210 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 
Delage: L’hérédité etc. P. 366. 
