264 Darwin, and after Darzvin. 



natural selection can have been concerned in the 

 origin and maintenance of specific characters. But 

 he does not seem to see that the consideration cuts 

 two ways — and much more forcibly against his 

 views than in favour of them. For while, as already 

 shown in the cliaptcr before last, it is sufficiently 

 easy to dispose of the consideration as Wallace uses 

 it (by simply pointing out with Darwin that any 

 causes other than natural selection which may have 

 been concerned in the genesis of specific characters, 

 must, if equally uniform in their operation, equally 

 give rise to permanence and constancy in their results) ; 

 on the other hand, it becomes impossible to explain 

 the stability of useless generic characters, if. as 

 Wallace's use of the argument requires, natural selec- 

 tion is the only possible cause of stability. The 

 argument is one that cannot be played with fast 

 and loose Either utility is the sole condition to 

 the stability of any diagnostic character (in which 

 case it is not open to Mr. Wallace to assume that 

 all generic or higher characters which are now use- 

 less have owed their origin to a past utility) ; or 

 else utility is not the sole condition to stability 

 (in which case his use of the present argument in 

 relation to specific characters collapses). We have 

 seen, indeed, in the chapter before last, that his use 

 of the argument collapses anyhow, or quite irrespec- 

 tive of his inconsistent attitude towards generic 

 characters, with which we were not then concerned. 

 But the point now is that, as a mere matter of logic, 

 the argument from stability as Wallace applies it 

 to the case of specific characters, is incompatible 

 with his argument that useless generic characters 



