And now, as regards the second point (_b_), even if we grant the assumption that natural selection is the only possible cause of the origin of species--or, which is the same thing, that every species has been originated by natural selection,--is it likewise the same thing whether we define the theory of natural selection as a theory of species or as a theory of adaptations? Professor Huxley's criticism endeavours to show that it is; but a little consideration is enough to show that it is not. What does follow from the assumption is, that, _so far as specific characters are concerned_, it is one and the same thing to say that the theory is a theory of species, and to say that it is a theory of adaptations. But specific characters are not conterminous with adaptive characters; for innumerable adaptive characters are not distinctive of species, but of genera, families, orders, classes, and sub-kingdoms. Therefore, if it is believed (as, of course, Professor Huxley believes) that the theory in question explains the evolution of all adaptive characters, obviously it is not one and the same thing to define it indifferently as a theory of species or as a theory of adaptations. Now, all this is not merely a matter of logic chopping. On the contrary, the question whether we are to accept or to reject the deduction that all species must necessarily have owed their origin to natural selection, is a question of no small importance to the general theory of evolution. And our answer to this question must be determined by that which we give to the ulterior question--Is the theory of natural selection to be defined as a theory of species, or as a theory of adaptations? * * * * * We now pass on to our consideration of Darwin's opinion touching the question, as stated by himself,--"The doctrine of utility, how far true?" As I cannot ascertain that Darwin has anywhere expressed an opinion as to whether natural selection has been necessarily concerned in the origin of all _species_, the issue here is as to whether he held this with regard to all _specific characters_. It will be remembered that while opposing this doctrine as erroneous both in logic and in fact, I have represented that it is not a doctrine which Darwin sanctioned; but, on the contrary, that it is one which he expressly failed to sanction, by recognizing the frequent inutility of specific characters. Mr. Wallace, on the other hand, alleges that Darwin did believe in the universal--as distinguished from the general--utility of such characters. And he adds that he has "looked in vain in Mr. Darwin's works" for any justification of my statements to the contrary[149]. Therefore I will endeavour to show that Mr. Wallace's search has not been a very careful one.