110 DIVERGENCE OF CHARACTER. Chap. IV. 



Divergence of Character, 



The principle, which I liavc dcsip^nated by this term, is of 

 high importance, and cxphiins, as I believe, several important 

 facts, in tlie first place, varieties, even strongly-marked ones, 

 though having somewhat of the character of species — as is 

 shown by the hopeless doubts in many cases how to rank 

 them — yet certainly differ from each other far less than do 

 good and distinct species. Nevertheless, according to my 

 view, varieties are species in the process of formation, or are, 

 as I have called them, incipient species. How, then, does the 

 lesser difference between varieties become augmented into the 

 greater difference between species ? That this does habitually 

 happen, we must infer from most of the innumerable species 

 throughout Nature presenting well-marked differences ; where- 

 as varieties, the supposed protot}-pes and parents of future 

 well-marked species, jiresent slight and ill-defined differences. 

 Mere chance, as we may call it, might cause one variety to 

 differ in some character from its parents, and the offspring of 

 this variety again to differ from its parent in the very same 

 character and in a greater degree ; but this alone would never 

 account for so habitual and large a degree of difference as that 

 between the species of the same genus. 



As has always been my practice, I have sought light on 

 this head from our domestic productions. We shall here find 

 something analogous. It will be admitted that the produc- 

 tion of races so different as short-horn and Hereford cattle, race 

 and cart horses, the several breeds of pigeons, etc., could never 

 have been effected by the mere chance accumulation of varia- 

 tions of a similar character during many successive generations. 

 In ])ractice, a fancier is, for instance, struck by a pigeon having 

 a sliglitly shorter beak ; another fancier is struck by a pigeon 

 having a rather longer beak ; and, on the acknowledged prin- 

 ciple that " fanciers do not and will not admire a medium stand- 

 ard, but like extremes," they both go on (as has actually oc- 

 curred with the sub-breeds of the tumbler-pigeon) choosing and 

 l)rceding from birds with longer and longer beaks, or with 

 shorter and shorter beaks. Again, we may suppose that at an 

 early period one man preferred swifter horses ; another stronger 

 and more bulky horses. The early differences would be very 

 Blight; in the course of time, from the continued selection of 

 swifter horses by some breeders, and of stronger ones by others, 

 the differences would become greater, and would be noted as 



