3o8 Darwin, and after Darwin. 



has put forward a theory of the adaptation of species, but not of 

 their origin, is therefore to misunderstand the first principles 

 of the theory. For, as has been pointed out, it is a necessary 

 consequence of the theory of selection that every species 

 must have some one or more structural or functional pecu- 

 liarities, in virtue of the advantage conferred by which it has 

 fought through the crowd of its competitors, and achieved a 

 certain duration. In this sense, it is true that every species 

 has been 'originated' by selection." 



Now, in the first place, I have nowhere said that "Darwin 

 has put forward a theory of the adaptation of species, but not 

 of their origin." I said, and continue to say, that he has 

 put forward a theory of adaptations in general, and that 

 where such adaptations appertain to species only (i.e. are 

 peculiar to particular species), the theory becomes "also a 

 theory of the origin of the species which present them.'' The 

 only possible misunderstanding, therefore, which can here be 

 alleged against me is, that I fail to perceive it as a " necessary 

 consequence of the theory of selection that every species must 

 have some one or more structural or functional peculiarities " 

 of an adaptive or utilitarian kind. Now, if this is a misunder- 

 standing, I must confess to not having had it removed by 

 Mr. Huxley's exposition. 



The whole criticism is tersely conveyed in the form of two 

 sequent propositions — namely, "Every species which exists, 

 exists in virtue of adaptation ; and whatever accounts for that 

 adaptation accounts for the existence of the species.'* My 

 answer is likewise two-fold. First, I do not accept the premiss ; 

 and next, even if I did, I can show that the resulting con- 

 clusion would not overturn my definition. Let us consider 

 these two points separately, beginning with the latter, as the 

 one which may be most briefly disposed of. 



I. Provisionally conceding that " every species which exists, 

 exists in virtue of adaptation," I maintain that my definition 

 of the theory of natural selection still holds good. For even 

 on the basis of this concession, or on the ground of this 

 assumption, the theory of natural selection is not shown to be 

 "primarily '' a theory of the origin of species. It follows, indeed, 

 from the assumption — is, in fact, part and parcel ot the as- 



