitutive type1 and that their        
distribution may be most various and    
quite independent of all the potencies  
for the primary processes  of ontogeny  
proper4 ,let us first add a few words   
about the concept  of 8secondary        
restitution0 and about the distribution 
of secondary  potencies in general4     
,primary ontogenetic processes founded  
upon primary potencies may 99imply99    
regulation1 or more correctly1          
restitution in many cases3 so it is1    
when fragments of the blastula form the 
whole organism1 or when the  mesenchyme 
cells of ,echinus reach their normal    
final position by an  attraction on the 
part of specific localities of the      
ectoderm in spite  of a very abnormal   
original position enforced upon them by 
experiment4  ,in these cases we speak of
 primary regulations or restitutions2   
disturbances are neutralised by the very
 nature of the process in  question4 ,we

 speak of secondary restitution whenever
 a disturbance  of organisation is      
rectified by processes foreign to the   
realm of  normality2 and these abnormal 
lines of events are revealed to us in   
the  first place by the activity of     
potencies which remain latent in        
ontogeny  proper4    ,we know already   
that a certain kind of secondary        
restitution has  been discovered lately1
 very contradictory to the theoretical  
views  of ,weismann2 the process of     
restoration being carried out not by any
  definite part of the disturbed        
organisation1 but by all the single     
elements of it4 ,the problem of the     
distribution of secondary potencies  in 
these cases of so-called                
8re-differentiation0 is to form our     
special  study in the next chapter4 ,in 
all other cases restoration processes   
start from specific localities2 if they 
occur on the site of the  wound which   
caused the disturbance1 we speak of     
regeneration2 if they  occur at some    

distance from the wound1 we call them   
adventitious  processes4 ,besides these 
three types of processes of restitution 
there  may be mentioned a fourth one1   
consisting in what is generally called  
compensatory hypertrophy2 the most      
simple case of such a compensatory      
process is when one of a pair of organs1
 say a kidney1 becomes larger  after the
 other has been removed4#dh ,finally1 at
 least in plants1 a  change of the      
directive irritability1 of so-called    
8geotropism0 for  instance1 in certain  
parts may serve to restore other more   
important  parts4    #dh ,but real      
compensatory differentiation occurs in  
the cases of  so-called 8hypertypy0 as  
first discovered by ,przibram and       
afterwards  studied by ,zeleny3 here the
 two organs of a pair show a different  
degree  of differentiation4 ,whenever   
the more specialised organ is removed   
the  less developed one assumes its     
form4 ,similar cases1 which might simply
  be called 8compensatory heterotypy10  

are known in plants1 though only        
relating to the actual fate of          
undifferentiated 8,anlagen0 in these    
organisms4 ,a leaf may be formed out of 
the ,anlage of a scale1 if all the      
leaves are cut off1 and so on4    ,in   
two of these general types of           
restitution1 in regeneration proper and 
in the production of adventitious       
organs1 the potencies which underlie    
these processes may be said to be       
8complex40 ,it is a complicated series  
of events1 a proper morphogenesis in    
itself1 for which the potency  has to   
account1 if1 for instance1 a worm newly 
forms its head by  regeneration1 or if a
 plant restores a whole branch in the   
form of an  adventitious bud4    ,such  
generalisations as are possible about   
the distribution of complex  potencies  
are reserved for a special part of our  
future discussion4    ,secondary        
restitution is always1 like ontogeny1 a 
process of  morphogenesis1 and therefore
 all the questions about single         

formative  stimuli1 and about internal  
and external conditions or means1 occur 
again4 ,but of course we cannot enter   
into these problems a second time1  and 
may only say that1 especially in        
regeneration proper1 the specific  type 
of the regenerative formation of any    
part may differ very much from  the     
ontogenetic type of its origin3 the end 
of both is the same1 but the  way can be
 even fundamentally different in every  
respect4    99,the ,stimuli of          
,restitutions99#di    #di ,for a fuller 
analysis compare my opening address     
delivered before  the section of        
8,experimental ,zoology0 at the ,seventh
 ,zoological  ,congress1 ,boston1 #aijg3
 8,the ,stimuli of ,restitutions0 7see  
,proceedings  of that ,congress74       
,but now we turn to the important       
question3 what is the precise           
stimulus#ej that calls forth processes  
of restitution2 or1 in other  words1    
what must have happened in order that   
restitution may occur8    #ej ,the      

problem of the stimulus of a secondary  
restitution as a  whole must not be     
confused with the very different        
question1 what the  single 8formative   
stimuli0 concerned in the performance of
 a certain  restitutive act may be4     
,with regard to restitution as a        
99whole99 these  single 8formative      
stimuli0 might properly be said to      
belong to its  8internal means0--in the 
widest sense of the word4    ,that the  
operation in itself1 by its removing of 
mechanical obstacles1  cannot be the    
true stimulus of any restitutions1 is   
simply shown by all  those restitutions 
that do not happen at the place of the  
wound4 ,if we  took a narrower point of 
view1 and if we only considered         
regeneration  proper from the wound     
itself1 we might probably at first be   
inclined to  advocate the doctrine that 
the removing of some obstacles might in 
fact  be the stimulus to the process of 
restoration2 but1 even then1 why is  it 
that just what is wanted grows out8 ,why

 is there not only growth1  but specific
 growth1 growth followed by             
specification8 ,the removing  of an     
obstacle could hardly account for that4 
,but1 of course1 taking  account of all 
the adventitious restitutions--that is1 
all restorations  not beginning at the  
wound itself--the theory that the       
removing of  obstacles is the stimulus  
to restoration becomes1 as we have said1
 quite  impossible4#ea    #ea ,t4 ,h4   
,morgan is very right in stating that1  
in regeneration1 the  8obstacle0 itself 
is newly formed by the mere process of  
healing1  previous to all restitution1  
and that true restitution happens all   
the  same4    ,but where then is the    
stimulus to be found8 ,there is another 
rather  simple theory of the 8,auslsung0
 of restitutions1#eb which starts  from 
the phenomena of compensatory           
hypertrophy and some occurrences  among 
plants4 ,the removal of some parts of   
the organism1 it is said1  will bring   
its other parts into better conditions  

of nutrition1 and  therefore these      
parts1 particularly if they are of the  
same kind1 will  become larger4 ,granted
 for the moment that such a view may    
hold in cases  when one of a pair of    
glands becomes larger after the other   
has been  removed1 or when pruning of   
almost all the leaves of a tree leads to
 the  rest becoming larger1 it certainly
 must fail to explain the fact that  in 
other cases true 99new99 formations may 
arise in order to restore a  damaged    
part1 or that the latter may be         
regenerated in its proper way4  ,for    
99merely quantitative99 differences in  
the mixture of the blood or of  the     
nourishing sap in plants can never be a 
sufficient reason for the  highly       
typical and 99qualitative99 structure of
 newly-formed restitutions4  ,and even  
in the most simple cases of a mere      
increase in the size of  some parts1    
that is1 in the simplest cases of       
so-called compensatory  hypertrophy1#ec 
it is at least doubtful1 if not very    

improbable1 that  the compensation is   
accomplished in such a purely passive   
way1 because  we know that in other     
cases it is usually the growth of the   
young parts  that actively attracts the 
nourishment3 there is first             
differentiation  and growth1 and        
99afterwards99 there is a change in the 
direction of the  nourishing fluids4    
#eb ,i merely mention here the still    
8simpler0 one--applicable of course  to 
regeneration proper exclusively--that   
for the simple reason of being          
8wounded10 99i4e499 being a surface open
 to the medium1 the 8wound0 brings      
forth all that is necessary to complete 
the organism4    #ec ,that compensatory 
hypertrophy cannot be due to 8functional
  adaptation0--to be analysed later     
on--was proved by an experiment of      
,ribbert's4 ,compensation may occur     
before the function has made its        
appearance1 as was shown to be the case 
in the testicles and mammae of  rabbits4
 799,arch4 ,entw4 ,mech499 #a1 #ahid1 p4

 #fi47    ,the process of true          
regeneration1 beginning at the locality 
of the wound  itself1 has been shown by 
,morgan1 even as regards its rate1 to   
occur  quite irrespectively of the      
animal being fed or not4#ed ,there could
  hardly be a better demonstration of   
the fundamental fact that food  assists 
restitution1 but does not 8cause0 it in 
any way4    #ed ,at any given time only 
the absolute size of the regenerated    
part is  greater in animals which are   
well fed2 the degree of differentiation 
is  the same in all4 ,zeleny has found  
that1 if all five arms of a starfish    
are removed1 each one of them will      
regenerate more material in a given     
time than it would have done if it alone
 had been removed4 ,but these           
differences also only relate to absolute
 size and not to the degree  of         
differentiation4 ,they possibly may be  
due in fact to conditions of            
nourishment1 but even here other        
explanations seems possible 7,zeleny1   

99,journ4 exp4 ,zool499 #b1 #aije74     
,but in spite of all we have said1 there
 seems to be some truth in  regarding   
the nutritive juices of animals and     
plants as somehow  connected with the   
stimulus of restitutions3 only in this  
very cautious  form1 however1 may we    
make the hypothesis4 ,it has been shown 
for both  animals and plants1 that      
morphogenesis of the restitutive type   
may be  called forth even if the parts1 
now to be 8regenerated0 have not been   
actually removed2 99e4g499 in the       
so-called super-regeneration of legs    
and tails in ,amphibia1 of the head in  
,planarians1 of the root-tip in  plants 
and in some other cases4 ,here it has   
always been a disturbance  of the normal
 connection of some parts with the rest 
of the organism  which proved to be the 
reason of the new formation4 ,this shows
 that  something to do with the         
communication among parts is at least   
connected  with restitution1 and this   
communication may go on either by the   

unknown  action of specific tissues or  
by the aid of the blood or sap4#ee ,but 
in what this change or break of specific
 communication consists1 is  absolutely 
unknown4 ,one might suppose that each   
part of the organisation  constantly    
adds some sort of ferment to the body   
fluids outside or  inside the cells1    
that the removing of any part will      
change the  composition of these fluids 
in this particular respect1 and that    
this  change acts as a sort of          
communication to summon the restituting 
parts  of the whole to do their duty4#ef
    #ee ,for a good discussion of       
8super-regeneration0 in the roots of    
plants see ,nmec1 99,studien ber die    
,regeneration991 ,berlin1 #aije4 ,goebel
  and ,winkler have succeeded in        
provoking the 8restitution0 of parts    
which  were not removed at all by simply
 stopping their functions 7leaves of    
certain plants were covered with        
plaster1 etc474 799,biol4 ,centralbl499 
#bb1  #aijb1 p4 #che2 99,ber4 ,bot4     

,ges499 #bj1 #aijb1 p4 #ha47 ,a fine    
experiment is  due to ,miehe4 ,the alga 
99,cladophora99 was subjected to        
8plasmolysis10 each  cell then formed a 
new membrane of its own around the      
smaller volume of  its protoplasm2 after
 that the plants were brought back to a 
medium of  normal osmotic pressure1 and 
then each single cell grew up into a    
little  plant 7all of them being of the 
same polarity674 ,two questions seem  to
 be answered by this fact3 loss of      
communication is of fundamental         
importance to restitution1 and the      
removal of mechanical obstacles plays   
no part in it1 for the mechanical       
resistances were the same at the end  of
 the experiment as they had been at the 
beginning4 799,ber4 ,bot4 ,ges499  #bc1 
#aije1 p4 #beg47 ,for fuller analysis of
 all the problems of this  chapter see  
my ,organische ,regulationen1 my reviews
 in the 99,ergebnisse  der ,anatomie und
 ,entwickelungsgeschichte991 vols4 viii4
 xi4 xiv41 and  my ,boston address      

mentioned above4 ,compare also ,fitting1
 99,ergebn4 d4  ,physiol499 vols4 iv4   
and v4    #ef ,the so-called 8inner     
secretion0 in physiology proper would   
offer a  certain analogy to the facts   
assumed by such an hypothesis4 ,compare 
the  excellent summary given by ,e4     
,starling at the seventy-eighth meeting 
of  the ,german                         
8,naturforscherversammlung10 ,stuttgart1
 #aijf4    ,but ,i see quite well that  
such a theory is very little            
satisfactory2  for what has to be done  
in restitution in each case is not a    
simple  homogeneous act1 for which one  
special material might account1 but is  
a very complicated work in itself4 ,it  
was the defect of the theory of         
8organ-forming substances0 as advocated 
by ,sachs1 that it overlooked  this     
point4    ,so all we know about the     
proper stimuli of restitutions is far   
from  resting on any valid grounds at   
all2 let us not forget that we are  here
 on the uncertain ground of what may be 

called the newest and  most up-to-date  
branch of the physiology of form4 ,no   
doubt1 there  will be something         
discovered some day1 and the idea of the
 8whole0 in  organisation will probably 
play some part in it4 ,but in what      
manner that  will happen we are quite   
unable to predict4    ,this is the first
 time that1 hypothetically at least1 the
 idea of the  whole has entered into our
 discussion4 ,the same idea may be said 
to  have entered it already in a more   
implicit form in the statement of the   
threefold harmony in ontogeny4    ,let  
us now see whether we can find the same 
problem of the 8whole0  elsewhere1 and  
perhaps in more explicit and less       
hypothetical form4  ,let us see whether 
our analytical theory of development is 
in fact as  complete as it seemed to be1
 whether there are no gaps left in it   
which  will have to be filled up4       
#c4 ,,the ,,problem ,,of ,,morphogenetic
 ,,localisation    4 ,,the ,,theory ,,of
 ,,the ,,harmonious-,,equipotential     

,,system    ,,first ,,proof ,,of ,,the  
,,autonomy ,,of ,,life    ,we have come 
to the central point of the first part  
of these lectures2  we shall try in this
 chapter to decide a question which is  
to give life  its place in ,nature1 and 
biology its place in the system of      
sciences4  ,one of the foundation stones
 is to be laid upon which our future    
philosophy of the organism will rest4   
99,the ,general ,problem99    ,our      
analytical theory of morphogenesis has  
been founded upon three  elementary     
concepts3 the prospective potency1 the  
means1 and the  formative stimulus4 ,its
 principal object has been to show that 
all  morphogenesis may be resolved into 
the three phenomena expressed by  those 
concepts2 in other terms1 that          
morphogenesis may be proved to  consist 
simply and solely of what is expressed  
by them4 ,have we indeed  succeeded in  
attaining this object8 ,has nothing been
 left out8 ,is it  really possible to   
explain every morphogenetic event1 at   

least in the  most general way1 by the  
aid of the terms potency1 means1 and    
stimulus8    ,all of these questions are
 apt to lead us to further              
considerations4  ,perhaps these         
considerations will give us a very clear
 and simple result  by convincing us    
that it is indeed possible to analyse   
morphogenesis in  our schematic way4    
,but if the answer were a negative one8 
,what would that suggest8    ,the full  
analysis of morphogenesis into a series 
of single formative  occurrences1       
brought about by the use of given means 
and on the basis of  given potencies1   
might assure us1 perhaps1 that1 though  
not yet1 still  at some future time1 a  
further sort of analysis will be        
possible3 the  analysis into the        
elemental facts studied by the sciences 
of inorganic  nature4 ,the organism     
might prove to be a machine1 not only in
 its  functions but also in its very    
origin4    ,but what are we to say if   
even the preliminary analysis1 which    

possibly  might lead to such an ultimate
 result1 fails8    ,let us then set to  
work4 ,let us try to consider most      
carefully the topic  in which our       
concept of the formative cause or       
stimulus may be said  to be centred1 the
 99localisation99 of all morphogenetic  
effects4 ,is it  always possible in fact
 to account for the typical localisation
 of every  morphogenetic effect by the  
discovery of a single specific formative
  stimulus8 ,you will answer me1 that   
such an analysis certainly is not       
possible at present4 ,but ,i ask you    
again1 are there any criteria that it   
is possible1 at least in principle2 or  
are there any criteria which will       
render such an aim of science impossible
 for all future time8      99,the       
,morphogenetic 8,system099    ,we know  
from our experimental work that many1 if
 not all1 of the  elementary organs in  
ontogeny show one and the same          
prospective  potency distributed equally
 over their elements4 ,if we now borrow 

a  very convenient term from mechanics1 
and call any part of the organism  which
 is considered as a unit from any       
morphogenetic point of view1 a          
morphogenetic 899system9910 we may sum  
up what we have learnt by saying  that  
both the blastoderm of the echinoderms1 
at least around its  polar axis1 and    
also the germ-layers of these animals1  
are 8systems0  possessing an equal      
potentiality in all of their elements1  
or1 in short1  that they are            
99equipotential systems994    ,but such 
a term would not altogether indicate the
 real character of  these systems4      
,later on we shall analyse more         
carefully than before the distribution  
of potencies which are the foundation   
both of regeneration proper and  of     
adventitious growth1 and then we shall  
see that1 in higher plants  for         
instance1 there is a certain 8system0   
which may be called the  organ proper of
 restitutions1 and which also in each of
 its elements  possesses the same       

restoring potency2 ,i refer to the      
well-known cambium4  ,this cambium1     
therefore1 also deserves the name of an 
8equipotential  system40 ,but we know   
already that its potencies are of the   
complex  type1 that they consist in the 
faculty of producing the 99whole991 of  
such a complicated organisation as a    
branch or a root1 that the term         
8equipotential system0 is here only to  
signify that such a complicated  unit   
may arise out of each of the cells of   
the cambium4    ,the potencies we have  
been studying in the blastula or        
gastrula of  echinoderms are not of the 
complex type3 our systems are           
equipotential  to the extent that each  
of their elements may play every        
99single99 part  in the totality of what
 will occur in the whole system2 it is  
to  this 99single99 part that the term  
8function of the position0 relates4  ,we
 therefore might call our systems       
equipotential systems with single       
potencies2 or1 more shortly1            

singular-equipotential systems4    ,but 
even this terminology would fail to     
touch precisely the very  centre of     
facts3 it is not only the simplicity or 
singularity of  their potencies which   
characterises the rle of our systems in 
morphogenesis1#eg but far more important
 with respect to the production  of form
 are two other leading results of the   
experimental researches4  ,the proper   
act to be performed by every element in 
each actual case is  in fact a single   
one1 but the potency of any element as  
such consists  in the possibility of    
many1 nay of indefinitely many1 single  
acts3  that then might justify us in    
speaking of our systems as 8indefinite  
equipotential10 were it not that another
 reason makes another title seem  still 
more preferable4 ,there are indeed      
indefinite singular potencies at  work  
in all of our systems during ontogeny3  
but the sum of what happens  to arise in
 every case out of the sum of the single
 acts performed by  all of the single   

equipotential cells is not merely a sum 
but a unit2  that is to say1 there      
exists a sort of harmony in every case  
among the  99real products99 of our     
systems4 ,the term                      
99harmonious-equipotential  system99    
therefore seems to be the right one to  
denote them4    #eg ,the name of        
singular-equipotential systems might    
also be applied  to elementary organs1  
the single potencies of which are awaked
 to  organogenesis by specific formative
 stimuli from without2 but that is  not 
the case in the systems studied in this 
chapter4    ,we now shall try first to  
analyse to its very extremes the meaning
 of  the statement that a morphogenetic 
system is harmonious-equipotential4     
99,the 8,harmonious-,equipotential      
,system099    ,we have an ectoderm of   
the gastrula of a starfish here before  
us2 we  know that we may cut off any    
part of it in any direction1 and that   
nevertheless the differentiation of the 
ectoderm may go on perfectly  well and  

result in a typical little embryo1 which
 is only smaller in  its size than it   
would normally be4 ,it is by studying   
the formation of  the highly complicated
 ciliary band1 that these phenomena can 
be most  clearly understood4    ,now let
 us imagine our ectoderm to be a        
cylinder instead of being  approximately
 a sphere1 and let us imagine the       
surface of this cylinder  unrolled4 ,it 
will give us a plane of two definite    
dimensions1 99a99 and  99b994 ,and now  
we have all the means necessary for the 
analytical study of  the differentiation
 of an harmonious-equipotential system4 
,our plane of the dimensions 99a99 and  
99b99 is the basis of the normal1       
undisturbed development2 taking the     
sides of the plane as fixed  localities 
for orientation1 we can say that the    
actual fate1 the  8prospective value0 of
 every element of the plane stands in a 
fixed and  definite correlation to the  
length of two lines1 drawn at right     
angles  to the bordering lines of the   

plane2 or1 to speak analytically1 there 
is a definite actual fate corresponding 
to each possible value of 99x99  and of 
99y994 ,now1 we have been able to state 
by our experimental work1  that the     
prospective value of the elements of our
 embryonic organ is not  identical with 
their 8prospective potency10 or their   
possible fate1 this  potency being very 
much richer in content than is shown by 
a single case  of ontogeny4 ,what will  
be the analytical expression of such a  
relation8    ,let us put the question in
 the following way3 on what factors does
  the fate of any element of our system 
depend in all possible cases  of        
development obtainable by means of      
operations8 ,we may express our  results
 in the form of an equation3--          
99p4v4 7,x7  f7 444 799    99i4e499 8the
 prospective value of the element 99,x99
 is a function of  4440--of what8    ,we
 know that we may take off any part of  
the whole1 as to quantity1 and  that a  
proportionate embryo will result1 unless

 the part removed is of  a very large   
size4 ,this means that the prospective  
value of any element  certainly depends 
on1 certainly is a function of1 the     
99absolute size99  of the actually      
existing part of our system in the      
particular case4 ,let  99s99 be the     
absolute size of the system in any      
actual experimental case  of            
morphogenesis3 then we may write 99p4v4 
7,x7  f7s 444 7994 ,but we  shall have  
to add still some other letter to this  
99s994    ,the operation of section was 
without restriction either as to the    
amount of the material removed from the 
germ1 or as to the direction of  the    
cut4 ,of course1 in almost every actual 
case there will be both a  definite size
 of the actual system and a definite    
direction of the cut  going             
hand-in-hand4 ,but in order to study    
independently the importance  of the    
variable direction alone1 let us imagine
 that we have isolated  at one time that
 part of our system which is bounded by 

the lines 99a#a  b#a991 and at another  
time an equal amount of it which has the
 lines  99a#b b#b99 as its boundaries4  
,now since in both cases a typical small
  organism may result on development1 we
 see that1 in spite of their equal  size
 the prospective value of every element 
of the two pieces cut  out of the germ  
may vary even in relation to the        
direction of the cut  itself4 ,our      
element1 99,x991 may belong to both of  
these pieces of the same  size3 its     
actual fate nevertheless will be        
different4 ,analytically1 it  may be    
said to change in correspondence to the 
actual position of the  actual boundary 
lines of the piece itself with regard to
 the fundamental  lines of orientation1 
99a99 and 99b992 let this actual        
position be expressed  by the letter    
99l991 99l99 marking the distance of    
one#eh of the actual  boundary lines of 
our piece from 99a99 or 99b993 then we  
are entitled to  improve our formula by 
writing 99p4v4 7,x7  f7s1 l 444 799     

7,fig4  #aa74    #eh ,the distance of   
the other boundary line from 99a99 or   
99b99 would be  given by the value of   
99s994    ,illustration3 ,fig4          
#aa4--;,diagram to show the             
,characteristics of an                  
8,harmonious-equipotential ,system40    
,the element 99,x99 forms part of the   
systems 99a b99 or 99a#a b#a99 or  99a#b
 b#b992 its prospective value is        
different in each case4    ,but the     
formula is not yet complete3 99s99 and  
99l99 are what the  mathematicians call 
variables3 they may have any actual     
value and there  will always be a       
definite value of 99p4v4991 99i4e499 of 
the actual fate  which is being         
considered2 to every value of 99s99 and 
99l991 which as  we know are independent
 of each other1 there corresponds a     
definite  value of the actual           
prospectivity4 ,now1 of course1 there is
 also a  certain factor at work in every
 actual case of experimental or normal  
development1 which is 99not99 a         

variable1 but which is the same in all  
cases4 ,this factor is a something      
embraced in the prospective potency  of 
our system1 though not properly         
identical with it4    ,the prospective  
potency of our system1 that is to say of
 each of its  elements1 is the sum total
 of what can be done by all2 but the    
fact  that a typically proportionate    
development occurs in every possible    
case1 proves that this sum comes into   
account1 not merely as a sum1  but as a 
sort of order3 we may call this order   
the 8relation of  localities in the     
absolutely normal case40 ,if we keep in 
mind that the  term 8prospective        
potency0 is always to contain this      
order1 or1 as we  may also call it1 this
 8relative proportionality10 which1     
indeed1 was  the reason for calling our 
systems 8harmonious10 then we may apply 
it  without further explanation in order
 to signify the 99non-variable99  factor
 on which the prospective value of any  
element of our systems  depends1 and1 if

 we denote the prospective potency1     
embracing order1  by the letter 99,e991 
we are now able to complete our formula 
by saying  99p4v4 7,x7  f7s1 l1 ,e7994  
,so far the merely analytical study of  
the  differentiation of                 
harmonious-equipotential systems4#ei    
#ei ,a far more thorough analysis of    
this differentiation has been  attempted
 in my paper1 8,die ,localisation       
morphogenetischer ,vorgnge4 ,ein        
,beweis vitalistischen ,geschehens10    
,leipzig1 #ahii4      99,instances of   
8,harmonious-,equipotential ,systems099 
,we must try at first to learn a few    
more positive facts about our  systems1 
in order that we may know how important 
is the part which they  play in the     
whole animal kingdom1 and in order that 
our rather abstract  analysis may become
 a little more familiar to us4 ,we know 
already that  many of the elementary    
morphogenetic organs have been really   
proved to  be harmonious-equipotential  
systems1 and that the same probably is  

true  of many others2 we also know that 
the immature egg of almost all animals  
belongs to this type1 even if a fixed   
determination of its parts may  be      
established just after maturation4      
,moreover1 we said1 when speaking  about
 some new discoveries on                
form-restitution1 that there are many   
cases in which the processes of         
restitution do not proceed from single  
localities1 the seat of complex         
potencies in the organism1 but in which 
each 99single99 part of the truncated   
organism left by the operation has  to  
perform one 99single99 act of           
restoration1 the full restitution being 
the result of the totality of all4      
,these cases must now be submitted to  a
 full analysis4    ,all of you have seen
 common sea-anemones or sea-roses1 and  
many of you  will also be familiar with 
the so-called hydroid polyps4           
99,tubularia99  is one genus of them3 it
 looks like a sea-anemone in miniature  
placed  on the top of a stem like a     

flower4 ,it was known already to ,allman
  that 99,tubularia99 is able to restore
 its flower-like head when that  is     
lost1 but this process was taken to be  
an ordinary regeneration1  until an     
,american zoologist1 ,miss ,bickford1   
succeeded in showing that  there was no 
regeneration process at all1 in the     
proper sense of the  word1 no budding of
 the missing part from the wound1 but   
that the new  tubularian head was       
restored by the combined work of many   
parts of the  stem4 ,further analysis   
then taught us that 99,tubularia99      
indeed is to be  regarded as the perfect
 type of an harmonious-equipotential    
system3 you  may cut the stem at        
whatever level you like3 a certain      
length of the  stem will always restore 
the new head by the co-operation of its 
parts4  ,as the point of section is of  
course absolutely at our choice1 it is  
clear1 without any further discussion1  
that the prospective value of  each part
 of the restoring stem is a 8function of

 its position10 that  it varies with its
 distance from the end of the stem2 and 
so at once  we discover one of the chief
 characteristics of our systems4 ,but   
also  the second point which enters into
 our formula can be demonstrated in     
99,tubularia993 the dependence of the   
fate of every element on the actual     
size of the system4 ,you would not be   
able to demonstrate this on very  long  
stems1 but if you cut out of a          
99,tubularia99 stem pieces which are    
less than ten millimetres in length1 you
 will find the absolute size  of the    
head restored to be in close relation to
 the length of the stem  piece1 and this
 dependence1 of course1 includes the    
second sort of  dependence expressed in 
our formula4    ,the figures will serve 
to show you a little more concretely    
what has  been described4 ,the head of  
99,tubularia99 consists of a sort of    
broad base  with a thin proboscis upon  
it1 both bearing a large number of      
tentacles2  these tentacles are the     

first things to be seen as primordia    
78,anlagen07  in the process of         
restitution4 ,you notice two rings of   
longitudinal  lines inside the stem2 the
 lines will become walls and then will  
separate from the stem until they are   
only connected with it at their  basal  
ends2 the new tentacles are ready as    
soon as that has happened1  and a       
process of growth at the end will serve 
to drive the new head out  of the       
so-called perisarc or horny skeleton1   
which surrounds the stem4  ,by comparing
 the two figures1 #ab 99e991 and 99g991 
you easily find out that  the absolute  
lengths of the two tentacle rings are   
very different1 and  that both are in   
proportion#fj to the actual size of the 
stem 7,fig4 #ab74    #fj ,this statement
 is 99not strictly99 correct for        
99,tubularia994 ,i found  799,archiv f4 
,entwickelungsmechanik991 ix4 #ahii71   
that a reduction of the  length of the  
stem is always followed by a reduction  
of the size of the  hydranth-primordium1

 but there is no real proportionality   
between them4  ,it is only for          
theoretical simplification that a strict
 proportionality  is assumed here1 both 
in the text and the diagram4 ,but there 
is an  almost strict proportionality in 
all cases of 8closed forms40            
,illustration3 ,fig4 #ab4--,tubularia4  
99a499 ,diagram of the 8,hydranth10 with
 its short and long tentacles4    99b499
 ,restitution of a new hydranth inside  
the perisarc 799p9974    99c499 ,the    
same--later stage2 the tentacles are    
complete2 the whole  hydranth will be   
driven out of the perisarc by a process 
of growth that  occurs at the locality  
marked 4    99d499 ,a stem of           
99,tubularia99 cut either at 99a#a b#a99
 or at 99a#b b#b991  or at 99a#a c994   
99e499 ,position of tentacles in the    
piece cut at 99a#a b#a994    99f499     
,position of tentacles in the piece cut 
at 99a#b b#b991  which is equal in      
length to 99a#a b#a994    99g499        
,position of tentacles in the piece cut 

at 99a#a c991  which is half as long as 
99a#a b#a994    ,so we find our formula 
99p4v4 7,x7  f7s1 l1 ,e799 very well    
illustrated in 99,tubularia994 ,the     
formula indeed may help us to predict1  
in any case1 where a certain part of the
 polyp's organisation is  to originate1 
at least if we know all that is included
 under our  letter 99,e991 99i4e499 the 
normal proportion of our form4 ,of      
course such  prediction would not have  
much practical importance in all our    
cases of  morphogenesis1 but            
nevertheless ,i should like to state    
here that it is  possible2 for many     
scientific authors of recent times have 
urged the  opinion that prediction of1  
and domination over1 what will happen1  
can  be the only true aims of sciences  
at all4 ,i myself judge these aims to   
be of second or third-rate importance   
only1 but1 if they may be reached  by   
what our purely theoretical study       
teaches1 so much the better4    ,another
 very typical case of a morphogenetic   

system of the harmonious  type is       
supplied by the phenomena of restoration
 in the ascidian  99,clavellina994 ,i   
cannot fully describe the organisation  
of this form  7,fig4 #ac;a71 and it must
 suffice to say that it is very         
complicated1  consisting of two very    
different chief parts1 the branchial    
apparatus  and the so-called intestinal 
sac2 if these two parts of the body of  
99,clavellina99 are separated one from  
the other1 each may regenerate the      
other in the typical way1 by budding    
processes from the wound4 ,but1 as  to  
the branchial apparatus1 there may      
happen something very different3  it may
 lose almost all of its organisation and
 become a small white  sphere1          
consisting only of epithelia            
corresponding to the germ-layers1  and  
of mesenchyme between them1 and then1   
after a certain period of  rest1 a new  
organisation will appear4 ,now this new 
organisation is  not that of a branchial
 apparatus but represents a very small  

but  complete ascidian 7,fig4 #ac74     
,such a fact certainly seems to be very 
important1 not to say very surprising2  
but still another phenomena may  be     
demonstrated on the animal which seems  
to be even more important4 ,you  first  
isolate the branchial apparatus from the
 other part of the body1  and then you  
cut it in two1 in whatever direction you
 please4 ,provided  they survive and do 
not die1 as indeed many of them do1 the 
pieces  obtained by this operation will 
each lose their organisation1 as did the
  whole branchial apparatus1 and then   
will each acquire another one1 and  this
 new organisation is also that of a     
99complete99 little 99,clavellina994    
,so we see that not only is the         
branchial apparatus of our animal       
capable  of being transformed into a    
whole animal by the co-operative work of
  all its parts1 but even each part of  
it may be transformed into a small      
99whole991 and it is quite at our       
disposal how large this part shall be1  

and what sort of a fragment of the      
original branchial apparatus it shall   
represent4    ,illustration3 ,fig4      
#ac4--;,clavellina4    99a499 ,diagram  
of the normal animal3 99,e99 and 99,j99 
openings2 99,k99   branchial apparatus2 
99,d99  intestine2 99,m99  stomach2     
99,h99  heart4    99b499 ,the isolated  
branchial apparatus4    99c-e499        
,different stages of reduction of the   
branchial apparatus4    99f499 ,the new 
99whole99 little ascidian4    ,we could 
hardly imagine a better instance of an  
harmonious-equipotential  system4    ,i 
cannot give you a description of all the
 other types of our systems  subservient
 to restitution1 and ,i can only mention
 here that the common  hydra and the    
flatworm 99,planaria99 are very fine    
examples of them4 ,but  to one special  
case of harmonious equipotentiality you 
must allow me to  direct your further   
attention4    ,it has been known for    
many years that the ,protozoa are also  
capable of  a restoration of their form 

and organisation after disturbances1 if 
at  least they contain a certain amount 
of their nuclear substance4 ,this       
process of restoration used to be       
regarded as belonging to the common     
type of regeneration proper1 until ,t4  
,h4 ,morgan succeeded in showing  that  
in the genus 99,stentor99 it follows    
just the very lines which we know       
already from our study of embryonic     
organs or from 99,tubularia992 that  an 
harmonious-equipotential system is at   
the basis of what goes on4  ,now1 you   
know that all ,protozoa are but one     
highly organised cell3 we  have         
therefore here an instance where the    
so-called 8elements0 of our             
harmonious-morphogenetic system are not 
cells1 but something inside of  cells2  
and this feature must appear to be of   
very great moment1 for it  first shows1 
as we have already pointed out on       
another occasion1 that  morphogenesis is
 not dependent on cell-division1 and it 
states at the  same time that our       

concept of the harmonious-equipotential 
system may  cover a very great          
area--that1 in fact1 it is a scheme of a
 very wide  extent4      99,the ,problem
 of the ,factor99 ,e    ,we turn back   
again to considerations of a more       
abstract form4 ,we left  our analysis of
 the differentiation of the             
harmonious-equipotential  systems1 and  
particularly of the phenomena of        
localisation during this                
differentiation1 at the point where we  
had succeeded in obtaining an  equation 
as the expression of all those factors  
on which the prospective  value1 the    
actual fate1 of any element of our      
systems depends1 99p4v4 7,x7   f7s1 l1  
,e799 was the short expression of all   
the relations involved2  99s99 and      
99l991 the absolute size of the system  
and the relative position  of the       
element with respect to some fixed      
points1 were independent  variables2    
99,e99 was a constant1 namely1 the      
prospective potency1 with  special      

regard to the proportions embraced by   
it4    ,we shall now study the          
significance of the factor 99,e994      
,what does this 99,e99 mean8 ,is it a   
short expression merely for an actual   
sum of elemental agents having a common 
resultant8 ,and1 if so1 of what  kind   
are these agents8 ,or what may 99,e99   
mean1 if it can be shown 99not99 to  be 
a short sign for a mere sum8      99,no 
,explanation ,offered by 8,means0 or    
8,formative ,stimuli099    ,for         
practical purposes it seems better if we
 modify the statement of our  question4 
,let us put it thus3 99,e99 is one of   
the factors responsible1  among         
variables1 for the localisation of      
organic differentiation2  what then do  
we actually know about the causal       
factors which play a  localising part in
 organogenesis8 ,we1 of course1 have to 
look back to  our well-studied          
8formative stimuli40 ,these stimuli1 be 
they 8external0  or 8internal10 come    
from without with respect to the        

elementary organ  in which any sort of  
differentiation1 and therefore of       
localisation1  occurs3 but in our       
harmonious systems no localising        
stimulus comes from  without1 as was the
 case1 for instance1 in the formation of
 the lens of  the eye in response to the
 optical vesicle touching the skin4 ,we 
know  absolutely that it is so1 not to  
speak of the self-evident fact that the 
general 8means0 of organogenesis have no
 localising value at all4#fa    #fa ,one
 might object here that in a piece of a 
99,tubularia99 stem1 for  instance1 the 
tissues are in direct contact with the  
sea-water at  the two points of the     
wounds only1 and that at these very     
points a  stimulus might be set up--say 
by a process of diffusion--which        
gradually  decreases in intensity on its
 way inward4 ,and a similar argument    
might  apply to the small but whole     
blastula of ,echinus1 and to all other  
cases4 ,but1 in the first place1 stimuli
 which only differ in intensity  could  

hardly call forth the typical and       
typically localised single  features    
realised in differentiation4 ,on the    
other hand--and this will  overthrow    
such an hypothesis completely--the      
dependence of the single  localised     
effects in every case on the 99absolute 
size99 of the fragment  or piece chosen 
for restoration renders quite impossible
 the assumption  that all the           
singularities in the differentiation of 
the harmonious  systems might be called 
forth by single stimuli originating in  
two  fixed places in an 99independent99 
way4 ,these would never result in any   
8harmonious10 any proportionate         
structure1 but a structure of the       
8normal0 proportionality 99and size99 at
 its two ends and non-existent in  the  
middle6    ,so we see there is nothing  
to be done1 either with the means or    
with the  formative stimuli2 both are   
entirely unable to account for those    
kinds  of localisation during           
differentiation which appear in our     

harmonious  systems4    ,but is there no
 possibility of explaining the phenomena
 of organogenetic  localisation by any  
other sort of interaction of parts8 ,two
 such  possibilities may at the first   
glance seem to exist4      99,no        
,explanation ,offered by a ,chemical    
,theory of ,morphogenesis99    ,though  
never set forth1 in the form of a       
properly worked-out theory1  the view   
has sometimes been advocated by         
biologists1 that a chemical  compound of
 a very high degree of complication     
might be the very basis  of both        
development and inheritance1 and that   
such a chemical compound  by its        
disintegration might direct             
morphogenesis4    ,let us first examine 
if such a view may hold for the most    
general  features of organic            
morphogenesis4 ,it seems to me that from
 the very  beginning there exists one   
very serious objection to every chemical
  theory of form-building1 in the mere  
fact of the possibility of the          

restoration of form starting from       
atypical localities4 ,the mere fact1    
indeed1 that there is such a thing as   
the regeneration of a leg of a  newt--to
 say nothing about restitution of the   
harmonious type--simply  contradicts1#fb
 it seems to me1 the hypothesis1 that   
chemical  disintegration of one compound
 may govern the course of morphogenetic 
events3 for whence comes the            
re-existence of the hypothetical        
compound1  newly to be disintegrated1   
after disintegration 99has99 been       
completed  once already8 ,and we even   
know that regeneration may go on several
 times  running from the same locality6 
#fb ,see my article in 99,biolog4       
,centralblatt991 #bg1 #aijg1 p4 #fi4    
,the  question is rendered still more   
complicated by the fact that in the case
  of the regeneration1 say1 of a leg it 
is not the original 8morphogenetic      
compound0 which is again required for   
disintegration1 after it has  become    
disintegrated once already1 but only a  

specific part of it3 just  that part of 
it which is necessary for producing the 
leg6 ,on the other  hand1 it would be   
impossible to understand1 on the basis  
of physical  chemistry1 how the isolated
 branchial apparatus of 99,clavellina99 
could  be transformed1 by chemical      
processes exclusively1 into a system of 
which only a certain 99part99 consists  
of that substance of which the          
starting-point had been composed in its 
99completeness994    ,but1 if we        
intentionally disregard this difficulty1
 in spite of  its fundamental character1
 how could the hypothesis of chemical   
disintegration give the reason for the  
differentiation of our                  
harmonious-equipotential systems1 with  
special regard to the  localisation of  
it2 how could it account1 in other      
words1 for the  appearance of typically 
localised specifications in an organ for
 which  no external localising causes   
can be predicated8    ,let us remember  
that a few original intimate differences

 exist in our  harmonious systems3 the  
main directions of the intimate         
protoplasmic  structure including       
polarity and bilaterality4 ,there are   
therefore  three times two specified    
poles in each of these systems1 at least
 in  bilateral organisms1 but no other  
differences are present in them4  ,a few
 very simple cases of harmonious        
differentiation might indeed  be        
understood on the theory of a           
disintegrating chemical compound  in    
connection with these few differences4  
,imagine that the original  compound1 of
 the quantity 99a991 is disintegrated to
 the amount of  99a99#a2 from 99a99#a   
are formed the two more simple          
compounds1 99b99  and 99c991 both of    
them in definite quantities2 then we    
have the three  chemical individuals1   
99a-a99#a1 99b99 and 99c991 as the      
constituents of  our harmonious system2 
and it now might be assumed1 without any
 serious  difficulty1 though with the   
introduction of some new hypotheses1    

that  the two poles of one of the       
fundamental axes of symmetry attract    
99b99 and  99c99 respectively1 99a-a99#a
 remaining unattracted between them4 ,we
 thus  should have the three elementary 
constituents of the system separated    
into three parts1 and as they all three 
are of a definite quantity1  their      
separation would mean that the system   
had been divided into three  parts1     
99a-a99#a1 99b99 and 99c991 also with   
regard to its proper form4  ,it is      
clear1 that by taking away any part of  
the original system1 by  means of       
operations1 there would be taken away a 
certain amount of the  original         
compound2 say that 99a_/n99 is left2    
then1 of course1 the three  constituents
 after the partial disintegration would 
be 99a-a#a_/n991  99b_/n99 and 99c_/n991
 and so it follows that the             
proportionality of  localisation would  
really be preserved in any case4    ,but
 these considerations1 evident as they  
seem to be in the most  simple case1    

fail to satisfy in a really general     
sense3 for two  different reasons4      
,first1 they could never account for the
 fact that  the differentiated organism 
by no means consists of so many         
different  compounds as it shows single 
parts of its differentiation1 but that1 
on the contrary1 it only consists1 as we
 know1 of a certain rather  limited     
number of true different morphogenetic  
elements1 these  elements occurring     
again and again--as for instance1       
nervous or  muscular elements--but      
typical each time in locality1 quantity1
 and  form4 ,and in the second place1   
the very 99form99 of elementary organs1 
their form as such1 does not at all go  
hand-in-hand with chemical  differences2
 this feature alone would absolutely    
overthrow any sort  of a chemical       
morphogenetic theory to account for the 
problem of  localisation4 ,take the     
typically arranged ring of the          
mesenchyme  cells in our                
,echinus-gastrula1 with its two         

spherical triangles1 so  typically      
localised2 look at any sort of skeleton1
 in ,radiolaria1 or in  starfishes1 or  
in vertebrates3 here you have form1 real
 form1 but form  consisting of only one 
material4 ,not only is the arrangement  
of the  elements of form typical here1  
99e4g499 the arrangement of the single  
parts of the skeleton of the hand or    
foot1 but also the special form  of each
 element is typical1 99e4g499 the form  
of each single bone of the  foot2 and1  
on a purely chemical theory of          
morphogenesis the sufficient  reason for
 the production of typical form in such 
a sense would be  wanting4 ,for atoms or
 molecules by themselves can only       
account for form  which is arranged1 so 
to speak1 according to spatial          
geometry--as in  fact they do in        
crystallography2 but they can never     
account for form  such as the skeleton  
of the nose1 or hand1 or foot4 ,you will
 answer  me perhaps1 that there may be  
non-chemical agents in the germ1#fc     

responsible for typical                 
form-localisation1 but by such reasoning
 you  would be departing from a purely  
chemical theory4 ,our next paragraph    
will be devoted to this side of the     
question4    #fc ,besides the specified 
poles determined by the polar-bilateral 
structure of the protoplasm4    ,that is
 the principal reason for rejecting all 
sorts of chemical  morphogenetic        
theories put forward to explain the     
problem of  localisation2 it is more    
explicit1 and therefore1 ,i suppose1    
still  more convincing than the more    
general consideration that the very     
fact of restitutions in itself must     
contradict the hypothesis that  a       
disintegration of compounds might be the
 directive agency in  morphogenesis4 ,to
 sum up3 ,specificity of organic form   
does not go  hand-in-hand with          
specificity of chemical composition1 and
 therefore  cannot depend on it2 and    
besides that1 specific organic form is  
such  that it can never be explained by 

atomic or molecular arrangement in  the 
chemical sense2 for1 to state it in a   
short but expressive manner1  the 8form0
 of an atom or molecule can never be    
that of a lion or a  monkey4 ,to assume 
that would be to go beyond the limits of
 chemistry in  chemistry itself4        
99,no ,machine ,possible ,inside the    
,harmonious ,systems99    ,and now we   
turn to the last possibility which is   
left to us in our  endeavour to         
8understand0 the localisation of the    
differentiation in our                  
harmonious-equipotential systems by the 
means of physics and chemistry4         
,outside causes have failed to account  
for it1 chemical disintegration  of a   
compound has failed too4 ,but could     
there not exist some sort of            
complicated interactions amongst the    
parts of the harmonious system          
themselves8 ,could there not exist some 
kind of a real machine in the  system1  
which1 if once set going1 would result  
in the differentiations  that are to    

take place8 ,then we might say that the 
8prospective  potency0 of the system is 
in fact that machine2 we should know    
what the  letter 99,e99 of our equation 
stood for3 viz41 a resultant action of  
many  complicated elemental             
interactions1 and nothing more4         
,weismann1 we know already1 had assumed 
that a sort of machine was the  prime   
mover of morphogenesis4 ,we have seen   
that his theory cannot be  true2 the    
results of experiments most strongly    
contradict it4 ,but1 of  course1 the    
experiments only showed us that 99such99
 a machine as 99he99  had imagined to   
exist could not be there1 that          
development could not be  governed by   
the disintegration of a given           
complicated structure into its  simplest
 parts4 ,but might not some other       
machine be imaginable8    ,we shall     
understand the word 8machine0 in a most 
general sense4 ,a  machine is a typical 
configuration of physical and of        
chemical  constituents1 by the acting of

 which a typical effect is attained4    
,we1 in fact1 lay much stress upon      
embracing in our definition of a        
machine the existence of chemical       
constituents also2 we therefore         
understand by the word 8machine0 a      
configuration of a much higher  degree  
of complication than for instance a     
steam-engine is4 ,of course  a machine1 
whose acting is to be typical with      
regard to the three  dimensions in      
space1 has to be typically constructed  
with regard to  these three dimensions  
itself2 a machine that was an           
arrangement of  elements in a strict    
plane could never have typical effects  
at right  angles to that plane4 ,this is
 a point which must well be kept in mind
  in all hypothetical considerations    
about machines that claim to explain    
morphogenesis4    ,it must be granted   
that a machine1 as we understand the    
word1 might very  well be the motive    
force of organogenesis in general1 if   
only normal1  that is to say1 if only   

undisturbed development existed1 and if 
a taking  away of parts of our systems  
led to fragmental development4    ,but  
we know that1 at least in our           
harmonious-equipotential systems1  quite
 another process occurs after parts have
 been taken away3 the  development that 
occurs is not fragmental but whole1 only
 on a smaller  scale4    ,and we know1  
further1 that this truly whole          
development sets in  irrespective of the
 amount and direction of the separation4
 ,let us first  consider the second of  
these points4 ,there may be a whole     
development  out of each portion of the 
system--above certain limits--which is1 
say1  of the volume 99,v994 ,good6 ,then
 there ought to exist a machine1 like   
that which exists in the whole          
undisturbed system1 in this portion     
99,v99  also1 only of smaller           
dimensions2 but it also ought to exist  
in the  portion 99,v99#a which is equal 
to 99,v99 in amount1 and also in        
99,v99#b1 in  99,v99#c1 99,v99#d and so 

on4 ,indeed1 there do exist almost      
indefinitely  many 99,v99n all of which 
can perform the whole morphogenesis1 and
 all  of which therefore ought to       
possess the machine4 ,but these         
different  portions 99,v99n are only    
partly different from each other in     
spatial  relation4 ,many parts of       
99,v99#b are also parts of 99,v99#a and 
of 99,v99#c  and of 99,v99#d and so on2 
that is to say1 the different volumes   
99,v99n  overlap each other successively
 and in such a manner that each         
following  one exceeds the preceding one
 in the line by a very small amount     
only4  ,but what then about our         
machines8 ,every volume which may       
perform  morphogenesis completely must  
possess the machine in its totality4 ,as
  now every element of one volume may   
play any possible elemental rle in      
every other1 it follows that each part  
of the whole harmonious system          
possesses any possible elemental part of
 the machine equally well1 all  parts of

 the system at the same time being      
constituents of different  machines4    
,a very strange sort of machine indeed1 
which is the same in all its  parts     
7,fig4 #ad76    ,illustration3 ,fig4    
#ad4--;,an 8,harmonious-equipotential   
,system0 of  whatever kind4             
,according to the 8machine-theory0 of   
life this system ought to possess  a    
certain unknown very complicated machine
 99in its completeness993               
799a997 in its total length1    and     
799b997 in each of the equal volumes    
99v991 99v99#a1 99v99#b1 99v99#c and    
so on1    and 799c997 in each of the    
unequal volumes 99w991 99x991 99y991 and
 so on1    and 799d997 in every         
imaginable volume1 no matter of what    
size4    ,therefore the 8machine-theory0
 of life is absurd4    ,but we have     
forgotten1 ,i see1 that in our operation
 the absolute amount  of substance taken
 away from the system was also left to  
our choice4  ,from this feature it      
follows that not only all the different 

99,v99n1  all of the same size1 must    
possess the hypothetic machine in its   
completeness1 but that all amounts of   
the values 99,v99n-99n991 99n99 being   
variable1 must possess the totality of  
the machine also3 and all values        
99,v99n-99n991 with their variable      
99n991 may again overlap each other4    
,here we are led to real absurdities6   
,but what is the conclusion of our      
rather wild considerations8    ,it seems
 to me that there is only one conclusion
 possible4 ,if we  are going to explain 
what happens in our                     
harmonious-equipotential  systems by the
 aid of causality based upon the        
constellation of single  physical or    
chemical factors and events1 there      
99must99 be some such  thing as a       
machine4 ,now the assumption of the     
existence of a machine  proves to be    
absolutely absurd in the light of the   
experimental facts4  99,therefore there 
can be neither any sort of a machine nor
 any sort of  causality based upon      

constellation underlying the            
differentiation of                      
harmonious-equipotential systems499     
,for a machine1 typical with regard to  
the three chief dimensions  of space1   
cannot remain itself if you remove parts
 of it or if you  rearrange#fd its parts
 at will4    #fd ,the pressure          
experiments and the dislocation         
experiments come into  account here2 for
 the sake of simplicity they have not   
been alluded to  in the main line of our
 argument4    ,here we see that our long
 and careful study of morphogenesis has 
been  worth while3 it has afforded us a 
result of the very first importance4    
99,the ,autonomy of ,morphogenesis      
,proved99    ,no kind of causality based
 upon the constellations of single      
physical  and chemical acts can account 
for organic individual development2 this
  development is not to be explained by 
any hypothesis about configuration  of  
physical and chemical agents4 ,therefore
 there must be something  else which is 

to be regarded as the sufficient reason 
of individual  form-production4 ,we now 
have got the answer to our question1    
what  our constant 99,e99 consists in4  
,it is not the resulting action of a    
constellation4 ,it is not only a short  
expression for a more complicated  state
 of affairs1 it expresses 99a true      
element of nature994 ,life1 at  least   
morphogenesis1 is not a specialised     
arrangement of inorganic  events2       
biology1 therefore1 is not applied      
physics and chemistry3 life  is         
something apart1 and biology is an      
independent science4    ,all our results
 at present1 indeed1 are negative in    
their form2 our  evidence was throughout
 what is called 99per exclusionem991 or 
indirect  or apagogic4 ,there were      
excluded from a certain number of       
possibilities  all except one2 a        
disjunctive proposition was stated in   
the form3 99,e99  is either this1 or    
that1 or the other1 and it was shown    
that it could  not be any of all these  

except one1 therefore it was proved to  
be that  one4 ,indeed1 ,i do not see how
 natural science could argue otherwise2 
no science dealing with inorganic       
phenomena does2 something new and       
elemental must always be introduced     
whenever what is known of other         
elemental facts is proved to be unable  
to explain the facts in a new  field of 
investigation4    ,we shall not hesitate
 to call by its proper name what we     
believe we have  proved about           
morphogenetic phenomena4 ,what we have  
proved to be true  has always been      
called 99vitalism991 and so it may be   
called in our days  again4 ,but if you  
think a new and less ambitious term to  
be better for  it1 let us style it the  
doctrine of the 99autonomy of life991 as
 proved  at least in the field of       
morphogenesis4 ,i know very well that   
the word  8autonomy0 usually means the  
faculty of 99giving99 laws to oneself1  
and  that in this sense it is applied   
with regard to a community of men2  but 

in our phrase autonomy is to signify the
 99being subjected99 to laws  peculiar  
to the phenomena in question4 ,this     
meaning is etymologically  defensible1  
and besides that ,i perhaps may remind  
you of a certain  chapter of ,professor 
,ward's ,gifford ,lectures1 in which he 
holds the view  that1 psychologically   
and epistemologically1 there is more    
than a mere  verbal relation between the
 civil and the natural 8law40           
,vitalism then1 or the autonomy of life1
 has been proved by us  indirectly1 and 
cannot be proved otherwise so long as we
 follow the  lines of ordinary          
scientific reasoning4 ,there can indeed 
be a sort of  direct proof of vitalism1 
but now is not the time to develop this 
proof1  for it is not of the purely     
scientific character1 not so nave as our
  present arguments are1 if you choose  
to say so4 ,an important part of our    
lectures next summer will be devoted to 
this direct proof4      899,entelechy990
    ,but shall we not give a name to our

 vitalistic or autonomous factor        
99,e991 concerned in morphogenesis8     
,indeed we will1 and it was not without 
design that we chose the letter 99,e99  
to represent it provisionally4 ,the     
great father of systematic philosophy1  
,aristotle1 as many of you will  know1  
is also to be regarded as the founder of
 theoretical biology4  ,moreover1 he is 
the first vitalist in history1 for his  
theoretical  biology is throughout      
vitalism2 and a very conscious vitalism 
indeed1  for it grew up in permanent    
opposition to the dogmatic mechanism    
maintained by the school of ,democritus4
    ,let us then borrow our terminology 
from ,aristotle1 and let that factor  in
 life phenomena which we have shown to  
be a factor of true autonomy be  called 
99,entelechy991 though without          
identifying our doctrine with what      
,aristotle meant by the word 4 ,we shall
 use this word only as a  sign of our   
admiration for his great genius2 his    
word is to be a mould  which we have    

filled and shall fill with new contents4
 ,the etymology of  the word  allows us 
such liberties1 for indeed we have shown
  that there is at work a something in  
life phenomena 8which bears the end  in 
itself10      4    ,our concept of      
entelechy marks the end of our analysis 
of individual  morphogenesis4           
,morphogenesis1 we have learned1 is     
8epigenesis0 not only  in the           
descriptive but also in the theoretical 
sense3 manifoldness  in space is        
produced where no manifoldness was1 real
 8evolutio0 is  limited to rather       
insignificant topics4 ,but was there    
nothing 8manifold0  previous to         
morphogenesis8 ,nothing certainly of an 
99extensive99  character1 but there was 
something else3 there was entelechy1 and
 thus  we may provisionally call        
entelechy an 899intensive               
manifoldness9940  ,that then is our     
result3 not evolutio1 but               
epigenesis--8epigenesis  vitalistica40  
99,some ,general ,remarks on ,vitalism99

    ,we now shall leave entelechy where 
it stands3 next summer we shall turn    
back to it and shall make its full      
logical and ontological analysis  our   
chief study4 ,at present we are         
satisfied with having proved its        
existence in nature1 with having laid   
some of the foundations of a  doctrine  
to be based upon it4 ,i hope that these 
foundations will evince  themselves     
strong3 that is all-important4#fe ,it   
indeed has been the  fault of all       
vitalism in the past that it rested on  
weak foundations4  ,therefore the       
discussion of the basis underlying our  
doctrine of the  autonomy of life is to 
occupy us still a considerable time4 ,we
 shall  devote to it two more of this   
year's lectures and three of the next2  
we  shall examine all sorts of phenomena
 of life in order to find out if  there 
are any further proofs of vitalism1     
independent perhaps1 of what  we way    
call our 99first proof991 which is based
 upon the analysis of the               

99differentiation of                    
harmonious-equipotential systems994 ,we 
shall find  some more independent       
proofs2 and besides that we shall find  
many kinds  of phenomena upon which     
future times perhaps may erect more of  
such  independent proofs4    #fe ,my    
8first proof of vitalism0 was first     
developed in the paper1 8,die           
,localisation morphogenetischer         
,vorgnge10 ,leipzig1 #ahii4 7,see       
additional  remarks in 99,organische    
,regulationem991 ,leipzig1 #aija1 and in
 99,archiv  fr ,entwickelungsmechanik991
 #ad1 #aijb47 ,i cannot admit that any  
really  serious objection has been      
brought forward against it4 7,see my    
articles  in 99,biologisches            
,centralblatt991 #bb1 #bc1 #bg1 and in  
99,ergebnisse d4 ,anat4  u4             
,entwickelungsgesch994 #aa1 #ad47 ,an   
historical sketch of vitalism will  be  
found in my book1 99,der ,vitalismus als
 ,geschichte und als ,lehre991          
,leipzig1 #aije4    ,for we shall be    

chary of bestowing the name 8proof0     
except on what is a  proof indeed1 of   
course according to our critical        
conviction4 ,vitalistic  views in       
biology have arisen in rather numerous  
forms during the last  fifteen years1   
especially in ,germany--though in very  
strong contrast to  the so-called       
official ,german biology--but ,i can    
only admit that one of  all the         
arguments of 8neo-vitalism0 has proved  
its statements4 ,i refer  to the theory 
of 8morphaesthesia0 as developed by     
,noll1 which we shall  study briefly in 
the next lecture4 ,i cannot concede that
 ,reinke or  ,schneider or ,pauly have  
really proved what they believe1 and ,i 
cannot  even allow to the most original 
thinker in this field1 ,gustav ,wolff1  
that he has given a real demonstration  
of his views4 ,he states that the       
existence of so-called 8primary         
purposefulness10 that is1 the existence 
of adaptive processes1 which cannot be  
imagined to have arisen on  ,darwinian  

principles1 is able to prove vitalism2  
but ,i say that it only  proves         
teleology1 which is a broader concept   
than vitalism4    ,the possibility of a 
machine at the root of the phenomena in 
question  always has to be excluded in  
order that vitalism may be proved1 and  
,i  cannot grant that the necessity of  
such an exclusion has been actually     
shown by any of my fellow-combatants    
against so-called mechanism1 except     
,noll4#ff    #ff ,we are dealing here   
with morphogenesis and so-called        
vegetative  physiology only2 to certain 
psychologists1 who have refuted the     
theory  of psycho-physical parallelism1 
,i must grant that they also have proved
  vitalism4 7,see ,volume ,,ii47        
99,the ,logic of our ,first ,proof of   
,vitalism99    ,let us devote the end of
 our present lecture to an account of   
the  logical means by which it has been 
possible to develop what we hope will   
be regarded as a true 99proof99 of life 
autonomy4    ,firstly1 we have looked   

upon the phenomena of morphogenesis     
without  any prepossessions2 we may say 
that we have fully surrendered ourselves
  to them2 we have not attacked them    
with any sort of dogmatism except  the  
inherent dogmatism of all reasoning4    
,but this dogmatism1 if it may  be      
called so1 does not postulate that the  
results of the inorganic  doctrines must
 hold for the organic world1 but only   
that both the  inorganic and the organic
 must be subject to certain most general
  principles4    ,by studying life as a 
given phenomenon1 by fully devoting     
ourselves to  our problem1 we not only  
have analysed into its last elements    
what was  given to us as our subject1   
but we also1 more actively1 have created
 new  combinations out of those         
elements3 and it was from the discussion
 of  these positive constructions that  
our argument for vitalism was derived4  
,we have analysed morphogenesis into    
elementary processes1 means1  potency1  
formative stimulus1 just as the         

physicist analyses mechanics  into time1
 velocity1 mass1 and force2 we have then
 rearranged  our elements into          
8systems0--the equipotential systems1   
the  harmonious-equipotential system in 
particular1 just as the physicist       
composes his elements into the concepts 
of momentum or of kinetic energy  or of 
work4 ,and finally1 we have discussed   
our compositions and have  obtained our 
result1 just as the physicist gets his  
ultimate results by  discussing work and
 kinetic energy and momentum4    ,of    
course the comparison is by no means    
intended to show that mechanics  and    
biology are sciences of the same kind4  
,in my opinion1 they are not  so at all2
 but nevertheless there do exist        
similarities of a logical  kind between 
them4    ,and it is not the formal1     
logical character alone which allows us 
to  compare biology with other natural  
sciences3 there is still something      
more1 there is one kind of assumption or
 postulate1 or whatever you  may choose 

to call it1 without which all science   
whatever would be  altogether           
99impossible994 ,i refer to the concept 
of 99universality994 ,all  concepts     
about nature which are gained by        
positive construction out of  elements  
resulting from analysis1 claim to be of 
99universal validity992  without that   
claim there could indeed be no science4 
,of course this is no place for a       
lecture on methodology1 and it          
therefore must suffice to make one      
remark with special regard to  our      
purpose1 which we should like to        
emphasise4 ,our concept of the          
harmonious-equipotential system--say    
rather1 our concept of the  prospective 
potency itself--presumes the            
understanding that indeed 99all99       
blastomeres and 99all99 stems of        
99,tubularia991 including those upon    
which  we have 99not99 carried out our  
experiments1 will behave like those we  
have experimented with2 and those       
concepts also presume that a certain    

germ of ,echinus1 99,a991 the           
blastomeres of which were not separated1
  would have given two whole larvae1 if 
separation had taken place1 while       
another germ1 99,b991 which actually    
gave us two larvae after separation1    
would only have given one without it4   
,without this presumption the  concept  
of 8potency0 is meaningless1 and1       
indeed1 every assumption of a  8faculty0
 or a 8possibility0 would be meaningless
 in the whole area of  science4    ,but 
this presumption can never be proved2 it
 can only be postulated4 ,it  therefore 
is only with this postulate that our    
first proof of vitalism  holds2 but this
 restriction applies to 99every99 law of
 nature4    ,i cannot force you to agree
 with this postulate3 but if you decline
  you are practically saying that there 
exists a sort of pre-established        
harmony between the scientific object   
and the scientist1 the scientist  always
 getting into his hands such objects    
only as have been  predestinated from   

the very beginning to develop two larvae
 instead of  one1 and so on4    ,of     
course1 if that is so1 no proof of      
natural laws is possible at all2  but   
nature under such views would seem to be
 really dmonic4    ,and so1 ,i hope1 you
 will grant me the postulate of the     
universality  of scientific             
concepts--the only 8hypothesis0 which we
 need for our  argument4      #d4 ,,on  
,,certain ,,other ,,features ,,of       
,,morphogenesis ,,advocating ,,its      
,,autonomy    ,our next studies on the  
physiology of form will be devoted in   
the first  place to some additional     
remarks about our                       
harmonious-equipotential  systems       
themselves1 and about some other kinds  
of morphogenetic  8systems0 which show a
 certain sort of relationship with them4
 ,for it is  of the greatest importance 
that we should become as familiar as    
possible  with all those facts in the   
physiology of form upon the analysis of 
which are to be based almost all of the 

future theories that we shall  have to  
develop in biology proper and           
philosophical4 ,our discussions1 so  far
 as they relate to questions of actual  
fact1 will contain only one  other topic
 of the same importance4    ,but though 
it is designed to complete and to deepen
 our analysis1  the present             
considerations may yet be said to mark a
 point of rest  in the whole of our     
discussions3 we have followed one single
 line of  argumentation from the        
beginning until now2 this line or this  
stream of  thought1 as you might call   
it1 is now to break into different      
branches  for a while1 as if it had     
entered from a rocky defile into a      
plain4  ,it seems to me that such a     
short rest will be not unconducive to a 
right understanding of all we have made 
out2 and such a full and real           
conceiving again1 such a realising of   
our problems of morphogenesis and  their
 solutions1 will be the best preparation
 for the philosophical part  of these   

lectures4                               
,,harmonious-,,equipotential ,,systems  
,,formed ,,by ,,wandering ,,cells       
,all of the harmonious-equipotential    
systems which we have studied so  far   
were the bases of histological          
differentiation2 that is to say1 the    
processes of their differentiation      
consisted in specifically localised     
elements of theirs becoming different   
99in situ994 ,now we know at least  one 
type of systems which also may be called
 harmonious-equipotential1  but the     
differentiation of which does not simply
 relate to elements at  a fixed place4  
,an additional phenomenon enters here   
into the sphere of  the others4 ,the    
elements not only become different where
 they are1 but  a specific changing of  
locality1 a specific kind of wandering1 
goes  hand-in-hand with differences     
relating to the prospective value to be 
attained4 ,i am speaking of the         
formation of the larval skeleton of  our
 well-known ,echinus4 ,we know that the 

mesenchyme cells1 which have  left the  
blastoderm and are arranged in a sort of
 ring of bilateral  structure1 are the  
starting-point of this skeleton3 it     
indeed originates  in a sort of         
secretive process on the part of the    
cells2 the cells  are moving about and  
are secreting carbonate of lime during  
their  wandering4 ,the experiments now  
have shown1 as we know1 that a whole1   
though smaller1 skeleton may also be    
formed1 if only a half or a quarter  of 
the mesenchyme cells are present1 as    
happens to be the case in all           
experiments with isolated blastomeres of
 the two or four-cell stage of          
cleavage4 ,it is clear that in these    
cases the performance of each single    
cell must be different from what it is  
in the normal case1 and that  the same  
sort of differences in the morphogenetic
 performances appears  again1 if the    
two- and the four-cell stage are        
compared with each other4  ,and there   
are still some other phenomena showing  

the possibility of  different           
performances being carried out by the   
individual cells4 ,peter  has shown that
 the number of mesenchyme cells may vary
 enormously under  certain conditions2  
but1 in spite of that1 the skeleton     
always will  be complete4 ,it may be    
said that this line of research is only 
of a  relative value to our own         
questions1 as1 of course1 variability   
relates  to different individuals3 but  
it seems to me that it adds a very good 
supplementary instance to what the      
experiment on the individual itself  has
 established4    ,we should only be     
repeating ourselves if we were to       
analyse again what  happens here as the 
expression of the                       
harmonious-equipotentiality  itself4    
,but indeed there occurs something new  
in this instance3 the  single mesenchyme
 cell not only has to perform in each   
case that single  act of specific       
secretion which the case requires1 but  
it also has to  wander to the right     

place in order to perform it2 there must
 be some  order1 not only about the acts
 of secretion after wandering1 but also 
in  the migrations themselves4 ,if      
undisturbed ontogeny alone were         
possible1  and if therefore a theory    
like that of ,weismann were in place1 we
 might  say perhaps that each           
mesenchyme-cell is specified not only as
 to its  performance in secretion1 but  
also with regard to its chemotactical   
irritability1 the latter being typically
 localised1 so that its effect  becomes 
typical1 thanks to the typical          
arrangement of all the cells  with      
respect to each other4 ,but that is     
certainly not the case4 ,now1 you  may  
ask yourselves if you could imagine any 
sort of a machine1 which  consists of   
many parts1 but not even of an          
absolutely fixed number1 all  of which  
are equal in their faculties1 but all of
 which in each single  case1 in spite of
 their potential equality1 not only     
produce together  a certain typical     

totality1 but also arrange themselves   
typically in  99order99 to produce this 
totality4 ,we 99are99 indeed familiar   
with certain  occurrences in nature     
where such curious facts are observed1  
but ,i doubt  if you would speak of     
8machines0 in these cases4 ,the         
mesenchyme-cells1  in fact1 behave just 
as a number of workmen would do who are 
to  construct1 say1 a bridge4 ,all of   
them 99can99 do every single act1 all of
  them also 99can99 assume every single 
position3 the result always is to  be a 
perfect bridge2 and it is to be a       
perfect bridge even if some of  the     
workmen become sick or are killed by an 
accident4 ,the 8prospective  values0 of 
the single workman change in such a     
case4    ,i well know that it is only an
 analogy which ,i am offering to you4   
,the mesenchyme-cells have not          
8learned10 have no 8experience40 ,all   
that is to occupy us next summer4 ,but  
in spite of it1 there is truth  in the  
analogy2 and perhaps you will prefer it 

to the merely abstract  consideration4  
,,on ,,certain ,,combined ,,types ,,of  
,,morphogenetic ,,systems    ,for the   
sake of completeness it may be remarked1
 only by the way1 that  the type of the 
proper harmonious-equipotential system  
may go hand in  hand with another type  
of 8systems0 which play a part in       
morphogenesis2  a type which we have    
shortly mentioned already and which will
 be studied  fully a few chapters later4
 ,we know that there are equipotential  
systems  with complex potencies3 that is
 to say1 systems which may produce a    
whole organism equally well from any one
 of their elements2 we know the  cambium
 of ,phanerogams to be such a system4   
,now it is easily understood  that the  
germ of our ,echinus1 say in the stage  
of two or four or eight  cleavage cells1
 is not only an harmonious-equipotential
 system1 but  a complex-equipotential   
system too4 ,not only may there arise a 
whole  organism out of #b_/d or #c_/d or
 #c_/h1 #d_/h1 #e_/h1 #f_/h1 #g_/h of   

its elements1  in which cases the       
harmonious rle of the single element    
with regard to  its single performance  
in a totality is variable1 but there may
 also  arise four whole single larvae   
out of the four cells of the four-cell  
stage1 or eight single whole larvae out 
of the eight-cell stage4#fg  ,in these  
cases1 of course1 each of the four or   
eight elements has  performed not a part
 of the totality1 changing with its     
8position10 but  the totality itself4   
,with respect to these possible         
performances the  8systems0 present in  
the four or eight-cell stages of        
cleavage must be  called                
complex-equipotential ones4    #fg ,the 
eight larvae would be incomplete in some
 respect1 but not with  regard to       
symmetry4 ,they would be 8whole0 ones1  
only showing certain  defects in their  
organisation4 ,see page #fe note #a1 and
 page #gc4    ,we propose to give the   
name of 99mixed-equipotential systems99 
to all  those equipotential systems     

which1 at the same time1 may be regarded
  as belonging to the harmonious or to  
the complex type4 ,it is not only  among
 cleavage-stages that they are to be    
found2 you may also find them  very     
clearly exhibited in our ascidian       
99,clavellina99 for instance4 ,we  know 
already that the branchial apparatus of 
this form is typically                  
harmonious-equipotential1 but it is     
complex-equipotential too1 for it  also 
may regenerate what is wanting in the   
proper way1 by a budding  from the      
wound2 and the same is true of many     
other cases1 the flatworm  99,planaria99
 for instance4    ,another type of      
systems1 which might be said to be of a 
higher degree1  is exhibited in some    
very strange phenomena of regeneration4 
,it was  first shown most clearly by    
some experiments of ,godlewski's that a 
whole tail may be regenerated from a    
wound inflicted on the body of  a newt1 
even if this wound involves section of  
only a portion of the  body-diameter4   

,section of the whole of the            
body-diameter of course  would cause the
 formation of the whole tail also2 but  
it was found that  even an incomplete   
cross-section of the body is capable of 
performing  the whole on a smaller      
scale4 ,the series of possible          
cross-sections  which are all capable of
 regeneration would have to be called a 
system of the complex type in this case2
 but1 now we learn that every           
99single99 cross-section is of the      
harmonious type1 we must speak of       
99complex-harmonious systems994 ,what we
 have described is not the only         
instance of our new type of             
morphogenetic systems4 ,some other      
instances  had been discovered a few    
years earlier1 though nobody had pointed
  out their true significance4 ,in the  
flatworm 99,planaria99 a partial        
cross-section is also capable of forming
 a whole structure1 say a head1  and all
 cases of so-called 8super-regeneration0
 after the infliction of  a complicated 

wound probably belong here also4    ,you
 may say that our two additions to the  
theory of systems are merely  formal1   
and indeed ,i am prepared to concede    
that we shall not learn  anything       
altogether new from their discussion3   
their analysis would lead  either to    
what was our 8first proof0 of the       
autonomy of life-phenomena  or to what  
will be our 8second0 one4 ,but the mere 
descriptions of the  facts discovered   
here will interest you1 ,i think1 and   
will fill your  minds with more vivid   
pictures of the various aspects of      
form-autonomy4    ,while dealing with   
our harmonious-equipotential systems as 
the  starting-points of processes of    
restitution1 99e4g499 in 99,tubularia991
  99,clavellina991 the flatworms1 and   
other instances1 we always have         
regarded cross-sections of the body as  
constituting the elements of            
equipotentiality4 ,now cross-sections1  
of course1 are by no means simple  in   
themselves1 but are made up of very     

different tissues1 which are  derivates 
of all three of the original germ       
layers--ectoderm1 mesoderm1  and        
endoderm4 ,owing to this composite      
character of the cross-sections1  taken 
as elements of harmonious systems1 a    
special phenomenon of  morphogenesis is 
presented to us1 which teaches somewhat 
more than the  mere concept of          
harmonious-equipotentiality can express4
 ,if composite  elements concerned in   
morphogenesis result in one whole       
organisation  in spite of the           
development of the single tissues of    
these elements  going on independently1 
then there must be a sort of            
correspondence  or reciprocity of the   
harmonious development among these      
tissue  constituents themselves2        
otherwise a proportionate form could not
 be the  final result4 ,we may          
conveniently speak of a 99reciprocity of
 harmony99 as  existing between the     
single tissues or germ layers which     
constitute many                         

harmonious-equipotential systems1 and   
there can be little doubt that we  have 
here an important feature with regard to
 general morphogenesis4#fh    #fh       
,reciprocal harmony may be reduced in   
some cases to the given  proportions of 
one original harmonious system1 from    
which the single  constituents of the   
complicated system1 showing reciprocal  
harmony1 are  derived4 ,then we have    
only an instance of 8harmony of         
constellation0  7see p4 #aji74 ,but     
reciprocal harmony seems to become a    
problem itself1  if it occurs in        
restitutions starting from quite a      
typical point1  selected by the         
experimenter4 ,it will be a problem of  
future research  to give an exact       
formula of what happens here4           
,reciprocal harmony also  occurs in     
regeneration proper4 ,it is known that  
the formation of the  regenerative bud  
and the differentiation of this bud     
follow each other4  ,as the bud is      
composed of different elementary        

systems1 it follows that  these         
different systems1 of which every single
 one is harmonious1 also  have to work  
in reciprocity to each other1 in order  
that one whole  proportionate formation 
may result4    ,a few other groups of   
morphogenetic facts may find their      
proper place  here1 though they are not 
properly to be regarded as additions to 
the  theory of harmonious systems but as
 forming a sort of appendix to it4      
,,the 8,,morphaesthesia0 ,,of ,,noll#fi 
#fi 99,biol4 ,centralblatt499 #bc1      
#aijc4    ,we may briefly mention that  
group of botanical phenomena1 by which  
the botanist ,noll has been led to the  
concept of what he calls                
8morphaesthesia10 or the 8feeling0 for  
form2 a concept1 the full  discussion of
 which would lead to almost the same    
conclusions as our  analysis of the     
harmonious systems has done4 ,in the    
,siphoneae1 a  well-known order of      
marine algae with a very complicated    
organisation  as to their exterior form1

 the protoplasm which contains the      
nuclei is  in a constant state of       
circulation round the whole body1 the   
latter  not being divided by proper     
cell-walls4 ,on account of this constant
  movement it is certainly impossible to
 refer morphogenetic localisation  to   
definite performances of the nuclei4    
,nor can any sort of structure  in the  
outer protoplasmic layer1 which is      
fixed1 be responsible for  it1 for there
 is no such structure there3 hence there
 must be a sort  of feeling on the part 
of the plant for its relative body      
localities1  and on account of this     
feeling morphogenesis occurs4 ,this     
8feeling0 is  styled 8morphaesthesia0 by
 ,noll1 and to it he tries to refer all 
sorts  of different botanical           
form-phenomena1#gj for instance what is 
called  8autotropism10 that is1 the fact
 that branches of plants always try to  
reassume their proper angle with regard 
to their orientation on the main  axis1 
if this orientation has been disturbed4 

,it may be an open question  if this    
particular application of the theory is 
right3 certainly  there seems to be much
 truth in the establishment of the      
concept of  morphaesthesia1 and we only 
have to object to its psychological     
name4  ,but that may be done in a more  
general form on a later occasion4    #gj
 ,certain phenomena of the physiology of
 growth of 99,geranium  ,robertianum991 
recently discussed by ,franc from a     
vitalistic point of  view 799,zeitschr4 
,entw4 lehre994 #a1 #aijg1 ,heft iv471  
might also belong  here4 ,i cannot see  
an independent proof of vitalism in     
these facts if  taken by themselves2 a  
pre-existing 8machine0 cannot be        
absolutely  excluded here4              
,,restitutions ,,of ,,the ,,second      
,,order    ,in the hydroid polyp        
99,tubularia991 already familiar to us  
as being a most  typical representative 
of the harmonious-equipotential systems1
 a very  interesting phenomenon has been
 discovered#ga1 almost unparalleled at  

present but nevertheless of a general   
importance1 a phenomenon that  we may   
call a restitution of a restitution1 or 
a restitution of the  second order4 ,you
 know that the first appearance of the  
new head of  99,tubularia991 after an   
operation1 consists in the formation of 
two rings  of red lines1 inside the     
stem1 these rings being the primordia of
 the  new tentacles4 ,i removed the     
terminal ring by a second operation soon
  after it had arisen1 disturbing in    
this way the process of restitution     
itself3 and then the process of         
restitution itself became regulated4    
,the  organism indeed changed its course
 of morphogenesis1 which was serving    
the purposes of a restitution1 in order 
to attain its purpose in spite  of the  
new disturbance which had occurred4 ,for
 instance1 it sometimes  formed two     
rings out of the one that was left to   
it1 or it behaved  in a different way4  
,as this difference of morphogenetic    
procedure is  a problem by itself1 to be

 discussed farther on1 we shall postpone
 a  fuller description of this case of a
 restitution of the second degree4      
#ga ,driesch1 99,arch4 ,entw4 ,mech499  
#e1 #ahig4    ,at present ,i do not see 
any way of proving independently the    
autonomy of  life by a discussion of    
these phenomena2 their analysis1 ,i     
think1 would  again lead us to our      
problem of localisation and to nothing  
else2 at  least in such an exact form of
 reasoning as we demand4      ,,on ,,the
 8,,equifinality0 ,,of ,,restitutions#gb
    #gb ,driesch1 99,arch4 ,entw4       
,mech499 #ad1 #aijb4    ,i have told you
 already that 99,tubularia99 in the     
phenomena of the  regulation of         
restitutions offers us a second problem 
of a great general  importance1 the     
problem of the 99,equifinality of       
,restitutions994 ,there  indeed may     
occur restitutions1 starting from one   
and the same initial  state and leading 
to one and the same end1 but using very 
different  means1 following very        

different ways in the different         
individuals of one  and the same        
species1 taken from the same locality1  
or even colony4    ,imagine that you    
have a piece of paper before you and    
wish to sketch  a landscape4 ,after     
drawing for some time you notice that   
you have  miscalculated the scale with  
regard to the size of the paper1 and    
that it will not be possible to bring   
upon the paper the whole of the         
landscape you want4 ,what then can you  
do8 ,you either may finish what you     
have begun to draw1 and may afterwards  
carefully join a new piece of  paper to 
the original one and use that for the   
rest of the drawing2 or  you may rub out
 all you have drawn and begin drawing to
 a new scale2 or  lastly1 instead of    
continuing as you began1 or erasing     
altogether1 you  may compromise as best 
you can by drawing here1 and erasing    
there1 and  so you may complete the     
sketch by changing a little1 according  
to your  fancy1 the proportions as they 

exist in nature4    ,this is precisely  
analogous to the behaviour of our       
99,tubularia994  99,tubularia99 also may
 behave in three different ways1 if1 as 
,i described  to you1 the terminal one  
of its two newly arisen rings of        
tentacle  primordia is removed again4   
,it may complete what is left1 say the  
basal  tentacle ring1 then put forth    
from the horny skeleton 7the 8perisarc07
  the new head as far as it is ready1   
and finally complete this head  by a    
regular process of budding regeneration4
 ,but it also may behave  differently4  
,it may 8erase0 by a process of         
retro-differentiation all  that has been
 left of what had already been formed1  
and then may form  99de novo99 the      
totality of the primordia of a new head4
 ,or1 lastly1 it  may remove a part of  
the middle of the one ring of tentacle  
rudiments  which was left1 and may use  
this one ring for the formation of two1 
which1 of course1 will not be quite in  
the normal relations of place  with     

regard to each other and to the whole1  
but will be regulated  afterwards by    
processes of growth4 ,thus1 indeed1     
there is a sort of  equifinality of     
restitution3 one starting-point1 one    
end1 but three  different means and     
ways4    ,it would1 of course1          
contradict the principle of univocality1
 as we  shall see more fully later on1  
to assume that there actually are       
different ways of regulation whilst all 
the conditions and stimuli are  the     
same4 ,we are obliged to assume1 on the 
contrary1 that this is not  the case1   
that there are certain differences in   
the constellation1 say  of the general  
conditions of age or of metabolism1     
which are responsible  for any given    
individual choosing one process of      
restitution instead  of another2 but    
even then the phenomenon of equifinality
 remains very  striking4    ,it has long
 been known that restitution in general 
does not always  follow the same lines  
of morphogenesis as are taken by        

ontogeny1 and it  was this feature that 
once led ,roux to point out that the    
adult forms  of organisms seem to be    
more constant than their modes of       
origin4 ,but1  comparing ontogeny with  
restitution in general1 we see that only
 the  ends are the same1 not the points 
of starting2 the latter are normal or   
non-typical in ontogeny1 atypical in    
restitution4 ,in the new discoveries  of
 an equifinality of restitutions we have
 the 99same99 starting-point1  which is 
decidedly non-typical but atypical1     
99i4e499 dependent on our  arbitrary    
choice1 leading by 99different99 ways   
always to the 99same99 end4    ,there   
may be many who will regard the fact of 
equifinality as a proof of  vitalism4 ,i
 should not like to argue in this easy  
way2 ,i indeed prefer  to include part  
of the phenomena of equifinality in our 
first proof of  autonomy1 and part in   
the second one1 which is to follow4     
,another important phenomenon of the    
equifinality of regulation was          

discovered by ,morgan4 ,a species of the
 flatworm 99,planaria99 was found to    
restore its totality out of small pieces
 either by regeneration proper1  if the 
pieces were fed1 or by a sort of        
rearrangement of material1  on the basis
 of its harmonious-equipotentiality1 if 
they were kept  fasting4 ,it is         
important to note that here we see one  
of the conditions  determining the      
choice of the way to restoration1 as we 
also do in the  well-known equifinal    
restitutions of the root in plants1     
where the  behaviour of the organism    
depends on the distance of the          
operation-wound  from the tip4#gc ,in   
99,tubularia99 the actual stage of      
restitution that  has been already      
reached by the stem when the second     
operation takes  place1 may account for 
the specification of its future         
organogenesis1  but this is not at all  
clearly ascertained at present4    #gc  
,the root may be restored by            
regeneration proper1 or by the          

production of adventitious roots1 or by 
one of the side-roots changing  its     
geotropism from horizontal to positive1 
according to the smaller or  greater    
distance of the wound from the tip4     
99,clavellina99 also shows equifinality 
in its restitution1 as has already  been
 shortly mentioned4 ,the isolated       
branchial apparatus may restitute       
itself by retro-differentiation to an   
indifferent stage followed by           
renovation2 or it may regenerate the    
intestine-sac in the proper way4        
,nothing is known here about the        
conditions1 except perhaps that young   
individuals seem more apt to follow the 
first of these two ways1 older  ones the
 second2 but there are exceptions to    
this rule4    ,the discussion of other  
instances of equifinality1 though       
important in  themselves1 would not     
disclose anything fundamentally new1 and
 so we may  close the subject with the  
remark that nothing can show better than
 the  fact of the equifinality of       

restitutions how absolutely inadequate  
all  our scientific conceptions are when
 confronted with the actual phenomena   
of life itself4 ,by analysis we have    
found differences of potencies1         
according as they are simple or complex2
 by analysis we have found  differences 
of 8systems10 differences of means1 and 
indeed we were glad  to be able to      
formulate these differences as strictly 
as possible3 but  now we see how1 in    
defiance of our discriminations1 one and
 the same  species of animals behaves   
now like one sort of our 8systems10 and 
now  like the other2 how it uses now one
 sort of 8potencies10 now another4      
,but even if it is granted that1 in the 
presence of such phenomena of  life1 our
 endeavour seems to be like a child's   
play on the shores of the  ocean1 ,i do 
not see any other way for us to go1 so  
long1 at least1 as  our goal is human   
science--that is1 a study of facts as   
demanded by our  mental organisation4   
,,remarks ,,on                          

8,,retro-,,differentiation0    ,we shall
 finish this part of our studies by     
mentioning a little more  explicitly one
 fundamental fact which has already     
entered incidentally  into our          
considerations1 viz4 99retro-99 or      
99back-differentiation994#gd  ,we know  
that it occurs in 99,clavellina99 and in
 99,tubularia992 we may add  that it    
also happens in 99,hydra991 and that in 
the flatworm 99,planaria99  the pharynx1
 if it is too large for a piece that is 
cut out1 may be  differentiated back and
 be replaced by a new pharynx1 which is 
smaller4    #gd                         
8,retro0-differentiation1 of course1 is 
not 8,re0-differentiation               
78,umdifferenzierung10 see p4 #aaa71    
though it may help it to occur4    ,it  
is not death and sloughing of parts that
 occurs in these cases1#ge  but a real  
process of active morphogenesis2 not1   
however1 a process  consisting in the   
production of visible manifoldness1 but 
the opposite4  ,loeb was the first to   

lay much stress upon this topic1 and    
indeed1 there  may appear a very strange
 problem in its wake3 the problem1      
whether  99all99 morphogenesis might be 
capable perhaps of going backwards under
  certain conditions4    #ge ,of course 
such a real decay of parts may happen in
 other cases4    ,it is important to    
note that in most#gf cases              
retro-differentiation  occurs in the    
service of restitution3 it goes on      
wherever restitution  requires it4 ,this
 fact alone would show that not very    
much could be  explained here by the    
discovery of modern chemistry1 important
 as  it is1 that one and the same       
8ferment0 or 8enzyme0 may affect both   
the composition and the decomposition of
 the same compound4 ,we could  regard   
what is called 8catalysis0 solely as an 
agent in the service of  entelechy4 ,but
 this point also will become clearer in 
another part of  the work4    #gf       
,certain cases of retro-differentiation 
occurring under conditions  of strict   

fasting will be described in a later    
chapter4          99,c499 ,,adaptation  
,,introductory ,,remarks ,,on           
,,regulations ,,in ,,general      ,we   
have finished our long account of       
individual morphogenesis proper4  ,if we
 look back upon the way we have         
traversed1 and upon those topics  in    
particular which have yielded us the    
most important general results1  the    
material for the higher analysis which  
is to follow1 it must  strike us1 ,i    
think1 that all these results relate to 
regulations4  ,in fact1 it is           
8secondary0 form-regulations1 according 
to our  terminology1 that we have been  
studying under the names of             
equifinality1  back-differentiation1    
restitution of the second order1 and so 
on1 and  our harmonious-equipotential   
systems have figured most largely in    
processes of secondary form-regulations 
also4 ,but even where that has  not been
 the case1 as in the analysis of the    
potencies of the germ in  development   

proper1 form-regulations of the other   
type have been our  subject1 regulations
 of the primary or immanent kind1 the   
connection  of normal morphogenetic     
events being regulatory in itself4 ,it  
was not  the phenomenon of organic      
regulation as such that afforded us the 
possibility of establishing our proof of
 the autonomy of morphogenesis3  that   
possibility was afforded us by the      
analysis of the distribution of         
potencies2 but upon this distribution   
regulation is based1 and thus  we may be
 said to have studied some types of     
regulation more or less  indirectly when
 analysing potencies4    ,it therefore  
seems to me that we shall have hopes of 
a successful issue  to our inquiries1 if
 we now1 on passing to what is called   
the physiology  of the vegetative       
functions1 proceed to focus our         
attention on the  concept of regulation 
as such4 ,and that is what we shall do3 
on our  way through the whole field of  
physiology1 we shall always stop at any 

occurrence that has any sort of         
regulatory aspect1 and shall always ask 
ourselves what this feature has to teach
 us4    ,but let us first try to give a 
proper definition of our concept4 ,we   
shall understand by 8regulation0 any    
occurrence or group of occurrences  on a
 living organism which takes place after
 any disturbance of  its organisation or
 normal functional state1 and which     
leads to a  reappearance of this        
organisation or this state1 or at least 
to a  certain approach thereto4         
,organisation is disturbed by any actual
  removal of parts2 the functional state
 may be altered by any change  among the
 parts of the organism on the one hand1 
by any change of the  conditions of the 
medium on the other2 for physiological  
functioning  is in permanent interaction
 with the medium4 ,it is a consequence  
of  what we have said that any removal  
of parts also changes the functional    
state of the organism1 but nevertheless 
organisation is more than a mere  sum of

 reactions in functional life4 ,all     
regulations of disturbances  of         
organisation may be called              
99restitutions991 while to regulations  
of  functional disturbances we shall    
apply the name 99adaptations994 ,it is  
with 99adaptations99 that we have to    
deal in the following4    ,let us begin 
our studies of adaptations in a field   
which may justly  be called a connecting
 link between morphogenesis and         
physiology  proper1 not yet wholly      
separated from the science of the       
organic form1  morphology4      #a4     
,,morphological ,,adaptation            
99,morphological adaptation99 is a      
well-established fact1 and ,i need only 
mention the striking differences between
 the land and water form of  amphibious 
plants1 or the differences between the  
same species of plants  in the ,alps and
 in the plains1 or the very different   
aspect of the arms  of an athlete and of
 an ascetic1 to recall to your memory   
what is meant  by this term4            

,morphological adaptation is no part of 
individual morphogenesis proper1  but   
occurs at the end of it2 at least it    
never occurs previous to the  full      
individual life of an organism1 previous
 to its true functional  life2 for it   
relates to the functions of the complete
 organism4      ,,the ,,limits ,,of     
,,the ,,concept ,,of ,,adaptation    ,it
 is especially1 though by no means      
exclusively1 among plants that          
morphological adaptation assumes its    
most marked forms2 and this topic1      
indeed1 may very easily be understood if
 we remember that plant-life  is in the 
very closest permanent dependence on the
 medium1 and that  this medium is liable
 to many changes and variations of all  
kinds4  ,in order to elucidate our      
problem1 it therefore seems convenient  
to  restrict our considerations for a   
while to the study of plants4 ,there    
exist very many external formative      
stimuli in the morphogenesis of         
vegetation3 would it then be possible to

 regard every effect of such  an        
external formative stimulus as a real   
morphological adaptation8  ,no2 for that
 would not meet the point4 ,the general 
99harmony99 of form  is indeed concerned
 if gravity forces roots to shoot forth 
below at a  spot where they can enter   
the ground1 or if light induces branches
 and  leaves to originate at places     
where they can obtain it for            
assimilation2  but gravity and light    
themselves are mere formative           
stimuli--of the  localising type--in    
these instances1 for they relate only to
 the  individual production of form1 not
 to the functioning of already  existing
 form4 ,we therefore are warned not to  
confuse the effects of  formative       
stimuli from without with real adaptive 
effects until we have  fully analysed   
the particular case4    ,we have drawn a
 sharp line between causes and means of 
morphogenesis1  applying the term       
8means0 to those conditions of the      
morphogenetic  process which relate     

neither to the specificity nor to the   
localisation  of its constituents1      
though they are necessary for the       
accomplishment  of the process in the   
most thorough manner4 ,would it be      
possible to  connect our new concept of 
an adaptation with our well-established 
concept of a means of morphogenesis in  
such a way that we might speak  of a    
morphological 8adaptation0 whenever any 
specific feature about  morphogenesis   
proves to be immediately dependent for  
its success on some  specific means1    
though it does not owe its localisation 
to that means  as its 8cause08 ,it seems
 to me that such a view would also fall 
wide  of the mark4 ,it is well known1   
for instance1 that the flowers of many  
plants never fully develop in the dark2 
light is necessary for their            
morphogenesis4 ,is1 therefore1 their    
growth in the presence of light to  be  
called a morphological 8adaptation0 to  
light8 ,certainly not3 they  simply     
99cannot99 originate without light1     

because they require it for  some       
reason4 ,it is precisely here that our  
conception of light as a  8means0 of    
morphogenesis is most fully justified4  
,there are many#gg  such cases2 and     
there are still others of an apparently 
different  type1 but proving the same4  
,all pathological forms produced in     
plants  by animal parasites or by       
parasitic fungi could hardly be called  
adaptations1 but must be attributed to  
some abnormality of means or of         
stimuli4 ,it may be that the organism   
reacts as well as possible in these     
cases1 and that if it reacted otherwise 
it would die--we know absolutely        
nothing about this question4 ,but even  
then there would only be some sort  of  
regulation 99in99 the process of        
pathological morphogenesis1 but 99the   
process99 itself could hardly be called 
adaptive4    #gg ,klebs has suppressed  
the reproductive phase of organisation  
altogether1 in fungi as well as in      
flowering plants1 or has made it  occur 

abnormally early1 merely by changing the
 8external conditions0  and by altering 
the 8internal0 ones correspondingly4    
,there is hardly  anything like an      
adaptation in these cases1 which1 by the
 way1 offer  certain difficulties to    
analysis1 as the boundaries between     
8cause0 and  8means0 are not very sharp 
here4    ,so far we have only learned   
what is not to be regarded as           
morphological  adaptation4 ,no response 
to external formative stimuli is in     
itself an  example of adaptation1 nor   
are processes dependent for their       
existence  on any kind of condition or  
means to be called1 simply because they 
are  dependent on them1 adaptations to  
those agents4 ,what then1 after all1 is 
a morphological adaptation8    ,let us  
remember what the word adaptation is    
really to mean in our  discussions3 a   
state of functioning is adapted--a state
 of functioning  must therefore have    
been disturbed2 but as functioning      
itself1 at least  in plants1 certainly  

stands in close relations to the medium1
 it follows  that all adaptations are in
 the last resort connected with those   
factors  of the medium which affect     
functioning4 ,in being correctives to   
the  disturbances of functioning they   
become correctives to the disturbing    
factors themselves4    ,but again1 the  
question seems to arise whether these   
factors of the  medium1 when they       
provoke an adaptation by some change    
that is followed  by functional         
disturbance1 do so in the capacity of   
8causes0 or of  8means10 and so it might
 seem that we have not gained very much 
so far  by our analysis4 ,the reproach1 
however1 would not be quite justified1  
it seems to me3 we indeed have gained a 
new sort of analytical concept1  in the 
realm of causal concepts in general1 by 
clearly stating the  point that         
adaptations are related directly to     
functionality1 and only  indirectly1    
through functionality1 to external      
changes4 ,by the aid of  this logical   

formulation we now are entitled to apply
 the term 8cause10  in our restricted   
sense of the word1 to every change of   
the medium  which is followed by any    
sort of adaptation in regard 99to       
itself994 ,our  definition stated that a
 8cause0 is any one of the sum of       
necessary  factors from without that    
accounts either for the localisation    
99or99 for  99the specification99 of the
 effect1 and the definition holds very  
well in  this case4 ,indeed1 the        
specification of the effect is          
determined 99by99  the outside factor in
 every case of an adaptation 99to99 it1 
by the mere  99fact99 of its being a    
specific adaptation to this specific    
factor4    ,we must not forget that in  
this chapter we are not studying real   
individual morphogenesis as the         
realisation of what has been inherited1 
but that at present we regard           
morphogenesis proper as an accomplished 
fact4 ,morphogenesis proper has laid the
 general lines of organisation2  and now

 adaptation during the functional life1 
so to speak1 imposes a  second kind of  
organisation upon the first4 ,it is for 
that reason that  the meaning of the    
word 8cause0 is now becoming a little   
different from  what it was before4     
,in order to study a little more in     
detail what has been discovered  about  
morphological adaptation in animals and 
plants1 let us separate  our materials  
into two groups1 one of them embracing  
adaptations with  regard to functional  
changes from without1 the other         
adaptations to  those functional changes
 which come from the very nature of     
functioning4  ,almost all of our        
previous general considerations have    
applied to the  former group1 with which
 we shall now proceed to deal4          
,,adaptations ,,to ,,functional         
,,changes ,,from ,,without#gh    #gh    
,compare ,herbst1 99,biol4 ,centralbl499
 #ae1 #ahie2 and ,detto1 99,die         
,theorie der direkten ,anpassung991     
,jena1 #aijd4 ,a full account of the    

literature will be found in these       
papers4    ,the differences between     
plants grown in very dry air1 very moist
 air1  and water1 respectively1 are most
 distinctly seen in all the tissues     
that assist in what is called           
transpiration1 that is1 the exchange of 
water-vapour between the plant and the  
medium1 but especially in the  epidermis
 and the conductive fibres1 both of     
which are much stronger  in plants grown
 in the dry4 ,indeed1 it seems from     
experiments that  transpiration is the  
most essential factor to which          
8adaptation0 occurs  in amphibious      
plants1 though the changes of the       
mechanical conditions  according to the 
medium also seem to have some sort of   
structural  effect4 ,if plants stand    
very deeply in water1 the conditions of 
illumination1 so important for          
assimilation in plants1 may have been   
altered1 and therefore much of the      
structural change can be attributed     
also to them4 ,it is unimportant in our 

general question what is due to  one of 
these factors and what to the other4    
,that there is a real sort  of          
adaptation cannot be doubtful2 and the  
same is true1 as experimental           
observations of the last few years have 
shown1 with regard to the  structural   
differences between so-called sun-leaves
 and shade-leaves  of plants grown in   
the air3 it has been actually shown here
 that the  functional life of the former
 goes on better in the sun1 of the      
latter  better in the shade4    ,it is  
very important to emphasise this point1 
as the adaptive character  of all sorts 
of structural differences in plants     
dependent on light  and on moisture has 
lately been denied1 on the supposition  
that there  is only a stopping of       
organogenesis in the case of the more   
simple1  a continuance in the case of   
the more complicated modification1 but  
nothing else4 ,indeed1 all morphological
 adaptation has been conceived  as only 
consisting in differences dependent upon

 the absence or the  presence of        
necessary means or causes of            
development1 and as offering  no problem
 of its own4 ,we have gained the right  
position from which  to oppose this     
argument1 it seems to me1 in our formula
 that all  adaptations do relate 99not99
 directly 99to99 the agents of the      
medium1  but to changes of functional   
states induced 99by99 those agents2 that
  adaptations only 99are99 8adaptations0
 by being correctives to the  functional
 state4    ,there simply 99is99 an      
8adaptation0 of structure in 99such99 a 
sense in all  the cases we have         
mentioned4 ,we can say neither more nor 
less4 ,granted  that one of the outside 
factors which comes into account is     
merely a  necessary 8means03 then why is
 the histological consequence of the    
presence of the means an actual         
adaptation to it as far as its relation 
to functioning is concerned--why is the 
consequence of its absence also  an     
adaptation to this absence in its       

relation to functioning8 ,why1 to       
complete the series1 is the degree of   
the consequence of its presence an      
adaptation to the degree of its         
presence8    ,all these relationships1  
which are so many facts1 have been      
absolutely  overlooked by those who have
 been pleased to deny morphological     
adaptation to functional changes from   
without4    ,to do full justice to them 
we may speak of 8primary0 regulative    
adaptations in all the cases mentioned  
above1 applying the word  8primary10    
just as was done with regard to         
restitutions1 to the fact  that there is
 some sort of regulation 99in99 the     
normal connection of  processes4 ,we    
reserve the title of 8secondary         
adaptations0 for cases  such as those   
described1 for instance1 by ,vchting1#gi
 where not  merely one and the same     
tissue originates adaptively with regard
 to the  degree of its normal           
functioning1 but where a profound       
disturbance  of all functioning         

connections1 due to the removal of      
portions of the  organisation1 is       
followed by histological changes at     
absolutely abnormal  localities2 that   
is1 where a real change of the 99kind99 
of functioning  is the consequence of   
the adaptation4 ,it1 of course1 will be 
found very  difficult to discriminate   
such phenomena from real restitutions1  
though  logically there exists a very   
sharp line between them4    #gi ,vchting
 799,jahrb4 wiss4 ,bot499 #cd1 #ahii7   
forced the bulbs of  plants to become   
parts of the stem1 and parts of the stem
 to form  bulbs2 in both cases the most 
characteristic changes in histology     
could be observed1 being in part        
adaptations1 but in part restitutions   
of the proper type4 7,see also my       
99,organische ,regulationen991 #aija1 p4
  #hd47 ,a true and simple instance of a
 8secondary adaptation0 seems to  be    
furnished in a case described by        
,boirivant4 ,in 99,robinia99 all the    
leaflets of a leaf-stalk were cut off3  

the leaf-stalk itself then  changed its 
structure in order to assist            
assimilation1 and also formed  real     
stomata4    ,a few more concrete        
instances may now close this account of 
adaptation  to functional changes coming
 from without4 ,though almost all the   
adaptive characters in the aquatic forms
 of amphibious plants represent  a less 
complicated state of organisation than  
the corresponding  structures in their  
terrestrial forms1 and therefore have   
wrongly  been regarded as simply due to 
a stopping of morphogenesis for want  of
 necessary means1 yet there are a few of
 them that are positive  complications  
in comparison with the land-forms3 the  
so-called  arenchyme1 especially well   
developed in the water-form of          
99,jussiaea99  is such an instance4     
,this tissue stands in the direct       
service of  respiration1 which is more  
difficult to be accomplished under water
 than  ordinarily1 and represents a true
 adaptation to the altered function4    

,among animals there is only one        
well-studied instance of our first type 
of adaptive morphological characters4   
99,salamandra atra991 the black         
salamander1 a species which only        
inhabits regions at least two thousand  
feet above sea-level1 does not bring    
forth its young until metamorphosis  has
 taken place4 ,the larvae1 however1 may 
be removed from the mother's  body at an
 earlier stage and forced to complete   
their development in  water4 ,under     
these circumstances1 as was shown in an 
excellent memoir  by ,kammerer1#hj they 
will change the whole histological type 
of their  gills and skin in order to    
meet the new functional conditions4 ,the
  change of the conditions of           
functioning is very severe here1 for    
whereas  the gills had served for       
nutrition and respiration in the        
uterus--by  a process of                
endosmosis--they now serve for          
respiration only1 and1 of  course1 are  
surrounded by quite an abnormal chemical

 medium4    #hj 99,arch4 ,entw4 ,mech499
 #ag1 #aijd4      ,,true ,,functional   
,,adaptation#ha    #ha ,roux1           
99,gesammelte ,abhandlungen991 vol4 i4  
#ahie2 in particular1 99,der  ,kampf der
 ,teile im ,organismus991 ,leipzig1     
#ahha4    ,but all other cases of       
morphological adaptation among animals1 
and  several in the vegetable kingdom   
too1 belong to our second group of      
these phenomena1 which in our analytical
 discussion we have called  adaptations 
to functional changes that result from  
the very nature  of functioning1 and    
which we shall now call by their        
ordinary name1  8functional adaptation40
    ,it was ,roux who first saw the     
importance of this kind of organic      
regulation and thought it well to give  
it a distinguishing name4 99,by         
functioning the organisation of organic 
tissues becomes better adapted  for     
functioning499 ,these words describe    
better than any others what  happens4   
,it is well known that the muscles get  

stronger and stronger the  more they are
 used1 and that the same holds for      
glands1 for connective  tissue1 etc4    
,but in these cases only quantitative   
changes come into  account4 ,we meet    
with functional adaptations of a much   
more complicated  and important kind1   
when for instance1 as shown by ,babk1#hb
 the  intestine of tadpoles changes     
enormously in length and thickness      
according as they receive animal or     
vegetable food1 being nearly twice  as  
long in the second case4 ,besides this  
the so-called mechanical  adaptations   
are of the greatest interest4    #hb    
99,arch4 ,entw4 ,mech499 #ba1 #aijf4 ,by
 a very detailed comparative study      
,babk was able to prove that it is the  
plant proteids to which the  effect of  
vegetable food is chiefly due2 thus we  
have an adaptation  to digestibility4   
,mechanical circumstances are only of   
secondary  importance4 7,see also       
,yung47    ,it has long been known1     
especially from the discoveries of      

,schwendener1  ,julius ,wolff1 and      
,roux1 that all tissues whose function  
it is to resist  mechanical pressure or 
mechanical tension possess a minute     
histological  structure specially       
suitable to their requirements4 ,this is
 most  markedly exhibited in the stem of
 plants1 in the tail of the dolphin1 in 
the arrangements of the lime lamellae in
 all bones of vertebrates4 ,all  these  
structures1 indeed1 are such as an      
engineer would have made them  who knew 
the sort of mechanical conditions they  
would be called upon to  encounter4 ,of 
course all these sorts of mechanically  
adapted structures  are far from being  
8mechanically explained10 as the verbal 
expression  might perhaps be taken to   
indicate1 and as indeed has sometimes   
been the  opinion of uncritical authors4
 ,the structures exist 99for99          
mechanics1  not 99by99 it4 ,and1 on the 
other hand1 all these structures1 which 
we  have called mechanically 8adapted0  
ones1 are far from being mechanical     

8adaptations10 in our meaning of the    
word1 simply because they are           
8adapted40 ,many of them indeed exist   
previous to any functioning1 they  are  
for the most part truly inherited1 if   
for once we may make use of  that       
ambiguous word4    ,but1 the merely     
descriptive facts of mechanical         
adaptedness having been  ascertained1   
there have now been discovered real     
mechanical processes  of adaptations    
also4 ,they occur among the statical    
tissues of plants1  though not in that  
very high degree which sometimes has    
been assumed  to exist2 they also occur 
in a very high perfection in the        
connective  tissue1 in the muscles and  
in the bone tissue of vertebrates4 ,here
  indeed it has proved possible to      
change the specific structure of the    
tissue by changing the mechanical       
conditions which were to be withstood1  
and it is in cases of healing of broken 
bones that these phenomena have         
acquired a very great importance1 both  

theoretically and practically3  the new 
joints also1 which may arise by force of
 circumstances1  correspond mechanically
 to their newly created mechanical      
function4    ,so far a short review of  
the facts of 8functionelle ,anpassung40 
,they  seem to prove that there does    
exist a morphological adaptation to     
functional changes which result from the
 very nature of functioning4 ,in  fact1 
the actual state of all functioning     
tissue1 the intensity of its  state of  
existence1 if you care to say so1 may be
 said to be due to the  functioning     
itself3 the so-called atrophy by        
inactivity being only one  extreme of a 
very long line of correspondences4#hc   
#hc ,atrophy of muscles by inactivity is
 not to be confused with atrophy  by    
cutting the motor nerve2 the latter is  
very much more complete4    ,we now1 of 
course1 have to ask ourselves if any    
more intimate analysis  of these facts  
is possible1 and indeed we easily       
discover that here  also1 as in the     

first of our groups of morphological    
adaptations1  there are always single   
definite agents of the medium1 which    
might be  called 8causes0 or 8means0 of 
the adaptive effects1 the word 8medium0 
being taken as embracing everything that
 is external to the reacting  cells4    
,but of course also here the            
demonstration of single formative       
agents does not detract in the least    
from the adaptive character of  the     
reaction itself4 ,so we may say1        
perhaps1 that localised pressure  is the
 formative stimulus for the secretion of
 skeleton substance at a  particular    
point of the bone tissue1 or of the     
fibres of the connective  tissue2 the   
merely quantitative adaptations of      
muscles might even  allow of a still    
more simple explanation4#hd ,but        
adaptations remain  adaptations in spite
 of that2 even if they only deserve the 
name of  8primary0 regulations4    #hd  
,loeb has advocated the view that the   
8adaptive0 growth of working  muscles is

 simply due to the presence of a greater
 number of molecules  in their          
protoplasm1 muscular activity being     
generated by a process of  chemical     
decomposition4      ,,theoretical       
,,conclusions    ,we have stated in the 
analytical introduction to this chapter 
and  elsewhere1 that functional changes1
 which lead to morphological            
adaptations of both of our groups1 may  
arise not only from changes of  factors 
in the medium1 but also from a removal  
of parts4 ,as such removal  is generally
 followed by restitution also1 it is    
clear that restitutions  and adaptations
 very often may go hand in hand1 as is  
most strikingly  shown in a fine series 
of experiments carried out by ,vchting1 
which we  have already alluded to4 ,here
 again ,i should like to lay the        
greatest  stress upon the fact that1 in 
spite of such actual connections1       
restitutions and adaptations always have
 been separated from another            
theoretically1 and that the forms are   

never to be resolved into sums  of the  
latter4 ,such a view has been advocated 
by some recent authors1  especially by  
,klebs1 ,holmes1 and ,child3#he it is   
refuted ,i think by the  simple fact    
that the first phase of every process of
 restitution1 be it  regeneration proper
 or be it a sort of harmonious          
differentiation1 goes  on without       
functioning at all1 and only 99for99    
future functioning4#hf    #he ,what has 
been really 99proved99 to exist by the  
very careful studies  carried out by    
,child1 is only certain cases of        
functional adaptation  to mechanical    
conditions of the strictest kind1 and   
relating to the  general mobility only1 
but nothing more2 such adaptations can  
be said to  accompany restitution4 ,see1
 for instance1 99,journ4 exp4 ,zool499  
#c1 #aijf1  where ,child has given a    
summary of his theory4    #hf ,even in  
,vchting's experiments 7see page #agd1  
note #a71 in which  adaptations are     
mixed with true restitutions in the     

closest possible  manner1 a few         
phenomena of the latter type could most 
clearly be  separated4 ,the stimulus    
which called them forth must have been  
one of  the hypothetic sort alluded to  
in a former chapter 7see page #aac74    
,the  best instances of true            
restitutions were offered in those      
cases1 where1  after the removal of all 
the bulbs1 typical starch-storing cells 
were  formed without the presence of any
 starch4    ,and there has been         
advocated still another view in order to
 amplify  the sphere of adaptation3 all 
individual morphogenesis1 not only      
restitution1 is adaptation1 it has been 
said4 ,in its strictest form  such an   
opinion of course would simply be       
nonsense3 even specific  adaptive       
structures1 such as those of bones1 we  
have seen to originate  in ontogeny     
previous to all specific functions1     
though for the help  of them1 to say    
nothing of the processes of the mere    
outlining of  organisation during       

cleavage and gastrulation4 ,but they are
 8inherited0  adaptations1 it has been  
answered to such objections4 ,to this   
remark we  shall reply in another       
chapter4 ,it is enough to state at      
present that  there 99is99 a certain    
kind of1 so to speak1 architectonic     
morphogenesis1  both typical and        
restitutive1 previous to specific       
functioning  altogether4    ,if now we  
try to resume the most general results  
from the whole field  of morphological  
adaptations1 with the special purpose of
 obtaining new  material for our further
 philosophical analysis1 we have        
reluctantly to  confess that1 at present
 at least1 it does not seem possible to 
gather  any new real proof of           
life-autonomy1 of 8vitalism10 from these
 facts1  though of course also no proof 
against it4    ,we have stated that     
there is in every case of both our types
 of  adaptive events a correspondence   
between the degree of the factor  to    
which adaptation occurs1 and the degree 

of the adaptive effect4  ,we here may   
speak of an 99answering99 between cause 
and effect with  regard to adaptation1  
and so perhaps it may seem as if the    
concept of  an 8answering reaction0     
78,antwortsreaktion071 which was        
introduced  into science by ,goltz#hg   
and which is to play a great part in our
  discussions of next summer1 may come  
into account3 but in our present  cases 
8answering0 only exists between a simple
 cause and a simple effect  and relates 
almost only to quantity and locality4   
,there is therefore  lacking the most   
important feature1 which1 as will be    
seen1 would have  made the new concept  
of value4    #hg 99,beitrge zur ,lehre  
von den ,functionen der ,nervencentren  
des  ,frosches991 ,berlin1 #ahfi4    ,we
 only1 ,i believe1 can state the fact   
that there 99are99 relations  between   
morphogenetic causes and effects which  
99are99 adaptations1 that  functional   
disturbances or changes are followed by 
single histogenetic  reactions from the 

organism1 which are compensations of its
 disturbed or  changed functional state4
 ,we are speaking of facts here1 of very
 strange  ones indeed4 ,but ,i feel     
unable to formulate a real proof against
 all  sorts of mechanism out of these   
facts3 there 99might99 be a machine1 to 
which all is due in a pre-established   
way4 ,of course we should hardly  regard
 such a machine as very probable1 after 
we have seen that it  99cannot99 exist  
in other fields of morphogenesis4 ,but  
we are searching  for a new and         
independent proof2 and that is indeed   
not to be found  here4#hh    #hh ,the   
8secondary adaptations0 observed by     
,vchting are too  complicated and too   
much mingled with restitutions to allow 
any definite  analysis of the fact of   
the 8secondary adaptation0 as such4     
,at present it must be taken as one of  
the fundamental 99facts99 of the        
organogenetic harmony1 that the cells of
 functioning tissues do possess  the    
faculty of reacting to factors which    

have changed the state of  functioning1 
in a way which normalises this state    
histologically4 ,and  it is a fact also 
that even cells1 which are not yet      
functioning but  are in the so-called   
embryonic or indifferent condition      
contributing to  the physiological      
completion of the tissue1 react to      
factors embracing  new functional       
conditions of the whole in a manner     
which leads to an  adaptation of that   
whole to those conditions4    ,this is a
 very important point in almost all     
morphological adaptation1  whether      
corresponding to functional changes from
 without or resulting  from the very    
nature of functioning4 ,in fact1 such   
cells as have already  finished their   
histogenesis are1 as a rule1 only       
capable of changing  their size         
adaptively1 but are not able to divide  
into daughter-cells  or to change their 
histological qualities fundamentally2 in
 technical  terms1 they can only assist 
8hypertrophy0 but not 8hyperplasia40    

,any  adaptive change of a tissue       
therefore1 that implies an increase in  
the  number of cellular elements or a   
real process of histogenesis1 has to    
start from 8indifferent0 cells1 that is 
to say1 cells that are 99not yet99      
functioning in the form that is typical 
of the tissue in question2 and1  strange
 to say1 these 8embryonic0              
cells--99i4e499 the 8cambium0 in higher 
plants and many kinds of cells in       
animals--99can99 do what the functional 
state requires4 ,it is to be hoped that 
future investigations will lay a        
greater stress upon this very important 
feature of all adaptation4      #b4     
,,physiological ,,adaptation#hi    #hi  
,general literature3 ,frhlich1 99,das   
natrliche  ,zweckmssigkeitsprincip in   
seiner ,bedeutung fr ,krankheit und     
,heilung991  #ahid4 ,driesch1 99,die    
organischen ,regulationen991 #aija4 ,a4 
,tschermak1 8,das  ,anpassungsproblem in
 der ,physiologie der ,gegenwart10 in a 
collection  of papers in honour of ,j4  

,p4 ,pawlow1 ,st4 ,petersburg1 #aijd4   
,bieganski1  8,ueber die ,zweckmssigkeit
 in den pathologischen ,erscheinungen10 
99,annal4  d4 ,naturphil499 #e1 #aijf4  
,among the general text-books of        
physiology those  by ,pfeffer           
799,pflanzenphysiologie991 #ahig-aijd7  
and von ,bunge 799,lehrbuch  d4 ,phys4  
d4 ,menschen991 #aija7 are the fullest  
on the subject of  8regulations40 ,see  
also different papers on general        
pathology by ,ribbert4    ,it is but a  
step from morphological adaptations to  
adaptations in  physiology proper4 ,the 
only difference between regulations of  
the  first type and those which occur in
 mere functioning is1 that the          
resulting products of the regulation are
 of definite shape and therefore        
distinctly visible in the first case1   
while they are not distinctly  visible  
as formed materials but are merely      
marked by changes in chemical  or       
physical composition in the latter4     
,metabolism1 it must never be forgotten1

 is the general scheme within  which all
 the processes of life in a given living
 organism go on2 but  metabolism means  
nothing else1 at least if we use the    
word in its  descriptive and            
unpretentious meaning1 than change in   
the physical  or chemical               
characteristics of the single           
constituents of that  organism4 ,in     
saying this1 we affirm nothing about the
 physical or  chemical nature of the    
actual processes leading to those       
physical or  chemical characteristics1  
and by no means are these 8processes0   
99a  priori99 regarded as being physical
 or chemical 99themselves993 indeed1  we
 have learned that in one large field1  
in the differentiation of  our          
harmonious systems they certainly are   
not4 ,now1 if the metabolism  does not  
end in any change of visible form1 then 
true physiological  processes1 or more  
particularly physiological regulations1 
are going on  before us4 ,but we are    
dealing with morphogenetic events or    

regulations1  if the result of          
metabolism is marked by any change in   
the constituents  of form4 ,this however
 may depend on rather secondary         
differences as to  the nature of        
regulation itself1 and any kind of      
metabolism may really  be of the        
regulatory type1 whether we actually see
 its result as a  constituent of form1  
99e4g499 owing to the production of some
 insoluble  compound1 or whether we do  
not4    ,i do not mean to say that these
 are the only differences between mere  
physiological activities or regulations 
and organogenesis proper1 as an         
originating of typical form-combination2
 but if we regard1 as we do in  this    
chapter1 the given organisation of a    
living being as a substratum  of its    
functional life1 morphological and      
physiological adaptations are  indeed of
 almost the same logical order4    ,we  
had best therefore begin our discussions
 with a recapitulation of  our problem4 
,we are studying adaptations in         

functioning--that means we  want to know
 how the organism behaves with regard to
 any change which  may take place in its
 functional state4 ,we apply the term   
regulation1  or in particular           
adaptation1 to any kind of reaction on  
the part of the  organism which         
re-establishes the normal state of      
functioning1 and we  now want to learn  
to what degree such adaptations exist in
 the field of  physiology4              
,,specific ,,adaptedness 99,,not99      
8,,adaptation0    ,it is important to   
keep well in mind our strictly          
formulated theme1 as  by doing so we    
shall be able to exclude at once from   
our materials a  large group of         
phenomena which occasionally have been  
called regulations  by physiological    
authors1 but which1 in fact1 are not of 
the adaptation  type and therefore      
cannot be said to afford those problems 
which  possibly might have been         
expected4 ,typical peculiarities in     
functional  life cannot be called       

8regulations0 for this very reason4 ,if1
 for  instance1 the organism selects    
specific amounts of specific kinds of   
organic food or of salts out of the     
combinations of salts or organic  food  
normally offered to it in the medium1 as
 indeed is most typically  shown for    
instance by the roots of plants1 there  
cannot be said to occur  a 8regulation0 
or 8adaptation0 with regard to the      
permeability of the  cell1 nor is it    
strictly a case of 8regulation10 if     
so-called selective  qualities are      
discovered in the processes of          
secretion1 say of the  epithelium of the
 kidney4    ,all these facts are typical
 and specific peculiarities in          
functioning  which are duly to be       
expected1 where a very typical and      
specific  organisation of the most      
elaborated kind exists4 ,indeed1 after  
studying  such an organisation we must  
not be astonished that functions in     
organisms follow lines which certainly  
they would not have taken without  it4  

,take the fact which is quoted very     
often1 that the migration of  compounds 
or of ions in the organisms can happen  
quite contrary to all  the laws of      
osmosis1 from the less concentrated to  
the more concentrated  side of a        
so-called 8membrane40 ,there 99is99 no  
simple 8membrane0 in the  organism1 but 
a complicated organisation of an almost 
unknown character  takes its place1 and 
nothing1 indeed1 is against the         
assumption that  this organisation may  
include factors which actually drive    
ions or  compounds to the side of higher
 concentration1 which indeed drive them 
by 8doing work10 if we like to speak in 
terms of energy2 and these  factors     
included in organisation may very well  
be of a true physical or  chemical      
nature4#ij    #ij ,according to         
investigations of the last two years1   
the physics of  colloids seems to play  
as important a part in physiology as    
osmosis  does2 we here meet 8means0 of  
functioning just as we have already had 

8means0 of organogenesis4    ,i lay     
great stress upon these statements1 as  
,i should like to be as  careful as     
possible in the admission of anything   
like a 8proof0 of  vitalism4 ,it was    
want of scientific criticism and rigid  
logic that  discredited the old         
vitalism2 we must render our work as    
difficult as  possible to ourselves1 we 
must hold the so-called 8machine theory0
 of  life as long as possible1 we must  
hold it until we are really forced to   
give it up4    ,in a more general form  
we now can sum up our discussion by     
saying3 ,there  never are adaptations in
 physiology1 requiring any special      
analysis1  where there are only         
complications or even apparent          
deviations from the  purely             
physico-chemical type of events which   
are1 so to say1 statical1  99i4e499     
fixed in quantity or quality1 however   
peculiar or typically  complicated they 
may be2 all such peculiarities indeed1  
may properly  be called 8adapted10 that 

is to say1 very well fitted to perform a
  specific part in the service of normal
 general functioning1 and they  are     
8adapted0 to their part by virtue of a  
certain 8adaptedness0 of the            
organisation2 but they are not          
8adaptations0 in any sense of the word4 
,,primary ,,and ,,secondary             
,,adaptations ,,in ,,physiology    ,we  
approach the subject of true            
adaptations1 that is1 of adapting       
processes1 as soon as any kind of       
variation in functioning occurs which   
corresponds to a variation of any factor
 of the medium in the widest  sense4    
,but even here our work is by no means  
done by simply showing  such a          
correspondence of outer and inner       
variations4 ,we know very well  already1
 from our former studies1 that now we   
are faced by a further  problem1 that we
 are faced by the question whether we   
have to deal with  simple primary kinds 
of adaptations or with the far more     
important  secondary ones4    ,as the   

discrimination between primary and      
secondary regulations proves  indeed to 
be of first-rate importance1 you will   
allow me1 ,i hope1 to  summarise our    
chief analytical statements regarding   
them in a most  general form4 ,we call  
primary regulatory any kind of          
morphogenetic or  functional            
performance1 which1 by its very intimate
 nature1 always  serves to keep the     
whole of organisation or of functions in
 its normal  state4 ,we call secondary  
regulations all features in the whole of
  morphogenesis or of functioning which 
serve to re-establish the normal  state 
after disturbances along lines which are
 outside the realm of  so-called        
normality4 ,this analytical             
discrimination will help us very  much  
to a proper understanding of physiology4
 ,but before we turn to  apply our      
definitions to actual facts1 another    
preliminary problem has  to be solved4  
,,on ,,certain ,,pre-,,requisites ,,of  
,,adaptations ,,in ,,general    ,we are 

thinking of the general and important   
question1 what types of  adaptations may
 be expected in the field of physiology 
and whether  there may be certain       
classes of regulatory events which      
possibly might  be expected to occur in 
the organism on 99a priori99 grounds1   
but which1  nevertheless1 are to be     
regarded as impossible after a more     
intimate  analysis of its nature1 even  
at the very beginning8 ,or1 in other    
words1  to what kinds of changes of the 
medium will an organism be found able or
  unable to adapt itself8    ,we know   
that the 99state of functioning99 must  
be altered in order to call  forth any  
sort of adaptation at all4 ,now1 there  
can be no doubt that 99a  priori99 it   
would seem to be very useful for the    
organism1 if it never  would let enter  
into its blood1 lymph1 etc41 be it      
through the skin or  through the        
intestine1 any chemical compound that   
would prove to be  a poison afterwards4 
,in fact1 a man1 judging on the         

principle of the  general usefulness of 
all the phenomena of the living1 might  
suppose  that there would exist a sort  
of adaptation against all poisons to the
  extent that they would never be       
allowed to enter the real interior of   
the body4 ,we know that such reasoning  
would be incorrect4 ,but we also  can   
understand1 ,i suppose1 that an 99a     
priori99 analysis of a more careful     
kind would have reasoned differently4   
,how could the functional state  of the 
organism be changed1 and how1 therefore1
 could adaptation be  called forth by   
any factor of the medium which had not  
yet entered the  organism1 but was only 
about to enter it8 ,not at all therefore
 is such  a regulation to be expected as
 we have sketched2 if there is to be any
  adaptation to poisons1 it only can    
occur after the poison has really  acted
 in some way1 and in this case we shall 
indeed find regulations4    ,you may    
perhaps regard this discussion as a     
little too academical  and              

hair-splitting1 but here again it was   
for the sake of ensuring a  perfectly   
sound foundation of our chief principles
 that ,i undertook it4  ,very often1    
indeed1 the question has been raised by 
the defenders of a  mechanistic theory  
of life1 ,why then did the organisms not
 reject all  poisons from the very      
beginning8 ,we now may reply to that    
only--how  99could99 they do so8 ,how   
could they 8know0 what is a poison and  
what is  not1 unless they had           
experienced it8--if we are allowed for a
 moment to  use very anthropomorphistic 
language4    ,we repeat1 therefore1 that
 the functional conditions of the       
organism  must have been actually       
changed in order that an adaptation may 
occur4  ,nothing is more essential to a 
clear understanding of our problems than
  to keep fully in mind the exact sense 
of this definition4      ,,on ,,certain 
,,groups ,,of ,,primary ,,physiological 
,,adaptations    99,general ,remarks on 
,irritability499--,turning now to more  

special groups  of problems concerning  
physiological adaptations1 let us begin 
with the  primary class of them1 and let
 us first say a few words on a subject  
which occasionally has been regarded as 
the basis of physiological  regulation  
in general4 ,i refer to a most important
 fact in the general  physiology of     
irritability4 ,irritability of any kind 
is known to be  re-established1 after it
 has been disturbed by the process of   
reacting  to the stimulus1 and in       
certain cases1 in which two             
different--or rather  two               
opposite--kinds of reactions are        
possible on the same substratum1  which 
increase with regard to one process     
whilst decreasing at the same  time with
 regard to the other4 ,the irritability 
of the muscle or of the  leaves of      
99,mimosa99 is a very good instance of  
the first case1 whilst the  second more 
complicated one cannot be illustrated   
better than by what  all experience has 
taught us about the irritability of the 

retina4 ,the  retina is more irritable  
by green rays and less by red ones the  
more  it has been stimulated by the     
latter1 and more sensitive to light in  
general the more it has been exposed to 
darkness2 and something very  similar is
 true1 for instance1 as regards         
phototactic irritability in  plants1 all
 these phenomena being in relation to   
the so-called law of  ,weber4#ia    #ia 
,i only mention here that certain modern
 psychologists have assigned  the true  
law of ,weber to the sphere of judgment 
and not of sensation4 ,if  applied to   
objective reactions only1 in their      
dependence on objective  stimuli1 it1 of
 course1 becomes less ambiguous1 and    
may1 in a certain  sense1 be said to    
measure 8acclimatisation0 with regard to
 the stimulus  in question4 ,the        
mathematical analogy of the law of      
,weber to the most  fundamental law of  
chemical dynamics seems very important4 
,as to 8acclimatisation0 in the more    
usual meaning of the word1 with  regard 

to a change of the general faculty of   
resisting certain agents  of the medium1
 8immunity0 proper is to form a special 
paragraph of what  follows1 and to      
8acclimatisation0 towards different     
degrees of salinity  7in algae or       
fishes7 some special remarks will also  
be devoted on a  proper occasion4 ,there
 remains only 8acclimatisation0 to      
different  temperatures2 but on this    
topic not much more than the fact is    
known  7see ,davenport1 99,arch4 f4     
,entw4 ,mech499 #b1 p4 #bbg74           
8,acclimatisation0  does not allow of a 
sharp general definition2 it may be the 
result of  very 99different99 kinds of  
adaptations in our sense of the word4   
,it seems to me that there would be     
little difficulty in harmonising the    
phenomenon of the inversion of          
irritability with the so-called         
principle  of the 8action of masses0 and
 with the laws of certain 8reversible0  
processes well known in chemistry4 ,as  
to the simple fact of the               

re-establishment of irritability after  
stimulation has occurred1 or1  in       
certain other cases1 the fact that in   
spite of permanent stimulation          
irritability seems to exist permanently 
also1 physical analogies or even        
explanations might very well be         
found4#ib    #ib ,i should think that   
the problem of the re-establishment of  
irritability1 in principle at least1    
arises even when there is not a  trace  
of so-called 8fatigue0 or of a          
8refractory period40 ,the process  of   
restoring may be so rapid as not to be  
noticeable1 nevertheless some  sort of  
restoring is to be postulated4 ,we may  
say the 8irritability0 of  an elastic   
ball is re-established by its           
elasticity4 ,a certain analogy  to this 
case may perhaps be found in the muscle4
 ,but the irritability  of nerves with  
respect to nervous conduction1 and of   
glands with  respect to secretion1 or of
 the articulations of 99,mimosa99 may be
 well  understood1 hypothetically at    

least1 if we assume that the ordinary   
course of metabolic events is apt in    
itself to lead to a certain state  or   
condition of the organs in question upon
 which their irritability  is based4    
,certain general conditions of          
functioning1 as for instance  the       
presence of oxygen for the contraction  
of the muscle1 would better  be looked  
upon as necessary 8means0 of functioning
 than as being part  of irritability as 
such4 8,fatigue10 of course1 may also be
 due to  the absence of such 8means0 or 
to abnormal conditions originated by    
functioning itself4    ,if now we ask   
whether there is anything like an       
adaptation appearing in  the general    
characteristics of irritation and       
irritability1 it seems to  me that we   
may answer the question in an           
affirmative manner1 as far as  primary  
regulation comes into account4 ,we1     
certainly1 have not studied  any        
abnormal regulatory lines of general    
functioning1 we only have  studied      

general functioning itself2 but1 indeed1
 there was a certain  sort of regulation
 99in99 functioning4 ,of course1 by     
showing that one  of the most general   
features of all functioning is          
primary-regulatory  in itself1 we do not
 deny the possibility of many specific  
functions  in which real secondary      
regulations actually do exist4 ,nothing 
indeed  is asserted about the           
99specific99 character of functioning in
 its  different types1 by proving that  
one of the 99general99 features of      
99all99  functioning may comparatively  
easily be understood4 ,it seems to me   
that  this important logical point has  
not always received the attention it    
deserved4    99,the ,regulation of ,heat
 ,production499#ic--;,having finished   
our  introductory remarks we now turn to
 the proper study of special            
physiological functioning with regard to
 its adaptive side1 and begin  with the 
most simple cases4    #ic ,rubner1      
99,die ,gesetze des ,energieverbrauches 

bei der ,ernhrung991  ,leipzig u4 ,wein1
 #aijb4    ,the so-called 8regulation of
 heat0 in warm-blooded vertebrates is an
  instance of a special function which  
can be said to be regulatory in  itself4
 ,there exists a normal blood heat for  
each species1 which is  maintained no   
matter whether the temperature of the   
medium rise or fall4  ,it might seem at 
first as if in this case there were a   
little more  of an adaptive regulation  
than only its well-known primary type2  
no  reversion1 one might say1 of the    
direction of one and the same process   
occurs in the regulation of heat        
production1 but one kind of process  is 
called into action if it is necessary to
 raise the temperature1 and  another    
whenever it is necessary to lower it4   
,even in the dilatation  and            
constriction of capillary vessels there 
are different nerves  serving for each  
operation respectively1 and far more    
important are the  increasing of        
transpiration for cooling1 the          

increasing of combustion  for           
heating--two radically different        
processes4 ,but1 nevertheless1 there  is
 a certain unity in these processes1 in 
so far as a specific locality  of the   
brain has been proved to be the 8centre0
 of them all2 it is to  this centre of  
course that the analysis of heat        
production considered as  a kind of     
regulation or adaptation must be        
directed4 ,such an ultimate  analysis1  
it seems to me1 would have to classify  
heat regulation under  the primary type 
of adaptations in physiology without any
 restriction4  ,the centre acts in one  
sense or in the other1 if stimulated by 
any  temperature beyond a very limited  
range1 and it is in the action of the   
centre that the 8regulation0 of heat    
consists4#id    #id ,the phenomenon of  
fever we leave out of account here2 it  
is  regarded by some as regulation1 by  
others as a disturbance of heat         
regulation4 ,of course1 if the first    
view should ever prove to be the  right 

one1 fever might be classified among the
 real regulations of the  secondary     
type4    99,primary ,regulations in the 
,transport of ,materials and ,certain   
,phenomena  of ,osmotic                 
,pressure499--,very similar phenomena of
 regulation are present  in many        
processes concerned in the whole of     
metabolism4 ,let us consider  for a     
moment the migration of materials in    
plants4 ,whenever any compound  is used 
at a certain place1 a permanent afflux  
of this compound to  that place sets in 
from all possible directions4 ,no doubt 
this is a  8regulation10 but it is also 
the function itself1 and besides that1  
a very simple function based almost     
entirely on well-known laws of  physical
 chemistry4 ,and in other cases1 as in  
the ascent of water to  the highest tops
 of our trees1 which purely physical    
forces are said to  be insufficient to  
explain1 we can appeal to the unknown   
organisation  of many cells1 and there  
is nothing to prevent our attributing to

 these  cells certain functions which   
are1 if you like to say so1 regulatory  
in themselves4 ,among other facts of    
so-called regulations there is the      
stopping of metabolic processes by an   
accumulation of their products3  as1 for
 instance1 the transformation of starch 
into sugar is stopped1  if the sugar is 
not carried away4 ,of course that is a  
regulation1 but  it again is an         
intrinsic one1 and it is one of the     
characteristics of  reversible chemical 
processes to be stopped in that way4 ,i 
know very  well that in this particular 
case a certain complication is added by 
the fact that it is a so-called ferment1
 the diastase1 which promotes  the      
transformation of starch into           
cane-sugar1 and that this ferment is    
actively produced by the organism3 but  
even its production would not  prove    
that any real kind of secondary         
regulation exists here1 if nothing  more
 were known about such an active        
production than this single case4    ,in

 a special series of experiments almost 
all carried out in ,wilhelm  ,pfeffer's 
botanical laboratory at ,leipzig1 an    
attempt has been made  to discover in   
what manner the cells of plants are able
 to withstand  very high abnormalities  
of the osmotic pressure of the          
medium--that is  to say1 very great     
changes in the amount of its salinity4  
,that many1  particularly the lower     
plants1 are able to stand such changes  
had been  ascertained already by the    
careful examinations of ,eschenhagen2   
but  recent years have given us a more  
profound insight into what happens4     
,von ,mayenburg#ie has found that sundry
 of the species of 99,aspergillus991    
the common mould1 are able to live in   
very highly concentrated solutions  of  
several salts 7,,kno#c and ,na#b,,so#d74
 ,they were found to regulate  their    
osmotic pressure not by taking in the   
salts themselves1 but by  raising the   
osmotic pressure of their own cell sap1 
producing a certain  amount of          

osmotically active substances1 probably 
carbohydrates4 ,if  in this case it were
 possible to assume that the osmotic    
pressure of  the medium were the real   
stimulus for the production of the      
osmotic  substances in the cell1        
stimulus and production both            
corresponding  in their degree1 we      
should be entitled to speak of a primary
 though  physiological#if regulation    
only2 and it seems to me that despite   
the  discoveries of ,nathansohn that    
certain algae and cells of higher plants
  are able to change the permeability of
 their surfaces in a way which          
regulates the distribution of single    
salts or ions in the sap of their  cells
 without any regard to pure osmotic     
equilibrium1 such a simple  explanation 
might be possible4#ig    #ie 99,jahrb4  
wiss4 ,bot499 #cf1 #aija4    #if        
,carbohydrates cannot be ionised1 and   
therefore there is no doubt  that in von
 ,mayenburg's experiments the organism  
itself is actively  at work4 ,as to     

compounds liable to ionisation1 it has  
been noticed by  ,maillard that a       
certain regulatory character is         
contained simply in the  physical fact  
that the degree of ionisation changes   
with concentration3  decrease of        
concentration for instance would be     
followed by an increase  of ionisation1 
and so the osmotic pressure may be      
preserved 799,c4 rend4  ,soc4 ,biol499  
#ec1 #aija1 p4 #hhj74    #ig ,in the    
different experiments of ,nathansohn    
799,jahrb4 wiss4 ,bot499  #ch1 #aijb1   
and #ci1 #aijc7 the salinity of the     
medium was changed in such  a way that  
there was in each case either an        
abnormal increase or an  abnormal       
decrease in the concentration of one    
single ion necessary  for metabolism4   
,the cell was found to stand these      
abnormal changes in  such a way that in 
the case of the increase of the         
concentration of  the medium it did not 
allow more than a certain amount of the 
ion in  question to come in1 and that in

 the case of the decrease it did not    
allow more than a certain quantity of   
the ion to go out4 ,it thus seems  as if
 the permeability of the surface were   
adjusted to a certain minimum  and to a 
certain maximum of every single ion or  
salt1 the permeability  being stopped   
from within to without1 whenever the    
minimum1 and from  without to within1   
whenever the maximum is reached in the  
cell sap2 both  irrespective of proper  
physical osmotic equilibrium            
78,physiologisches  ,gleichgewicht074   
,thus1 in fact1 there only would be a   
case of primary  regulation1 nothing    
more4 ,it would all appear rather       
similar to what  occurs in the kidney4  
,of course we do not assert that our    
explanation is  right1 but it is        
possible and is at the same time the    
most simple1 and  it is our general     
practice always to prefer the most      
simple hypotheses4    ,there are many   
regulation phenomena connected with     
osmotic pressure  and permeability in   

animal physiology also1 though at       
present they are  not worked out as     
fully as possible4 ,the works of        
,frdricq1 ,j4 ,loeb1  ,overton and      
,sumner#ih would have to be taken into  
account by any  one who wished to enter 
more deeply into these problems4 ,we can
 only  mention here that permeability to
 water itself also plays its part1 and  
that1 according to ,overton's           
experiments1 it is a kind of solubility 
of the media in the very substance of   
the cell surface on which all           
permeability and its regulation depend4 
#ih ,many fishes are able to withstand  
great changes in the osmotic  pressure  
of sea-water2 the osmotic pressure of   
their body fluids1 though  never in a   
real physical equilibrium with the      
pressure of the medium1  nevertheless   
may vary whenever the abnormal          
conditions of the latter  exceed certain
 limits4    99,chromatic ,regulations in
 ,algae499--,the phenomena of osmotic   
pressure and  its regulation may be said

 to be the preliminaries of metabolism  
proper1  conditions necessary for it to 
take place4 ,now there is another branch
  of such preliminaries to metabolism1  
in which the most interesting           
regulation phenomena have been lately   
discovered4 ,it is well known that  what
 is called assimilation in plants1 that 
is1 the formation of organic  compounds 
out of carbon dioxide 7,,co#b7 and      
water1 occurs only in  the light by     
means of certain pigments4 ,this pigment
 is in all higher  plants and in many   
others the green chlorophyll1 but it may
 be different  in certain species of    
algae1 and can generally be said#ii to  
be of  the colour complementary to the  
colour of those rays which especially   
are to be absorbed and to be used for   
assimilation4 ,but here we have         
8adaptedness10 not adaptation4 ,it was  
in some species of primitive  algae1 the
 99,oscillariae991 that ,gaidukow#ajj   
found a very interesting  instance of an
 active regulation in the formation of  

pigments4 ,these  algae always assume a 
colour which corresponds to the         
accidental colour  of the rays of the   
medium and is complementary to it2 they 
become green  in red light1 yellow in   
blue light1 and so on--that is1 they    
always  actively take that sort of      
colouring which is the most suitable to 
the actual case4#aja ,there indeed      
occurs a sort of complementary          
photography in these algae2 but1 though 
adaptive1 it could hardly be  said to   
exceed the limits of 8primary           
phenomena40    #ii ,see ,stahl1         
99,naturw4 ,wochenschrift991 ,n4 ,f4 #e1
 #aijf1 ,no4 #ai4    #ajj 99,arch4      
,anat4 ,phys4991 ,phys4 ,abt4 ,suppl41  
#aijb4    #aja ,the adaptive phenomena  
discovered by ,gaidukow depend upon a   
real  alteration in the formation of    
pigments4 ,in the 7primary7 chromatic   
adaptation of pupae of ,lepidoptera with
 respect to the colour of  the ground   
they live upon1 we only have the        
variable effects of  pre-established    

chromatophores 7,poulton1 99,phil4      
,trans4 ,london991 #agh ,b1  #ahhh2     
,merrifield1 99,trans4 ,ent4 ,soc4      
,london991 #ahih74 ,the same holds for  
chromatic adaptations in crabs 7,gamble 
and ,keeble1 99,quart4 ,journ4 ,micr4   
,sci499 #dc1 #aijj2 ,minkiewicz1        
99,arch4 ,zool4 exp4 et gn499 sr4 #d1   
#g1 notes1  #aijg74    99,metabolic     
,regulations499--,and now we enter the  
field of regulations in  metabolism     
itself4 ,there are two kinds of outside 
factors of fundamental  importance for  
all metabolic processes3 food is one1   
and oxygen is the  other4 ,and          
metabolism as a whole is of two         
different aspects also3  it both serves 
for assimilation proper--that is1       
building up--and it  supplies the energy
 for driving the functional machine4 ,it
 is clear  that food alone--together of 
course with the assimilating means of   
the  organism1 can account for the first
 type of metabolism1 while both food    
and oxygen1 or some sort of substitute  

for the latter1 as in certain  bacteria1
 supply functional energy4 ,of course we
 are not entitled to say  that the      
importance of so-called oxidation or    
respiration is exhausted  by its        
energetic rle3 it certainly is not1 for 
if it were1 the organism  would only be 
stopped in its functions if deprived of 
oxygen but  would not die4 ,it seems    
that certain substances always arise in 
the  metabolism1 in the processes of    
decomposition1 which have to be burnt up
  in order not to become poisonous4 ,but
 we shall return to the phenomena  of   
organic oxidation in another chapter of 
the book1 and shall deal with  them from
 a more general point of view4#ajb      
#ajb ,the theory of oxidation we have   
shortly sketched here was  developed in 
chapter ,b4 #e1 of my 99,organische     
,regulationen994 ,recent  discoveries of
 ,winterstein's 799,zeitschr4 allg4     
,physiol499 #f1 #aijg7  have given the  
strongest support to my hypothetic      
statements1 and1 in  fact1 can be said  

to have brought the doctrine of organic 
oxidation  to a critical point4 ,there  
can be no doubt that oxygen not only    
plays  the 8antipoisonous0 rle ,i had   
assigned to it1 but that it is not  even
 of such great importance for the supply
 of functional energy as  former times  
had assumed4 ,no doubt it serves to     
drive the functional  machine1 but      
decomposition of certain chemical       
constituents of the  organism serves    
this purpose even more4 ,the latter does
 so in the most  fundamental and        
original manner1 so to speak1 whilst    
oxidation only  burns up its products4  
,almost all elemental functions1 in     
nerve-tissue  at least1 go on very well 
in the absence of oxygen1 provided that 
certain 8poisonous0 substances1         
resulting from this anarobic            
metabolism1 are constantly removed4 ,in 
normal conditions that is  done by      
oxygen1 and in doing so oxygen certainly
 assists the supply  of energy1 but it  
does not furnish the whole of it4 ,the  

difference  between so-called 8arobic0  
and 8anarobic0 life almost completely   
disappears under such a view1 and many  
so-called 8regulations10 of  course1    
disappear at the same time2 there is no 
more 8intramolecular  respiration40     
,let us now try to take a short survey  
of all the regulations discovered       
relating to the substitution of one kind
 of food for another4 ,we have  said    
that food serves in the first place as  
building material1 in the  second place 
as fuel4 ,it only deserves brief mention
 that1 as all recent  investigations    
have shown1 fats1 carbohydrates1 and    
albumen are equally  well able to serve 
as fuel4#ajc    #ajc ,but nevertheless  
albumen is not to be replaced altogether
 in  vertebrates by fat or carbohydrate2
 it probably serves some special        
function besides combustion1 even in the
 adult4    ,it is in the state of       
fasting1 99i4e499 in the case of a real 
absence of  99all99 nourishing          
materials1 that the organism has proved 

to be capable  of regulations of the    
most marked nature1 with regard to the  
combustion  of its own materials4       
,respiration1 we know1 must go on if    
death is to  be avoided1 and now indeed 
it has been found that this process     
attacks  the different tissues of the   
organism subjected to fasting in such an
  order that1 after the combustion of   
the reserves1 the most unimportant      
tissues with regard to life in general  
are destroyed first1 the most  important
 ones last4 ,thus in vertebrates the    
nerve cells and the heart  are preserved
 as long as possible2 in infusoria it is
 the nucleus2 in  flatworms1 as the very
 careful studies of ,e4 ,schultz#ajd    
have lately  shown1 it is the nerve     
cells and the sexual cells which longest
 resist  destruction1 whilst almost all 
the rest of the organisation of these   
animals may disappear4 ,i should not say
 that we can do very much with  these   
facts at present in our theoretical     
discussion1 but they are  certainly     

witness of very astonishing adaptive    
powers4#aje    #ajd 99,arch4 ,entw4     
,mech499 #ah1 #aijd4    #aje ,to a      
physiological friend of mine ,i owe the 
suggestion that it is  the permanently  
functioning tissues which stand hunger  
better than the  others1 at least if the
 sexual cells might be regarded as      
capable of  a 99scrtion interne99 in all
 cases4 ,then the adaptations in the    
state  of hunger might be said to be    
reduced in some degree to 8functional   
adaptation40 ,but it must remain an open
 question1 it seems to me1  whether such
 a view may indeed hold in the face of  
the facts observed in  99,planaria99 and
 infusorians4    ,we now turn to study  
the cases of a compensation of          
nourishments  serving for the real      
building up of the organism4 ,albumen1  
we know1 is  absolutely indispensable   
for animals1 even for adults1 though    
nothing is  known about the purpose it  
serves in the latter2 its place can be  
taken  of course by those less          

complicated compounds which result from 
its  first decomposition1 effected by   
pepsin and trypsin1 but nothing else    
will do4 ,the salts of sea-water1       
according to ,herbst's experiments1 may 
only vary to a very small degree if the 
development of marine animals  is to go 
on well2 potassium may be replaced by   
caesium or rubidium1  and that is all4  
,much the same is true of the salts     
necessary to  plants4 ,it will not      
surprise us very much to hear that algae
 can also  be successfully fed with the 
potassium salts of organic compounds1   
and  higher plants with acid amides or  
glucoses instead of carbonic acid1 as   
those products are normal steps in their
 assimilation2 and it may also  be      
fairly easily understood that nitrogen  
can be offered in organic form  instead 
of as a nitrate4    ,it was in the group
 of fungi that really important         
adaptations with  regard to the proper  
form-producing alimentation were first  
discovered1  and these are of a very    

complicated kind indeed4 ,fungi are     
known to  be satisfied with one single  
organic compound instead of the group of
  three--fat1 carbohydrate and          
albumen--necessary for animals4 ,now    
,pfeffer  showed that the most different
 and indeed very abnormal compounds were
  able to bring his subjects to a       
perfect growth and morphogenesis2 and1  
moreover1 he found that1 if several     
kinds of such food were offered         
together1 they were consumed quite      
indifferently as to their chemical      
constitution1 but only with regard to   
their nutritive value3 that sort  of    
food which had produced a better growth 
than another when both  were offered    
separately was found to save the latter 
from consumption  whenever both were    
offered together4    ,here we are faced 
by one of the most typical cases of     
regulations in  metabolic physiology3   
the organism is able to decompose       
compounds of  the most different        
constitution1 which have never been     

offered to it  before2 but nevertheless1
 it must remain an open question whether
 real  8secondary0 regulation has       
occurred1 as nothing is known in detail 
about  the single steps of metabolism in
 these fungi4 ,there 99might99 be some  
ferments equally able to destroy        
different classes of compounds1#ajf  and
 that the most nutritive compound is    
used up first 99may99 be a  question of 
physico-chemical equilibrium4    #ajf   
,in all cases where fungi of the same   
species are able to live on  different  
hosts1 that is1 to penetrate membranes  
of a different chemical  character1 a   
similar objection as to the 8secondary0 
type of such a  regulation may be made4 
,that is almost all#ajg that is actually
 known of adaptation with regard  to the
 use of an abnormal food supply4 ,though
 important1 it cannot be  said to be    
very much4 ,but could we expect very    
numerous regulations  here at all after 
what we laid down in a former paragraph 
about the  possibilities of adaptive    

regulation in general8 ,the functional  
state  must have been altered in order  
that such regulations may occur4 ,now   
there is no doubt that this state may be
 really altered only if an  abnormal    
food has first been taken in altogether 
by the cell-protoplasm  of the          
body-surfaces1 but never if it has only 
entered the cavity of the  intestine1   
which1 strictly speaking1 is a part of  
the exterior medium4  ,fungi indeed not 
only take in the abnormal food1 but also
 know what  to do with it1 but all      
animals are obliged to treat first with 
their  chemical secretions what happens 
to be present in their intestine1 in    
order that it may be taken up by their  
living cells1 and one hardly  can wonder
 that these secretions are only formed  
in correspondence to  a limited number  
of outside stimuli4 ,in fact1 as soon as
 we look upon  what adaptive or         
regulatory work happens in metabolism   
99inside99 the body  interior1 we meet1 
even in animals1 regulations of a far   

more developed  type4    #ajg ,the      
discovery of ,weinland that adult dogs  
are able to produce  8lactase0 in their 
pancreas1 whenever they are fed1 quite  
abnormally1  with milk-sugar1 has       
recently been said to be vitiated by an 
analytical  mistake4    ,discoveries of 
the last few years have taught us that  
almost all  metabolic processes in the  
organism1 including oxidation1 are      
carried  out by the aid of special      
materials1 the so-called enzymes or     
ferments4 ,these are known to exist in  
the most different forms even in  the   
inorganic world4 ,they are simply       
chemical compounds1 of specific  types1 
that bring about chemical reactions     
between two other chemical  materials1  
which in their absence would either not 
go on at all or would  go on very       
slowly4 ,we cannot enter here into the  
much disputed chemical  theory of what  
is called 8catalysis03 we can only say  
that there is no  objection to our      
regarding almost all metabolic processes

 inside the  organism as due to the     
intervention of ferments or catalytic   
materials1  and that the only difference
 between inorganic and organic ferments 
is  the very complicated character of   
the latter and the very high degree of  
their specification4    ,such a         
statement1 of course1 does not say that 
all metabolism has proved  to be of a   
chemical nature3 the 99action99 of the  
ferment when produced  is chemical1 but 
we do not know at all 99how99 the       
ferment is produced2  we only know that 
a high degree of active regulation is   
shown in this  production4 ,in fact1 it 
has been proved in some cases1 and      
probably will  be proved in a great many
 more in the near future1 that all      
metabolic  ferments1 whether they       
promote oxidation or assimilation proper
 or  chemical decomposition1 are        
produced in a regulatory manner with    
regard  to the specific compound to be  
dissociated or to be built up4 ,in this 
way the whole field of metabolism is    

really covered by 8regulations40  ,are  
they real 8secondary0 ones8 ,of course  
the regulatory correspondence  applies  
to the process of 99secretion99 in the  
99first99 place1 not to the  actual     
formation of the ferment inside the     
cell4 ,the correspondence as  to        
secretion1 no doubt1 is of the primary  
type2 is there any secondary  regulation
 with regard to the real 99production99 
of the ferment8 ,i am  sorry that ,i    
cannot answer this question             
affirmatively4 ,nothing is  99known99 at
 present1 even here1 that really proves 
the existence of  adaptation of the     
secondary type3 there 99might99 be a    
sort of statical  8harmony0 at the base 
of it all1 established before all       
functioning  99for99 functioning4#ajh   
#ajh ,compare the excellent review of   
the subject by ,bayliss and  ,starling  
in the 99,ergebnisse der ,physiologie991
 #e1 #aijf1 p4 #ffd4 ,the  reader who   
misses here an analysis of the brilliant
 discoveries  of ,pawlow and his        

followers1 relating to so-called        
8psychical and  associative secretion10 
will find these facts dealt with in     
another  section of the book4 ,these    
facts1 indeed1 would prove vitalism1 it 
seems  to me4    ,the only facts of     
secondary metabolic regulations which   
are known at  present have been found in
 combination with phenomena of          
restitution  after real disturbances of 
organisation1 where1 indeed1 numbers and
  numbers of regulatory changes of      
metabolism1 both in animals and plants1 
have also been recorded4 ,but there is  
not one case of a secondary  regulation 
really known to affect pure metabolism  
alone4#aji ,this is a  new indicium of  
the primacy of 99form99 in the organism4
    #aji ,it would be a true secondary  
metabolic regulation1 if after the      
extirpation of one gland another        
different one were to assume its        
function4 ,nothing is known in this     
respect except a few rather doubtful    
observations about the interchange of   

functions between thymus and  thyroid1  
except also the fact that the so-called 
lymph-glands increase  in size after the
 extirpation of the spleen4 ,even here1 
of course1 a  sort of 8restitution0     
would be included in adaptation proper4 
,,immunity ,,the ,,only ,,type ,,of ,a  
,,secondary ,,physiological ,,adaptation
    ,there is only one class of         
physiological processes in which the    
type  of the real secondary regulation  
occurs4 ,the discoveries of the last    
twenty years have proved beyond all     
doubt1 and future discoveries will      
probably prove even more conclusively1  
that the so-called 99immunity99  against
 diseases is but one case out of        
numerous biological phenomena  in which 
there is an adaptive correspondence     
between abnormal chemical  stimuli and  
active chemical reactions on the part of
 the organism and in  its interior1     
exceeding by far everything that was    
formerly supposed to  be possible in    
organic regulation4    ,the adaptive    

faculty of the organism against         
inorganic poisonous  substances#aaj is  
but small comparatively1 and is almost  
always due not  to a real process of    
active regulation but to the action of  
substances  pre-existing in the         
organism--that is1 to a sort of         
adaptiveness but  not adaptation4       
,metallic poisons1 for instance1 may be 
transformed into  harmless compounds by 
being combined with albumen or sulphuric
 acid  and thus becoming insoluble1 or  
free acids may be neutralised1 and so   
on2 but all these processes go on to a  
certain extent only1 and1 as  was       
mentioned already1 are almost always the
 result of reactions with  pre-existing 
materials4 ,only in a few cases is there
 any sort of true  adaptation to        
metallic substances1 such as sublimate  
and1 in a very  small degree1 arsenic1  
comparable in some respects with the    
adaptation  to abnormally high          
temperatures4 ,the organism which has   
been accustomed  to receive at first    

very small amounts1 say1 of sublimate1  
and then  receives greater and greater  
amounts of this substance by degrees1   
will  at the end of this treatment be   
able to stand a quantity of the poison  
that would have been instantly fatal if 
administered at the first  dose4#aaa    
,but the explanation of this adaptation 
is not known in any  case2 there seems  
to be some similarity between it and the
 so-called  histogenetic immunity       
against organic poisons4    #aaj ,a good
 review is given by ,e4 ,fromm1 99,die  
chemischen ,schutzmittel  des           
,tierkrpers bei ,vergiftungen991        
,strassburg1 #aijc4    #aaa ,davenport1 
99,arch4 ,entw4 ,mech499 #b1 #ahie-ahif1
 and ,hausmann1  99,pflger's ,arch499   
#aac1 #aijf4    ,it is in the fight     
against animal and vegetable poisons1   
such as those  produced by bacteria1 by 
some plants and by poisonous snakes1    
that the  true adaptation of the        
organism reaches its most astonishing   
degree4  ,the production of so-called   

8anti-bodies0 in the body fluids is not 
the  only means applied against noxious 
chemical substances of this kind3 the   
existence of so-called histogenetic     
immunity is beyond all doubt1 and       
,metschnikoff#aab certainly was also    
right in stating that the cells  of the 
organism themselves repel the attack of 
living bacteria4 ,cells  of the         
connective tissue and the white blood   
cells1 being attracted by  them as well 
as by many other foreign bodies1 take   
them in and kill  them4 ,this process1  
called 8phagocytosis0 is of special     
frequency among  lower animals1 but it  
also contributes to what is called      
inflammation  in higher ones4#aac ,and  
there are still other kinds of defence  
against  parasites1 as for instance the 
horny or calcareous membranes1 employed 
to isolate trichinae and some kinds of  
bacteria4 ,but all this is of  almost   
secondary importance as compared with   
the adaptive faculties of  the          
warm-blooded vertebrates1 which produce 

anti-poisonous substances in  their     
lymph and blood4    #aab 99,leons sur la
 pathologie compare de l'inflammation991
 ,paris1 #aijb4    #aac ,the other steps
 or phases in the process of            
inflammation have also  been regarded as
 adaptive3 the increased quantity of    
body fluid for  instance is said to     
serve to dilute poisonous substances4   
,it is impossible to say here#aad more  
than a few words about the  phenomena   
and the theory of immunity proper1 which
 have attained the  dimensions of a     
separate science4 ,let me only mark     
those general points  which are of the  
greatest theoretical interest4          
,discoveries of the most  recent years  
have shown not only that against the    
8toxins0 of bacteria1  snakes1 and some 
plants1 the organism is able actively to
 produce  so-called 8anti-toxins0--that 
is1 soluble substances which react with 
the toxins and destroy their poisonous  
character--whenever required1  but that 
against any foreign body of the albumen 

group a specific  reaction may occur1   
resulting in the coagulation of that    
body4 ,but the  destruction of the      
noxious substance or foreign albumen    
actually present  is not all that is    
accomplished by the organism4 8,acquired
 immunity0  proper1 that is1 security   
against the noxious material for a more 
or  less extensive period of the        
99future991 depends on something more4  
,not  only is there produced as much of 
the so-called 8anti-body0 as is         
necessary to combine with the noxious1  
or at least foreign substances  which   
are present1 but 99more99 is produced   
than is necessary in the  actual case4  
,on this over-production depends all    
active immunity1  whether natural or1 as
 in some kinds of vaccination1          
artificial2 and  so-called 8passive0    
immunity1 obtained by the transfusion of
 the serum  of an actively immune       
organism into another also depends upon 
this  feature4#aae    #aad ,see ,jacoby1
 99,immunitt und ,disposition991        

,wiesbaden1 #aijf4    #aae 99,collected 
,studies on ,immunity by ,ehrlich and   
his ,collaborators991  translated by    
,ch4 ,bolduan1 ,new ,york and ,london1  
#aijf4    ,this phenomenon in           
particular--the production of 99more99  
of the  antitoxin or the 8precipitin0   
than is actually necessary--seems to    
render almost impossible any merely     
chemical theory of these facts4 ,the    
reaction between toxin and antitoxin1   
albumen and precipitin is indeed        
chemical2 it may in fact be carried out 
in a test-tube2 but whether the         
production of the anti-body itself is   
also chemical or not could hardly  be   
ascertained without a careful and       
unbiassed analysis4 ,there can be  no   
doubt that the well-known theory of     
,ehrlich1#aaf the so-called  theory of  
side-chains 78,seitenkettentheorie07 has
 given a great impulse  to the progress 
of science2 but even this theory1       
irrespective of its  admissibility in   
general1 is not a real chemical one3 the

 concept of a  regeneration of its      
so-called haptophore groups is a        
strictly biological  concept4#aag       
#aaf ,so-called genuine or innate       
immunity1 in contrast to the immunity   
which is acquired1 is of course a case  
of adaptedness only and not of          
adaptation4 ,there also exists a high   
degree of specific adaptedness in  some 
animals with regard to their faculty of 
coagulating blood4 7,see ,leo  ,loeb1   
99,biol4 ,bull499 #i1 #aije47    #aag   
,we cannot do more than barely mention  
here the problem of the  localisation of
 anti-body production4 ,in general it   
seems to be true  that anti-bodies are  
produced by those cells which require to
 be  protected against toxins2 that     
would agree with the general rule1 that 
all compensation of the change of any   
functional state proceeds from the  part
 changed in its function4    ,and1      
indeed1 here if anywhere we have the    
biological phenomenon of  adaptation in 
its clearest form4 ,there are very      

abnormal changes of the  functional     
state of the organism1 and the organism 
is able to compensate  these changes in 
their minutest detail in almost any     
case4 ,the problem  of the specification
 of the reactions leading to immunity   
seems to me1  as far as ,i can judge as 
an outsider1 to stand at present in the 
very  forefront of the science4 ,there  
cannot be the slightest doubt that      
especially against all sorts of foreign 
albumens the reaction is as  strictly   
specific as possible2 but there are some
 typical cases of  specificity in the   
production of antitoxins also4 ,it is1  
of course1  the 99fact99 of specific    
correspondence between stimulus and     
reaction1  that gives to immunity its   
central position among all adaptations1 
no matter whether the old hypothesis of 
the production of specific  anti-bodies 
proves tenable1 or whether1 as has been 
urged more recently  by some authors1   
the anti-body is always the same but    
reacts differently  according to the    

medium4 ,in the latter case it would be 
the medium that  is regulated in some   
way by the organism in order to attain a
 specific  adaptedness4      ,,no       
,,general ,,positive ,,result ,,from    
,,this ,,chapter    ,but now let us look
 back to the sum of all the             
physiological reactions  studied1 and   
let us see if we have gained a new proof
 of the autonomy of  life from our long 
chapter4    ,we freely admit we have not
 gained any really new 99proof991 but we
 may  claim1 ,i think1 to have gained   
many indicia for the statement that  the
 organism is not of the type of a       
machine1 in which every single          
regulation is to be regarded as properly
 prepared and outlined4    ,it is       
precisely in the field of immunity that 
such a machine-like  preparation of the 
adaptive effects seems almost impossible
 to be  imagined4 ,how indeed could     
there be a machine1 the chemical        
constituents  of which were such as to  
correspond adaptively to almost every   

requirement8--to say nothing of the fact
 that the production of 99more99  of the
 protecting substance than is actually  
necessary could hardly be  said to be   
8chemical40    ,in fact1 we are well    
entitled to say that we have reached    
here the very  heart of life and of     
biology4 ,if nevertheless we do not call
 the sum of  our facts a real proof of  
vitalism1 it is only because we feel    
unable  to formulate the analysis of    
what happens in such a manner as to make
  a machine as the basis of all         
reactions absolutely unimaginable and   
unthinkable4 ,there 99might99 be a true 
machine in the organism producing       
immunity with all its adaptations4 ,we  
cannot disprove such a doctrine by      
demonstrating that it would lead to a   
real 99absurdity991 as we did in our    
analysis of differentiation of form2    
there is only a very high degree of     
improbability in our present case4 ,but 
an indirect 99proof99 must reduce  to   
99absurdity99 all the possibilities     

except one1 in order to be a proof4     
,mechanistic explanations in all        
branches of functional physiology       
proper1 so much in vogue twenty years   
ago1 can indeed be said to  have failed 
all along the line3 the only advantage  
they have brought  to science is the    
clearer statement of problems to which  
we are now  accustomed4 ,but we are not 
fully entitled to say#aah that there    
never  will be any mechanistic          
explanation of physiological functions  
in the  future4 ,it may seem as         
improbable as anything can be2 but we   
wish to  know not what is improbable but
 what is not possible4    #aah ,here    
again ,i should like to except from this
 statement the  discoveries of ,pawlow4 
,see page #bjd1 note #a4    ,now of     
course you might answer me that after we
 have indeed  shown that the production 
of form1 as occurring on the basis of   
harmonious-equipotential systems1 is a  
fact that proves vitalism1  the acts    
taking place on the basis of that form  

after its production  would have been   
proved to be vitalistic also1 or at     
least to be in  some connection with    
vitalistic phenomena4 ,certainly they   
would1 and  ,i myself personally should 
not hesitate to say so4 ,but that is not
  the question4 ,we have to ask3 ,is any
 new proof1 99independent of every      
other991 to be obtained from the facts  
of physiological adaptation in          
themselves8 ,and there is really none4  
,mere regulatory correspondence  between
 stimuli and reactions1 even if it be of
 the adaptive type and  occur in almost 
indefinite forms1 never really disproves
 a machine as  its basis so long as the 
stimuli and reactions are 99simple99 and
 uniform4  ,next summer1 however1 we    
shall see that vitalism may be proved by
 such a  correspondence if the two      
corresponding factors are not simple and
 not  uniform4    ,we most clearly see  
at this point what it really was in our 
analysis of  differentiation that       
allowed us to extract a real proof of   

vitalism from  it4 ,not the mere fact of
 regulability1 but certain specific     
relations  of space1 of locality1 lay at
 the very foundation of our proof4      
,these  relations1 indeed1 and only     
these relations1 made it possible to    
reduce 99ad absurdum99 any possible     
existence of a machine as the actual    
basis of what we had studied4 ,in our   
next chapter again it will be           
space-relations1 though analysed in a   
different manner1 that will enable  us  
to add a second real proof of vitalism  
to our first one4    ,with this chapter 
we conclude the study of organic        
regulation in all its  forms1 as far as 
morphogenesis and metabolism are in     
question4    ,but our analysis of these 
regulations would be incomplete and     
indeed  would be open to objections1 if 
we did not devote at least a few words  
to two merely negative topics1 which    
will be taken more fully into           
consideration later on4      ,a ,,few   
,,remarks ,,on ,,the ,,limits ,,of      

,,regulability    ,there has never been 
found any sort of 8experience0 in       
regulations  about morphogenesis or in  
adaptations of the proper physiological 
type4 ,nothing goes on 8better0 the     
second time than it did the first       
time2#aai everything is either complete1
 whenever it occurs1 or it does  not    
occur at all4    #aai ,the few cases of 
an 8improvement0 of morphogenetic acts  
in  hydroids described by myself are too
 isolated at present to be more  than   
mere problems 799,arch4 ,entw4 ,mech499 
#e1 #ahig74 ,the same is true1 it  seems
 to me1 with regard to certain recent   
discoveries made by ,r4 ,pearl  on      
99,ceratophyllum99 799,carnegie ,inst4  
,wash4 ,publ499 ,no4 #eh1 #aijg72 and by
  ,zeleny on a medusa 799,journ4 exp4   
,zool499 #e1 #aijg74 ,pawlow's          
discovery1  that the enzymotic          
composition of the pancreatic fluid in  
dogs becomes  more and more adapted to a
 specific composition of the food       
7either meat  or bread and milk7 the    

longer such a specific composition is   
offered  to the individual animal1 may  
probably be understood as a case of mere
  functional adaptation of the cells of 
the digestive glands1 if it stands      
criticism at all 7see ,bayliss and      
,starling1 99,ergeb4 ,physiol499 #e1    
#aijf1  p4 #fhb74    ,that is the first 
of our important negative statements    
about  regulations2 the second relates  
to the phrase just used1 8or it does    
not occur at all40 ,there are indeed    
limits of regulability2 adaptations  are
 not possible to every sort of change of
 the physiological state3  sickness and 
death could not exist if they were2 nor 
is restitution  possible in all cases   
where it might be useful4 ,it is a      
well-known fact1  that man is only able 
to heal wounds but is altogether        
destitute of the  faculty of            
regeneration proper4 ,but even lower    
animals may be without  this faculty1 as
 are the ctenophores and the nematodes  
for instance1 and  there is no sort of  

correspondence between the faculty of   
restitution  and the place in the animal
 kingdom4 ,it is not altogether         
impossible  that there may be found1    
some day1 certain conditions under which
 every  organism is capable of restoring
 any missing part2 but at present we    
know absolutely nothing about such      
conditions4#abj    #abj ,experiments    
carried out in the 8,biologische        
,versuchsanstalt0 at  ,vienna indeed    
have shown that many animal types are   
capable of at least  a certain degree of
 restitution1 although they had         
previously been  denied this faculty by 
zoologists4    ,but no amount of        
negative instances can disprove an      
existing  positive--which is what we    
have been studying4 ,our analysis based 
upon  the existence of regulations is as
 little disparaged by cases where no    
regulability exists as optical studies  
are by the fact that they cannot  be    
undertaken in absolute darkness4        
99,d499 ,,inheritance3 ,,second ,,proof 

,,of ,,the ,,autonomy ,,of ,,life       
,all organisms are endowed with the     
faculty of re-creating their own        
initial form of existence4    ,in words 
similar to these ,alexander ,goette1 it 
seems to me1 has given  the shortest and
 the best expression of the fact of     
inheritance4 ,indeed1  if the initial   
form in all its essentials is           
re-created1 it follows from  the        
principle of univocality1 that1         
99ceteris paribus991 it will behave     
again as it did when last it existed4   
,by the fact of inheritance life becomes
 a rhythmic phenomenon1 that is  to say1
 a phenomenon1 or better1 a chain of    
phenomena1 whose single  links reappear 
at constant intervals1 if the outer     
conditions are not  changed4      ,,the 
,,material ,,continuity ,,in            
,,inheritance    ,it was first stated by
 ,gustav ,jaeger and afterwards worked  
out into  a regular theory by ,weismann1
 that there is a continuity of material 
underlying inheritance4 ,taken in its   

literal meaning this statement is       
obviously self-evident1 though none the 
less important on that account4  ,for as
 all life is manifested on bodies1 that 
is on matter1 and as the  development of
 all offspring starts from parts of the 
parent bodies1  that is from the matter 
or material of the parents1 it follows  
that in  some sense there is a sort of  
continuity of material as long as there 
is  life--at least in the forms we know 
of4 ,the theory of the continuity of    
8germ-plasm0 therefore would be true1   
even if germ-cells were produced  by any
 and every part of the organism4 ,that1 
as we know1 is not actually  the case3  
germ-cells1 at least in the higher      
animals and in plants1 are  produced at 
certain specific localities of the      
organism only1 and it is  with regard to
 this fact that the so-called theory of 
the 8continuity of  germ-plasm0 acquires
 its narrower and proper sense4 ,there  
are distinct  and specific lines of     
cell-lineage in ontogenesis1 so the     

theory states1  along which the         
continuity of germ-protoplasm is kept   
up1 which1 in  other words1 lead from   
one egg to the other1 whilst almost all 
other  lines of cell-lineage end in     
8somatic0 cells1 which are doomed to    
death4 ,what has been stated here is a  
fact in many cases of descriptive       
embryology1 though it can hardly be said
 to be more than that4 ,we know         
already1 from our analytical and        
experimental study of morphogenesis1    
that ,weismann himself had to add a     
number of subsidiary hypotheses to  his 
original theory to account for the mere 
facts of regeneration proper  and the   
so-called vegetative reproduction in    
plants and in some animals1  and we have
 learned that newly discovered facts    
necessitate still more  appendixes to   
the original theory4 ,in spite of that1 
,i regard it as  very important that the
 fact of the continuity of some material
 as one  of the foundations of          
inheritance has clearly been stated1    

even if the  specialised form of the    
theory1 as advocated by ,weismann in the
 doctrine  of the 8germ-lineages0       
78,keimbahnen07 should prove unable to  
stand  against the facts4    ,the       
important problem now presents itself3  
,what is the material1 the  matter1     
which is handed down from generation to 
generation as the  basis of inheritance8
 ,weismann1 as we know1 regarded it as a
 very  complicated structure1 part of   
which by its disintegration became the  
foundation of individual embryology4 ,we
 have disproved1 on the authority  of   
many facts1 the latter part of this     
assumption2 but of course the  first    
part of it may turn out to be true in   
spite of this4 ,we have no  means at    
present to enable us to say 99a priori99
 anything positive or  negative about   
the important question of the nature of 
that matter1 the  continuity of which in
 inheritance is in some sense a         
self-evident fact1  and we therefore    
shall postpone the answer until a later 

point of our  analytical discussion4    
,,on ,,certain ,,theories ,,which ,,seek
 ,,to ,,compare ,,inheritance ,,to      
,,memory    ,it will be advisable first 
to study some other theoretical views   
which  have been put forward with regard
 to inheritance4 ,the physiologist      
,hering1 as early as #ahgf1 compared all
 heredity to the well-known fact  of    
memory1 assuming1 so to say1 a sort of  
remembrance of all that  has happened to
 the species in the continuity of its   
generations2  and several ,german       
authors1 especially ,semon1 have lately 
made this  hypothesis the basis of more 
detailed speculation4    ,it is not     
clear1 either from ,hering's paper#aba  
or from ,semon's  book1#abb what is     
really to be understood here by the word
 8memory10  and1 of course1 there might 
be understood by it very different      
things1  according to the author's      
psychological point of view4 ,if he is a
  8parallelist0 with regard to so-called
 psychical phenomena1 he would use  the 

word memory only as a sort of collective
 term to signify a resultant  effect of 
many single mechanical events1 as far as
 the material world of  his parallel    
system comes into account1 with which of
 course the problem  of inheritance     
alone deals2 but if he maintains the    
theory of so-called  psycho-physical    
interaction1 the psychical would be to  
him a primary  factor in nature1 and so 
also would memory4 ,as we have said1 it 
is by no  means clear in what sense the 
word 8memory0 is used by our authors1   
and  therefore the 99most99 important   
point about the matter in question must 
remain 99in dubio994    #aba 99,ueber   
das ,gedchtnis als eine allgemeine      
,function der organischen  ,materie991  
,wien1 #ahgj4 ,new edition in           
99,klassiker d4 exakt4 ,wiss4991        
,leipzig1 ,engelmann4    #abb 99,die    
,mneme991 ,leipzig1 #aijd4    ,but      
another topic is even more clear in the 
theory of inheritance1 as  stated in    
,hering's and ,semon's writings4 ,the   

hypothetical fact that  so-called       
8acquired characters0 are inherited is  
undoubtedly the chief  assumption of    
that theory4 ,indeed1 it would be       
difficult to understand  the advantage  
of the ambiguous word memory1 had it not
 to call attention  to the hypothetic   
fact that the organism possesses the    
faculty of  8remembering0 what once has 
happened to it or what it once has      
8done10  so to speak1 and profiting by  
this remembering in the next generation4
  ,the zoologist ,pauly indeed has      
stated this view of the matter in very  
distinct and clear terms4    ,as we soon
 shall have another occasion to deal    
with the much-discussed  problem of the 
8inheritance of acquired characters10 we
 at present  need only say a few words  
about the 8memory-theory0 as a supposed 
8explanation0 of heredity4 ,undoubtedly 
this theory postulates1 either  avowedly
 or by half-unconscious implication1    
that all the single  processes in       
individual morphogenesis are the outcome

 either of  adaptations of the          
morphological type1 which happened to be
 necessary  in some former generation1  
or of so-called contingent 8variations10
 of  some sort or other1 which also     
happened once in the ancestral line4    
,such a postulate1 of course1 is        
identical with what is generally called 
the theory of descent in any of its     
different forms4 ,this theory is  to    
occupy us in the next lectures2 at      
present we only analyse the             
8memory-theory0 as a theory of heredity 
in itself4 ,in any case1 to  regard     
memory as the leading point in          
inheritance1 at least if it is to       
signify what is called memory in any    
system of psychology1 would be to       
postulate that either adaptation or     
contingent 8variation0 has been the     
origin of every morphogenetic process4  
,indeed1 the ,american physiologist     
,jennings did not hesitate to defend    
such a view most strongly1 and many     
others seem to be inclined to do the    

same4    ,but such an assumption most   
certainly cannot be true4    ,it cannot 
be true1 because there are many         
phenomena in morphogenesis1  notably all
 the phenomena akin to restitution of   
form1 which occur  in absolute          
perfection even the very first time they
 happen4 ,these  processes1 for the     
simple reason of their 99primary        
perfection991 cannot  be due either to  
8learning0 from a single adaptation1 or 
to accidental  variation4 ,we shall     
afterwards employ a similar kind of     
argument to  refute certain theories of 
evolution4 ,it therefore may be of a    
certain  logical interest to notice that
 at present1 combating the memory-theory
  of inheritance1 and hereafter1        
combating certain theories of descent1  
we select not 8adaptation0 or           
8variation0 as the central points to be 
refuted1 but the assumed 99contingency99
 of both of them4    ,the word 8memory10
 therefore1 may be applied to the       
phenomena of  inheritance only in a very

 figurative meaning1 if at all4 ,we do  
not  wholly deny the possibility of an  
inheritance of acquired characters1 as  
will be seen later on1 and to such a    
fact there might perhaps be applied     
such a term as 8memory0 in its real     
sense1 but we simply 99know99 that      
there 99is99 something in inheritance   
which has no similarity whatever  to    
what is called 8memory0 in any species  
of psychology4 ,a primary  perfection of
 processes occurring quite abnormally   
proves that there is  a 8knowing0 of    
something--if we may say so--but does   
not prove at all  that there is a       
8remembering40      ,,the               
,,complex-,,equipotential ,,system ,,and
 ,,its ,r,,le ,,in ,,inheritance#abc    
#abc ,driesch1 99,organ4 ,regul499      
#aija4    ,but we thus far have reached 
only negative results4 ,is the question 
necessarily to remain at this point1    
which could hardly be said to be  very  
satisfying2 or could we perhaps get     
better1 that is1 positive  results about

 inheritance by a change of our analytic
 methods8 ,let us  try to analyse the   
facts that occur in inheritance instead 
of beginning  with hypotheses which     
claim to be complete explanations4      
,perhaps we  shall gain1 if but small1  
yet certainly fixed results by an       
analysis  which goes from the facts to  
the theory and not from the theory to   
the  facts4    ,let the discussions that
 are to follow be placed upon a basis as
 broad  as possible4    ,our studies of 
morphogenetic restitution have shown us 
that besides the                        
harmonious-equipotential systems another
 and widely different type of           
morphogenetic 8systems0 799i4e499       
unities consisting of elements equal in 
morphogenetic faculty7 may also be the  
basis of restitution processes4  ,whilst
 in the harmonious system the           
morphogenetic acts performed by  every  
single element in any actual case are   
single acts1 the totality  of all the   
single acts together forming the        

harmonious whole1 in the  other type of 
systems now to be examined1 complex     
acts1 that is1 acts  which consist of a 
manifoldness in space and in time1 can  
be performed  by each single element1   
and actually are performed by one or the
 other  of them4 ,we therefore have     
given the title of                      
8complex-equipotential  systems0 to the 
systems in question1 as all our         
denominations are based  on the concept 
of the prospective morphogenetic        
potency1 that is of the  possible fate  
of the elements4    ,the cambium of the 
,phanerogams may be regarded as the very
 type of a  complex-equipotential       
system1 promoting restitution of form4  
,it runs  through the whole stem of our 
trees1 in the form of a hollow tube1    
placed between the inner and the outer  
cell-layers of the stem1 and  either    
branch or root may originate from any   
single one of its cells1  just as       
circumstances require4 ,we might call   
the cambium a system of the  8complex0  

type of course1 even if every one of its
 constituents were  able to form only a 
root or only a branch by way of         
restitution4 ,but in  fact one and the  
same element can form both of these     
complex-structures2  it depends only on 
its relative position in the actual part
 of the stem  isolated for the purposes 
of experiment1 what will be accomplished
 in  every case4 ,here we have a state  
of affairs1 which we shall encounter    
again when studying regeneration in     
animals3 every element of the system    
may be said to contain potencies for the
 8ideal whole10 though this  ideal whole
 will never be realised in its proper   
wholeness4#abd    #abd ,the 8ideal      
whole0 is also proved to exist1 if any  
99given99  8,anlage10 say of a branch1  
is forced to give origin to a root1 as  
has  really been observed in certain    
plants4 ,this case1 like many other     
less extreme cases of what might be     
called 8compensatory heterotypy10  are  
best to be understood by the aid of the 

concept of 8prospective  potency40 ,it  
is very misleading to speak of a        
metamorphosis here4 ,i  fully agree with
 ,kraan about this question4 ,see also  
page #aab1 note #a1  and my 99,organ4   
,regul499 pp4 #gg1 #gh4    ,but there is
 no need to recur to the 8ideal whole0  
in many other cases  of adventitious    
restitution in plants4 ,on isolated     
leaves of the  well-known begonia1 a    
whole plant1 containing all the         
essential parts1  may arise from any    
single cell#abe of the epidermis1 at    
least along the  veins1 and in some     
liverworts it has been shown by         
,vchting1 that almost  every cell of the
 whole is able to reproduce the plant1  
as is also the  case in many algae4     
#abe ,winkler has discovered the        
important fact1 that the adventitious   
buds formed upon leaves may originate   
either from one single cell of  the     
epidermis or from several cells         
together2 a result that is very         
important with respect to the problem of

 the distribution of 8potencies40    ,in
 the animal kingdom it is chiefly and   
almost solely the phenomena  of         
regeneration proper which offer typical 
instances of our systems1  since        
adventitious restitution1 though        
occurring for instance in the           
restitution of the lens of vertebrates  
from the iris1 and though  connected    
also with the events in regeneration    
proper1#abf is of but  secondary        
importance in animal restitution1 at    
least1 if compared with  restitution in 
plants4 ,if we study the regeneration of
 a leg in the  common newt1 we find that
 it may take place from every section1  
the  point of amputation being quite at 
our choice4 ,without regarding here  the
 exact order of the regeneration        
phenomena1 which is almost unknown  at  
present1 we in any case can say without 
any doubt that the line  of consecutive 
possible cross-sections forms a         
complex-morphogenetic  system1 as every 
one of them is able to give rise to a   

complex organ1  viz4 the foot and part  
of the leg4 ,it is an open question     
whether this  complex system is to be   
called 8equipotential0 or not4 ,it      
indeed seems  to be inequipotential at  
the first glance1 for each single       
section has  to form a different        
organogenetic totality1 namely1 always  
that specific  totality which had been  
cut off2 but if we assume hypothetically
 that  the real 8,anlage0 which is      
produced immediately by the cells of the
  wounded surface is the very same for  
all of them1 and that it is the  actual 
state of organisation which determines  
to what result this  ,anlage is to      
lead1#abg we may say that the series of 
consecutive  cross-sections of a newt's 
leg does form a morphogenetic system of 
the  complex-equipotential type1        
promoting secondary regulations of form4
    #abf ,the 8regeneration0 of the     
brain of annelids for instance is far   
better regarded as an adventitious      
formation than as regeneration  proper3 

nothing indeed goes on here at the      
locality of the wound2 a new  brain is  
formed out of the ectoderm at a certain 
distance from it4    #abg ,a full       
8analytical theory of regeneration0 has 
been developed  elsewhere 799,organ4    
,regul499 p4 #dd1 etc474 ,i can only    
mention here that  many different       
problems have to be studied by such a   
theory4 ,the  formation of the 8,anlage0
 out of the body and the differentiation
 of  it into the completely formed      
results of regeneration are two of them4
  ,the former embraces the question     
about the potencies not only of the     
regenerating body but of the elements of
 the ,anlage also2 the latter  has to   
deal with the specific order of the     
single acts of regenerative  processes4 
,now all these difficulties vanish1 if  
we consider the regeneration of         
animals1 such for instance as many worms
 of the annelid class or our  familiar  
ascidian 99,clavellina991 in which      
regeneration in both directions  is     

possible4 ,the wound at the posterior   
end of the one half which  results from 
the operation forms a posterior body    
half1 the wound at  the anterior end of 
the other half forms an anterior one4   
,again1 it is  the ideal whole which we 
meet here3 each section of the body     
indeed may  be said to contain the      
potencies for the production of the     
totality1  though actually this totality
 is always realised by the addition of  
two  partial organisations4 ,the title  
of complex-equipotential systems thus   
seems to be fully justified as applied  
to the systems which are the  basis of  
regeneration3 each section of the       
regenerating body may in fact  produce  
the same complex whole1 or may1 if we   
prefer to say so1 at least  prepare the 
ground for that complex ,anlage1 out of 
which the complex  totality is actually 
to arise1 in the same manner4    ,it    
often occurs in science1 that in rather 
strange and abnormal  conditions        
something becomes apparent which might  

have been found  everywhere1 which is   
lying before our eyes quite obviously4  
,are  we not in just such a condition at
 present8 ,in order to study the        
complex-equipotential systems1 we turn  
to the phenomena of regeneration  and of
 restitution in general2 we occasionally
 even introduce hypotheses  to render   
our materials more convenient for our   
purposes2 and all the  time there is one
 sort of complex-equipotential system in
 the body of  every living being1 which 
only needs to be mentioned in order to  
be  understood as such1 and which indeed
 requires no kind of preliminary        
discussion4 ,the system of the          
propagation cells1 in other words the   
sexual organ1 is the clearest type of a 
complex-equipotential system  which     
exists4 ,take the ovary of our          
sea-urchin for instance1 and there  you 
have a morphogenetic system every       
element of which is equally  capable of 
performing the same complex             
morphogenetic course--the  production of

 the whole individual4    ,further on we
 shall deal exclusively with this       
variety of our systems1  and in doing so
 we shall be brought back to our problem
 of heredity4 ,but  it had its uses to  
place our concept of the                
complex-equipotential system  upon such 
a broad basis3 we at once gave a large  
range of validity to  all that is to    
follow--which1 indeed1 does not apply to
 inheritance  alone1 though its         
significance in a theory of heredity may
 be called its  most important          
consequence4      ,,the ,,second ,,proof
 ,,of ,,life-,,autonomy4 ,,entelechy    
,,at ,,the ,,bottom ,,of ,,inheritance  
,after we had established the concept of
 the harmonious-equipotential  system in
 a former chapter1 we went on to study  
the phenomena of the  differentiation of
 it1 and in particular the problem of   
the localisation  of all                
differentiations4 ,our new concept of   
the complex-equipotential  system is to 
lead us to an analysis of a different   

kind3 we shall pay  special attention to
 the origin1 to the 99genesis99 of our  
complex systems  that show              
equipotentiality4    ,if we review the  
process of ontogenesis1 we are able to  
trace back every  complex system to a   
very small group of cells1 and this     
small group of  cells again to one      
single cell4 ,so in plants the cambium  
may be shown  to have originated in a   
sort of tissue-rudiment1 established at 
a very  early period1 and the ovary may 
be demonstrated to be the outcome of a  
group of but a few cells1 constituting  
the first visible 8,anlage0 of the      
reproductive organs4 ,at the end then1  
or from another point of view at  the   
beginning1 a single cellular element    
represents the very primordial          
egg-cell4    ,the whole cambium1 there  
can be no doubt1 must be regarded as the
 result  of a consecutive number of     
cell-divisions of the one cell from     
which it  originates4 ,so must it be    
with the ovary4 ,the primordial egg-cell

 has  undergone a long line of          
consecutive divisions2 the single eggs  
are the  last result of them4    ,we now
 proceed to some considerations which   
have a certain  logical similarity to   
those which inaugurated our analysis of 
the  differentiation of the             
harmonious-equipotential systems1 though
 the  facts in question are very        
different4    ,viewed by itself without 
any kind of prepossessions1 as it might 
be by any one who faces a new problem   
with the single postulate of            
introducing new natural entities--to use
 the scholastic phrase--as  little as   
possible1 the development of the single 
egg might be regarded  as proceeding on 
the foundation of a very complicated    
sort of machine1  exhibiting a different
 kind of construction in the three chief
  dimensions of space1 as does also the 
organism which is to be its result4     
,but could such a theory--irrespective  
of all the experimental facts  which    
contradict it--could such a theory stand

 before the 99one99 fact1  that there   
occurs a 99genesis99 of that            
complex-equipotential system1  of which 
our one single egg forms a part8 ,can   
you imagine a very  complicated machine1
 differing in the three dimensions of   
space1 to  be divided hundreds and      
hundreds of times and in spite of that  
to  remain always the same whole8 ,you  
may reply that during the period  of    
cell-divisions there is still no        
machine1 that the machine is            
established only after all the divisions
 are complete4 ,good2 but what  then    
constructs this machine in the          
definitive cells of our systems1 say  in
 the eggs8 ,another sort of machine     
perhaps8 ,that could hardly be said  to 
be of much use4 ,or that entelechy of   
which we have spoken8 ,then you  would  
recur to our first proof of vitalism and
 would burden entelechy  with a specific
 performance1 that is with the          
construction of the  hypothetic machine 
which you are postulating in every      

single egg4 ,but of  course you would   
break the bounds of physics and         
chemistry even then4    ,it seems to me 
that it is more simple1 and so to say   
more natural1 not  to recur to our first
 proof of life-autonomy in order to keep
 to the  8machine theory0 in this new   
branch of inquiry1 but to consider facts
 as  they offer themselves to analysis4 
,but then indeed we are entitled to draw
 an independent second proof of  the    
autonomy of life from our analysis of   
the genesis of systems of the           
complex-equipotential type4 ,we say it  
is a mere absurdity to assume that  a   
complicated machine1 typically different
 in the three dimensions of  space1     
could be divided many many times1 and in
 spite of that always  be the whole3    
therefore there cannot exist any sort of
 machine as the  starting-point and     
basis of development4    ,let us again  
apply the name entelechy to that which  
lies at the very  beginning of all      
individual morphogenesis4    ,entelechy 

thus proves to be also that which may be
 said to lie at  the very root of       
inheritance1#abh or at least of the     
outcome of  inheritance2 the individual 
formation of the next generation is     
shown  not to be performed by a machine 
but by a natural agent 99per se994      
#abh ,and1 of course1 at the root of    
every new starting of certain  parts of 
morphogenesis also1 as in regeneration  
and in adventitious  budding2 these     
processes1 as we know1 being also       
founded upon  8complex-equipotential    
systems10 which have had their          
8genesis40      ,,the ,,significance    
,,of ,,the ,,material ,,continuity ,,in 
,,inheritance    ,but what about the    
material continuity appearing in        
inheritance1 which  we have said to be  
almost self-evident1 as life is only    
known to exist  on material bodies8 ,is 
there not1 in fact1 a serious           
contradiction  in admitting at the same 
time entelechy on the one side and a    
sort  of material condition on the other

 as the basis of all that leads to  and 
from inheritance8 ,next summer the      
relation between matter and our         
autonomous agent of life will be studied
 more fully2 at present it must  be     
enough to state in a more simple and    
realistic way1 what we hold  this       
relation to be4 ,there is no            
contradiction at all in stating that    
material continuity is the basis of     
inheritance on the one side1 and        
entelechy on the other4 ,it would be    
very inconvenient for us if there  were 
any3 for the material continuity is a   
mere fact and our entelechy  we hope we 
have proved to exist also2 if now there 
were any sort of  contradiction in      
assuming the existence of both of them1 
of course it  would be fatal to our     
proof4    ,let us try to comprehend what
 is meant by the statement that         
entelechy  and something material are at
 work in inheritance at the same time4  
,entelechy has ruled the individual     
morphogenesis of the generation which   

is regarded as being the starting-point 
for inheritance1 and will rule  also the
 morphogenesis of the generation which  
is to follow2 entelechy  determines the 
egg to be what it is1 and the           
morphogenesis starting from  this egg to
 be what it is also4 ,entelechy1 at     
present1 is not much more  for us than a
 mere word1 to signify the autonomous1  
the irreducible of  all that happens in 
morphogenesis with respect to 99order991
 in the one  generation and in the next4
 ,but may not the material continuity   
which  exists in inheritance account    
perhaps for the material elements       
99which  are to be ordered998 ,in such a
 way1 indeed1 ,i hope we shall be able  
to  reconcile entelechy and the material
 basis of heredity4 ,may it not be  that
 there exist some 8means0 for           
morphogenesis1 which are handed down    
from generation to generation1 always   
controlled by entelechy1 and which      
constitute the real significance of the 
continuity of matter during             

inheritance8      ,,the ,,experimental  
,,facts ,,about ,,inheritance           
,discoveries of the last few years do   
seem to show that such means  of a      
material character1 though not the      
foundation of that order of  processes  
which is inherited1 are nevertheless    
among the most necessary  conditions for
 the accomplishment of inheritance in   
general4 ,it is  scarcely necessary to  
remind you that for very many years all 
concrete  research on heredity          
proper--that is1 the actual comparison  
of the  various specific characters in  
the generations of the grandfather1 the 
father1 and the child--was due to       
,galton4 ,you may also be aware that in 
spite of ,galton's inestimable services 
it was not till #aijj that one of  the  
active principles concerned in          
inheritance was found independently  by 
de ,vries1 ,correns1 and ,tschermak1 and
 that this principle happened  to be one
 that 99had99 been discovered already1  
stated with the utmost  clearness and   

precision by the ,augustinian monk1     
,gregor ,mendel1#abi as  early as #ahfe1
 though it had been completely forgotten
 ever since4    #abi ,new edition in the
 8,klassiker d4 exakt4 ,wiss40 ,leipzig1
 ,engelmann2  see also ,bateson1        
99,mendel's ,principles of ,heredity991 
,cambridge1 #aijb4    ,the so-called    
8rule of ,mendel0 is based upon         
experiments with hybrids1  that is1 with
 the offspring of parents belonging to  
different species1  or1 at least1       
varieties1 but it relates not to the    
characters of the  generation resulting 
immediately from hybridisation1 the     
8first0  generation of hybrids1 as we   
shall call it1 but to the characters of 
that generation which is the result of  
crossing the hybrids with each  other1  
provided that this leads to any         
offspring at all4 ,there are many  cases
 indeed1 both amongst animals and       
plants1 where the offspring of  the     
hybrids1 or in other terms the 8second0 
generation1 is found to  consist of     

individuals of three different          
types--the mixed#acj type  of the       
hybrids themselves1 and the two pure    
types of the grandparents4  ,whenever   
the individuals of the 8second0         
generation are separated into  these    
three different types1 hybrids are said 
to 8split40 ,it is the  fact of this    
splitting on the one hand1 and on the   
other hand a certain  statement about   
the numbers of individuals in the three 
different types  of the 8second0        
generation1 that gives its real         
importance to ,mendel's  rule4    #acj  
,for the sake of simplicity ,i shall not
 deal here with those  cases of         
hybridisation in which one quality is   
8recessive10 the other  8dominant10 but 
only allude to the cases1 less numerous 
though they be1  where a real mixture of
 maternal and paternal qualities occurs4
    ,before discussing what may follow  
from ,mendel's discovery for the  theory
 of heredity1 we must lay stress on the 
fact that there are many  exceptions to 

his rule4 ,in quite a number of cases   
the hybrids are of  one or more types1  
which remain constant3 there is no      
splitting at all  in the second         
generation4 ,but that does not affect   
the rule of ,mendel in  those cases     
where it is true4 ,where there is a     
8splitting0 in the second  generation1  
there also are the numerical proportions
 stated by ,mendel2  there never are    
other relations among the numbers of    
individuals of the  mixed and of the two
 pure types than those given by his     
rule4 ,i regard  it as very important   
that this real meaning of ,mendel's     
principle should  be most clearly       
understood4    ,from the fact of the    
splitting of hybrids in the second      
generation most  important consequences 
may be drawn for the theory of          
inheritance2 the  split individuals1 if 
crossed with each other1 always give an 
offspring  which remains pure2 there is 
no further splitting and no other change
  whatever4 ,the germ-cells produced by 

the split individuals of the second     
generation may therefore be said to be  
8pure10 as pure as were those of  the   
grandparents4 ,but that is as much as to
 say that the pureness of  the          
germ-cells has been preserved in spite  
of their passing through the  8impure0  
generation of the hybrids1 and from this
 fact it follows again  that the union  
of characters in the hybrids must have  
been such as to  permit pure separation3
 in fact1 the germ-cells produced by    
,mendelian  hybrids may hypothetically  
be regarded as being pure               
themselves4#aca    #aca ,this hypothesis
 was first suggested by ,sutton and is  
at present  held by orthodox            
,mendelians2 but probably things are a  
little more  complicated in reality1 as 
seems to be shown by some facts in the  
behaviour of so-called 8extracted       
recessives40 ,in ,morgan's              
99,experimental  ,zoology991 ,new ,york1
 #aijg1 a full account of the whole     
matter is given4    ,we have not yet    

considered one feature of all           
experiments in  hybridisation1 which    
indeed seems to be the most important of
 all for  the theory of inheritance1 if 
taken together with the fact of the     
pureness of the germs4 ,the rule of     
,mendel always relates to one single    
character of the species or varieties   
concerned in hybridisation1 and  if it  
deals with more than one character1 it  
regards every one of them  separately2  
indeed1 the rule holds for every one of 
them irrespective  of the others4 ,we   
cannot study here how this most         
important fact of  the independence of  
the single characters of a species with 
regard to  inheritance leads to the     
production of new races1 by an abnormal 
mixture  of those characters4 ,we only  
take advantage of the fact              
theoretically1  and in doing so1 ,i     
believe1 we can hardly escape the       
conclusion that  the independence of the
 single characters in inheritance1 taken
  together with the pureness of the     

germ-cells in the most simple form  of  
hybrids1 proves that there occurs in    
inheritance a sort of handing  over of  
single and separate morphogenetic agents
 which relate to the  single            
morphogenetic characters of the adult4  
,we may use ,bateson's  word            
8allelomorphs0 for these agents1 or     
units1 as they may be called1  thereby  
giving expression to the fact that the  
single and separate  units1 which are   
handed over in inheritance1 correspond  
to each other in  nearly related species
 without being the same4    ,and so we  
have at least an inkling of what the    
material continuity of  inheritance is  
to mean1 though1 of course1 our 8single 
and separate  morphogenetic agents10 or 
8units0 or 8allelomorphs0 are in        
themselves  not much more than unknown  
somethings described by a word2 but even
 then  they are 8somethings40           
,besides the researches relating to the 
rule of ,mendel and its  exceptions1    
founded1 that is1 upon a study of the   

8second0 generation of  hybrids1 there  
is another important line of research   
lately inaugurated  by ,herbst1 which   
investigates the first generation in    
hybridisation4  ,the hybrids themselves 
are studied with the special purpose of 
finding  out whether the type of the    
single hybrid may change according to   
the  conditions of its development1 both
 outer and inner4 ,the discoveries  thus
 made may lead some day to a better     
understanding of the intimate  nature of
 the 8units0 concerned in heredity1 and 
perhaps to some  knowledge of the       
arranging and ruling factor in          
morphogenesis also4    ,starting from   
the discovery of ,vernon1 that the      
hybrids of sea-urchins  are of different
 types according to the season1         
,herbst#acb was able  to show that      
differences among the hybrids with      
regard to their being  more of the      
paternal or more of the maternal type1  
are in part certainly  due to           
differences in temperature4 ,but there  

proved to be still another  factor at   
work1 and ,herbst has succeeded in      
discovering this factor by  changing the
 internal conditions of morphogenesis4  
,whenever he forced  the eggs of        
99,sphaerechinus99 to enter into the    
first#acc phase of  artificial          
parthenogenesis and then fertilised them
 with the sperm of  99,echinus991 he was
 able to approximate the offspring      
almost completely  to the maternal type1
 whilst under ordinary conditions the   
hybrids in  question follow the paternal
 far more than the maternal             
organisation4    #acb 99,arch4 ,entw4   
,mech499 #ba1 #bb1 and #bd1 #aijf-g2 see
 also ,doncaster1  99,phil4 ,trans4     
,royal ,soc499 ,london1 ,b4 #aif1 #aijc4
 ,the influence of  different           
temperature upon the organisation of the
 hybrids is not  always quite pure1     
inasmuch as the paternal and the        
maternal forms may  themselves be       
changed by this agent4 ,in spite of that
 there exists an  influence of the      

temperature upon the hybrid 99as such991
 at least with  regard to certain       
features of its organisation4    #acc   
,only the nucleus of the egg had entered
 its first stages of  activity4    ,what
 is shown1 in the first place1 by these 
discoveries is the  importance of an    
arranging and ruling factor in spite of 
all units4 ,the  organism is always one 
99whole99 whether the paternal          
properties prevail  or the more         
complicated maternal ones2 in other     
words1 all so-called  properties that   
consist in the 99spatial relations of   
parts99 have nothing  to do with 8units0
 or 8allelomorphs10 which indeed cannot 
be more  than necessary means or        
materials1 requiring to be ordered4 ,as 
to the  character of the morphogenetic  
single and separate units themselves    
,herbst is inclined to regard them as   
specific chemical substances which      
unite correspondingly during nuclear    
conjugation1 forming a sort of  loose   
chemical compound4 ,it would depend on  

the constitution of this  compound      
whether germ-cells of hybrids could     
become pure or not4      ,,the ,r,,le   
,,of ,,the ,,nucleus ,,in ,,inheritance 
,at the end of our studies on heredity  
we hardly can avoid saying a  few words 
about the problem of the localisation of
 the morphogenetic  units in the        
germ-cells themselves4 ,is it in the    
protoplasm or in the  nucleus that they 
are placed8 ,you all know that this     
question was for  a long time regarded  
as more important than any other1 and   
perhaps  you have already blamed me for 
not raising it until now4 ,but in my    
opinion results gained by the purely    
analytical method and carefully         
established1 are always superior to     
those which are of a merely  descriptive
 nature and doubtful besides4 ,the      
famous problem of the part  played by   
the nucleus in inheritance is both      
descriptive and doubtful3  it is only1  
so to say1 of factual1 not of analytical
 importance1 and  quite insoluble at    

present4    ,as for our second proof of 
vitalism1 stating that no kind of       
machine  inside the germ-cells can      
possibly be the foundation of their     
morphogenesis1 it is clear that the     
protoplasm and the nucleus may both     
come into account here on equal terms4  
,if you prefer to say so1 it is to  the 
nucleus and to its division in          
particular that the second proof of     
autonomy relates1 while the first1      
though not over-looking the presence  of
 nuclei1#acd deals 8especially0 with the
 protoplasmic nature of its  8systems40 
#acd ,the first proof of vitalism1      
indeed1 rests upon the analysis of  the 
differentiation of an                   
harmonious-equipotential system as a    
99whole993  this 99whole99 cannot be a  
machine that would relate to            
differentiation as  a 99whole992 the    
question whether there might be any     
machines distributed  99in99 the whole1 
in the form of the nuclei is of no      
importance at all in  this argument4    

,moreover the pressure experiments 7see 
page #fc7 prove the  unimportance of    
such 8machines0 for the specificity of  
differentiation1  and the second proof  
of vitalism shows that the nuclei cannot
 be  regarded as machines accounting for
 differentiation in 99any99 way4        
,what then can we say1 on the basis of  
actual facts1 about the part taken  by  
the protoplasm and by the nucleus in    
inheritance1 now that we have  learnt   
from our analytical discussion that both
 of them cannot be any  kind of         
morphogenetic machine1 but can only be  
means of morphogenesis8  ,let us state  
our question in the following way3      
whereabouts in the  germ-cells are those
 8means0 of morphogenesis localised1 the
 existence  of which we infer from the  
material continuity in the course of    
generations in general and from the     
facts discovered about hybridisation  in
 particular8    ,the first of the facts 
generally said to support the view that 
the  nucleus of the germ-cells exerts a 

specified influence upon the  processes 
of development and inheritance1 relates 
to the proportion  between protoplasm   
and nuclear material in the egg and in  
the spermiae4  ,this proportion is very 
different in the two sexual products1 as
 we  know1 there being an enormous      
preponderance of the protoplasm in the  
egg1 of the nucleus in the spermatozoon4
 ,this seems to indicate that  the      
proportion between protoplasm and       
nucleus is fairly indifferent  for      
inheritance1 as all the facts go to show
 that inheritance from  the father is as
 common as inheritance from the mother4 
,it is in the  nucleus1 and in the      
nucleus alone1 that any similarity of   
organisation  exists between the two    
sexual products1 so very different in   
all other  respects3 therefore the      
nucleus should be the organ of          
inheritance4 ,the  phenomena of nuclear 
division1 of karyokinesis1 which are    
quite equal in  both sexual cells1 are  
certainly well fitted to support this   

hypothesis4    ,there seems indeed to be
 some truth in this reasoning1 but      
nevertheless  it must remain            
hypothetical2 and it must never be      
forgotten that  there may be very       
probably some sort of morphogenetic     
importance in  protoplasm also4 ,rauber 
and afterwards ,boveri#ace have tried to
 prove  experimentally that it is on the
 nuclear chromatic substance only that  
inheritance depends1 but the first of   
these authors failed to get any  results
 at all1 and the latter obtained only   
ambiguous ones4 ,godlewski1  on the     
contrary1 has fertilised purely         
protoplasmic egg-fragments of  the      
sea-urchin with the sperm of quite      
another group of ,echinoderms1  and     
obtained in spite of that a few stages  
of development of the  pure maternal    
type4 ,this experiment seems to place   
the morphogenetic  importance of        
protoplasm beyond all doubt4    #ace    
,boveri tried to fertilise enucleated   
fragments of the egg of                 

99,sphaerechinus99 with the sperm of    
99,echinus994 ,he failed to get any     
results in isolated experiments1 but    
found a few small larvae of the  pure   
99,echinus99 type in large cultures     
consisting of shaken eggs4 ,but  later  
experiments on hybridisation in         
sea-urchins have shown that a full      
hybrid of 99,echinus99 and              
99,sphaerechinus99 may be purely        
paternal also4    ,i should prefer not  
to make any definite statement about our
 problem at  present4 ,our actual       
knowledge of the organisation and       
metabolism of both  nucleus and         
protoplasm is so extremely small and may
 relate to such very  insignificant     
topics1 that any definite decision is   
impossible4 ,i myself  believe that the 
nucleus plays an important part in      
heredity1 perhaps  even a greater one   
than protoplasm1 but this is only my    
belief4#acf    #acf ,surely the new     
results of ,herbst1 mentioned above1 are
 another  indication of the importance  

of something in the nucleus4 ,the first 
stage in parthenogenesis1 which he used 
in his experiments1 is a nuclear        
phenomenon4    ,the discovery of ,gruber
 and others1 that ,protozoa are only    
capable of  restitution if they contain 
at least a fragment of the nucleus1 has 
also been used occasionally as a proof  
of the morphogenetic importance  of the 
nucleus4 ,but might not this absence of 
restitution where nuclear  material is  
lacking be understood equally well on   
the hypothesis of ,loeb  and ,r4 ,s4    
,lillie that the nucleus is a centre of 
oxidation in the cell8  ,remove the     
heart from a vertebrate and the animal  
will not digest any  more2 but in spite 
of that the heart is not the organ of   
digestion4    ,and so we lay stress once
 more upon this point3 that the         
experimental  results of hybridisation  
and the analytical results obtained by  
the  discussion of the                  
complex-equipotential systems are of    
greater value  to the theory of heredity

 than all speculation about the         
importance or  unimportance of special  
constituents of the cell1 of whose      
organisation1  chemistry1 and physics1  
scarcely anything is known at           
present4#acg    #acg ,boveri 799,ergebn4
 b4 d4 ,konstitution etc4 des           
,zellkerns991 ,jena1  #aijd2 and        
8,zellen-,studien ,,vi40 99,jen4        
,zeitschr499 #dc1 #aijg7 has made it    
highly probable by experiments that the 
different chromosomes of the  nucleus of
 the sexual products play a different   
part in morphogenesis1  though not in   
the sense of different single           
representatives of  different single    
organs4 ,this doctrine1 of course1 would
 not alter  the whole problem very much3
 the chromosomes would only be 99means99
 of  morphogenesis and nothing else1 no 
matter whether they were of equal or  of
 different formative value4 ,it only is 
with regard to the problem of  the      
determination of sex 7see page #ajg1    
note #c71 that the morphogenetic        

singularity of 99one99 certain specific 
chromosome can be said to be  proved4   
,,variation ,,and ,,mutation            
,heredity1 it has been said1 may be     
understood as resting upon the fact     
that each organism forms its own initial
 stage again1 and that this  initial    
stage always encounters conditions of   
the same kind4    ,if this statement    
were quite correct1 all the individuals 
of a given  species would be absolutely 
alike everywhere and for ever4 ,but they
  are not alike2 and that they are not  
alike everywhere and for ever is  not   
merely the only real foundation of the  
so-called theory of descent  we possess1
 but also forces us to change a little  
our definition of  heredity1 which now  
proves to have been only a sort of      
approximation to  the truth1 convenient 
for analytical discussion4    ,in the   
first place1 the conditions which       
surround the initial stages  of         
morphogenesis are not quite equal in    
every respect3 and indeed  the offspring

 of a given pair of parents1 or better1 
to exclude all  complications resulting 
from sexual reproduction1 or amphimixis1
 as  ,weismann called it--the offspring 
of one given parthenogenetic female  are
 not all equal among themselves4 ,the   
individuals of each generation  are well
 known to vary1 and it is especially in 
this country that the  so-called        
individual or fluctuating variation has 
been most carefully  studied by         
statistical methods1 ,galton and ,weldon
 being the well-known  pioneers in this 
field4#ach ,in fact1 if we are allowed  
to assume that  this sort of variation  
is the outcome of a variation of        
conditions--in  the most general meaning
 of the word--we only follow the opinion
  which has almost universally been     
adopted by the biologists#aci that  are 
working at this branch of the subject4  
,variation proper is now  generally     
allowed to be the consequence of        
variations in nutrition2  the           
contingencies of the latter result in   

contingencies of the former1  and the   
law of contingencies is the same for    
both1 being the most  general law of    
probability4 ,of course under such an   
aspect fluctuating  variation could     
hardly be called an exception1 but      
rather an addition to  inheritance4     
#ach ,h4 ,m4 ,vernon1 99,variations in  
,animals and ,plants991 ,london1 #aijc4 
#aci ,de ,vries1 99,die                 
,mutationstheorie991 i41 #aija2 and     
,klebs1 99,jahrb4  wiss4 ,bot499 #db1   
#aije4    ,but there are other          
restrictions of our definition of       
heredity4 ,the  initial stage which is  
formed again by an organism is not      
always quite  identical in itself with  
the initial stage of its own parent3    
,bateson  and de ,vries were the first  
to study in a systematic way these real 
exceptions#adj to true inheritance4 ,as 
you know1 de ,vries has given  them the 
name of 8mutations40 ,what is actually  
known on this subject is  not much at   
present1 but nevertheless is of great   

theoretical value1  being the only real 
foundation of all theories of descent1  
as we shall  see in the next lectures4  
8,mutations0 are known to exist at      
present only  among some domesticated   
animals and plants4 ,nothing of a more  
general  character can be said about    
their law or meaning4#ada    #adj ,they 
would not be 8real exceptions0 if ,klebs
 799,arch4 ,entw4 ,mech499  #bd1 #aijg7 
were right in saying that both          
variations and mutations owe  their     
existence to external agents4 ,what is  
really 99proved99 by ,klebs  is the     
possibility of changing the 99type99 of 
a curve of variation and  of provoking  
certain discontinuous varieties by      
external means4 ,see  also ,blaringhem  
799,comptes rend499 #aije-f1 and 99,soc4
 de ,biol499 #ei1 #aije71  and          
,mac,dougal 799,rep4 ,depart4 ,bot4     
,res41 #eth ,year-book ,carnegie        
,inst4991  ,washington1 #abi74    #ada  
,h4 de ,vries1 99,species and           
,varieties3 their ,origin by            

,mutation991  ,london1 #aije4 ,a short  
review of the 8mutation-theory0 is given
 by ,franc  in 99,zeitschrift f4 d4     
,ausbau d4 ,entwickelungslehre991 i4    
#aijg4 ,it is well  known that ,gautier1
 and1 in the first place1 ,korshinsky1  
advocated a  similar view previous to   
the authors named in the text4          
,,conclusions ,,from ,,the ,,first      
,,main ,,part ,,of ,,these ,,lectures   
,in finishing our chapter on            
inheritance1 we at the same time have   
finished the first main part of our     
lectures2 that part of them which  has  
been devoted exclusively to the study of
 the morphogenesis of the               
99individual991 including the           
functioning of the adult individual     
form4  ,we now turn to our second part1 
which is to deal with the problems of   
the diversities of individual forms1    
with morphological systematics4 ,the    
end of our chapter on inheritance has   
already led us to the threshold of  this
 branch of biological science4    ,the  

chief result of the first main part of  
our lectures has been to  prove that an 
autonomy of life phenomena exists at    
least in some  departments of individual
 morphogenesis1 and probably in all of  
them2  the real starting-point of all   
morphogenesis cannot be regarded as a   
machine1 nor can the real process of    
differentiation1 in all cases where  it 
is based upon systems of the harmonious 
equipotential type4 ,there  cannot be   
any sort of machine in the cell from    
which the individual  originates1       
because this cell1 including both its   
protoplasm and its  nucleus1 has        
undergone a long series of divisions1   
all resulting in  equal products1 and   
because a machine cannot be divided and 
in spite of  that remain what it was4   
,there cannot be1 on the other hand1 any
 sort  of machine as the real foundation
 of the whole of an harmonious system1  
including many cells and many nuclei1   
because the development of this  system 
goes on normally1 even if its parts are 

rearranged or partly  removed1 and      
because a machine would never remain    
what it had been in  such cases4    ,if 
our analytical discussions have thus led
 us to establish a typical  kind of     
vitalism1 it follows that we can by no  
means agree with ,wilhelm  ,roux in his 
denomination of the analytical science  
of the individual  form and             
form-production as                      
8,entwickelungsmechanik10 8developmental
  mechanics10 a title1 which1 of course1
 might easily be transformed  into that 
of 8morphogenetic mechanics10 to embrace
 not only normal  development1 but      
restitution and adaptation too4 ,we feel
 unable to speak  of 8mechanics0 where  
just the contrary of mechanics1 in the  
proper  meaning of the word1 has been   
proved to exist4    ,names of course are
 of comparatively small importance1 but 
they  should never be allowed to be     
directly misleading1 as indeed the term 
8,entwickelungsmechanik0 has already    
proved to be4 ,let us rather say1       

therefore1 that we have finished with   
this lecture that part of our  studies  
in biology which has had to deal with   
morphogenetic physiology  or            
physiological morphogenesis4    ,once   
more we repeat1 at this resting-point in
 our discussions1 that both  of our     
proofs of life-autonomy have been based 
upon a careful analysis  of certain     
facts about the distribution of         
morphogenetic potencies in  two classes 
of morphogenetic systems1 and upon      
nothing else4 ,to recall  only one      
point1 we have not said that            
regeneration1 merely because it  is a   
kind of restitution of the disturbed    
whole1 compels us to admit  that        
biological events happen in a specific  
and elemental manner1 but1  indeed1     
regeneration 99does99 prove vitalism1   
because it is founded upon  the         
existence of certain                    
complex-equipotential systems1 the      
analysis of  the genesis of which leads 
to the understanding of life-autonomy4  

,this  distinction1 in fact1 is of the  
greatest logical importance4            
,,part ,,ii    ,,systematics ,,and      
,,history    99,a499 ,,the ,,principles 
,,of ,,systematics      ,,rational      
,,systematics    ,all systematics which 
deserves the predicate 8rational0 is    
founded  upon a concept or upon a       
proposition1 by the aid of which a      
totality  of specific diversities may be
 understood4 ,that is to say3 every     
system claiming to be rational gives us 
a clue by which we are able to          
apprehend either that there cannot exist
 more than a certain number of          
diversities of a certain nature1 or that
 there can be an indefinite  number of  
them which follow a certain law with    
regard to the character  of their       
differences4    ,solid geometry1 which  
states that only five regular bodies are
 possible1  and points out the          
geometrical nature of these bodies1 is a
 model  of what a rational system should
 be4 ,the theory of conic sections  is  

another4 ,take the general equation of  
the second degree with two  unknowns1   
and study all the possible forms it can 
assume by a variation  of its constants1
 and you will understand that only four 
different types  of conic sections are  
possible--the circle1 the ellipse1 the  
hyperbola1  and the parabola4    ,in    
physics and chemistry no perfect        
rational systems have been  established 
hitherto1 but there are many systems    
approaching the ideal  type in different
 departments of these sciences4 ,the    
chemical type of  the monohydric        
saturated alcohols1 for instance1 is    
given by the formula  ,cn,h#bn#a,,oh1   
and in this formula we not only have an 
expression of  the law of composition   
which all possible alcohols are to      
follow1--but1  since we know empirically
 the law of quantitative relation       
between  99n99 and various physical     
properties1 we also possess in our      
formula a  general statement with       
respect to the totality of the          

properties of any  primary alcohol that 
may be discovered or prepared in the    
future4 ,but  chemistry has still higher
 aims with regard to its systematics3   
all of  you know that the so-called     
8periodic law of the elements0 was the  
first  step towards a principle that may
 some day give account of the relation  
of all the physical and chemical        
properties of any so-called element     
with its most important constant1 the   
atomic weight1 and it seems to be       
reserved for the present time to form a 
real fundamental system of the          
8elements0 on the basis of the periodic 
law by the aid of the theory  of        
electrons4 ,such a fundamental system of
 the elements would teach us  that there
 can only be so many elements and no    
more1 and only of such a  kind4 ,in     
crystallography a similar end has been  
reached already by means  of certain    
hypothetic assumptions1 and systematics 
has here accounted  for the limited     
number and fixed character of the       

possible forms of  crystalline symmetry4
    ,it is not difficult to understand  
the general logical type of all         
rational systems1 and logic indeed can  
discover it without appealing  to       
concrete sciences or to geometry4       
,rational systematics is always         
possible whenever there exists any      
fundamental concept or proposition      
which carries with it a principle of    
division2 or to express it somewhat     
differently1 which would lead to        
contradictions1 if division were to  be 
tried in any but one particular manner4 
,the so-called 8genus10 as  will easily 
be perceived1 then embraces all its     
8species0 in such a  manner that all    
peculiarities of the species are        
represented already in  properties of   
the genus1 only in a more general form1 
in a form which  is still unspecified4  
,the genus is both richer in content and
 richer in  extent than are the species1
 though it must be added that its       
richness  in content is1 as it were1    

only latent3 but it may come into       
actuality  by itself and without any    
help from without4    ,we are dealing   
here with some of the most remarkable   
properties of the  so-called synthetic  
judgments 99a priori99 in the sense of  
,kant1 and1  indeed1 it seems that      
rational systematics will only be       
possible where  some concept of the     
categorical class or some proposition   
based upon  such concept lies at the    
root of the matter or at least is       
connected  with it in some way4 ,in     
fact1 all rational systems with regard  
to the  relations of symmetry in natural
 bodies deal ultimately with space2 or  
better1 all systems in such fields are  
able to become rational only if  they   
happen to turn into questions of spatial
 symmetry4    ,all other genera and     
species1 whether of natural bodies or of
 facts1  can be related only on the     
basis of empirical abstraction1 99i4e499
 can  never attain rationality3 here1   
indeed1 the genus is richer in extent   

and poorer in content than are the      
species4 ,the genus is transformed  into
 the species1 not by any inherent       
development of latent properties1  but  
by a mere process of addition of        
characteristic points4 ,it is           
impossible to deduce the number or law  
or specifications of the species  from  
the genus4 ,mere 8classification10 if we
 may reserve the honorable  name of     
systematics for the rational type1 is   
possible here1 a mere  statement in the 
form of a catalogue1 useful for         
orientation but for  nothing more4 ,we  
may classify all varieties of hats or of
 tables in the  same way4               
,,biological ,,systematics    ,at this  
point we return from our logical        
excursion to our proper subject  of     
biology2 for ,i am sorry to say         
biological systematics is at present  of
 our second type of systematics         
throughout3 it is classification pure   
and simple4 ,we have a catalogue in our 
hands1 but nothing more4    ,such a     

statement of fact conveys not a particle
 of censure1 casts not  the least       
reflection on the gifted men who created
 the classification of  animals or      
plants4 ,it is absolutely necessary to  
have such a catalogue1  and indeed the  
catalogue of the organisms can be said  
to have been  improved enormously during
 the advance of empirical and           
descriptive  biological science4 ,any   
classification improves as it becomes   
more  8natural10 as the different       
possible schemes of arrangement1 the    
different reasons of division1 agree    
better and better in their results2     
and1 in fact1 there has been a great    
advance of organic classification  in   
this direction4 ,the 8natural0 system   
has reached such perfection1  that what 
is related from one point of view seems 
nearly related also  from almost all    
points of view which are applicable1 at 
least from those  which touch the most  
important characteristics4 ,there has   
been a real  weighing of all the        

possible reasons of division1 and that  
has led to a  result which seems to be  
to some extent final4    ,but1          
nevertheless1 we do not understand the  
99raison d'tre99 of the  system of      
organisms2 we are not at all able to say
 that there must be  these classes or   
orders or families and no others1 and   
that they must be  such as they are4    
,shall we ever be able to understand    
that8 ,or will organic systematics      
always remain empirical classification8 
,we cannot answer this question4  ,if we
 could1 indeed1 we should have what we  
desire6 ,as simple relations  of space  
are certainly not the central point of  
any problematic rational  organic       
systematics even of the future1 the     
question arises1 whether  there could be
 found any principle of another type in 
the realm of  synthetic 99a priori99    
judgments which could allow an inherent 
sort of  evolution of latent            
diversities1 as do all judgments about  
spatial  symmetry4 ,at the end of the   

second course of these lectures1 which  
is to  be delivered next summer1 we     
shall be able to say a few more words   
about  this important point4    ,the    
concept of what is called 8a type10 due 
almost wholly to ,cuvier and  ,goethe1  
is the most important of all that       
classification has given to  us4 ,hardly
 second in importance is the discovery  
of the 8correlation of  parts10 as a    
sort of connection which has the        
character of necessity  without being   
immediately based upon causality4 ,rdl  
seems to be  the only modern author who 
has laid some stress on this topic4 ,the
  harmony which we have discovered in   
development is also part of this        
correlation4 ,when1 later on1 we come to
 discuss analytically our well          
established entelechy as the ultimate   
basis of individual organisation1  we   
shall be able to gain more satisfactory 
ideas with respect to the  meaning of   
the non-causal but necessary connection1
 embraced in the  concepts of type and  

of correlation of parts4    ,the type is
 a sort of irreducible arrangement of   
different parts2 the  correlation deals 
with the degree and the quality of what 
may be called  the actual make of the   
parts1 in relation to one another3 all  
ruminants1  for instance1 are           
cloven-footed1 the so-called dental     
formulae are  characteristic of whole   
groups of mammals4 ,of course all such  
statements  are empirical and have their
 limits3 but it is important that they  
are  possible4#adb    #adb ,recent years
 have created the beginnings of a       
systematics based on  chemical          
differences of metabolism and its       
products3 such differences in  fact have
 been found to go hand in hand with     
diversities of the type in  some cases  
7v4 ,bunge1 ,przibram1 etc474    ,it has
 been the chief result of comparative   
embryology to show that the  type as    
such is more clearly expressed in       
developmental stages than  it is in the 
adults1 and that therefore the          

embryological stages of  different      
groups may be very much more similar to 
each other than are  the adults3 that is
 the truth contained in the so-called   
8biogenetisches  ,grundgesetz40 ,but the
 specific differences of the species are
 not  wanting in any case of ontogeny1  
in spite of such similarities in        
different groups during development4    
,we have applied the name 8systematics0 
or1 if rationality is excluded1         
8classification0 to all that part of a  
science which deals with  diversities   
instead of generalities3 in such a wide 
meaning systematics1  of course1 is not 
to be confused with that which is       
commonly called so  in biology1 and     
which describes only the exterior       
differences of form4  ,our systematics  
is one of the two chief parts of        
biology2 what are  called comparative   
anatomy and comparative embryology are  
its methods4  ,for it must be well      
understood that these branches of       
research are only  methods and are not  

sciences by themselves4          99,b499
 ,,the ,,theory ,,of ,,descent      #a4 
,,generalities    ,it is most generally 
conceded at the present time that the   
actually  existing state of all         
organisms whatsoever is the result of   
their  history4 ,what does that mean8   
,what are the foundations upon which the
  assumption rests8 ,what is the        
relation of systematics to history8 ,in 
raising such questions and              
considerations we are treading the      
ground  sacred to the theory of descent4
    ,i well know that you prefer the    
name 8theory of evolution0 for what  ,i 
am speaking of3 but it may be misleading
 in various respects4 ,we  already know 
that quite a determinate meaning has    
been given to the word  8evolutio0 as   
applied to individual morphogenesis1    
8evolutio0 being  here opposed to       
8epigenesis40 ,now there would be       
nothing against the  use of the word    
evolution in a wider sense--indeed it is
 often applied  nowadays to denote the  

fact that a something is actually       
8evolved0 in  embryology--if only our   
entelechy had taken the place of the    
machine  of the mechanists4 ,but that is
 the very point3 there must be a real   
8evolving0 of a something1 in order that
 the word evolution may be  justified   
verbally3 and that is not the case in   
so-called phylogeny4 ,at  least we know 
nothing of an evolutionary character in 
the problematic  pedigree of the        
organisms1 as we shall see more fully   
hereafter4 ,the  term 8theory of        
descent0 is therefore less open to      
objection than is the  usual ,english   
term4 ,the word transformism1 as used by
 the ,french1 would  also be a very good
 title4    ,the theory of descent is the
 hypothetic statement that the organisms
  are really allied by blood among each 
other1 in spite of their                
diversities4#adc ,the question about    
their so-called monophyletic  or        
polyphyletic origin is of secondary     
importance compared with the  statement 

of relationship in general4    #adc ,we 
prefer this unpretending definition of  
the theory of descent  to every other4  
,as soon as one introduces into the     
definition the  concept of the          
8transmutability of species10 the term  
8species0 would  require a special      
definition1 and that would lead to      
difficulties which  it is unnecessary to
 deal with for our main purposes4 ,it   
has been  remarked by ,kraan1           
799,ausichten und ,gesprche ber die     
individuelle und  specifische           
,gestaltung in der ,natur997 and by     
several other writers1  that the problem
 of mutability or immutability of course
 relates to the  individuals in the     
first place4 ,i should like to add to   
this remark that  the possibility must  
be admitted of the individuals being    
transmutable1  whilst the 8species0 are 
not transmutable at the same time1 the  
line  of the 8species0 being a fixed    
order1 through which the 8individuals0  
have to pass in the course of their     

generations4 ,what is meant here  will  
become clearer1 when we study the       
different possible aspects of           
8phylogeny40    ,there are two different
 groups of facts which have suggested   
the idea  of transformism3 none of these
 facts can be said to be conclusive1 but
  there certainly is a great amount of  
probability in the whole if taken       
together4    ,the first group of        
evidences which lead to the hypothesis  
of the real  relationship of organisms  
consists of facts relating to the       
geographical  distribution of animals   
and plants and to palontology4 ,as to   
geography1  it seems to me that the     
results of the floral and faunal study  
of groups  of islands are to be         
mentioned in the first place4 ,if1      
indeed1 on  each of the different       
islands1 99,a99 99,b99 99,c99 and       
99,d991 forming a group1  the species of
 a certain genus of animals or plants   
are different in a  certain respect1 and
 show differences also compared with the

 species  living on the neighbouring    
continent1 of which there is geological 
evidence that the islands once formed a 
part1 whilst there is no change  in the 
species on the continent itself for very
 wide areas1 then1 no  doubt1 the       
hypothesis that all these differing     
species once had a common  origin1 the  
hypothesis that there is a certain      
community among them all1  will serve to
 elucidate in some way what would seem  
to be very abstruse  without it4 ,and   
the same is true of the facts of        
palaeontology4 ,in  the geological      
strata1 forming a continuous series1 you
 find a set of  animals1 always typical 
and specific for every single           
stratigraphical  horizon1 but forming a 
series just as do those horizons4 ,would
 not the  whole aspect of these facts   
lose very much of its peculiarity if you
  were to introduce the hypothesis that 
the animals changed with the  strata8   
,the continuity of life1 at least1 would
 be guaranteed by such an  assumption4  

,the geographical and geological        
evidences in favour of the theory of    
descent are facts taken from sciences   
which are not biology proper2 they  are 
not facts of the living but only facts  
about the living4 ,that is not  quite   
without logical importance1 for it shows
 that not biology alone  has led to the 
transformism hypothesis4 ,were it       
otherwise1 transformism  might be said  
to be a mere hypothesis 99ad hoc992 but 
now this proves to  be not the case1    
though we are far from pretending that  
transformism  might be regarded as      
resting upon a real 99causa vera994     
,but let us study the second group of   
facts which support the theory of       
descent4 ,it is a group of evidences    
supplied by biology itself that we  meet
 here1 there being indeed some features 
in biology which can be  said to gain   
some light1 some sort of elucidation1 if
 the theory of  descent is accepted4 ,of
 course1 these facts can only be such as
 relate  to specific diversities1 and   

indeed are facts of systematics2 in     
other  words1 there exists something in 
the very nature of the system of        
organisms that renders transformism     
probable4 ,the system of animals and    
plants is based upon a principle which  
might be called the principle  of       
99similarities and diversities by       
gradation992 its categories are not     
uniform but different in degree and     
importance1 and there are different     
kinds of such differences4 ,no doubt1   
some light would be shed upon this      
character of the system1 if we were     
allowed to assume that the relation     
between similarities and diversities1   
which is gradual1 corresponded to  a    
blood-relationship1 which is gradual    
also4      ,,the ,,covert ,,presumption 
,,of ,,all ,,theories ,,of ,,descent    
,we have used very neutral and somewhat 
figurative words1 in order to  show what
 might be called the logical value of   
the theory of descent1  in order to     
signify its value with respect to       

so-called 8explanation40  ,we have      
spoken of the 8light0 or the            
8elucidation0 which it brings1 of  the  
8peculiarity of aspect0 which is        
destroyed by it4 ,we have used this     
terminology intentionally1 for it is    
very important to understand that  a    
specific though hidden addition is made 
almost unconsciously to the  mere       
statement of the hypothesis of descent  
as such1 whenever this  hypothesis is   
advocated in order to bring light or    
elucidation into any  field of          
systematic facts4 ,and this additional  
hypothesis indeed must be  made from the
 very beginning1 quite irrespective of  
the more detailed  problems of the law  
of transformism1 in order that 99any99  
sort of  so-called explanation by means 
of the theory of descent may be possible
  at all4 ,whenever the theory that1 in 
spite of their diversities1 the         
organisms are related by blood1 is to be
 really useful for explanation1  it must
 necessarily be assumed in every case   

that the steps of change1  which have   
led the specific form 99,a99 to become  
the specific form 99,b991  have been    
such as only to change 99in part99 that 
original form 99,a994 ,that  is to say3 
the similarities between 99,a99 and     
99,b99 must never have become           
overshadowed by their diversities4      
,only on this assumption1 which indeed  
is a newly formed additional  subsidiary
 hypothesis1 joined to the original     
hypothesis of descent in  general--a    
hypothesis regarding the very nature of 
transformism--only  on this almost      
hidden assumption is it possible to     
speak of any sort of  8explanation0     
which might be offered by the theory of 
transformism to  the facts of geography1
 geology1 and biological systematics4   
,later on  we shall study more deeply   
the logical nature of this              
8explanation02 at  present it must be   
enough to understand this term in its   
quasi-popular  meaning4    ,what is     
explained by the hypothesis of          

descent--including the additional       
hypothesis1 that there always is a      
prevalence of the similarities  during  
transformism--is the fact that in       
palaeontology1 in the groups  of island 
and continent faunae and florae taken as
 a whole1 as well as  in the single     
categories of the system1 the           
similarities exceed the  diversities4   
,the 99similarities99 now are           
8explained02 that is to say1  they are  
understood as resting on but one        
principle3 the similarities  are        
understood as being due to              
inheritance2#add and now we have but one
  problem instead of an indefinite      
number4 ,for this reason ,wigand granted
  that the theory of descent affords    
what he calls a numerical reduction  of 
problems4    #add ,it seems to me that  
my argument gives a broader logical     
basis  to the theory of descent than    
does that of ,g4 ,wolff 799,die         
,begrndung  der ,abstammungslehre991    
,mnchen1 #aijg74 ,wolff starts from the 

concept  of organic teleology1 and thus 
finds the only reason for accepting  the
 theory of transformism in the existence
 of so-called 8rudimentary  organs02    
these organs would form an obstacle to  
teleology if they could  not be regarded
 as inherited4    ,understanding then   
what is explained by the theory of      
descent with its  necessary appendix1 we
 also understand at once what is 99not99
 elucidated  by it3 the diversities of  
the organism remain as unintelligible as
 they  always were1 even if we know that
 inheritance is responsible for what  is
 similar or equal4 ,now there can be no 
doubt that the diversities are  the more
 important point in systematics2 if     
there were only similarities  there     
would be no problem of systematics1 for 
there would be no system4  ,let us be   
glad that there are similarities in the 
diversities1 and that  these            
similarities have been explained in some
 way2 but let us never  forget what is  
still awaiting its explanation4         

,unfortunately it has been  forgotten   
far too often4      ,,the ,,small       
,,value ,,of ,,pure ,,phylogeny    ,and 
so we are led to the negative side of   
the theory of transformism1  after      
having discussed its positive half4 ,the
 theory of descent as  such1 without a  
real knowledge of the factors which are 
concerned in  transformism1 or of the   
law of transformism1 in other terms1    
leaves the  problem of systematics      
practically where it was1 and adds      
really nothing  to its solution4 ,that  
may seem very deplorable1 but it is     
true4    ,imagine so-called historical  
geology1 without any knowledge of the   
physical and chemical factors which are 
concerned in it3 what would  you have   
except a series of facts absolutely     
unintelligible to you8 ,or  suppose that
 some one stated the cosmogenetic theory
 of ,kant and ,laplace  without there   
being any science of mechanics3 what    
would the theory mean  to you8 ,or      
suppose that the whole history of       

mankind was revealed to  you1 but that  
you had absolutely no knowledge of      
psychology3 what would  you have but    
facts and facts and facts again1 with   
not a morsel of real  explanation8      
,but such is the condition in which     
so-called phylogeny stands4 ,if it  is  
based only on the pure theory of        
transformism1 there is nothing          
explained at all4 ,it was for this      
reason that the philosopher ,liebmann   
complained of phylogeny that it         
furnishes nothing but a 8gallery of     
ancestors40 ,and this gallery of        
ancestors set up in phylogeny is not    
even certain2 on the contrary1 it is    
absolutely uncertain1 and very  far from
 being a fact4 ,for there is no sound   
and rational principle  underlying      
phylogeny2 there is mere fantastic      
speculation4 ,how could it  be otherwise
 where all is based upon suppositions   
which themselves have  no leading       
principle at present8 ,i should not like
 to be misunderstood  in my polemics    

against phylogeny4 ,i fully grant you   
that it may be  possible in a few cases 
to find out the phylogenetic history of 
smaller  groups with some probability1  
if there is some palaeontological       
evidence in support of pure comparative 
anatomy2 and ,i also do not  hesitate to
 allow that such a statement would be of
 a certain value with  regard to a      
future discovery of the 8laws0 of       
descent1 especially if  taken together  
with the few facts known about          
mutations4 ,but it is quite  another    
thing with phylogeny on the larger      
scale4 ,far more eloquent than  any     
amount of polemics is the fact that     
vertebrates1 for instance1 have  already
 been 8proved0 to be descended from1    
firstly1 the amphioxus2  secondly1 the  
annelids2 thirdly1 the 99,sagitta99 type
 of worms2 fourthly1  from spiders2     
fifthly1 from 99,limulus991 a group of  
crayfishes2 and  sixthly1 from          
echinoderm larvae4 ,that is the extent  
of my acquaintance  with the literature1

 with which ,i do not pretend to be     
specially  familiar4 ,emil du           
,bois-,reymond said once that phylogeny 
of this sort is  of about as much       
scientific value as are the pedigrees of
 the heroes of  ,homer1 and ,i think we 
may fully endorse his opinion on this   
point4      ,,history ,,and             
,,systematics    ,a few words should be 
devoted to the relations between history
 and  systematics in biology4 ,is there 
no contradiction between historical     
development and a true and rational     
system which1 we conceded1 might  exist 
some day in biological sciences1 even   
though it does not at  present8 ,by no  
means4 ,a totality of diversities is    
regarded from quite  different points of
 view if taken as the material of a     
system1 and if  considered as realised  
in time4 ,we have said that chemistry   
has come  very near to proper rational  
systematics1 at least in some of its    
special fields2 but the compounds it    
deals with at the same time may  be said

 to have originated historically also1  
though not1 of course1  by a process of 
propagation4 ,it is evident at once that
 the geological  conditions of very     
early times prohibited the existence of 
certain  chemical compounds1 both       
organic and inorganic1 which are known  
at  present4 ,none the less these       
compounds occupy their proper place in  
the system4 ,and there may be many      
substances theoretically known to       
chemical systematics which have never   
yet been produced1 on account  of the   
impossibility of arranging for their    
proper conditions of  appearance1 and   
nevertheless they must be said to       
8exist40 8,existence10  as understood in
 systematics1 is independent of special 
space and of  special time1 as is the   
existence of the laws of nature3 we may 
speak of  a ,platonic kind of existence 
here4 ,of course it does not contradict 
this  sort of ideal existence if reality
 proper is added to it4    ,thus the    
problem of systematics remains1 no      

matter whether the theory  of descent be
 right or wrong4 ,there always remains  
the question about  the totality of     
diversities in life3 whether it may be  
understood by  a general principle1 and 
of what kind that principle would be4   
,as1  in fact1 it is most probably by   
history1 by descent1 that organic       
systematics is brought about1 it of     
course most probably will happen  some  
day that the analysis of the causal     
factors concerned in the  history will  
serve to discover the principle of      
systematics also4    ,let us now glance 
at the different kinds of hypotheses    
which have been  established in order to
 explain how the descent of the         
organisms might  have been possible4 ,we
 have seen that the theory of           
transformism alone  is not worth very   
much as a whole1 unless at least a      
hypothetical  picture can be formed of  
the nature of the transforming factors3 
it is  by some such reasoning that      
almost every author who has defended the

  theory of descent in its universality 
tries to account for the manner in      
which organisms have acquired their     
present diversities4      #b4 ,,the     
,,principles ,,of ,,darwinism    ,there 
is no need in our times and particularly
 in this country1 to  explain in a full 
manner the theory known under the name  
of ,darwinism4  ,all of you know this   
theory1 at least in its outlines1 and so
 we may  enter at once upon its analytic
 discussion4 ,a few words only ,i beg   
you to allow me as to the name of       
8,darwinism0 itself4 ,strange to say1   
,darwinism1 and the opinion of ,charles 
,darwin about the descent of  organisms1
 are two different things4 ,darwin1 the 
very type of a man  devoted to science  
alone and not to personal               
interests1--,darwin was  anything but   
dogmatic1 and yet ,darwinism is         
dogmatism in one of its  purest forms4  
,darwin1 for instance1 gave the greatest
 latitude to the  nature of the         
variations which form the battleground  

of the struggle  for existence and      
natural selection2 and he made great    
allowances for  other causal            
combinations also1 which may come into  
account besides  the indirect factors of
 transformism4 ,he was ,lamarckian to a 
very  far-reaching extent4 ,and he had  
no definite opinion about the origin    
and the most intimate nature of life in 
general4 ,these may seem to  be defects 
but really are advantages of his theory4
 ,he left open the  question which he   
could not answer1 and1 in fact1 he may  
be said to be a  good illustration of   
what ,lessing says1 that it is not the  
possession  of truth but the searching  
after it1 that gives happiness to man4  
,it was  but an outcome of this mental  
condition that ,darwin's polemics never 
left the path of true scientific        
discussions1 that he never in all his   
life abused any one who found reason to 
combat his hypotheses1 and that  he     
never turned a logical problem into a   
question of morality4    ,how different 

is this from what many of ,darwin's     
followers have made out  of his         
doctrines1 especially in ,germany2 how  
far is 8,darwinism0 removed  from       
,darwin's own teaching and character6   
,it is to ,darwinism of the 99dogmatic99
 kind1 however1 that our next           
discussions are to relate1 for1 thanks  
to its dogmatism1 it has the  advantage 
of allowing the very sharp formulation  
of a few causal  factors1 which 99a     
priori99 might be thought to be         
concerned in organic  transformism1     
though we are bound to say that a really
 searching  analysis of these factors   
ought to have led to their rejection    
from the  very beginning4    ,the       
logical structure of dogmatic ,darwinism
 reveals two different parts1  which    
have nothing at all to do with one      
another4      ,,natural ,,selection     
,we shall first study that part of it   
which is known under the title  of      
natural selection1 irrespective of the  
nature of the causes of  primary        

differences1 or1 in other words1 the    
nature of variability4  ,this part may  
be said to belong to ,darwin's personal 
teachings and not  only to 8,darwinism40
 ,the offspring of a certain number of  
adults show  differences compared with  
each other2 there are more individuals  
in the  offspring than can grow up under
 the given conditions1 therefore there  
will be a struggle for existence amongst
 them1 which only the fittest  will     
survive2 these survivors may be said to 
have been 8selected0 by  natural means4 
,it must be certain from the very       
beginning of analysis that natural      
selection1 as defined here1 can only    
eliminate what cannot survive1 what     
cannot stand the environment in the     
broadest sense1 but that natural        
selection never is able to create       
diversities4 ,it always acts negatively 
only1 never positively4 ,and therefore  
it can 8explain0--if you will  allow me 
to make use of this ambiguous word--it  
can 8explain0 only why  certain types of

 organic specifications1 imaginable 99a 
priori991 do  99not99 actually exist1   
but it never explains at all the        
existence of the  specifications of     
animal and vegetable forms that are     
actually found4 ,in  speaking of an     
8explanation0 of the origin of the      
living specific forms  by natural       
selection one therefore confuses the    
sufficient reason for  the non-existence
 of what there is not1 with the         
sufficient reason for  the existence of 
what there is4 ,to say that a man has   
explained some  organic character by    
natural selection is1 in the words of   
,ngeli1 the  same as if some one who is 
asked the question1 8,why is this tree  
covered  with these leaves10 were to    
answer 8,because the gardener did not   
cut  them away40 ,of course that would  
explain why there are no more leaves    
than those actually there1 but it never 
would account for the existence  and    
nature of the existing leaves as such4  
,or do we understand in the  least why  

there are white bears in the ,polar     
,regions if we are told that  bears of  
other colours could not survive8    ,in 
denying any real explanatory value to   
the concept of natural  selection ,i am 
far from denying the action of natural  
selection4 ,on  the contrary1 natural   
selection1 to some degree1 is           
99self-evident992  at least as far as it
 simply states that what is incompatible
 with  permanent existence cannot exist 
permanently1 it being granted that  the 
originating of organic individuals is   
not in itself a guarantee of            
permanency4 ,chemical compounds1 indeed1
 which decompose very rapidly  under the
 conditions existing at the time when   
they originated may also  be said to    
have been eliminated by 8natural        
selection40 ,it is another  question1 of
 course1 whether in fact all            
eliminations among organic  diversities 
are exclusively due to the action of    
natural selection in  the proper        
,darwinian sense4 ,it has been pointed  

out already by several  critics of      
,darwinism and most clearly by ,gustav  
,wolff1 that there are  many cases in   
which an advantage with regard to       
situation will greatly  outweigh any    
advantage in organisation or physiology4
 ,in a railway  accident1 for instance1 
the passengers that survive are not     
those who  have the strongest bones1 but
 those who occupied the best seats2 and 
the eliminating effect of epidemics is  
determined at least as much by          
localities1 99e4g499 special houses or  
special streets1 as by the degree  of   
immunity4 ,but1 certainly1 natural      
selection is a 99causa vera99 in many   
other cases4    ,we now may sum up our  
discussion of the first half of         
,darwinism4  ,natural selection is a    
negative1 an eliminating factor in      
transformism2  its action is            
self-evident to a very large degree1 for
 it simply  states that things do not   
exist if their continuance under the    
given  conditions is impossible4 ,to    

consider natural selection as a positive
  factor in descent would be to confound
 the sufficient reason for the          
non-existence of what is not1 with the  
sufficient reason of what is4           
,natural selection has a certain        
important logical bearing on            
systematics1 as a science of the future1
 which has scarcely ever been  alluded  
to4 ,systematics of course has to deal  
with the totality of the  possible1 not 
only of the actual diversities2 it      
therefore must remember  that more forms
 may be possible than are actual1 the   
word 8possible0  having reference in    
this connection to originating1 not to  
surviving4  ,moreover1 systematics is   
concerned not only with what has been   
eliminated by selection1 but also with  
all that might have originated  from the
 eliminated types4 ,by such reasoning   
natural selection gains a  very         
important aspect--but a logical aspect  
only4      ,,fluctuating ,,variation    
,,the ,,alleged ,,cause ,,of ,,organic  

,,diversity    ,the second doctrine of  
dogmatic ,darwinism states that all the 
given  diversities among the organisms  
that natural selection has to work  upon
 are offered to natural selection by    
so-called fluctuating  variation2 that  
is1 by variation as studied by means of 
statistics4  ,this sort of variation1   
indeed1 is maintained to be indefinite  
in  direction and amount1 at least by   
the most conservative ,darwinians2 it   
has occasionally been called a real     
differential2 in any case it is  looked 
upon as being throughout contingent with
 regard to some unity  or totality2     
which1 of course1 is not to mean that it
 has not had a  sufficient reason for   
occurring4    ,it could hardly be said  
to be beyond the realm of possibility   
that such  differences among organic    
species as only relate to degree or     
quantity  and perhaps to numerical      
conditions also1 might have been        
8selected0 out  of given contingent     
variations1 if but one postulate could  

be regarded  as fulfilled4 ,this        
postulate may appropriately be stated as
 the fixation  of new averages of       
variation by inheritance4 ,let the      
average value of  a variation1 with     
regard to a given property of a given   
species be 99n99  and let the value     
99n99  99m99--99m99 being               
variable--which is represented in  fewer
 individuals of course than is 99n991 be
 such as to offer advantages  in the    
struggle for existence2 then the        
individuals marked by 99n99  99m99  will
 have the greater chance of surviving4  
,our postulate now states  that1 in     
order that a permanent increase of the  
average value of the  variation in      
question may be reached1 99n99  99m99 in
 any of its variable  forms must be able
 to become the average value of the     
second generation1  as 99n99 was the    
average value of the first4 ,out of the 
second generation  again it would be the
 few individuals marked by 99n99  99m99 
99o991 which  would be selected2 99n99  

99m99  99o99 would be the new average2  
afterwards  99n99  99m99  99o99  99p99  
would be selected1 would become the new 
average1  and so on4 ,a black variety   
for instance might be selected by such a
  series of processes out of a          
grey-coloured one without difficulty4   
,but our postulate is not beyond all    
doubt3 certain experiments1 at  least1  
which have been carried out about the   
summation of variations  of the true    
fluctuating type by any kind of         
selection seem to show  that there may  
be a real progress for a few            
generations1 but that this  progress is 
always followed by a reversion4 ,of     
course our experience  is by no means   
complete on this subject1 and1 indeed1  
it may be shown  in the future that     
positive transforming effects of        
fluctuating  variability1 in connection 
with selective principles1 are possible 
in  the case of new quantitative        
differences 7in the widest sense71 but  
we  are not entitled to say so at       

present4    ,and this is the only       
condition on which we can give credit to
 the second  doctrine of dogmatic       
,darwinism4 ,its second principle1      
indeed1 proves  to be absolutely        
inadequate to explain the origin of any 
other kind of  specific properties      
whatever4    ,i cannot enter here into  
the whole subject of ,darwinian         
criticism4#ade  ,our aims are of a      
positive character1 they desiderate     
construction  and only use destruction  
where it is not to be avoided4 ,so ,i   
shall  only mention that dogmatic       
,darwinism has been found to be unable  
to  explain every kind of mutual        
adaptations1 99e4g499 those existing    
between  plants and insects2 that it can
 never account for the origin of those  
properties that are indifferent to the  
life of their bearer1 being mere        
features of organisation as an          
arrangement of parts2 that it fails in  
the face of all portions of organisation
 which are composed of many  different  

parts--like the eye--and nevertheless   
are functional units  in any passive or 
active way2 and that1 last not least1 it
 has been  found to be quite inadequate 
to explain the first origin of all newly
  formed constituents of organisation   
even if they are not indifferent3  for  
how could any rudiment of an organ1     
which is not functioning at all1  not   
only be useful to its bearer1 but be    
useful in such a degree as to  decide   
about life or death8    #ade ,see       
,wigand1 99,der ,darwinismus und die    
,naturforschung ,newton's und           
,cuvier's991 ,braunschweig1 #ahgd-g2    
,ngeli1 99,mechanisch-physiologische    
,theorie der ,abstammungslehre991       
,mnchen1 #ahhd2 ,g4 ,wolff1 99,beitrge  
zur  ,kritik der ,darwin'schen ,lehre991
 #bnd ed4 ,leipzig1 #ahih2 etc4    ,it  
is only for one special feature that ,i 
should like to show1 by  a more full    
analysis1 that dogmatic ,darwinism does 
not satisfy the  requirements of the    
case4 ,the special strength of          

,darwinism is said to  lie in its       
explaining everything that is useful in 
and for organisms2  the competitive     
factor it introduces does indeed seem to
 secure at least  a relative sort of    
adaptedness between the organism and its
 needs4 ,but  in spite of that1 we shall
 now see that ,darwinism fails          
absolutely to  explain those most       
intimate organic phenomena which may be 
said to be  the most useful of all4     
,darwinism in its dogmatic form is not  
able to explain the origin of any  sort 
of organic restitution2 it is altogether
 impossible to account for  the         
restitutive power of organisms by the   
simple means of fluctuating  variation  
and natural selection in the struggle   
for existence4 ,here we  have the       
logical 99experimentum crucis99 of      
,darwinism4    ,let us try to study in  
the ,darwinian style the origin of the  
regenerative faculty1 as shown in the   
restitution of the leg of a  newt4 ,all 
individuals of a given species of the   

newt1 say 99,triton  taeniatus991 are   
endowed with this faculty2 all of them  
therefore must  have originated from    
ancestors which acquired it at some time
 or other4  ,but this necessary         
supposition implies that all of these   
ancestors must  have lost their legs in 
some way1 and not only one1 but all four
 of  them1 as they could not have       
acquired the restitutive faculty        
otherwise4  ,we are thus met at the very
 beginning of our argument by what must 
be  called a real absurdity1 which is   
hardly lessened by the assumption that  
regeneration was acquired not by all    
four legs together1 but by one  after   
the other4 ,but it is absolutely        
inevitable to assume that 99all99  the  
ancestors of our 99,triton99 must have  
lost one leg1 or more correctly1  that  
only those of them survived which had   
lost one6 ,otherwise not all  newts at  
the present day could possess the       
faculty of regeneration6 ,but  a second 
absurdity follows the first one2 out of 

the ancestors of our  newt1 which       
survived the others by reason of having 
lost one of their  legs1 there were     
selected only those which showed at     
least a very small  amount of healing of
 their wound4 ,it must be granted that  
such a step  in the process of          
selection1 taken by itself1 would not at
 all seem to  be impossible2 since      
healing of wounds protects the animals  
against  infection4 ,but the process    
continues4 ,in every succeeding stage of
 it  there must have survived only those
 individuals which formed just a  little
 more of granulative tissue than did the
 rest3 though 99neither99  they         
themselves 99nor99 the rest could use   
the leg1 which indeed was  not present6 
,that is the second absurdity we meet in
 our attempt at a  ,darwinian           
explanation of the faculty of           
regeneration2 but ,i believe the  first 
one alone was sufficient4    ,if we were
 to study the 8selection0 of the faculty
 of one of the  isolated blastomeres of 

the egg of the sea-urchin to form a     
whole larva  only of smaller size1 the  
absurdities would increase4 ,at the very
  beginning we should encounter the     
absurdity1 that of all the individuals  
there survived only those which were not
 whole but half2 for 99all99            
sea-urchins are capable of the          
ontogenetical restitution in question1  
99all99 of their ancestors therefore    
must have acquired it1 and they  could  
do that only 99if99 they became halved  
at first by some accident  during early 
embryology4 ,but we shall not insist any
 further on this  instance1 for it would
 not be fair to turn into ridicule a    
theory which  bears the name of a man   
who is not at all responsible for its   
dogmatic  form4 ,indeed1 we are speaking
 against ,darwinism of the most dogmatic
  form only1 not against ,darwin        
himself4 ,he never analysed the         
phenomena  of regeneration or of        
embryonic restitution--they lay in a    
field very  unfamiliar to him and to his

 time4 ,i venture to say that if he had 
taken  them into consideration1 he would
 have agreed with us in stating that    
his theory was not at all able to cover 
them2 for he was prepared to  make great
 concessions1 to ,lamarckism for        
instance1 in other branches of  biology1
 and he did not pretend1 to know what   
life itself is4    ,darwin was not a    
decided materialist1 though materialism 
has made  great capital out of his      
doctrines1 especially in ,germany4 ,his 
book1  as is well known1 is entitled    
8,the ,origin of 99,species9910 that is 
of  organic 99diversities991 and he     
himself possibly might have regarded all
  restitution as belonging to the       
original properties of life1 anterior to
  the originating of diversities4       
,personally he might possibly be called 
even a vitalist4 ,thus dogmatic         
8,darwinism0 in fact is driven into all 
the absurdities mentioned above1 whilst 
the 8doctrine of ,darwin0 can  only be  
said to be wrong on account of its      

failing to explain mutual  adaptation1  
the origin of new organs1 and some other
 features in organic  diversities2 the  
original properties of life were left   
unexplained by it  intentionally4       
,,darwinism ,,fails ,,all ,,along ,,the 
,,line    ,the result of our discussion 
then must be this3 selection has proved 
to  be a negative factor only1 and      
fluctuating variation as the only way   
in which new properties of the organisms
 might have arisen has proved  to fail  
in the most marked manner1 except       
perhaps for a few merely  quantitative  
instances4 ,such a result betokens the  
complete collapse  of dogmatic          
,darwinism as a general theory of       
descent3 the most typical  features of  
all organisms remain as unexplained as  
ever4    ,what then shall we put in the 
place of pure ,darwinism8 ,let us first 
try  a method of explanation which was  
also adopted occasionally by ,darwin    
himself3 let us study that form of      
transformation theories which is        

commonly known under the title of       
,lamarckism4      #c4 ,,the ,,principles
 ,,of ,,lamarckism4    ,as the word     
8,darwinism0 does not signify the proper
 theoretical system  of ,charles        
,darwin1 so ,lamarckism as commonly     
understood nowadays is a  good deal     
removed from the original views of ,jean
 ,baptiste ,lamarck4  ,lamarckism is    
generally regarded as reducing all      
organic diversities to  differences in  
the needs of individual life1 but       
,lamarck himself1 as  must be emphasised
 from the very beginning1 did not at all
 maintain the  opinion that the great   
characteristics of the types were only  
due to  such accidental factors4 ,he    
supposed a sort of law of organisation  
to  be at the root of systematics1 as   
developed in history1 and the needs  of 
life were only responsible1 according to
 him1 for splitting the  given types of 
organisation into their ultimate        
branches4 ,thus ,lamarck1  to a great   
extent at any rate1 belongs to a group  

of authors that we  shall have to study 
afterwards3 authors who regard an       
unknown law of  phylogenetic development
 as the real basis of transformism4     
,modern  so-called ,neo-,lamarckism1 on 
the other hand1 has indeed conceded the 
principle of needs to be the sole       
principle of transformism4 ,let us then 
study ,lamarckism in its dogmatic modern
 form4      ,,adaptation ,,as ,,the     
,,starting-,,point    ,all facts of     
morphological adaptations--facts which  
we have analysed  already from a        
different point of view1 as being among 
the most typical  phenomena of organic  
regulation--form the starting-point of  
this  theory1 and it must be granted    
that they form a very solid foundation1 
for they are facts4 ,the theory only has
 to enlarge hypothetically the  realm of
 these facts1 or rather the realm of the
 law that governs them4  ,indeed1 it is 
assumed by ,lamarckism that the organism
 is endowed with  the faculty of        
responding to 99any99 change of the     

environment which may  change its       
function by a morphologically expressed 
alteration of its  functional state and 
form1 which is adapted to the state of  
conditions  imposed from without4 ,of   
course1 as stated in this most general  
form1  the assumption is not true1 but  
it is true within certain limits1 as  we
 know2 and there seems to be no reason  
why we should not believe  that there   
are many more cases of adaptation than  
we actually know at  present1 or that1  
in former phylogenetic times1 the       
organisms were more  capable of active  
adaptation than they are now4 ,so to a  
certain extent1  at least1 ,lamarckism  
can be said to rest upon a 99causa      
vera994    ,it is important to notice   
that this 99causa vera99 would imply    
vitalistic  causality when taken in the 
wide meaning which ,lamarckism allows to
  it3 indeed1 the power of active       
adaptation to indefinite changes would  
imply a sort of causal connection that  
is nowhere known except in the          

organism4 ,lamarck himself is not very  
clear about this point1 he seems  to be 
afraid of certain types of uncritical   
vitalism in vogue in his  days2 but     
modern writers have most clearly seen   
what the logical  assumptions of pure   
,lamarckism are4 ,next to ,cope1 ,august
 ,pauly#adf may  be said to be the most 
conscious representative of a sort of   
so-called  psychological vitalism1 which
 indeed ,lamarckism as a general and    
all-embracing theory must have as its   
basis4    #adf 99,darwinismus und       
,lamarckismus991 ,mnchen1 #aije4        
,,the ,,active ,,storing ,,of           
,,contingent ,,variations ,,as ,a       
,,hypothetic ,,principle    ,this point 
will come out more fully1 if now we turn
 to study a certain  group of           
principles1 upon which dogmatic         
,lamarckism rests3 ,i say  principles   
and not facts1 for there are no facts   
but only hypothetic  assumptions in this
 group of statements4 ,we do know a     
little about  adaptations1 at least to a

 certain extent1 and it was only about  
the  sphere of the validity of a law1   
which was known to be at work in        
certain cases1 that hypothetical        
additions were made4 ,in the second     
group of the foundations of ,lamarckism 
we know absolutely nothing2  accidental 
variations of form are supposed to      
occur1 and the organism is  said to     
possess the faculty of keeping and      
storing these variations and  of handing
 them down to the next generation1 if   
they happen to satisfy  any of its      
needs4    ,but these needs are not of   
the actual type1 brought forth by a     
change of  the functional state of the  
individual1 as in the case of           
adaptations3  they are of a somewhat    
mysterious nature4 ,a glance at the     
theory of the  origin of the movements  
which are called acts of volition in the
 human  child may serve to elucidate    
what is meant4    ,acts of volition are 
said thus to originate in random        
movements of the  new-born infant3      

certain of these accidental motions     
which happen to  relieve some pain or to
 afford some pleasure are 8remembered10 
and are  used another time quite        
consciously to bring forth what is liked
 or to  remove what is disliked4 ,so    
much for the present on a very difficult
  subject1 which will occupy us next    
year at much greater length4 ,it is     
clear that at least three fundamental   
phenomena are concerned in this  theory 
of the origin of acts of volition3 the  
liking and disliking1 the  keeping in   
mind1 and the volition itself4 ,the real
 act of volition1  indeed1 is always    
based upon a connection of all these    
factors1 these  factors now being       
connected in such a way that even their 
kind of  connection may be said to be a 
fourth fundamental principle4 ,in order 
that the particular effect may be       
obtained which is wanted because it is  
liked1 the possible ways leading to it1 
which appeared among the random         
movements in the very beginning1 are now

 regarded as 8means0 and may now  be    
said to be 8used40 ,but that is as much 
as to say that the 8means0  are judged  
with respect to their usefulness for the
 actual purpose1 and  therefore         
99judgment99 is the fourth foundation of
 the act of volition4    ,in fact1      
,pauly does not hesitate to attribute   
judgment1 along with the  other         
psychological elements1 to the organisms
 whilst undergoing their                
transformation4 ,there has been formed1 
for instance1 by accidental  variation  
some pigment which by its chemical      
nature brings the organism  into a      
closer connection with the light of the 
medium2 the individual  likes that1     
keeps the pigment for itself and        
produces it again in the  next          
generation2 and indeed it will safeguard
 any sort of improvement  which chance  
may effect in this primitive 8eye40     
,such a view is said  to hold well with 
respect to the origin of every new      
organ4 ,and this  psychological argument

 is also said to afford the real        
explanation of  adaptation proper4      
,adaptation also is regarded not as a   
truly primary  faculty of the organism1 
but as a retention or provoking of      
metabolic  states which occurred by     
accident originally and were then found 
to  be useful2 now they are reproduced  
either in every single case of          
individual morphogenesis1 without regard
 to actual requirements1 or  else only  
in response to such3 in the first case  
they are 8inherited10  in the second    
they only occur as regulations4 ,thus   
the process of  judgment1 together with 
all the other elemental factors of      
psychical  life concerned in it1 has    
been made to account for adaptation     
proper4  ,the whole theory has          
accordingly become very uniform and     
simple4      ,,criticism ,,of ,,the     
8,,inheritance ,,of ,,acquired          
,,characters0 ,,assumed ,,by            
,,lamarckism    ,in addressing ourselves
 to the criticism of ,neo-,lamarckism we

 shall  neglect as far as possible all  
the different psychological principles  
concerned in it--which in any case would
 need rather a great amount of          
epistemological sifting--and shall keep 
to those hypothetic facts which  are    
supposed to be such as may be actually  
observed in nature4    ,all of you know 
that the so-called inheritance of       
acquired characters  lies at the root of
 ,lamarckism2 and from this hypothesis  
our critical  analysis is to start1     
disregarding a larger or smaller number 
of  psychological principles that are   
brought into the field4    ,the name of 
8acquired characters0 may 99a priori99  
be given to three  different types of   
phenomena3 firstly1 variations including
 mutations2  secondly1 disease or       
injuries2 and thirdly1 the results of   
the actual  process of adaptation of    
every kind4    ,in the first of these   
groups1 the true problem of the         
inheritance of  8acquired0 characters   
appears only with certain restrictions4 

,all  variations and mutations are      
indeed 8acquired0 by one generation so  
far as the earlier generation did not   
possess them1 but mutations1 at  least1 
cannot be said to be acquired by the    
actual adult personality3  they are     
innate in it from its very beginning1   
and therefore may better  be called     
congenital4#adg ,congenital properties  
of the mutation type  are1 in fact1     
known to be inherited3 their inheritance
 does not present  any problem of its   
own1 but is included in the changes of  
the hereditary  condition to which they 
are due altogether4#adh ,all properties 
of the  variation type1 on the other    
hand1 having been studied statistically1
  are known to be inherited1 to a       
certain small extent1 as we have seen   
already whilst studying ,darwinism1     
though they are possibly always  liable 
to reversion4 ,modern science1 as we    
know1#adi regards them as  due to       
changes of nutrition1 in the most       
general meaning of the word4  ,under    

such a view variations might indeed be  
said to belong to the  acquired group of
 organic specifications2 their          
inheritance1 as will  be seen later on1 
would hardly be quite a pure instance of
 what we are  searching for4 ,in no case
 can true variations claim to be of     
great  importance in problems of        
transformism4    #adg ,this would not be
 true1 if the varieties of plants       
produced by  ,blaringhem1 ,klebs1 and   
,mac,dougal by means of 99external99    
agents were  really 8mutations0 7comp4  
page #bch1 note #c74    #adh ,of course1
 the inheritance of mutations would     
imply a certain sort  of 8inheritance of
 acquired characters10 on the condition 
stated in the  preceding note4 ,but1    
probably1 the germs of the next         
generation might  be regarded here as   
being directly affected by the external 
agent1 in a  manner that will briefly be
 mentioned later on in the text4    #adi
 ,comp4 page #bch1 note #b4    ,but what
 is known about the inheritance of those

 properties which  beyond any doubt may 
be said to have originated in the adult 
individual  as such1 and of which       
lesions and adaptations proper1 as shown
 for  instance among amphibious plants1 
are instances of the two most  typical  
groups8#aej ,weismann did good service  
by putting an end to  the scientific    
credulity which prevailed with regard to
 this subject4  ,weismann was led by his
 theory of the germ plasm to deny the   
inheritance  of acquired characters of  
the typical kinds4 ,he could not imagine
 how  the effect of any agent upon the  
adult1 be it of the merely passive or   
of the adaptive kind1 could have such an
 influence upon the germ as to  force it
 to produce the same effect in spite of 
the absence of that  agent4 ,in fact1   
that is what the inheritance of acquired
 characters  would render necessary1 and
 a very strange phenomenon it would be1 
no doubt4 ,but1 of course1 taken alone1 
it could never be a decisive  argument  
against such inheritance4 ,i fully      

agree1 that science is  obliged to      
explain new facts by what is known      
already1 as long as it is  possible2 but
 if it is no longer possible1 the theory
 of course has to  be changed1 and not  
the facts4 ,on this principle one would 
not neglect  the fact of an inheritance 
of acquired properties1 but on the      
contrary  one perhaps might use it as a 
new evidence of vitalism4    #aej       
,certain ,english authors have applied  
the term 8modification0 to  all kinds of
 organic properties acquired from       
without1 whether they are  adapted or   
not4    ,but are there any facts8    ,at
 this point we come to speak about the  
second group of ,weismann's  reasonings4
 ,he not only saw the difficulty of     
understanding inheritance  of acquired  
characters on the principles of the     
science of his time1  but he also       
criticised the supposed facts2 and      
scarcely any of them  stood the test of 
his criticism4 ,indeed1 it must fairly  
be granted that  not one case is known  

which really proves the inheritance of  
acquired  characters1 and that injuries 
certainly are never found to be         
inherited4  ,in spite of that1 ,i do not
 believe that we are entitled to deny   
the  possibility of the inheritance of a
 certain group of acquired characters   
in an absolute and dogmatic manner1 for 
there are a few facts which seem  at    
least to tend in the direction of such  
an inheritance1 and which seem  to show 
that it might be discovered perhaps one 
day1 if the experimental  conditions    
were changed4    ,i am not referring    
here to the few cases in which bacteria 
were made  colourless or non-virulent by
 outside factors1 or in which certain   
fungi were forced to permanent agamic   
reproduction by abnormal external       
conditions and were shown to retain     
their 8acquired properties0  after the  
external conditions had been restored4  
,in these cases only  reproduction by   
simple division occurred1 and that does 
not imply the  true problem of          

inheritance4 ,nor am ,i referring to the
 few cases of  non-adaptive             
8modifications0 found by ,standfuss and 
,fischer1 in which  butterflies that had
 assumed an abnormal kind of            
pigmentation under  the influence of    
abnormal temperature acting upon the    
pupa1 were seen  to form this same kind 
of pigmentation in the next generation  
under  normal conditions of temperature4
 ,these cases1 though important in      
themselves1 are capable perhaps of a    
rather simple explanation1 as in  fact  
has been suggested4 ,some necessary     
means both of inheritance and of        
morphogenesis1 the former being present 
in the propagation cells1 may  be said  
to have been changed or destroyed by    
heat1 and therefore1 what  seems to be  
inherited after the change of the body  
only1 would actually  be the effect of a
 direct influence of the temperature    
upon the germ  itself4#aea ,let me be   
clearly understood3 ,i do not say that  
it is so1  but it may be so4 ,what seems

 to me to be more important than        
everything  and to have a direct bearing
 on the real discovery of the           
inheritance  of acquired characters in  
the future1 is this4 ,in some instances 
plants which had been forced from       
without to undergo certain typical      
morphological adaptations1 or at least  
changes through many generations1       
though they did not keep the acquired   
characters permanently in spite  of the 
conditions being changed to another     
type1 were yet found to lose  the       
acquired adaptations not suddenly but   
only in the course of three  or more    
generations4 ,a certain fern1           
99,adiantum991 is known to assume a     
very typical modification of form and   
structure1 if grown on serpentine2  now 
,sadebeck1#aeb while cultivating this   
serpentine modification of              
99,adiantum99 on ordinary ground1 found 
that the first generation grown in  the 
ordinary conditions loses only a little 
of its typical serpentine  character1   

and that the next generation loses a    
little more1 so that  it is not before  
the fifth generation that all the       
characters of the  serpentine           
modification have disappeared4 ,there   
are a few more cases  of a similar type 
relating to plants grown in the plains  
or on the  mountains4 ,there also it was
 found to take time1 or rather to take  
the  course of 99several99 generations1 
until what was required by the new      
conditions was reached4 ,of course these
 cases are very very few compared  with 
those in which a 99sudden99 change of   
the adaptive character1  corresponding  
to the actual conditions1 sets in2 but  
it is enough that  they do exist4       
#aea ,of course the inheritance of      
specific values from the results of     
fluctuating variations1 leading to new  
averages of variability 7see  p4 #bfe71 
may also be understood in this manner1  
the conditions of  nourishment acting   
upon the adult and upon its germs       
equally well4    #aeb 99,berichte b4 d4 

,sitzung4 d4 ,ges4 f4 ,bot4991 ,hamburg1
 #ahhg1 #c ,heft4    ,would it not be   
possible at least that adaptations which
 last  for thousands of generations or  
more might in fact change the  adaptive 
character into a congenital one8 ,then  
we not only should  have inheritance of 
acquired characters1 but should have a  
sort  of explanation at the same time   
for the remarkable fact that  certain   
histological structures of a very       
adapted kind are formed  ontogenetically
 before any function exists1 as is known
 to be the  case with the structures in 
the bones of vertebrates1 for instance4 
,experiments are going on at ,paris1 and
 perhaps in other places of  scientific 
research also1 which1 it is hoped1 will 
show that animals  reared in absolute   
darkness for many generations will lose 
their  perfectly formed eyes1 and that  
animals from the dark with very         
rudimentary eyes will be endowed with   
properly functioning ones1 after  they  
have been reared in the light for       

generations4 ,such a result indeed      
would account for the many animals1 of  
the most different groups1 which  live  
in dark caves and possess only rudiments
 of eyes3 functional  adaptation is no  
longer necessary1 so-called atrophy by  
inactivity sets  in1 and the results    
8acquired0 by it are inherited4#aec     
#aec ,quite recently ,kammerer 799,arch4
 ,entw4 ,mech499 #be1 #aijg1 p4 #g7 has 
published very important experiments on 
the inheritance of 8acquired0           
modifications with regard to the        
peculiarities of reproduction in        
99,salamandra atra99 and 99,s4          
maculosa994 ,it seems rather            
improbable--though  not absolutely      
impossible--that the germ cells were    
directly affected by  the external      
modifying agent in this case4    ,but   
enough of possibilities4 ,let us be     
content at present to know at  least a  
few real instances with regard to the   
slowness of the process of  what might  
be said to be 8re-adaptation0 in some   

plants4 ,this process  shows us a way by
 which our problem may some day be      
solved2 it allows  us to introduce      
inheritance of acquired characters as a 
legitimate  hypothesis at least1 which  
not only will explain many of the       
diversities  in systematics             
historically1 but also can be called1   
though not a 99causa  vera991 yet       
certainly more than a mere fiction4     
,,other ,,principles ,,wanted    ,we    
have only dealt with the probability of 
the inheritance of  morphological or    
physiological#aed adaptation4 ,if that  
could really be  considered as one of   
the factors concerned in the theory of  
descent1  many1 if not all of those     
congenital diversities among organic    
species  which are of the type of a true
 structural correspondence to their     
future functional life1 might be        
regarded as explained1 that is1  as     
reduced to one and the same principle4  
,but nothing more than an  explanation  
of 99this99 kind of diversities is      

effected by our principle1  and very    
much more remains to be done1 for       
organic diversities not only  consist in
 specifications and differences as to   
histology1 but are to a  much more      
important degree1 differences of        
organisation proper1 that is1  of the   
arrangement of parts1 in the widest     
sense of the word4#aee    #aed ,we have 
not spoken about the hypothetic         
inheritance of pure  physiological      
adaptations1 for it is clear without    
further discussion  that innate specific
 immunity1 for instance1 being a        
specific  8adaptedness0 799see99 p4     
#ahf7 99might99 be due to the           
inheritance of the  results of active   
immunity as an adaptation1 just as      
adaptive congenital  structures         
99might99 be due to such an inheritance4
    #aee ,c4 ,e4 v4 ,baer clearly       
discriminated between the type1 the     
degree  of organisation1 and the        
histological structure4 ,all these three
 topics  indeed have to be taken into   

account separately2 the third alone is  
of  the adaptive type4 ,all of them may 
be independent of each other3 the       
,amoeba may be as adapted histologically
 as is a high vertebrate1 but it  is of 
much lower type2 and in its own type it 
is of a lower degree of  organisation   
than ,radiolaria are4    ,would it be   
possible to interpret the origin of this
 sort of systematic  diversities by a   
reasoning similar to that by which we   
have understood1  at least              
hypothetically1 congenital adaptedness8 
,dogmatic ,lamarckism1 we know1 uses two
 principles as its foundations2  one of 
them1 adaptation and its inheritance1 we
 have studied with what  may be called a
 partly positive result4 ,the other is  
the supposed  faculty of the organism to
 keep1 to store1 and to transfer those  
variations or mutations of a not        
properly adaptive sort which1 though    
originating by chance1 happen to satisfy
 some needs of the organism4            
,,criticism ,,of ,,the ,,hypothesis ,,of

 ,,storing ,,and ,,handing ,,down       
,,contingent  ,,variations    ,strange  
to say1 this second hypothesis of       
dogmatic ,lamarckism1 invented  with the
 express purpose of defeating ,darwinism
 and taking the place of  its           
fluctuating variability1 which was found
 not to do justice to the  facts--this  
second hypothesis of dogmatic           
,lamarckism is liable to just  the same 
objections as dogmatic ,darwinism       
itself4    ,as it is important to       
understand well the real logical nature 
of  our objections to both of the great 
transformistic theories1 we  think it   
well to interrupt our argument for a    
moment1 in order to  consider a certain 
point which1 though very important in   
itself1  seems of only secondary        
importance to us in our present         
discussion4  ,dogmatic ,darwinism--,i do
 not say the doctrine of ,charles       
,darwin--is  materialistic at bottom1   
and indeed has been used by many to     
complete  their materialistic view of   

the universe on its organic side4 ,the  
word  8materialism0 must not necessarily
 be taken here in its metaphysical      
sense1 though most materialists are     
dogmatic metaphysicians4 ,it also  can  
be understood as forming part of a      
phenomenological point of view4         
,materialism as a doctrine of science   
means simply this3 that whether         
8nature0 be reality or phenomenon1 in   
any case there is but one ultimate      
principle at its base1 a principle      
relating to the movements of  particles 
of matter4 ,it is this point of view    
which dogmatic ,darwinism  strengthens2 
on the theory of natural selection and  
fluctuating  variations1 due to         
accidental differences of nutrition1    
organisms are  merely arrangements of   
particles of matter1 nothing else2 and  
moreover1  their kinds of arrangement   
are understood1 at least in principle4  
,lamarckism1 on the other hand1 is not  
materialistic1 but most markedly        
vitalistic--psychistic even2 it takes   

life for granted when it begins  its    
explanations4    ,you may tell me that  
,darwin did the same1 that he expressly 
states that  his theory has nothing to  
do with the origin of life2 that the    
title  of his work is 8,the ,origin of  
99,species9940 ,it would certainly be   
right  to say so1 at least with         
reference to ,darwin personally2 but in 
spite  of that1 it must be granted that 
,darwin's doctrine contains a certain   
germ of materialism which has been fully
 developed by the ,darwinian            
dogmatists1 while ,lamarckism is        
antimaterialistic by its very nature4   
,now it is very important1 ,i think1 to 
notice that this difference  between the
 two theories is unable to disguise one 
main point which is  common to both3 and
 it is to this point1 and to this point 
only1 that  our chief objections against
 both these theories converge at        
present4    ,the 99contingency99 of the 
typical organic form is maintained by   
,darwinism  as well as by ,lamarckism3  

both theories1 therefore1 break down for
  almost the same reasons4 ,the term    
8contingency0 can signify very          
different relations1 having but little  
in common2 but it is sufficient  for our
 present purpose to observe that there  
may be distinguished  roughly two main  
classes of contingencies1 which may     
provisionally be  called the            
8contingency of being10 and the         
8contingency of occurring40  ,it is with
 the contingency of being that criticism
 of ,darwinism and  ,lamarckism of the  
dogmatic type has to deal4 ,darwinism   
dealt with  variations occurring at     
random2 the organic form was the result 
of  a fixation of only one kind of such 
variations1 all others being            
extinguished by selection4 ,in other    
terms1 the specific organised  form1 as 
understood by ,darwinism1 was a unit    
only to the extent that  all its        
properties related to one and the same  
body1 but for the rest  it was a mere   
aggregation or summation4 ,it may be    

objected to this  statement1 that by    
being inherited in its specificity the  
,darwinian  form proved to be a unit in 
a higher sense of the word1 even in the 
opinion of dogmatic ,darwinians2 and    
this objection1 perhaps1 holds good  as 
far as inheritance is concerned4 ,but on
 the other hand1 it must  never be      
forgotten that the word 8unit0 had quite
 a vague and empty  meaning even then1  
as indeed everything the organism is    
made up of  is regarded as being in     
itself due to a contingent primary      
process1  which has no relation to its  
fellow-processes4 8,unit10 indeed1 in   
spite  of inheritance--which1 by the    
way1 is alleged also to be a merely     
materialistic event--means to           
,darwinians no more when applied to the 
organism than it does when applied to   
mountains or islands1 where of  course a
 sort of 8unit0 also exists in some     
sense1 as far as one and the  same body 
comes into account1 but where every     
single character of this  unit1 in every

 single feature of form or of quality1  
is the result of  factors or agents each
 of which is independent of every other4
    ,to this sort of contingency of     
being1 as maintained by ,darwinians1    
criticism has objected1 as we know1 that
 it is quite an impossible  basis of a  
theory of descent1 since it would       
explain neither the first  origin of an 
organ1 nor any sort of harmony among    
parts or among whole  individuals1 nor  
any sort of restitution processes4      
,now ,lamarckism of the dogmatic kind1  
as will easily be seen1 only  differs   
from ,darwinism in this respect1 that   
what according to the  latter happens to
 the organism passively by means of     
selection1 is  according to the former  
performed actively by the organism1 by  
means of  a 8judgment0--by the retention
 and handing down of chance variations4 
,the specificity of the form as a whole 
is contingent also according  to        
,lamarckism4 ,and1 indeed1 criticism    
must reject this contingency of  being  

in exactly the same way as it rejected  
the contingency of form  maintained by  
,darwinians4    ,as far as the          
inheritance of truly adaptive characters
 comes into  account--that is1 the      
inheritance of characters which are due 
to the  active faculty of adaptation    
possessed by the organism1 bearing a    
vitalistic aspect throughout--hardly    
anything could be said against          
,lamarckism1 except that inheritance of 
acquired characters is still  an        
hypothesis of small and doubtful value  
at present4 ,but that  99specific       
organisation proper99 is due to         
99contingent99 variations1 which        
accidentally have been found to satisfy 
some needs of the individual and        
therefore have been maintained and      
handed down1 this reasoning is quite  an
 impossibility of exactly the same kind 
as the argument of ,darwinism4    ,the  
process of restitution1 perfect the very
 first time it occurs1 if it  occurs at 
all1 is again the classical instance    

against this new sort of  contingency1  
which is assumed to be the basis of     
transformism4 ,here we  see with our    
eyes that the organism can do more than 
simply perpetuate  variations that have 
occurred at random and bear in          
themselves no  relation whatever to any 
sort of unit or totality4 ,there        
99exists99 a  faculty of a certain      
higher degree in the organism1 and this 
faculty  cannot possibly have originated
 by the process which ,lamarckians#aef  
assume4 ,but if their principle fails in
 one instance1 it fails as a            
99general99 theory altogether4 ,and now1
 on the other hand1 as we actually  see 
the individual organism endowed with a  
morphogenetic power1  inexplicable by   
,lamarckism1 but far exceeding the      
organogenetic faculty  assumed by that  
theory1 would it not be most reasonable 
to conclude from  such facts1 that there
 exists a certain organising power at   
the root of  the transformism of species
 also1 a power which we do not          

understand1  which we see only partially
 manifested in the work of restitutions1
  but which certainly is not even       
touched by any of the ,lamarckian       
arguments8 ,there does indeed exist what
 ,gustav ,wolff has called primary      
purposefulness 78primre                 
,zweckmssigkeit071 at least in          
restitutions1  and this is equally      
unexplainable by ,darwinism and by the  
dogmatism of  the ,lamarckians4    #aef 
,i repeat once more that we are dealing 
here with dogmatic  8,neo-0,lamarckism  
exclusively4 ,this theory indeed claims 
to explain 99all99  features and        
properties of organic bodies on the     
basis of the feeling  of needs and      
storing of contingent fulfilments and on
 this basis alone1  just as dogmatic    
8,neo0-,darwinism claims to account for 
99all99 those  phenomena on the ground  
of contingent variations and natural    
selection4  ,darwin himself1 as we have 
seen1 intentionally left unexplained    
certain  primary features of life and   

therefore cannot be blamed for having   
failed to explain them1 though even then
 his theory remains wrong4  ,lamarck    
personally considered a real primary    
organisatory law of  phylogeny as being 
of fundamental importance1 and therefore
 he is not in  the least responsible if 
8,neo-,lamarckism0 fails as a universal 
theory4    ,but before entering into    
this area of hypothesis1 let us mention 
a few  more objections to be made to the
 theory of the contingency of form as   
put forward by ,lamarckians4 ,in the    
first place1 let us say a few words     
about the appropriateness of the term   
8contingency0 as used in this           
connection4 ,the forms are regarded as  
contingent by ,lamarckians inasmuch  as 
the variations which afterwards serve as
 8means0 to the 8needs0 of  the organism
 occur quite accidentally with regard to
 the whole organism4  ,it might be said 
that these 8needs0 are not contingent   
but subject  to an inherent destiny1 but
 this plea is excluded by the           

,lamarckians  themselves1 when they say 
that the organism experiences no need   
until it  has enjoyed the accidental    
fulfilment of the same4 ,so the only    
thing in  ,lamarckian transformism which
 is not of a contingent character would 
be  the psychological agent concerned in
 it1 as being an agent endowed with  the
 primary power of feeling needs after it
 has felt fulfilment1 and of  judging   
about what the means of future          
fulfilment are1 in order to keep  them  
whenever they offer4 ,but these are     
characteristics of life itself1         
irrespective of all its specific forms1 
which alone are concerned in            
transformism4 ,now indeed1 ,i think1 we 
see as clearly as possible that         
,darwinism and ,lamarckism1 in spite of 
the great contrast of materialism  and  
psychologism1 shake hands on the common 
ground of the contingency of  organic   
forms4    ,the whole anti-,darwinistic  
criticism therefore of ,gustav ,wolff   
for  instance1 may also be applied to   

,lamarckism with only a few changes  of 
words4 ,how could the origin of so      
complete an organ as the eye of         
vertebrates be due to contingent        
variations8 ,how could that account for 
the harmony of the different kinds of   
cells in this very complicated  organ   
with each other and with parts of the   
brain8 ,and how is it to be  understood1
 on the assumption of contingency1 that 
there are two eyes of  almost equal     
perfection1 and that there are two feet1
 two ears8 ,islands  and mountains do   
not show such symmetry in 99their99     
structures4    ,we shall not repeat our 
deduction of the origin of restitutions1
 of  regeneration for instance1 on the  
dogmatic ,lamarckian theory4 ,as we     
have said already1 it would lead to     
absurdities as great as in the  case of 
dogmatic ,darwinism1 and indeed we      
already have mentioned that             
,lamarckians would hardly even attempt  
to explain these phenomena4  ,it follows
 that dogmatic ,lamarckism fails as a   

general theory about  form4#aeg    #aeg 
,compare also the excellent criticism of
 ,lamarckism lately given by  ,g4       
,wolff1 99,die ,begrndung der           
,abstammungslehre991 ,mnchen1 #aijg4    
,there is finally one group of facts    
often brought forward against           
,lamarckism by ,darwinian authors#aeh   
which may be called the logical         
99experimentum crucis99 of this         
doctrine1 an 99experimentum99 destined  
to prove fatal4 ,you know that among the
 polymorphic groups of bees1  termites1 
and ants1 there exists one type of      
individuals1 or even  several types1    
endowed with some very typical features 
of organisation1  but at the same time  
absolutely excluded from reproduction3  
how could  those morphological types    
have originated on the plan allowed by  
the  ,lamarckians8 ,of what use would   
8judgment0 about means that are offered 
by chance and happen to satisfy needs1  
be to individuals which die  without    
offspring8 ,here ,lamarckism becomes a  

simple absurdity1 just as  ,darwinism   
resulted in absurdities elsewhere4      
#aeh ,it has also very often been said  
by ,darwinians that ,lamarckism is  only
 able to explain those cases of         
adaptedness which relate to active      
functioning but not mere passive adapted
 characters1 like 8mimicry0 for         
example4 ,but this argument 99taken by  
itself991 it seems to me1 would not  be 
fatal to ,neo-,lamarckism in the special
 form ,august ,pauly gave to this       
doctrine4    ,we were speaking about    
dogmatic ,darwinism then1 and it is     
about dogmatic  ,lamarckism that we are 
reasoning at present2 both theories must
 fall in  their dogmatic form1 though a 
small part of both can be said to stand 
criticism4 ,but these two parts which   
survive criticism1 one offered by       
,lamarck1 the other by ,darwin1 are far 
from being a complete theory of         
transformism1 even if taken together3   
they only cover a small area of  the    
field concerned in the theory of        

descent4 ,almost everything is still  to
 be done1 and we may here formulate1    
briefly at least1 what we expect  to be 
accomplished by the science of the      
future4      #d4 ,,the ,,real ,,results 
,,and ,,the ,,unsolved ,,problems ,,of  
,,transformism    ,what has been        
explained to a certain extent by the two
 great theories  now current is only    
this4 ,systematic diversities consisting
 in mere  differences as to intensity or
 number may perhaps owe their origin to 
ordinary variation4 ,they may at least1 
if we are entitled to assume  that      
heredity in some cases is able to hand  
on such variations without  reversion1  
which1 it must be again remarked1 is by 
no means proved by  the facts at        
present4 ,natural selection may share in
 this process by  eliminating all those 
individuals that do not show the        
character which  happens to be useful4  
,that is the ,darwinian part of an      
explanation of  transformism which may  
be conceded as an hypothesis4 ,on the   

other side1  congenital histological    
adaptedness may be regarded             
hypothetically as  due to an inheritance
 of adaptive characters which had been  
acquired by  the organism's activity1   
exerted during a great number of        
generations4  ,that is the ,lamarckian  
part in the theory of descent4    ,but  
nothing more is contributed to this     
theory either by the doctrine  of       
,darwin or by that of ,lamarck4 ,so it  
follows that almost everything  has     
still to be done2 for no hypothesis at  
present accounts for  the foundation of 
all systematics1 viz41 for the          
differences in  organisation1 in all    
that relates to the so-called types as  
such and  the degree of complication in 
these types1 both of which 7types and   
degree of complication7 are independent 
of histological adaptation and          
adaptedness4    ,what then do we know   
about any facts that might be said to   
bear on  this problem8 ,we have stated  
already at the end of our chapter       

devoted  to the analysis of heredity    
that what we actually know about any    
deviation of inheritance proper1 that   
is1 about congenital differences        
between the parents and the offspring1  
relating to mere tectonics1  is         
practically nothing3 indeed1 there are  
at our disposal only the  few facts     
observed by de ,vries or derived from   
the experience of  horticulturalists and
 breeders4 ,we may admit that these     
facts at  least prove the               
possibility#aei of a discontinuous      
variation1 that  is of 8mutation10      
following certain lines of tectonics and
 leading to  99constant99 results2 but  
everything else1 that is everything     
about a real  theory of phylogeny1 must 
be left to the taste of each author who 
writes  on the theory of the ,living4   
,you may call that a very unscientific  
state  of affairs1 but no other is      
possible4    #aei ,but nothing more4    
,all 8mutations0 hitherto observed in   
nature  or 7comp4 page #bch1 note #c7   

experimentally produced relate only to  
8varieties0 and not to 8species40 ,one  
could hardly say that the  recent       
investigations about the production of  
mutations by 99external99  means have   
strengthened their importance for the   
general theory of  transformism4        
,and1 in fact1 it has been admitted by  
almost all who have dealt with          
transformism without prepossessions that
 such is the state of affairs4  ,lamarck
 himself1 as we have mentioned already1 
was not blind to the fact  that a sort  
of organisatory law must be at the base 
of all transformism1  and it is well    
known that hypothetical statements about
 an original law  of phylogeny have been
 attempted by ,ngeli1 ,klliker1 ,wigand1
 ,eimer1  and many others4 ,but a full  
discussion of all these 8laws0 would    
hardly  help us much in our theoretical 
endeavour1 as all of them1 it must be   
confessed1 do little more than state the
 mere fact that some unknown  principle 
of organisation must have been at work  

in phylogeny1 if we are  to accept the  
theory of descent at all4    ,it is     
important to notice that even such a    
convinced ,darwinian as  ,wallace1 who  
is well known to have been an           
independent discoverer of the           
elimination principle1 admitted an      
exception to this principle in at  least
 one case--with regard to the origin of 
man4 ,but one exception of  course      
destroys the generality of a principle4 
,as we ourselves feel absolutely        
incapable of adding anything specific   
to the general statement that there     
99must99 be an unknown principle of     
transformism1 if the hypothesis of      
descent is justified at all1 we may     
here close our discussion of the        
subject4      #e4 ,,the ,,logical       
,,value ,,of ,,the ,,organic ,,form     
,,according ,,to ,,the ,,different      
,,transformistic ,,theories    ,a few   
words only must be added about two      
topics3 on the character of  organic    
forms as regarded by the different      

transformistic theories1 and  on the    
relation of transformism in general to  
our concept of entelechy4    ,we have   
learnt that both ,darwinism and         
,lamarckism1 in their dogmatic  shape1  
regard the specific forms of animals and
 plants as being  contingent2 in fact1  
it was to this contingency that         
criticism was  mainly directed4 ,we     
therefore are entitled to say that to   
,darwinism and  ,lamarckism organic     
forms are accidental in the very sense  
of the 99forma  accidentalis99 of the   
old logicians4 ,there are indefinite    
forms possible1  according to these     
theories1 and there is no law relating  
to these  forms4 ,systematics1 under    
such a view1 must lose1 of course1 any  
really  fundamental importance4 8,there 
is no rational system about organisms03 
that is the ultimate statement of       
,darwinism and of ,lamarckism on this   
doubtful question4 ,systematics is a    
mere catalogue1 not at present  only1   
but for ever1 by the very nature of the 

organisms4 ,it is not  owing to the     
indefinite number of possible forms that
 both our theories  came to deny the    
importance of systematics1 but to the   
want of a 99law99  relating to this     
indefinite number3 among chemical       
compounds indefinite  possibilities also
 exist in some cases1 but they obey the 
law of the  general formula4 ,it is very
 strange that ,darwinians of all people 
are  in the forefront of systematic     
research in all countries3 do they not  
see that what they are trying to build  
up can only relate to accidental        
phenomena8 ,or have they some doubts    
about the foundations of their own      
theoretical views1 in spite of the      
dogmatic air with which they defend     
them8 ,or is it the so-called historical
 interest which attracts them8    ,a new
 question seems to arise at this point3 
,have not we ourselves  neglected       
history in favour of systematics and    
laws8 ,our next lecture1  the last of   
this year1 will give the answer to this 

question4    ,at present we continue our
 study of the possible aspects of       
systematics4  ,it is not difficult to   
find out what meaning organic forms     
would assume  under any phylogenetic    
theory opposed to the theories of       
contingency4  ,it was their defence of  
contingency1 that is1 their lack of any 
law  of forms1 that caused these        
theories to be overthrown--reduced to   
absurdities even--and therefore1 it     
follows that to assume any kind of      
transformistic law is at the same time  
to deny the accidental character  of the
 forms of living beings4    ,there is no
 99forma accidentalis994 ,does that mean
 that the 99forma  essentialis99 is     
introduced by this mere statement8 ,and 
what would 99that99  assert about the   
character of systematics8      ,,the    
,,organic ,,form ,,and ,,entelechy      
,this problem is not as simple as it    
might seem to be at the first  glance1  
and1 in fact1 it is insoluble at        
present4 ,it is here that the  relation 

of the hypothetic transformistic        
principle to our concept of  entelechy  
is concerned4    ,we know that          
entelechy1 though not material in       
itself1 uses material  means in each    
individual morphogenesis1 handed down by
 the material  continuity in            
inheritance4 ,what then undergoes change
 in phylogeny1  the means or the        
entelechy8 ,and what would be the       
logical aspect of  systematics in either
 case8    ,of course there would be a   
law in systematics in any case2 and     
therefore  systematics in any case would
 be rational in principle4 ,but if the  
transformistic factor were connected    
with the means of morphogenesis1  one   
could hardly say that specific form as  
such was a primary essence4  ,entelechy 
would be that essence1 but entelechy in 
its generality and  always remaining the
 same in its most intimate character1 as
 the  specific diversities would only be
 due to a something1 which is not  form1
 but simply means to form4 ,but the     

99harmony99 revealed to us in  every    
typical morphogenesis1 be it normal or  
be it regulatory1 seems  to forbid us to
 connect transformism with the means of 
morphogenesis4  ,and therefore we shall 
close this discussion about the most    
problematic  phenomena of biology with  
the declaration1 that we regard it as   
more  congruent to the general aspect of
 life to correlate the unknown          
principle concerned in descent with     
entelechy itself1 and not with  its     
means4 ,systematics of organisms        
therefore would be in fact  systematics 
of entelechies1 and therefore organic   
forms would be  99formae essentiales991 
entelechy being the very essence of form
 in its  specificity4 ,of course        
systematics would then be able to assume
 a truly  rational character at some    
future date3 there might one day be     
found  a principle to account for the   
totality of possible#afj forms1 a       
principle based upon the analysis of    
entelechy4#afa ,as we have allowed  that

 ,lamarckism hypothetically explains    
congenital adaptedness in  histology1   
and that ,darwinism explains a few      
differences in quantity1  and as such   
properties1 of course1 would both be of 
a contingent  character1 it follows that
 our future rational system would be    
combined  with certain accidental       
diversities4 ,and so it might be said to
 be  one of the principal tasks of      
systematic biological science in the    
future to discover the really rational  
system among a given totality of        
diversities which cannot appear rational
 at the first glance1 one sort  of      
differences1 so to speak1 being         
superimposed upon the other4    #afj    
,the word 8possible0 relating to        
originating1 of course1 not to          
surviving4 ,it is here that natural     
selection may acquire its logical       
importance alluded to above 7see page   
#bfd74    #afa ,the discussions in the  
second volume of this book will show the
  possible significance of such an      

analysis4 ,we at present are dealing    
with entelechy in a quasi-popular       
manner4          99,c499 ,,the ,,logic  
,,of ,,history      ,history1 in the    
strictest sense of the word1 is the     
enumeration of the  things which have   
followed one another in order of time4  
,history deals  with the single1 with   
regard both to time and space4 ,even if 
its facts  are complex in themselves and
 proper to certain other kinds of human 
study1 they are nevertheless regarded by
 history as single4 ,facts1 we  had     
better say1 so far as they are regarded 
as single1 are regarded  historically1  
for what relates to specific time and   
space is called  history4    ,taken as a
 simple enumeration or registration1    
history1 of course1  cannot claim to be 
a 8science0 unless we are prepared to   
denude that  word of all specific       
meaning4 ,but that would hardly be      
useful4 ,as a  matter of fact1 what has 
actually claimed to be history1 has     
always  been more than a mere           

enumeration1 even in biology proper4    
,so-called  phylogeny implies1 as we    
have shown1 that every one of its actual
  forms contains some rational elements4
 ,phylogeny always rests on  the        
assumption that only some of the        
characters of the organisms  were       
changed in transformism and that what   
remained unchanged may be  explained by 
the fact of inheritance4    ,but this1  
remember1 was the utmost we were able to
 say for phylogeny4  ,it remains        
fantastic and for the most part         
unscientific in spite of  this small    
degree of rationality1 as to which it is
 generally not very  clear itself4 ,for 
nothing is known with regard to the     
positive factors  of transformism1 and  
we were only able to offer the          
discussion of a few  possibilities in   
place of a real theory of the factors of
 descent4    ,in spite of that it will  
not be without a certain logical value  
to begin  our analysis of history in    
general by the discussion of            

possibilities  again4 ,biology proper   
would hardly allow us to do more3 for   
the  simple 8fact0 of history is not    
even a 8fact0 in this science1 but an   
hypothesis1 albeit one of some          
probability4    ,as discussions of mere 
possibilities should always rest on as  
broad a  basis as possible1 we shall    
begin our analysis by raising two       
general  questions4 ,to what kinds of   
realities may the concept of history    
reasonably be applied8 ,and what        
different types of 8history0 would be   
possible 99a priori991 if the word      
history is to signify more than a mere  
enumeration8      #a4 ,,the ,,possible  
,,aspects ,,of ,,history    ,of course1 
we could select one definite volume in  
space and call all the  consecutive     
stages which it goes through1 its       
history3 it then would be  part of its  
history that a cloud was formed in it1  
or that a bird passed  through it on the
 wing4 ,but it would hardly be found    
very suggestive to  write the history of

 space-volumes4 ,in fact1 it is to      
99bodies99 in space  that all history   
actually relates1 at least indirectly1  
for even the  history of sciences is in 
some respect the history of men or of   
books4  ,it may suffice for our analysis
 to understand here the word body in its
  popular sense4    ,now in its relation
 to bodies history may have the three   
following  aspects1 as far as anything  
more than a simple enumeration comes    
into  account4 ,firstly1 it may relate  
to one and the same body1 the term  body
 again to be understood popularly4 ,so  
it is when the individual  history of   
the organism is traced from the egg to  
the adult1 or when the  history of a    
cloud or of an island or of a volcano is
 written4 ,secondly1  the subject-matter
 of history may be formed by the single 
units of a  consecutive series of bodies
 following each other periodically4 ,to 
this  variety of history the discoveries
 of ,mendel and his followers would     
belong in the strictest sense1 but so   

does our hypothetical phylogeny  and a  
great part of the history of mankind4   
,and lastly1 there is a  rather         
complicated kind of sequence of which   
the 8history0 has actually  been        
written4 ,history can refer to bodies   
which are in no direct  relation with   
one another1 but which are each the     
effect of another body  that belongs to 
a consecutive series of body-units      
showing periodicity4  ,this sounds      
rather complicated2 but it is only the  
strict expression  of what is perfectly 
familiar to you all4 ,our sentence      
indeed is  simply part of the definition
 of a history of art or of literature   
for  instance--or1 say1 of a            
phylogenetic history of the nests of    
birds4 ,the  single pictures are the    
subjects of the history of art1 and     
nobody would  deny that these pictures  
are the effects of their painters1 and  
that  the painters are individuals of   
mankind--that is1 that they are bodies  
belonging to a consecutive series of    

body-units showing periodicity4 ,of     
course1 it is only improperly that we   
speak of a history of pictures or  of   
books or of nests4 ,in fact1 we are     
dealing with painters1 and with  men of 
letters or of science1 and with certain 
birds1 and therefore  the third type of 
history may be reduced to the second4   
,but it was not  without value to pursue
 our logical discrimination as far as   
possible4    ,so far we have always     
spoken of history as being more than a  
mere  enumeration1 but we have not      
ascertained what this 8more0 signifies4 
,it  is not very difficult to do so3 in 
fact1 there are three different types   
of history1 each of a different degree  
of importance with respect to the       
understanding of reality4    ,in the    
first place1 history may start as a mere
 enumeration at the  beginning1 and at  
the end1 in spite of all further        
endeavour1 may  99remain99 that and     
nothing more4 ,that may occur in the    
first as well  as in the second group of

 our division of history with regard to 
its relation to bodies4 ,take a cloud   
and describe its history from  the      
beginning to the end3 there would never 
be much more than pure  description4 ,or
 take one pair of dogs and describe them
 and their  offspring for four          
generations or more3 ,i doubt if you    
will get beyond  mere descriptions in   
this case either4 ,the only step beyond 
a mere  enumeration which we can be said
 to have advanced in these instances1   
consists in the conviction1 gained at   
the end of the analysis1 that  nothing  
more than such an enumeration is in any 
way 99possible994    ,quite the opposite
 happens when 8history0 deals with the  
individual  from the egg to the adult3  
here the whole series of historical     
facts is  seen to form one whole4 ,this 
case therefore we shall call not        
history1  but 99evolution991 an evolving
 of something2 the word 8evolution0     
being  understood here in a much wider  
sense than on former occasions1#afb and 

99including991 for instance1 the        
embryological alternative 8evolutio0 or 
8epigenesis40    #afb ,see pp4 #bf1 #de1
 #ed1 etc4    ,and half-way between     
enumeration and evolution there now     
stands a type  of history which is more 
than the one and less than the other3   
there is  a kind of intelligible        
connection between the consecutive      
historical  stages and yet the concept  
of a whole does not come in4 ,the       
geological  history of a mountain or of 
an island is a very clear instance of   
this  class4 ,it is easy to see here1   
how what 99has been99 always becomes the
  foundation of what 99will be99 in the 
99next99 phase of the historical        
process4 ,there is a sort of            
99cumulation99 of consecutive phases1   
the  later ones being impossible without
 the earlier4 ,so we shall speak  of the
 type of 8historical cumulation0 as     
standing between evolution  and bare    
temporal sequence4 ,by means of         
historical cumulations history  may     

fairly claim to 8explain0 things4 ,we   
8understand0 a mountain or an  island in
 all its actual characteristics1 if we  
know its history4 ,this  8historical    
understanding0 rests on the fact that   
what first appeared  as an inconceivable
 complex has been resolved into a       
sequence of single  events1 each of     
which may claim to have been explained  
by actually  existing sciences4 ,the    
complex has been explained as being1    
though not  a real 8whole10 yet a sum of
 singularities1 every element of which  
is  familiar4    ,but you may tell me   
that my discussion of evolution and of  
cumulation1  as the higher aspects of   
history1 is by no means complete2 nay1  
more--that it is altogether wrong4 ,you 
would certainly not be mistaken  in     
calling my analysis incomplete4 ,we have
 called one type of history  evolution1 
the other cumulation2 but how have these
 higher types been  reached8 ,has       
historical enumeration itself1 which was
 supposed to  stand at the beginning of 

all analysis1 or has 8history0 itself in
 its  strictest sense1 as relating to   
the single as such1 risen unaided into  
something more than 8history08 ,by no   
means3 history has grown beyond  its    
bounds by the aid of something from     
without4 ,it is unhistorical  elements  
that have brought us from mere history  
to more than history4  ,we have created 
the concept of evolution1 not from our  
knowledge of the  single line of events 
attendant on a single egg of a frog1 but
 from our  knowledge that there are     
billions or more of frogs' eggs1 all    
destined  to the same 8history10 which  
therefore is not history at all4 ,we    
have  created the concept of cumulation 
not from the historical study of  a     
single mountain1 but from our knowledge 
of physics and chemistry  and so-called 
dynamical geology3 by the aid of these  
sciences we  8understood0 historically1 
and thus our understanding came from    
another  source than history itself4    
#b4 ,,phylogenetic ,,possibilities      

,does history always gain its importance
 from what it is not8 ,must  history    
always lose its 8historical0 aspect1 in 
order to become of  importance to human 
knowledge8 ,and can it 99always99 become
 8science0 by  such a transformation8   
,we afterwards shall resume this        
discussion on  a larger scale1 but at   
present we shall apply what we have     
learned to  hypothetic phylogeny4 ,what 
then are the possibilities of phylogeny1
 to  what class of history would it     
belong if it were complete8 ,of course1 
we  shall not be able to answer this    
question fully2 for phylogeny is 99not99
  complete1 and scarcely anything is    
known about the factors which act  in   
it4 ,but in spite of that1 so much1 it  
seems to me1 is gained by our  analysis 
of the possible aspects of history and  
of the factors possibly  concerned in   
transformism1 that we are at least able 
to formulate the  possibilities of a    
phylogeny of the future in their strict 
logical  outlines4    ,darwinism and    

,lamarckism1 regarding organic forms as 
contingent1 must  at the same time      
regard organic history as a cumulation2 
they indeed  99might99 claim to furnish 
an historical explanation in the realm  
of  biology--if only their statements   
were unimpeachable1 which as we have    
seen1 they are not4    ,but any         
transformistic theory1 which locates the
 very principle of  phylogeny in the    
organism itself1 and to which therefore 
even organic  forms would be not        
accidental but essential1 might be      
forced to regard  the descent of        
organisms as a true evolution4 ,the     
singularities in  phylogenetic history  
would thus become links in one whole3   
history  proper would become more than  
history4 ,but ,i only say that phylogeny
  99might99 be evolution1 and in fact ,i
 cannot admit more than this 99a        
priori991 even on the basis of an       
internal transformistic principle1  as  
has been assumed4 ,such a principle also
 might lead always from one  typical    

state of organisation to the next3 but  
99ad infinitum994#afc  ,then phylogeny1 
though containing what might in some    
sense be called  8progress10 would not  
be 8evolution02 it might even be called 
cumulation  in such a case1 in spite of 
the internal transforming principle1    
though1  of course1 cumulation from     
within would always mean something very 
different from cumulation from          
without4#afd    #afc ,an immanent       
vitalistic phylogeny 99without99 a      
pre-established end  has recently been  
advocated by ,h4 ,bergson 799,l'volution
 cratrice991  ,paris1 #aijg74    #afd   
,in this connection the problem may be  
raised1 whether there can be  such a    
thing as unchangeable 8species0 in spite
 of the mutability of the  individuals4 
,compare page #bea1 note #a4    ,but we 
must leave this problem an open         
question1 as long as our actual         
knowledge about transformism remains as 
poor as it is4 ,we need only add1  for  
the sake of logical interest1 that      

phylogeny1 as a true evolution1  would  
necessarily be characterised by the     
possibility of being repeated4      #c4 
,,the ,,history ,,of ,,mankind    ,we   
only assume hypothetically that         
phylogeny has happened1 and we know     
scarcely anything about the factors     
concerned in it4 ,now1 it certainly     
would be of great importance1 if at     
least in a small and definite field  of 
biology we were able to state a little  
more1 if the 99mere fact99 of           
phylogeny1 of 8history10 were at least  
beyond any doubt within a certain  range
 of our biological experience4 ,and     
indeed there is one department  of      
knowledge1 where history1 as we know1   
99has happened991 and where we  also    
know at least some of the factors       
concerned in it4    ,i refer to the     
history of mankind2 and ,i use the      
expression not at all  in its           
anthropological or ethnographical sense1
 as you might expect  from a biologist1 
but in its proper and common sense as   

the history of  politics and of laws and
 of arts1 of literature and of sciences3
 in a  word1 the history of             
civilisation4 ,here is the only field1  
where we know  that there actually      
99are99 historical facts3 let us try to 
find out what  these facts can teach us 
about their succession4    ,the theory  
of history in this narrower meaning of  
the word has been  the subject of very  
numerous controversies in the last      
twenty years1  especially in ,germany1  
and these controversies have led very   
deeply into  the whole philosophical    
view of the universe4 ,we shall try to  
treat our  subject as impartially as    
possible4    ,hegel says1 in the        
introduction to his 99,phnomenologie des
 ,geistes993  899,die ,philosophie muss 
sich hten erbaulich sein zu wollen990   
78,philosophy must beware of trying to  
be edifying074 ,these words1  indeed1   
ought to be inscribed on the lintel of  
the door that leads  into historical    
methodology1 for they have been sadly   

neglected by  certain theoretical       
writers4 ,instead of analysing history  
in order to  see what it would yield to 
philosophy1 they have often made        
philosophy1  especially moral           
philosophy1 the starting-point of       
research1 and history  then has had to  
obey certain doctrines from the very    
beginning4    ,we shall try as far as we
 can not to become 8erbaulich0 in our   
discussions4 ,we want to learn from     
history for the purposes of  philosophy1
 and we want to learn from history as   
from a phenomenon in  time and in space1
 just as we have learnt from all the    
other phenomena  regarding life in      
nature4 ,every class of phenomena of    
course may  be studied with respect to  
generalities as well as with respect to 
particulars4 ,the particular1 it is     
true1 has not taught us much in our     
studies so far4 ,perhaps it may be      
successful in the domain of history     
proper4    ,if ,i take into             
consideration what the best authors of  

the last century  have written about    
human history with respect to its       
general value1 ,i  cannot help feeling  
that none of them has succeeded in      
assigning to  history a position where  
it would really prove to be of great    
importance  for the aims of             
philosophical inquiry4 ,is that the     
fault of the authors  or of human       
history8 ,and what then would explain   
the general interest  which almost every
 one takes1 and which ,i myself take in 
history in  spite of this unsatisfactory
 state of things8      ,,cumulations    
,,in ,,human ,,history    ,let us begin 
our analytical studies of the value and 
the meaning of  human history1 by       
considering some opinions which deserve 
the foremost  place in our discussion1  
not as being the first in time1 but as  
being  the first in simplicity4 ,i refer
 to the views of men like ,buckle1      
,taine1  and ,lamprecht1 and especially 
,lamprecht1 for he has tried the hardest
 to  justify theoretically what he      

regards the only scientific aim of      
history  to be4 ,if we may make use of  
our logical scheme of the three possible
  aspects of history1 it is clear from  
the beginning that the history of       
mankind1 as understood by the three     
authors we have named1 but most         
particularly by ,lamprecht1 is neither a
 mere enumeration nor a true  evolution1
 but that it has to do with             
99cumulations991 in the clearest  of    
their possible forms4 ,the processes of 
civilisation among the  different       
peoples are in fact to be compared      
logically with the origin  of volcanoes 
or mountain-ranges in ,japan1 or in     
,italy1 or in ,america1  and show us a  
typical series of consecutive phases1 as
 do these4 ,there  exists1 for instance1
 in the sphere of any single            
civilisation an  economic system1       
founded first on the exchange of natural
 products1  and then on money4 ,there   
are1 or better1 perhaps1 there are said 
to  be1 characteristic phases succeeding

 one another in the arts1 such as  the  
8typical10 the 8individualistic10 and   
the 8subjective0 phases4 ,any           
civilisation may be said to have its    
8middle ages10 and so on4 ,all these    
are 8laws0 of course in the meaning of  
8rules0 only1 for they are far  from    
being elemental1 they are not           
8principles0 in any sense4 ,and there   
are other sorts of 8rules0 at work for  
exceptional cases3 revolutions  have    
their rules1 and imperialism1 for       
instance1 has its rules also4    ,now1  
as the consecutive phases of history    
have been shown to be  true cumulations1
 it follows that the rules which are    
revealed by  our analysis1 are rules    
relating to the very origin of          
cumulations  also4 ,the real 99element99
 upon which the cumulation-phases1 and  
the  cumulation-rules together rest1 is 
the human individual as the bearer  of  
its psychology4 ,nobody1 it seems to me1
 has shown more clearly than  ,simmel   
that it is the human individual1 99qua99

 individual1 which is  concerned in     
99every99 kind of history4    ,history1 
viewed as a series of cumulations1 may  
in fact claim to  satisfy the intellect 
by 8explaining0 a good deal of          
historical facts4  ,it explains by means
 of the elemental factor of individual  
psychology1  which every one knows from 
himself1 and by the simple concept that 
there  is a cumulation1 supported by    
language and by writing as its principal
  factors1 which both of course rest on 
psychology again4 ,psychology1  so we   
may say1 is capable of leading to       
cumulation phenomena2 the  cumulations  
in history are such that we are able to 
understand them by  our everyday        
psychology2 and history1 so far as it is
 of scientific  value1 consists         
exclusively of cumulations4    ,no doubt
 there is much truth in such a          
conception of history2 but  no doubt    
also1 it puts history in the second rank
 as compared with  psychology2 just as  
geology stands in the second rank as    

compared with  chemistry or physics4    
,geology and human history may lead to  
generalities  in the form of rules1 but 
these rules are 99known99 to be not     
elemental  but only cumulative2 and     
moreover1 we know the elements concerned
 in  them4 ,the elements1 therefore1 are
 the real subjects for further studies  
in the realm of philosophy1 but not the 
cumulations1 not the rules1  which are  
known to be due to accidental           
constellations4 ,of course1 the         
8single0 is the immediate subject of    
this sort of history1 but the  single as
 such is emphatically pronounced to be  
insignificant1 and the  cumulations and 
the cumulative rules1 though 8singles0  
in a higher sense  of the word1 are     
shown to be anything but elementalities4
    ,therefore1 on a conception of human
 history such as that of ,buckle1       
,taine1 ,lamprecht1 and others1 we1 of  
course1 ought to take an interest  in   
history1 because what is 8explained0 by 
historical research touches  all of us  

most personally every day and every     
year4 ,but our philosophy1  our view of 
the world1 would remain the same without
 history as it is  with it4 ,we only    
study history1 and especially the       
history of our own  civilisation1       
because it is a field of actuality which
 directly relates  to ourselves1 just as
 we study for practical purposes the    
railway  time-tables of our own country1
 but not of ,australia2 just as we study
  the local time-table in particular4   
,if the mere 99rerum cognoscere causas99
 is regarded as the criterium of        
science1 history of ,lamprecht's type of
 course is a science1 for its           
explanations rest upon the demonstration
 of the typical constellations  and of  
the elemental factor or law from which  
together the next  constellations are   
known necessarily to follow4 ,but       
history of this kind  is not a science  
in the sense of discovering 99den       
ruhenden ,pol in der  ,erscheinungen    
,flucht994      ,,human ,,history ,,not 

,,an 8,,evolution0    ,quite another    
view of history has been maintained by  
,hegel1 if his  explanations about the  
99,entwicklung des objectiven ,geistes99
 78the  development of the objective    
mind07 may be co-ordinated with our     
strictly logical categories of the      
possible aspects of history4 ,but ,i    
believe we are entitled to say that it  
was a real 99evolution99 of mankind     
that ,hegel was thinking of2 an         
evolution regarding mankind as spiritual
  beings and having an end1 at least    
ideally4 ,one psychical state was       
considered by ,hegel to generate the    
next1 not as a mere cumulation  of      
elemental stages1 but in such a way that
 each of the states would  represent an 
elementality and an irreducibility in   
itself2 and he  assumed that there was a
 continuous series of such stages of the
 mind  through the course of            
generations4 ,is there any sufficient   
reason in  historical facts for such an 
assumption8    ,the mind 8evolves0      

itself from error to truth by what might
 be called  a system of contradictions1 
according to ,hegel1 with respect to    
logic  as well as to morality2 the sum  
of such contradictions becoming smaller 
and less complicated with every single  
step of this evolution4 ,no doubt  there
 really occurs a process of logical and 
moral refining1 so to say1  in the      
individual1 and no doubt also1 the      
results of this process1  as far as     
attained1 can be handed down to the next
 generation by the  spoken word or by   
books4 ,but it is by no means clear1 ,i 
think1 that this  process is of the type
 of a real evolution towards an end1 so 
far as it  relates to the actual series 
of generations as such4 ,on the         
contrary1  it seems to me that we have  
here simply what we meet everywhere in  
history--a sort of cumulation resting   
upon a psychological basis4    ,the     
dissatisfaction that exists at any      
actual stage of contradiction1  both    
moral and logical1 is one of the        

psychical factors concerned2  the       
faculty of reasoning is the other4 ,now 
it is a consequence of the  reasoning   
faculty that the dissatisfaction        
continually decreases1 or  at least     
changes in such a way that each partial 
result of the logical  process brings   
with it the statement of new problems4  
,the number of  such problems may become
 less1 as the logical process advances1 
and1  indeed1 there is an ideal state1  
both logical and moral1 in which there  
are no more problems1 but only results1 
though this ideal could hardly  be      
regarded as attainable by the 99human99 
mind4 ,in the history of those  sciences
 which are wholly or chiefly of the 99a 
priori99 type1 this  process of         
deliverance from contradictions is most 
advantageously to  be seen4 ,it is      
obvious in mechanics and thermodynamics1
 and the theory  of matter is another   
very good instance4 ,a certain result is
 reached2  much seems to be gained1 but 
suddenly another group of facts presents

  itself1 which had been previously     
unknown or neglected4 ,the first result 
has to be changed or enlarged2 many     
problems of the second order arise2     
there are contradictions among them1    
which disappear after a certain         
alteration of what was the first        
fundamental result1 and so on4 ,and the 
same is true about morality1 though the 
difficulties are much greater  here1 as 
a clear and well-marked standard of     
measurement of what is good  and what is
 bad1 is wanting1 or at least1 is not   
conceded unanimously4  ,but even here   
there is a consensus on some matters3   
one would hardly go  back to slavery    
again1 for instance1 and there are still
 other points  in morality which are    
claimed as ideals at least by a great   
majority of  moral thinkers4    ,but all
 this is not true 8evolution10 and      
indeed1 ,i doubt if such an  evolution  
of mankind could be proved at present in
 the sense in which  ,hegel thought it  
possible4 ,the process of logical and   

moral deliverance  from contradictions  
99might99 come to an end in 99one99     
individual2 at least  that is a logical 
possibility1 or it might come to an end 
in1 say1  six or ten generations4 ,and  
there is1 unfortunately for mankind1 no 
guarantee that the result will not be   
lost again and have to be acquired  a   
second time4 ,all this proves that what 
,hegel regarded as an evolution  of the 
race is only a cumulation4 ,there is    
nothing evolutionary relating  to the   
generations of mankind as such4 ,at     
least1 nothing is proved about  such an 
evolution4#afe    #afe ,on account of   
the limited size of the earth a certain 
final stage  of human civilisation might
 be expected in a future time2 but it   
would  be the size of the earth which   
determined this end1 and not the process
  of civilisation itself4    ,you may   
call my view pessimistic1 and indeed you
 may be right so far  as the sum total  
of human beings as such is in question4 
,but1 be it  pessimistic or not1 we are 

here moving on scientific ground only1  
and  have merely to study the           
probability or improbability of         
problematic  facts1 and with such a view
 in our mind1 we are bound to say that a
  true logical and moral evolution of   
mankind is not at all supported  by     
known facts4 ,there is a process of     
logical and moral perfection1  but this 
process is 99not one991 is not 8single0 
in its actuality2 it is  not connected  
with the one and single line of history1
 but only with a  few generations each  
time it occurs1 or even with one        
individual1 at  least ideally4 ,and this
 process is not less a process of       
cumulation  than any other sort of      
development or so-called 8progress0 in  
history  is4 ,philosophers of the       
,middle ,ages1 in fact1 sometimes       
regarded human  history as 99one99      
evolutionary unity1 beginning with the  
,creation and  ending with the ,day of  
,judgment2 but every one must agree1 ,i 
think1  that even under the dogmatic    

assumptions of orthodoxy history would  
by  no means 99necessarily99 be an      
8evolution40 ,even then the paths taken 
by  different individuals or different  
branches of the human race on their  way
 to redemption 99can99 be regarded as   
independent lines4    ,thus ,hegel's    
conception of an evolution of mankind1  
it seems to me1  fails to stand         
criticism4 ,by emphasising that there   
are certain lines of  development in    
history which bring with them a stimulus
 to perfection1  and that these lines   
relate to all that is highest in        
culture1 ,hegel  certainly rendered the 
most important service to the theory of 
history2  but in spite of that he has   
revealed to us only a special and       
typical  kind of cumulation process1 and
 nothing like an evolution4 ,we may say 
that the very essence of history lies in
 this sort of cumulation1 in  this      
8pseudo-evolution0 as we might say2 and 
if we like to become moral              
metaphysicians we might add1 that it is 

for the sake of the possibility  of this
 sort of cumulation that man lives his  
earthly life2 the ,hindoos  say so1     
indeed1 and so do many ,christians4 ,but
 even if we were to depart  from our    
scientific basis in this way we should  
not get beyond the realm  of            
cumulations4    ,all this1 of course1 is
 not to be understood to affirm that    
there never  99will99 be discovered any 
real evolutionary element in human      
history--in  the so-called              
8subconscious0 sphere perhaps--but at   
present we  certainly are ignorant of   
such an element4      ,,the ,,problem   
,,of ,,the 8,,single0 ,,as ,,such    ,if
 history has failed to appear as a true 
evolution1 and if1 on the  other hand1  
it reveals to us a great sum of         
different cumulations1 some  of very    
great importance1 others of minor       
importance1 what then remains  of the   
importance of the single historical     
event in its very singleness8  ,what    
importance can the description of this  

event have with regard to  our          
scientific aims8 ,we could hardly say at
 present that it appears to  be of very 
much importance at all4 ,the historical 
process as a whole  has proved to be not
 a real elemental unit1 as far as we    
know1 and such  elemental units as there
 are in it have proved to be of         
importance only  99for99 individual     
psychology but not 99as99 history4      
,history has offered  us only instances 
of what every psychologist knew already 
from his own  experience1 or at least   
might have known if he had conceived his
 task in  the widest possible spirit4   
,but is no other way left by which true 
history might show its real  importance 
in spite of all our former analysis8    
,can history be saved  perhaps to       
philosophical science by any new sort of
 reasoning which we  have not yet       
applied to it here4    ,as a matter of  
fact1 such new reasoning has been tried1
 and  ,rickert1#aff in particular1 has  
laid much stress upon the point  that   

natural sciences have to do with        
generalities1 while historical  sciences
 have to do with the single in its      
singleness only1 and1 in  spite of that1
 are of the highest philosophical       
importance4 ,he does not  think very    
highly of so-called 8historical laws10  
which must be mere  borrowings from     
psychology or biology1 applied to       
history proper1 and  not touching its   
character as 8history40 ,we agree with  
these statements  to a considerable     
extent4 ,but what then about 8history   
proper10 what  about 8the single in its 
very singleness08    #aff 99,die        
,grenzen der naturwissenschaftlichen    
,begriffsbildung991  ,tbingen and       
,leipzig1 #aijb4    ,let us say at first
 a few words about this term 8single0 so
 very often  applied by us4 ,in the     
ultimate meaning of the word1 of course1
 the  series of actual sensations or    
8presentations0 is the 8single0 which is
  given 8historically0 to each          
individual1 and therefore to the writer 

of  history also1 and in fact1 history  
as understood by ,rickert is based  to a
 great extent upon this primordial      
meaning of single 8givenness40  ,the    
word 8single10 in his opinion1 relates  
to the 99actual and true                
specification99 of any event1 or group  
of events1 at a given time and  at a    
given locality in space1 these events   
possessing an identity of  their own and
 never being repeated without change of 
identity4 ,if the  subject-matter of    
history is defined like this1 then there
 are1 indeed1  8,grenzen der            
naturwissenschaftlichen                 
,begriffsbildung0 with regard to        
history1 for natural sciences have      
nothing to do with the single in such   
an understanding of the word4           
,rickert says somewhere that history as 
a real evolution1 as one  totality of a 
higher order1 would cease to be proper  
history3 and he  is right4 ,history1 in 
fact1 would soon lose the character of  
specific  attachment to a given space   

and to a given time1 and would lose its 
8non-repeatability10 in the logical     
sense at least1 if it were one  99unit99
 in reality3 as soon as it was that1 it 
would have become a  logical generality1
 an element in nature1 so to say1 in    
spite of its  factual singularity4 ,but 
history is not obliged to become that1  
,rickert  states2 and we may add that   
history in fact cannot become that1     
because  it simply proves not to be an  
evolution as far as we know at present4 
,but what importance does ,rickert      
attach to his history specified and     
non-repeatably single8    ,history has a
 logic of its own1 he says2 the scheme  
of its logic is not  the syllogism1 but 
the 99relation to 8values4099 ,so far as
 the single  historical facts can be    
related to values1 they are of          
historical  importance1 and in such a   
way only does history in its proper     
sense  become important in itself and   
through itself at the same time4 ,must  
history always lose its historical      

aspect to become of importance to  human
 knowledge8 ,that is the question we    
asked whilst considering the  general   
logical types of the 8evolution0 and    
8cumulation0 that arose out  of the     
analysis of the historical facts of     
problematic phylogeny4 ,it  now might   
seem that this question may be answered1
 and that it may be  answered by a clear
 and simple 8,no40 ,the history of      
mankind1 according  to ,rickert1 seems  
to be important in itself1 and without  
borrowing from  any other branch of     
study4 ,but is his reasoning altogether 
cogent and  convincing8    ,has it      
really been able to attribute to history
 in the strictest sense  such an        
importance for philosophy1 for the      
theory of the universe1 8fr  die        
,weltanschauung10 that history proper   
may in fact be allowed to take  its     
place beside science proper8    ,the    
relation to values is not to include any
 kind of 8,bewertung0 of  judgment1     
,rickert allows4 ,in fact1 history of   

any kind would hardly  satisfy the      
reader1 if moral judgment were its      
basis4 ,every reader1 of  course1 has a 
moral judgment of his own1 but1         
unfortunately1 almost  every reader's   
judgment is different from his          
neighbour's1 and there  is no uniformity
 of moral principles as there is of     
geometrical ones4  ,we shall come back  
to this point4 ,at present we only state
 the fact  that indeed moral judgment   
can never be the foundation of history1 
and  that ,rickert was very right to say
 so3 it is enough to put the names  of  
,tolstoy and ,nietzsche together to     
understand how devoid of even  the      
smallest general validity would be a    
history resting upon moral  principles4 
,but what then are the 8values0 of      
,rickert to which history has to        
relate1 if moral values in their proper 
sense have to be excluded8 ,it is  here 
that his discussions begin to become    
obscure and unsatisfactory1  and the    
reason is fairly intelligible4 ,he is   

trying to prove the  impossible2 he     
wants to put history beside science in  
its real  philosophical importance1 in  
spite of the fact that all evidence to  
establish this is wanting4    ,these    
8values10 to which every historical act 
in its singularity has to  be related in
 order to become an element of real     
history1 are they after  all nothing but
 those groups of the products of        
civilisation which in  fact absorb the  
interest of men8 ,is it to groups of    
cultural phenomena1  such as arts1      
science1 the ,state1 religion1 war1     
economics1 and so on1  that 8historical0
 facts have to be related8 ,yes1 as far 
as ,i understand  our author1 it is     
simply to these or other even less      
important groups  of cultural           
effects--cultural 8cumulations10 to     
apply our term--that a  single action of
 a man or a group of men must bear some 
relation in  order to become important  
historically4    ,but what does that    
mean8 ,is the relation to such 8values0 

to be  regarded as really rendering     
history equal to the sciences of nature 
in  philosophical importance8    ,in the
 first place1 there is no more agreement
 about such 8values0 than  there is in  
the field of morals4 ,imagine1 for      
instance1 a religious  enthusiast or    
recluse writing history6 ,i fancy there 
would be very  little mention of        
warriors and politicians3 war and       
politics would  not be 8values0 in      
99any99 sense to such a man4 ,and we    
know that there  are others to whom     
those products of civilised life rank   
amongst the  first4 ,rickert well notes 
that there is one great objection to his
  doctrine--the character of            
universality#afg is wanting to his      
history1  or rather to the values       
forming its basis2 for there cannot be1 
or at  least there actually is not at   
present1 a 99consensus omnium99 with    
regard  to these 8values40    #afg ,the 
word 8universality0 to be understood    
here in quite an  unpretentious         

quasi-popular meaning1 not strictly     
epistemologically4    ,i am convinced   
that ,rickert is right in his conception
 of real 8history0  as the knowledge of 
the single acts of mankind4 ,but this   
conception  proves just the contrary of 
what ,rickert hoped to prove2 for       
history in  this sense is moulded by the
 actual products of culture1 that is1 by
  the effects which actually exist as   
groups of cultural processes1 and  it   
cannot be moulded by anything else2 the 
historian correlates history  with what 
99interests99 him personally4    ,here  
now we have met definitively the        
ambiguous word3 history indeed  is to   
end in 8interest0 and in being          
8interesting40 ,there is nothing  like a
 real 8value0 in any sense underlying   
history2 the word 99value99  therefore  
would better give place to the term     
8centre of interest0--a  collection of  
stamps may be such a 8centre40 ,history1
 then1 as the  knowledge of cultural    
singularities1 is 8interesting10 and its

 aspects  change with the interests of  
the person who writes history3 there is 
no  commonly accepted foundation of     
history4#afh    #afh ,to avoid mistakes 
,i wish to say here most emphatically   
that1  according to ,rickert1 the method
 of history is regarded as completely   
99free99 from subjectivity as soon as   
its 8values0 are once 99established994  
,but this cannot avail to save the      
theory4    ,and it follows that history 
as regarded by ,rickert cannot serve as 
the preliminary to philosophy4 ,it      
99may99 be#afi of use for personal      
edification or for practical life3      
granting that the 8centres of  interest0
 as referred to are of any real ethical 
or at least factual  importance4 ,but   
you may take away from history even the 
greatest  personalities1 and your view  
of the universe1 your philosophy1 would 
remain the same1 except of course so far
 as these personalities  themselves have
 contributed to philosophy in any way4  
#afi ,this is a rather optimistic       

conception of 8history40 ,personally1 ,i
  must confess that even its emotional  
and practical importance seems to  me to
 be at least diminished by the retarding
 effects which all sorts  of            
8historical0 considerations--in science 
as well as in arts and in  public       
life--carry with them4 ,all real        
progress is non-historical--and  its    
champions almost always have become     
martyrs3 this fact seems not to         
recommend history as a means of         
education1 except for persons of a very 
strong character4    ,now1 on the other 
hand1 it is worth noticing that1 even if
 there were  generally accepted         
8values10 history as the doctrine of    
singularities  would be deprived of     
philosophical importance4 ,its single   
cases would  then be merely             
99instances99 of certain types of       
actions and occurrences  which have been
 proved to be 8valuable10 99i4e499 to be
 centres of  interest1 before-hand4     
,rickert has observed that the relation 

to  any judgments about moral values    
would render history unhistorical1  for 
the generalities to which it is related 
would be the main thing  in such a case4
 ,but he did not notice1 as far as ,i   
can see1 that  history1 if related to   
99any99 8values0 whatever--if there were
 any  generally conceded--would become  
8non-historical0 just as well3 for the  
99generalities99 as expressed in the    
8values0 would be the main thing in     
this case also4 ,in fact1 there is no   
escape from the dilemma3--either no     
general centres of interest1 and        
therefore a mere subjective 8history02  
or general 8values10 and therefore      
history a mere collection of  instances4
    ,the 8limits of concepts in natural 
sciences0 then are the same as the      
limits of 99intellectual99 concepts in  
general4 ,for intellectual1 99i4e499    
logical1 8values0 are the only centres  
of interest that can lay claim  to      
universality4 ,there are indeed other   
groups of important concepts1  the      

ethical ones1 but they are outside      
intellectuality and may enter           
philosophy only as problems1 not as     
solutions4 ,therefore1 history in  its  
true sense1 even if related to the      
ethical group of concepts1  has no      
bearing on philosophy4 ,philosophically 
it remains a sum of  contingencies1 in  
which certain laws of cumulation and    
certain series of  cumulation may be    
discovered4 ,but these series and these 
laws1 if taken  scientifically1 only    
offer us instances of psychological     
elementalities4  ,they also might be    
instances of primary ethical states and 
relations1 if  there were such relations
 of more than a mere subjective and     
personal  validity1 which at present at 
least seems not to be the case4         
,,conclusions ,,about ,,systematics     
,,and ,,history ,,in ,,general      ,we 
have finished our analysis of the       
history of mankind as the only  instance
 of an historical biological process    
that is actually known to  exist and is 

not only assumed hypothetically4        
,what we have learnt from this analysis1
 though certainly important in  itself1 
has not afforded us any new result for  
theoretical biology4    ,the history of 
mankind is proved to be of philosophical
 importance1  at present1 so far only as
 it offers instances to the science of  
psychology2 besides that it may be of   
value and importance to many  conditions
 of practical and emotional life4       
,there is only one science1 and only one
 kind of logic too4 8,in one sense  the 
only science0--that was the predicate   
attached to natural sciences  by ,lord  
,gifford1 as you will remember from our 
first lecture4 ,it is not  without      
interest to note that at the end of our 
course of this year1  we find occasion  
to realise on what a deep insight into  
logical and  philosophical relations    
that sentence was grounded4    ,we now  
leave the theory of human history1 which
 has been to us nothing  more than a    
branch of biological phylogeny in       

general4 ,we have dealt  with it from   
quite a simple realistic point of view1 
not burdened by any  epistemology4 ,we  
have taken psychical states as          
realities1 just as we  have taken as    
realities all parts of the animal body2 
and it seems to  me that we were        
entitled to do so1 as it was only       
history 99about99 the  actions of men we
 were dealing with1 not their actions   
themselves4 ,next  summer we shall begin
 with studying action as action1 and    
then1 in fact1  a well-founded          
epistemology will be among our first    
requirements4 ,and  history also will   
come on the scene once more4    ,it is  
the main result of our last chapters1   
devoted to systematics1  transformism1  
and human history in particular1 that no
 conclusions  really useful for further 
philosophical discussion can at present 
be  gained from these topics2 there     
either is too little actual knowledge1  
or there are only combinations of       
natural elementalities1 but no          

elementalities of any new kind4    ,to  
sum up3 we expected that a rational     
system might be a biological  result of 
the future1 but we could not claim at   
all to possess such a  system4 ,we said 
that transformism might be proved one   
day to be a true  evolution1 governed by
 one immanent principle1 which then     
would have to  be regarded as a new     
primary factor in nature1 but we did not
 know the  least about that principle4  
,human history1 on the other hand--that 
is1 the only historical process         
concerned with life that is actually    
known to have occurred--could not  teach
 us anything of an elemental character1 
since human history1 at  present at     
least1 did not appear to us as a true   
evolution1 but only as  a sum of        
cumulations1 and the singularities of   
this history1 taken by  themselves1     
could only be of practical or emotional 
interest4    ,thus it is from the study 
of the living 99individual99 only1 that 
we  have so far gained elemental        

principles in biology4 ,the analysis of 
individual morphogenesis and of         
individual inheritance has yielded  us  
the concept of entelechy as the chief   
result of the first part of  our        
lectures4 ,we shall be able to get more 
proofs of the autonomy of  the          
individual life in the beginning of the 
second part2 indeed1 the  beginning of  
that part will bring us to a full       
understanding of what the  living       
individual is1 and what it is not4 ,and 
then the real philosophy  of life1 that 
is1 the philosophy of the individual1   
will occupy us for  the greater half of 
our lectures of next summer4            
,,index        ,absolute1 #e            
,acclimatisation1 #aia      ,acquired   
characters1 #bag1 #bgf f4               
,adaptation 7definition71 #aff1 #aga1   
#ahe      to changes from without1 #agb 
ff4      functional1 #aad1 #agf ff4     
and ,lamarckism1 #bgb1 #bhj             
mechanical1 #agg f4      morphological1 
#afh ff4      physiological1 #ahd ff4   

primary and secondary1 #ahh f4          
,adaptedness1 #ahf f4                   
99,adiantum991 #bgi      ,adventitious1 
#ee1 #gd1 #aaa1 #bba      ,albumen1 #bjj
      ,allelomorphs1 #bca               
,amphibious plants1 #agb ff4            
,annelids1 #fe1 #gj1 #bba               
,answering reaction1 #aha               
,anti-bodies1 #bjf f4      ,antitoxins1 
#bjg f4      99,a priori991 #f          
,aristotle1 #add      99,ascaris991 #ic 
99,aspergillus991 #aie                  
,assimilation1 #ag      ,atrophy1 #agh  
,autonomy of life1 #adc1 #bbd f41 #cbd  
,babk1 #agg      ,baer1 ,c4 ,e4 v41 #dh 
f4 #bhb      ,bateson1 #bbi ff41 #bch   
,bayliss1 #bjd1 #bab      99,begonia991 
#bba      ,bergson1 #cje      ,berkeley1
 #f      ,berthold1 #ia                 
,biogenetisches ,grundgesetz1 #bdh      
,biology1 #h ff41 #ae f4                
,blaringhem1 #bch1 #bgf                 
,blastoderm1 #ci      ,blastomeres1 #cf1
 #ei1 #fa f41 #gi      ,blastula1 #cg1  
#fa1 #gi      ,blumenbach1 #bf          

,boirivant1 #agd      ,bonnet1 #bf      
,boveri1 #bi1 #fj1 #ie1 #bce f4         
,buckle1 #cjh1 #caj      ,bunge1 v41    
#bdh      ,btschli1 #ia        ,calcium1
 #ig      ,calkins1 #cc      ,cambium1  
#abj1 #ahc1 #bbj      ,catalysis1 #afd1 
#bjc      ,categories1 #f f4            
,cause1 #ii ff4      ,cell1 #bg f4      
-division1 #bh ff41 #ec1 #id            
-lineage1 #eh1 #gj      -theory1 #bg f4 
,chemical theory 7of morphogenesis71    
#acd ff4      ,chemistry1 systematics   
of1 #bdd4      ,child1 ,c4 ,m41 #ahj    
,chromatic regulations1 #aig            
,chromatin1 #bh f4      ,chromosomes1   
#cj1 #bcg      ,chun1 #ff               
,classification1 #bdf f4                
99,clavellina991 #abi1 #aed1 #afb f4    
,cleavage1 #ce ff41 #ec1 #eh1 #fj1 #fc1 
#ga1 #ib      ,colloids1 #ahg           
,compensatory process1 #aab             
,complex potencies1 #aab1 #abj          
,conic sections1 #bdc      ,conjugation1
 #cc      ,conklin1 #hf                 
,contingency1 #bah1 #bhd ff4 #cjd       

,continuity of germ-plasm1 #bae1 #bbg   
,cope1 #bgc      ,correlation 7of       
masses71 #ic      7of parts71 #bdg      
,correns1 #bbh      ,crampton1 #gj f4   
,crayfish1 #aje      ,ctenophores1 #ff  
,cumulation1 #cja ff41 #cjh ff41 #cad1  
#cag      ,cuvier1 #bdg        ,darwin1 
,ch41 #bfj ff41 #bga1 #bhc              
,darwinism1 #bfj ff41 #bga1 #bhc ff41   
#bic ff41 #cjd      ,davenport1 #aia1   
#bjf      ,delage1 #cb      ,descent1   
theory of1 #bej ff4      ,description1  
#ab1 #ej      ,detto1 #agb              
,directive stimuli1 #ajb ff4            
,doncaster1 #bcb      ,dreyer1 #ib      
99,echinus991 #bg1 #cc ff41 #fj ff41    
#fh1 #ha1 #he1 #hg1      #ih1 #ajd1     
#ajh1 #aaa1 #aed1 #bcb1 #bce            
,ectoderm1 #da1 #ha1 #abb      ,egg1    
#ca1 #cc f4      ,ehrlich1 #bjg f4      
,eimer1 #bib      ,elementary organs1   
#df ff4      processes1 #df ff4         
,elements of nature1 #i      ,embryo1   
#dd      frog's1 #ei1 #fe1 #fg          
half1 #ei1 #fa1 #ff ff4      whole1 #fa1

 #fg f4      ,endoderm1 #da1 #ha        
,entelechy1 #adc f41 #bbd f41 #bie      
,entwickelungsmechanik1 #eg1 #gj1 #gh1  
#bda      ,enumeration1 #big1 #cjj      
,enzymes1 #afd1 #bjc      ,epigenesis1  
#bf1 #de1 #ed1 #gb1 #add1 #cja          
,equifinality 7of restitutions71 #aei f4
      ,equipotential1 #hc               
,eschenhagen1 #aie      ,evolutio1 #bf1 
#de f41 #ed1 #ei1 #fa1 #fd1 #gb1 #add1  
#bje1 #cja      ,evolution1 #h1 #ba1    
#df1 #bej1 #cja1 #cje1 #caa ff41 #cag   
,experience1 #g f41 #ab1 #bab           
,experiment1 #ea1 #ef f4                
8,explaining10 #ea1 #cji      ,explicit 
potency1 #hd        ,fasting1 #aii f4   
,ferments1 #afd1 #bjc f4                
,fertilisation1 #cb ff4      ,fischer1  
#bgh      ,foges1 #ajg      ,form1      
closed or open1 #di      ,form1 organic1
 specific1 #af ff41 #be1 #ib1 #bic ff4  
,forma accidentalis1 #bic               
essentialis1 #bid f4      ,formative    
stimuli1 #ajb ff41 #aac1 #aah1 #acc     
,franc1 #aeh1 #bci      ,frdricq1 #aif  

,frog1 embryo of1 #ei1 #fe1 #fg         
,fromm1 #bje      ,function             
7mathematical71 #hj      ,fungi1        
metabolism of1 #bja        ,gaidukow1   
#aig f4      ,galls1 #aja      ,galton1 
#bbh1 #bch      ,gamble and ,keeble1    
#aih      ,gastrula1 #da1 #fa1 #ha      
,gautier1 #bci      ,geographical       
distribution1 #bea f4      ,geometry1   
solid1 #bdc      ,germ-layers1 #da1 #dd1
 #fa      -lineage1 #bae      -plasm1   
#eb1 #bae      ,gifford1 ,lord1 #a ff41 
#cbb      ,godlewski1 #aje1 #aee1 #bce  
,goebel1 #aaf      ,goethe1 #bdg        
,goette1 #dh1 #ef1 #bad      ,goltz1    
#aha      ,growth1 #cj1 #ic f4          
,gruber1 #bcf        ,haeckel1 #cg1 #da 
,half-embryo1 #ei1 #fa1 #ff ff4         
,haller1 ,a4 v41 #bf      ,harmony1 #ajg
 ff41 #aag1 #bie      ,hausmann1 #bjf   
,heat production1 #aic      ,hegel1     
#cjg1 #caa ff4      ,herbst1 #if ff41   
#ajb1 #ajd ff41 #agb1 #agg1 #bjj1 #bcb1 
#bcf      ,heredity1 #ba1 #eb           
,hering1 #baf f4      ,hertwig1 ,o41    

#fj1 #fe      ,hertwig1 ,r41 #cb f41    
#fj1 #ajg      ,his1 #ef1 #ic           
,history1 #b1 #ad1 #ba1 #bej1 #beg1 #big
 ff4      of mankind1 #cjf ff4          
,holmes1 #ahj      ,hume1 #f            
,hypertrophy1 #aab1 #aad                
,hypertypy1 #aab        ,idealism1 #e1  
#g      ,immunity1 #bjd ff4             
,implicit potency1 #hd      ,improvement
 7of morphogenesis71 #bab               
,indifferent cells1 #ahb                
,inflammation1 #bjf      ,inheritance1  
#ce1 #bad ff4      of acquired          
characters1 #bag1 #bge ff41 #bij        
,irritability1 #aij ff4        ,jacoby1 
#bjg      ,jaeger1 #bad      ,jennings1 
#bah        ,kammerer1 #agf1 #bhj       
,kant1 #f f4      ,kirchhoff1 #ej       
,klebs1 #if1 #agj1 #ahj1 #bch1 #bgf     
,klliker1 #bib      ,korshinsky1 #bci   
,kraan1 #bba1 #bea        ,lamarck1 #bga
 f41 #bia      ,lamarckism1 #bga f41    
#bhd ff41 #bic ff41 #cjd                
,lamprecht1 #cjh1 #caj      ,larva1 #da 
f41 #dd      ,law of nature1 #ac1 #af   

,leibniz1 #f      ,lens 7of eye71 #aje1 
#bba      ,liebmann1 #bef      ,life1 #i
 f41 #af1 #ba      ,lillie1 ,r4 ,s41    
#bcf      ,limits of regulability1 #bab 
,lithium1 #ii      8,living10 #i1 #af   
,localisation1 #aja1 #ajc1 #aah ff4     
,locke1 #f      ,loeb1 ,j41 #cb1 #ajb1  
#afd1 #agi1 #aif1 #bcf      ,loeb1 ,l41 
#bjh      ,lyon1 #hg        ,mac,dougal1
 #bch f41 #bgf      ,machine            
7definition71 #aci      ,machine-theory 
of life1 #ach ff41 #ahg1 #baj           
,maillard1 #aif      ,manifoldness1 #be 
f41 #cj1 #de      intensive1 #add       
,materialism1 #bhc      ,materials1     
transport of1 #aid      ,matter1 theory 
of1 #h      ,maturation1 #ca1 #hg       
,mayenburg1 v41 #aie      ,means1 of    
morphogenesis1 #hi ff41 #aja1 #aac1     
#aah1 #bbh1 #bcd      ,memory1 #baf f4  
,mendel1 #bbi f4      ,merrifield1 #aih 
,mesenchyme1 #ci1 #da1 #ajd1 #aaa1 #aea 
f4      ,metabolic regulations1 #aih f4 
,metabolism1 #af1 #ahd      of fungi1   
#bja      ,metschnikoff1 #bjf           

,micromeres1 #cf1 #fj      ,miehe1 #aaf 
,mill1 ,j4 ,s41 #eg      99,mimosa991   
#aia      ,minkiewicz1 #aih             
,modification1 #bgg      ,molluscs1 #gj 
f41 #hf      ,morgan1 ,t4 ,h41 #cb1 #ff 
f41 #ie1 #ajg1 #aad f41 #afb1 #bcj      
,morphaesthesia1 #aeg                   
,morphogenesis1 #bj1 #eb1 #gf1 #aab1    
#aah f4      ,morphology1 #ab           
,movements1 organic1 #ag                
,mutations1 #bcg f41 #bgf1 #bia         
,ngeli1 #bff1 #bib      ,nathansohn1    
#aif      ,natural selection1 #bfa f41  
#bij      ,nature1 #e ff4      ,nmec1   
#aaf      ,newport1 #eg      ,newt      
7regeneration of71 #aee1 #bba f4        
,noll1 #adf1 #aeg f4      ,nomothetic1  
#ad f4      ,normal1 #gh      ,nuclear  
division1 #bh f41 #fb1 #fd f41 #gb1 #bce
      ,nucleus1 #bh1 #ce      rle of    
nucleus in inheritance1 #bcc f4         
,organ-forming substances1 #aag         
99,oscillariae991 #aig      ,osmotic    
pressure1 #ic1 #ahg1 #aid f4            
,overton1 #aif f4      ,oxidation1 rle  

of1 #aih f4        ,palaeontology1 #beb 
,parallelism 7psycho-physical71 #adf    
,parthenogenesis1 #cb      ,pauly1 #adf1
 #bag1 #bgc f4      ,pawlow1 #bjd1 #baj1
 #bab      ,pearl1 ,r41 #bab            
,pfeffer1 #aie1 #bja      ,phagocytosis1
 #bjf      ,phenomenon1 #e f4           
,philosophy1 natural1 #d      of nature1
 #d1 #g1 #i      of the organism1 #i1   
#ae      ,phylogeny1 #bee1 #bia1 #big1  
#cjd ff4      ,physiology1 #ab      of  
development 7morphogenesis71 #bj        
99,planaria991 #acj1 #aee1 #afb f41 #bjj
      ,plants1 #dh f4      ,plato1 #b   
,pluteus1 #db      ,poisons1 #bje ff4   
,pole1 #cf      ,polarity1 #ajf         
,potencies1 complex1 #aab1 #abj         
explicit1 #hd      implicit1 #hd        
primary1 #hd1 #aaa      prospective1 #gg
 ff41 #hc1 #hi1 #aah1 #abe1 #bda        
secondary1 #hd1 #aaj      ,poulton1 #aih
      ,precipitin1 #bjg f4              
,pressure experiments1 #fc1 #ada        
,primary potency1 #hd1 #aaa             
purposefulness1 #adf1 #bhg              

regulation1 #he1 #agd1 #ahh             
,progress1 #cje      ,pronuclei1 #ee    
,prospective potency1 #gg ff41 #hc1 #hi1
 #aah1 #abe1 #bda      value1 #gg f41   
#hj1 #abb      ,protista 7,protozoa71   
#bg1 #acj1 #bcf      ,protoplasm1 #bh1  
#cj      morphogenetic rle of1 #fg      
,przibram1 #aab1 #bdh        ,rdl1 #bdg 
,rauber1 #bce      ,reaction1 answering1
 #aha      ,reciprocity of harmony1 #aef
 f4      ,re-differentiation1 #ge1 #aaa1
 #afc      ,regeneration1 #ee1 #gd1     
#aje1 #aaa1 #bba      super-1 #aae f4   
,regulation1 #fh1 #gc1 #he1 #aaa1 #afe  
defined1 #aff      metabolic1 #aih f4   
secondary1 #he1 #afe1 #ahh      ,reinke1
 #adf      ,restitution1 #ba1 #gd1 #aaj1
 #aab ff4      defined1 #aff      and   
,darwinism1 #bfg      and ,lamarckism1  
#bhf      of second order1 #aeh         
,retina1 #aia                           
,retro-differentiation1 #afc f4         
,rhumbler1 #ic      ,ribbert1 #aad      
,rickert1 #cae ff4      ,roux1 #bf1 #dh1
 #ee ff41 #ff f41 #gf1 #hi1 #ib f41     

#ajh1 #afa1 #agf f41 #bda      ,rubner1 
#aic        ,sachs1 #aag      ,sadebeck1
 #bgi      99,salamandra991 #age1 #bha  
,schneider1 #adf      ,schultz1 ,e41    
#bjj      ,schultze1 ,o41 #fg           
,schwendener1 #agg      ,science1 #ad1  
#big      natural1 #a ff4      rational1
 #ab      ,sea-urchin1 99see99 ,echinus 
,secondary potency1 #hd1 #aaj           
regulation1 #he1 #afe1 #ahh             
,secretion1 internal1 #aaf1 #bjj        
,segmentation1 #ce      ,selective      
qualities 7of tissues71 #ahf            
,self-differentiation1 #ajh      ,semon1
 #baf f4      ,sex1 #ajg      ,single1  
the1 #cae ff4      ,skeleton1 #dj ff41  
#dd1 #dg1 #ib      ,spemann1 #aje       
,spermatozoon 7spermia71 #cb ff4        
,splitting 7of hybrids71 #bbi f4        
,stahl1 #aig      ,standfuss1 #bgh      
,starfish1 #dd1 #ha1 #abb               
,starling1 ,e41 #aaf1 #bjd1 #bab        
99,stentor991 #aca      ,stimuli1       
directive1 #ajb ff4      formative1 #ajb
 ff41 #aac1 #aah1 #acc      of          

restitutions1 #aac f4      ,structure of
 protoplasm1 #ff1 #fi1 #gb f4 #he1 #hh  
,substance1 living1 #ag      ,sumner1   
#aif      ,super-regeneration1 #aae f4  
,surface-tension1 #ia      ,sutton1 #bcj
      ,symmetry1 #ci1 #fh1 #gj1 #gb1    
#hi1 #ih      ,system1 combined types   
of1 #aec ff4      complex1 #bai f4      
complex-harmonious1 #aee                
equipotential1 #abj                     
harmonious-equipotential1 #aba ff41 #aea
 f4      mixed-equipotential1 #aed      
morphogenetic1 #aai f41 #afc1 #bda      
,systematics1 #ad ff41 #ba1 #bdc f41    
#bec1 #bfd1 #bic1 #bif        ,taine1   
#cjh1 #caj      ,theology1 natural1 #a  
ff4      ,thomson1 ,j4 ,a41 #af         
,thymus1 #bjd      ,thyroid1 #bjd       
,tissue1 #ch      ,toxins1 #bjg f4      
,transformism1 #bea      ,truth1 #g     
,tschermak1 #bbh      99,tubularia991   
#abf ff41 #acc1 #aeh ff4      ,type1    
#dh1 #bdg f41 #bhb1 #bia                
8,understanding0 7historically71 #cjb   
,universality1 postulate of1 #adh f4    

,universe1 #e      ,univocality1        
principle of1 #afa        8,values10    
#cag ff4      prospective1 #gg f41 #hj1 
#abb      ,variation1 #bah1 #bcg f41    
#bgf      ,variation1 fluctuating1      
contingent1 #bfd f41 #bgc f41 #bhb1 #bij
      ,vernon1 #bcb1 #bch               
,vitalism1 #adc1 #ade f41 #baj f41 #bbd 
f41 #bcd1 #bdj f41 #bgb1 #bgg           
,vchting1 #agd1 #agi f41 #ahb1 #bba     
,volition1 acts of1 #bgd      ,vries1   
de1 #bbh1 #bch f4        ,wallace1 #bib 
,ward1 ,j41 #h1 #adc      ,weber1 law   
of1 #aia      ,weinland1 #bjb           
,weismann1 #cc1 #eb ff41 #eh f41 #gb1   
#gd f41 #ajc1      #aaa1 #ach1 #bad f41 
#bcg1 #bgg f4      ,weldon1 #bch        
,whole1 the1 #bh1 #hj1 #aag             
-embryo1 #fa1 #fg f4      ,wigand1 #bee1
 #bff1 #bib      ,wilson1 ,e4 ,b41 #bg1 
#fe1 #gj f41 #hf f41 #ajg               
,windelband1 #ac f4      ,winkler1 #aaf1
 #bba      ,winterstein1 #aii           
,wolff1 ,c4 ,f41 #bf      ,wolff1 ,g41  
#aje1 #adf1 #bee1 #bff1 #bhg f4         

,wolff1 ,j41 #agg        ,yung1 #agg    
,zeleny1 #aab1 #aae1 #bab      ,zur     
,strassen1 #ic                          
,,the ,,end               99,printed    
by99 ,r4  ,r4 ,,clark1 ,,limited1       
99,edinburgh994                         
,,heredity ,,and ,,selection            
,,in ,,sociology                        
,,by                               ,g4  
,,chatterton ,,hill                     
,demy #hvo1 ,cloth1 #fjj pages4         
,price #abs4 #f;d4 net4                 
99,post ,free1 ,price99 #abs4 #aa;d4    
,,some ,,press ,,opinions    8,a most   
praiseworthy and suggestive work--should
 certainly be studied by  every serious 
thinker40--99,morning ,post499    8,mr4 
,hill is decidedly doctrinaire1 but his 
book is packed with  scientific and     
sociological facts1 and it gives the    
reader healthy  intellectual            
exercise40--99,christian ,world499      
8,shows wide reading1 is written in a   
forcible and clear style1 and  contains 
much that is interesting1 fresh1 and    

acute40--99,aberdeen ,free  ,press499   
8,it is a book of equal calibre with    
,mr4 ,kidd's and goes even deeper  than 
that remarkable production into the     
springs of life and                     
conduct40--99,methodist ,recorder499    
8,this most suggestive and valuable     
work1 which contains abundant           
sociological data40--99,aberdeen        
,journal499    8,mr4 ,george ,chatterton
 ,hill has written a volume of          
surpassing interest  not alone to       
scientific but to theological           
students40--99,catholic ,times499       
,published by ,a4  ,c4 ,,black1 ,,soho  
,,square1 ,,london1 ,w4                 
,,rudolf ,,eucken',s                    
,,philosophy ,,of ,,life                
,,by                               ,w4  
,r4 ,,boyce ,,gibson                    
,,lecturer ,,in ,,philosophy ,,in ,,the 
,,university ,,of ,,london              
,,second ,,edition         ,crown #hvo1 
,cloth1 with ,frontispiece ,portrait of 
,rudolf ,eucken4                        

,price #cs4 #f;d4 net4                  
99,post ,free1 ,price99 #cs4 #aj;d4     
,,some ,,press ,,opinions    8,mr4      
,gibson has given us in small compass a 
lucid exposition of the  philosophical  
system of ,eucken1 who is ,professor of 
,philosophy in  ,jena4444 ,this is a    
most suggestive and stimulating book4   
,in a very  real sense it has brought   
philosophy down to earth and is         
deserving of  serious                   
study40--99,aberdeen ,free ,press499    
8,to it the interested reader will turn 
with expectation1 and his  expectation  
is likely to be more than realised4 ,for
 ,dr4 ,boyce ,gibson  is himself a      
scholar1 as well as an enthusiastic     
lover of this great                     
scholar40--99,expository ,times499      
8,no reader should fail to find pleasure
 in a book so full of fresh and         
stimulating thought1 expressed with     
great felicity of language40--99,the    
,scottish ,review499    8,it is done    
with just the proper combination of     

sympathy and  criticism40--99,british   
,weekly499    8,this little book on     
,eucken's ,philosophy is of quite       
exceptional  interest and               
importance40--99,the ,inquirer499       
8,professor ,boyce ,gibson 444 has      
performed a real service in promoting   
the acquaintance of ,english1 and       
,american students with a thinker whose 
distinctive views give him a special    
claim to their attention4444  ,professor
 ,gibson has achieved a notable success1
 writing briefly1  lucidly1 and         
sympathetically40--99,the ,new ,age499  
,published by ,a4  ,c4 ,,black1 ,,soho  
,,square1 ,,london1 ,w4