280 Darwin, and after Darwin. 



changes which are from the first congenital, though 

 not utilitarian. Indeed, there are not a few facts 

 (Hoffmann's plants, Weismann's butterflies, &c.), 

 which can only be explained either in this way, or 

 as above (a). And in the present connexion it is 

 immaterial which of these alternative explanations 

 we choose to adopt, seeing that they equally 

 refute our opponents' objection. And not only 

 do these considerations (a) and (b] refute this 

 particular objection ; they overturn on new and 

 independent grounds the whole of our opponents' 

 generalization. For the generalization is. that the 

 principle of utility, acting through natural selection, 

 is " necessarily " the sole principle which can be 

 concerned in hereditary changes of specific type. 

 But here we perceive both a possibility (a) and a 

 probability (), if not indeed a certainty, that quite 

 other principles have been largely concerned in the 

 production of such changes. 



(c) Altogether apart from these considerations, 

 there remains a much more important one. For 

 the objection that fixed or "stable" climatic 

 varieties differ from true species in not being sub- 

 ject to heredity, raises the question What are we 

 to understand by a " species " ? This question, which 

 was thus far purposely left in abeyance, had now 

 to be dealt with seriously. For it would clearly 

 be irrational in our opponents to make this highly 

 important generalization with regard to species and 

 specific characters, unless they are prepared to tell 

 us what they mean by species, and therefore by 

 characters as specific. In as far as there is any 

 ambiguity on this point it makes entirely for our 



