102 Darwin, and after Darwin. 



together a great array of facts, the more carefully 

 one reads his book the more apparent does it become 

 that no single one of the facts is in itself conclusive 

 evidence of the transmission to progeny of char- 

 acters which are acquired through use-inheritance or 

 through direct action of the environment. Every one 

 of the facts is susceptible of explanation on the 

 hypothesis that the principle of natural selection 

 has been the only principle concerned. This, how- 

 ever, it must be observed, is by no means equivalent 

 to proving that characters thus acquired are not 

 transmitted. As already pointed out, it is imprac- 

 ticable with species in a state of nature to disso- 

 ciate the distinctively Darwinian from the possibly 

 Lamarckian factors; so that even if the latter 

 are largely operative, we can only hope for direct 

 evidence of the fact from direct experiments on 

 varieties in a state of domestication. To this branch 

 of our subject, therefore, we will now proceed. 



