268 Theories Treating of Inheritance 



to the phylogenetic moment at which it was produced 

 in their ancestors, whereas in the latter this reaction 

 commenced only when the animal was exposed, after 

 leaving the egg, to the influences of the external world, 

 and was rendered necessary only in consequence of very 

 definite circumstances external to the organism? We 

 see thus that the question of the repetition of phylogeny 

 by ontogeny finds no answer at all. It seems to us 

 further that there remains only the erroneous view that 

 entire phylogenetic epochs could have gone by, without 

 leaving behind any trace in the egg, so that the progress 

 of each ontogeny would be nothing else than a phylogeny 

 which is almost entirely repeated each time. 



In the second edition of his work Delage recognized 

 himself that the significance attributed by him to the 

 functional stimulus in ontogeny is exaggerated. 201 And 

 he admits that he was embarrassed in explaining by 

 it both the special fact of the formation of an organ so 

 complicated and so well adapted to its purpose as the 

 eye, for which during embryonal life there was never- 

 theless lacking any functional stimulus, and also the 

 phenomena of regeneration, or the general fact that 

 nearly all organs without exception show, from the first 

 stages of their development on, an adaptation to the func- 

 tions which they \vill perform only later. 202 



LeDantec 



According to LeDantec's theory, each individual, 

 living, elementary mass or plastid "contains a mixture 

 of different plastic substances, which are distributed in 

 such a way that assimilation represented by the equation : 



201 Delage: Ibid. P. 862. Remark. 

 202 Delage : Ibid. P. 870, 



