36 THE ORIGIN OF SPECIES n 



to point out any obvious reason for the appearance 

 of the variety. Doubtless there were determining 

 causes for these as for all other phenomena ; but 

 they do not appear, and we can be tolerably certain 

 that what are ordinarily understood as changes in 

 physical conditions, as in climate, in food, or the 

 like, did not take place and had nothing to do with 

 the matter. It was no case of what is commonly 

 called adaptation to circumstances ; but, to use a 

 conveniently erroneous phrase, the variations arose 

 spontaneously. The fruitless search after final 

 causes leads their pursuers a long way ; but even 

 those hardy teleologists, who are ready to break 

 through all the laws of physics in chase of their 

 favourite will-o'-the-wisp, may be puzzled to dis- 

 cover what purpose could be attained by the stunted 

 legs of Seth Wright's ram or the hexadactyle 

 members of Gratio Kelleia. 



Varieties then arise we know not why ; and it is 

 more than probable that the majority of varieties 

 have arisen in this " spontaneous " manner, though 

 we are, of course, far from denying that they may 

 be traced, in some cases, to distinct external in- 

 fluences ; which are assuredly competent to alter 

 the character of the tegumentary covering, to 

 change colour, to increase or diminish the size of 

 muscles, to modify constitution, and, among plants, 

 to give rise to the metamorphosis of stamens into 

 petals, and so forth. But however they may have 

 arisen, what especially interests us at present is, to 



