Characters as Adaptive and Specific. 171 



to perceive that they constitute any grounds for 

 holding the doctrine that all specific characters are, 

 or formerly have been, directly or indirectly due to 

 natural selection. My own reasons for dissenting 

 from this Wallacean doctrine are as follows. 



From what has just been said, it will be apparent 

 that the question in debate is not merely a question 

 of fact which can be settled by a direct appeal to 

 observation. If this were the case, systematic natur- 

 alists could soon settle the question by their detailed 

 knowledge of the structures which are severally 

 distinctive of any given group of species. But so far 

 is this from being the case, that systematic naturalists 

 are really no better qualified to adjudicate upon the 

 matter than are naturalists who have not devoted so 

 much of their time to purely diagnostic work. The 

 question is one of general principles, and as such 

 cannot be settled by appeals to special cases. For 

 example, suppose that the rest of this chapter 

 were devoted to a mere enumeration of cases where 

 it appears impossible to suggest the utility of certain 

 specific characters, although such cases could be 

 adduced by the thousand, how shcnld I be met at the 

 end of it all ? Not by any one attempting to suggest 

 the utility, past or present, of the characters named ; 

 but by being told that they must all present some 

 hidden use, must be vestigial, or else must be due to 

 correlation. By appealing to one or other of these as- 

 sumptions, our opponents are always able to escape the 

 necessity of justifying their doctrine in the presence of 

 otherwise inexplicable facts. No matter how many 

 seemingly " indifferent characters " we may thus accumu- 



