256 Darwin, and after Darwin. 



their origin to the principle of utility. Yet this same 

 school does not maintain any such generalization, 

 either with regard to varietal characters on the one 

 hand, or to generic characters on the other. On the 

 contrary, Professor Huxley, Mr. Wallace, and all 

 other naturalists who agree with them in refusing to 

 entertain so much as the abstract possibility of any 

 cause other than natural selection having been pro- 

 ductive of species, fully accept the fact of other 

 causes having been largely concerned in the production 

 of varieties, genera, families, and all higher groups, 

 or of the characters severally distinctive of each. 

 Indeed, Mr. Wallace does not question what appears 

 to me the extravagant estimate of Professor Cope, 

 that the non-adaptive characters distinctive of those 

 higher groups are fully equal, in point of numbers, to 

 the adaptive. But, surely, if the theory of evolution 

 by natural selection is, as we all agree, a true theory 

 of the origin of species, it must likewise be a true 

 theory of the origin of genera ; and if it be supposed 

 essential to the integrity of the theory in its former 

 aspect that all specific characters should be held to 

 be useful, I fail to see how, in regard to its latter 

 aspect, we are so readily to surrender the necessary 

 usefulness of all generic characters. And exactly the 

 same remark applies to the case of constant "varieties," 

 where again the doctrine of utility as universal is not 

 maintained. Yet, according to the general theory of 

 evolution, constant varieties are what Darwin termed 

 "incipient species," while species are what may be 

 termed " incipient genera." Therefore, if the doctrine 

 of utility as universal be conceded to fail in the case 

 pf varieties on the one hand and of genera on the 



