280 Theories Treating of Inheritance 
between each chemical and the corresponding morpho- 
logical stage of development; for this morphological 
character of different chemical reactions has not so far 
been observed in any phenomena of the inorganic world, 
since it has absolutely no analogue in the process of 
crystallization which is a property of the molecular struc- 
ture of already formed, stable substances, that is of 
substances in perfect statico-chemical equilibrium. But 
we may mention the fact—and after all which has been 
said above no further proof of it is required—that the 
fundamental phenomena, such as the regeneration of 
amputated organs, the occasional reappearance especially 
in crosses of atavistic characters long since disappeared, 
and especially the ontogenetic repetition of phylogeny 
and the inheritance of acquired characters, not only find 
no explanation in all these hypotheses of chemical 
development but are on the contrary absolutely irrecon- 
cilable with them. 
Darwin, Galton, DeVries, Weismann 
It would be useless for our purpose to tarry especially 
over any one of these four theories, the underlying idea 
of all being the same identical conception of preformistic 
germs. The progressive elaboration of this idea which 
has proceeded gradually from the first to the last of these 
theories presents however the following noteworthy 
phenomenon. Preformistic germs, which were devised 
by Darwin, one could well say, chiefly for the purpose of 
accounting for the inheritance of acquired characters, 
were then deprived by Galton in great part but not com- 
pletely of this property, and finally with DeVries, and 
still more with Weismann became themselves the greatest 
difficulty for accepting that inheritance. 
