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.2°! 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 will perform only later.2°? 
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: 
201Delage: Ibid. P. 862. Remark. 
*°*Delage: Ibid. P. 870, 
