2i6 Inheritance of Acquired Characters 



tions of physico-chemical nature, which are concerned 

 in any way in the fundamental specific characters of 

 vital processes, the expressions increase and decrease have 

 no significance at all. 



Nevertheless it would not have been advisable not 

 to mention here these later explanations of the atrophy 

 of organs which have become useless and of co-ordinated 

 variations, because the fact that Weismann substituted 

 them for his earlier ones, shows that he himself regarded 

 the earlier explanations as insufficient, and because the 

 artificiality of these new explanations shows very clearly 

 the almost insurmountable difficulty encountered in the 

 attempt to explain these phylogenetic phenomena if the 

 inheritance of acquired characters is rejected. 



But the phenomenon which more than any other 

 remains an enigma when the inheritance of acquired 

 characters is rejected, and which when this inheritance 

 is accepted becomes not only self explanatory, but sets 

 the whole mechanism of inheritance in the clearest light, 

 is that of the repetition of phylogeny by ontogeny, and 

 just because of this we reserved it for the last. 



"Whenever a new species is formed/' writes Delage, 

 "it is accomplished by the addition of one or more new 

 characters, at the end of ontogeny, after all the old 

 specific characters have already appeared. And since this 

 goes on from the very commencement it is evident that 

 the characters must appear in ontogeny, in the same 

 sequence as in their phylogenetic formation." 164 



But if there is no inheritance of acquired characters 

 why should the new character be invariably just added 

 to those already present, and only after the development 

 of the latter is completed ? Why should it not be possible 



le *Delage: L'heredite etc. P. 366. 



