Appendix I. 177 



But, it is further represented, " even if we admit the 

 existence of this affinity, an unknown controlling force 

 must be added to this mysterious arrangement, in order 

 to marshal the molecules which enter the [growing] repro- 

 ductive cell in such a manner that their arrangement 

 corresponds with the order in which they emerge as cells 

 at a later period/' Surely, however, for Weismann of all 

 naturalists it ought not to be difficult to find this "■ unknown 

 controlling force." For of all naturalists he is perhaps the 

 most ready to invoke the agency of natural selection as 

 sufficient to explain every case — actual or imaginable — of 

 adaptation. Now, here is a case where natural selection, 

 one would think, is positively bound to act — supposing 

 that there be such things as gemmules. For, if "the 

 carriers of heredity" are gemmules, it is evident that their 

 mutual " affinities " must be adaptively " marshalled " at 

 each step of phylogenetic evolution, before any further 

 advance of such evolution can be possible. And I do 

 not see anything more " inconceivable " in supposing the 

 establishment of such mutual affinities step by step through 

 natural selection, than in supposing any other course of 

 adaptive development by similar means. For, as Darwin 

 has well shown, while anticipating this particular objection 

 to his theory, — " The assumed elective affinity of each 

 gemmule for that particular cell which precedes it in due 

 order of development is supported by many analogies." 

 The analogies which he then gives are so numerous that 

 I must here refer to his own discussion of the subject 1 — 

 a discussion which is entirely ignored by Weismann. 



Lastly, the principal ground, as far as I can see, 

 which Weismann has for regarding Darwin's theory in 

 any shape " inconceivable," is his own supposition that 

 there is as complete an anatomical separation between the 



1 Variation, Sec, 2nd ed., vol. ii. pp. 374-6. 



N 



