THE ORIGIN OF SPECIES 151 



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 th^se 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 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 " spontaneous " manner, though we are, of course, far 

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

 distinct external influences ; which are assuredly com- 

 petent 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 from the same stock. This is 

 strikingly exemplified by the case of Gratio Kelleia, who 

 married a woman with the ordinary pentadactyle ex- 

 tremities, and had by her four children, Salvator, George, 

 Andr6, and Marie. Of these children Salvator, the eldest 



