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 



