222 Inheritance of Acquired Characters 
natural selection, panmixia or something else, and that 
consequently they have become arrested in successive 
ontogeneses at successively earlier stages of development. 
But the question cannot be repeated often enough; how 
can this theory explain the growth of these organs up to 
a certain stage of development and their retrogression 
and disappearance in the later stages? 
In short, it seems to us that one cannot imagine a 
more complete overthrow even from a purely logical 
point of view, where it is only a matter of avoiding con- 
tradiction on one’s own premises, than thzt suffered by 
Weismann in the attempt to find an explanation of the 
repetition of phylogeny by ontogeny, and one can hardly 
bring forward a more thorough failure of a theory built 
up laboriously with the object of explaining all the differ- 
ent phenomena of heredity, even the most peculiar and 
secondary ones, than appears in the fact that this theory 
is not even capable of giving the least explanation of the 
most general biogenetic phenomenon—the one which 
underlies all the others. And this contradiction and this 
failure do not appear so much in the minute and partic- 
ular parts of Weismann’s theory, in which it deals with 
this or that peculiar detail, but much rather in the theory 
itself in all its generality, which disputes the inheritance 
of acquired characters. Weismann and his supporters 
can, if the most evident facts are not enough for them, 
deny this law of recapitulation. But that they admit it 
and nevertheless dispute inheritance, this is a contradic- 
tion from which the opponents of the Lamarckian 
principle cannot escape now or ever—a destructive rock 
upon which all their theories are wrecked. 
If now we sum up succinctly the discussion in this 
