344 ME. G. J. EOMANES ON PHYSIOLOGICAL SELECTION. 



therefore that, even i£ they were each conceded to have arisen in 

 a number of individuals simultaneously, they vpould not have 

 benefited those individuals in their straggle for existence vpith 

 the parent form. Hence their re-absorption by intercrossing 

 would not be hindered by natural selection, which is the agency 

 here invoked by Mr. Darwin to account for their continuance, 

 This consideration, however, introduces us to the third and last 

 of the difficulties with which the theory of natural selection is 

 beset. 



Inutility of Specieic Charactees. 

 The only answer which Mr. Darwin makes to this difficulty is, 

 that structures and instincts which appear to us useless may 

 nevertheless be useful. Bat this seems to me a wholly inadequate 

 answer. Although in many cases it may be true, as indeed it is 

 shown to be by a number of selected illustrations furnished by 

 Mr. Darwin, still it is impossible to believe that it is always, or 

 even generally so. In other words, it is impossible to believe 

 that in all, or even in most, cases where minute specific differences 

 of structure or of instinct are to all appearance useless, they are 

 nevertheless useful. Observe, the case would be different if the 

 great majority of specific distinctions, like the great majority of 

 larger distinctions, were of obvious utilitarian significance. In 

 this case we might reasonably set down the exceptions as proof 

 of the rule, or hold that they appear to be exceptions only on 

 account of our ignorance. But it is certainly too large a demand 

 upon our faith in natural selection to appeal to the argument 

 from ignorance, when the facts require that this appeal should be 

 made over so very large a number of instances. We might, for 

 example, most reasonably conclude that the callosities on the hind 

 legs of horses, or the instinct of covering their excrement shown 

 by certain roaming Carnivora, are of some such hidden use to the 

 animals as to have preserved them in their struggle for existecce. 

 I say, we might reasonably conclude this, provided that such 

 instances were exceptional. But seeing that so enormous a 

 number of specific peculiarities are in the same predicament, it 

 surely becomes the reverse of reasonable so to pin our faith to 

 natural selection as to conclude that all these peculiarities must 

 be useful, whether or not we can perceive their utility. Por by 

 doing this we are but reasoning in a circle. The only evidence 

 we have of natural selection is furnished by the observed utility 



