xii.] THE ORIGIN OF SPECIES. 231 



Two circumstances are well worthy of remark in both these 

 cases. In each, the variety appears to have arisen in full force, 

 and, as it were, per saltum ; a wide and definite difference 

 appearing, at once, between the Ancon ram and the ordinary 

 sheep ; between the six-fingered and six-toed Gratio Kelleia and 

 ordinary men. In neither case is it possible to point out any 

 obvious reason for the appearance of the variety. Doubtless 

 there were determining causes for these as for all other pheno 

 mena ; but they do not appear, and we can be tolerably certain 

 that what are ordinarily understood as changes in physical con 

 ditions, 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 discover 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 

 &quot; spontaneous &quot; manner, though we are, of course, far from 

 denying that they may be traced, in some cases, to distinct 

 external influences ; 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 remark that, once in 

 existence, varieties obey the fundamental law of reproduction 

 that like tends to produce like, and their offspring exemplify it by 

 tending to exhibit the same deviation from the parental stock as 

 themselves. Indeed, there seems to be, in many instances, a pre 

 potent influence about a newly-arisen variety which gives it what 

 one may call an unfair advantage over the normal descendants 



