186 Darwm, and after Darwin. 



overlooked by those who have maintained the frequency of 

 such characters, and that is, their almost necessary instability V 



This argument he proceeds to elaborate at con- 

 siderable length, but fails to perceive what appears 

 to me the obvious answer. Provided that the cause 

 of the useless character is constant, there is no 

 difficulty in understanding why the character is 

 stable. Utility is not the only principle that can 

 lead to stability: any other principle must do the 

 same, provided that it acts for a sufficient length 

 of time, and with a sufficient degree of uniformity, 

 on all the individuals of a species. This is a con- 

 sideration the cogency of which was clearly recog-, 

 nized by Darwin, as the following quotations will 

 show. Speaking of unadaptive characters, he says 

 they may arise as merely 



" fluctuating variations, which sooner or later become constant 

 through the nature of the organism and of surrounding conditions, 

 but not through natural selection V 



Elsewhere we read : 



" Each of the endless variations which we see in the plumage 

 of our fowls must have had some efficient cause ; and if the 

 same cause were to act uniformly during a long series of genera- 

 tions on many individuals, all probably would be modified in 

 the same manner." 



As special illustrations of this fact I may quote 

 the following cases from Darwin's works. 



"Dr. Bachman states that he has seen turkeys raised from 

 the eggs of wild species, lose their metallic tints, and become 

 spotted in the third generation. Mr. Yarrell many years ago 

 informed me that the wild ducks bred in St James' Park lost 



1 Darwinism, p. 138. 



1 Origin of Species, p. 176 : italics mine, as also in the following. 



