192 Inheritance of Acquired Characters 
nevertheless in these that this reduction reaches its 
maximum. 
However that may be, we might nevertheless admit 
either that, as panmixia supposes, fortuitous minus 
variations preponderate over plus variations, or that the 
principle of the economy of the organism is alone enough 
to secure the victory to those individuals whose useless 
organs are most atrophied. But, even in that case how 
could panmixia and the principle of economy in the 
organism explain the fact that the atrophic state of 
organs which have become useless, such as appears in 
adult organisms, results in the course of ontogeny from 
an involutive process of these organs which are better 
developed in the early stages than in the later stages? 
Although in so doing we anticipate a question which we 
shall examine again later in all its generality, we may 
note here that the most that panmixia and the principle 
of economy could do would be to explain the fact that 
the more recent a species with a given atrophied organ 
is, the earlier should be the stage of development at 
which the organ in question is arrested in ontogeny, 
whereas in the ancestral species it attained a greater 
development. But how can they explain how certain 
tissues and organs develop during ontogeny up to a 
certain and fairly advanced point and thereafter at a 
certain moment undergo a physiologic involution result- 
ing in their degeneration and often in their complete 
disappearance ? 
As we pass on now from continuous, gradual atrophy 
of useless organs to the slowly progressive formation of 
useful organs and so to phyletic evolution in general, we 
must declare at the outset that of all the objections that 
have been urged and which can yet be urged against the 
