122 ORIGIN OF SPECIES 



DIVERGENCE OF CHARACTER 



The principle, which I have designated by this term, is of 

 high importance, and explains, as I believe, several impor- 

 tant facts. In the 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 far less from each other 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 habit- 

 ually happen, we must infer from most of the innumerable 

 species throughout nature presenting well-marked differ- 

 ences ; whereas varieties, the supposed prototypes and par- 

 ents of future well-marked species, present slight and ill-de- 

 fined 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 production 

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

 and cart horses, the several breeds of pigeons, &c., could 

 never have been effected by the mere chance accumulation of 

 similar variations during many successive generations. In 

 practice, a fancier is, for instance, struck by a pigeon having 

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

 having a rather longer beak; and on the acknowledged 

 principle that "fanciers do not and will not admire a me- 

 dium standard, but like extremes," they both go on (as 

 has actually occurred with the sub-breeds of the tumbler- 

 pigeon) choosing and breeding from birds with longer and 

 longer beaks, or with shorter and shorter beaks. Again, we 

 may suppose that at an early period of history, the men of 



