3IO Darwin, and after Darwin. 



must do so. For the latter statement imports a completely 

 new assumption— namely, that every variety which becomes 

 a species must do so because it has been " selected into " a 

 species. In short, what we are here told is, that if we believe 

 the selection principle to have given origin to some species, 

 we must further believe, "as a necessary consequence," that 

 it has given origin to all species. 



The above reply, which is here quoted verbatim from 

 Nature, Vol. 38, p. 616-18, proceeded to show that it does 

 not belong to " the first principles of the theory of natural 

 selection " to deny that no other cause than natural selection 

 can possibly be concerned in the origin of species ; and facts 

 were given to prove that such unquestionably has been 

 the case as regards the origin of "local" or "permanent" 

 varieties. Yet such varieties are what Darwin correctly 

 terms "incipient" species, or species in process of taking 

 origin. Therefore, if Professor Huxley's criticism is to stand 

 at all, we must accept it " as a necessary consequence of the 

 theory of selection," that every such variety '■ which exists, 

 exists in virtue of adaptation " — a statement which is proved 

 to be untrue by the particular cases forthwith cited. But as 

 this point has been dealt with much more fully in the text of the 

 present treatise, I shall sum up the main points in a few words. 



The criticism is all embodied in two propositions — namely, 

 (a) that the theory of natural selection carries with it, as 

 a " necessary consequence," the doctrine that survival of the 

 fittest has been the cause of the origin of all species ; and 

 {b) that therefore it amounts to one and the same thing 

 whether we define the theory as a theory of species or as 

 a theory of adaptations. Now, as a mere matter of logical 

 statement, it appears to me that both these propositions are 

 unsound. As regards the first, if we hold with Darwin that 

 other causes have co-operated with natural selection in the 

 origination of some (i. e. many) species, it is clearly no part 

 of the theory of natural selection to assume that none of 



