VARIATION UNDER DOMESTICATION 15 



with closely-allied species, we generally perceive in 

 each domestic race, as already remarked, less uni- 

 formity of character than in true species. Domestic 

 races of the same species, also, often have a somewhat 

 monstrous character ; by which I mean, that, although 

 differing from each other, and from other species of 

 the same genus, in several trifling respects, they often 

 differ in an extreme degree in some one part, both 

 when compared one with another, and more especially 

 when compared with all the species in nature to which 

 they are nearest allied. With these exceptions (and 

 with that of the perfect fertility of varieties when 

 crossed, — a subject hereafter to be discussed), domestic 

 races of the same species differ from each other in the 

 same manner as, only in most cases in a lesser degree 

 than, do closely-allied species of the same genus in a 

 state of nature. I think this must be admitted, when 

 we find that there are hardly any domestic races, either 

 amongst animals or plants, which have not been 

 ranked by competent judges as mere varieties, and by 

 other competent judges as the descendants of aborigin- 

 ally distinct species. If any marked distinction ex- 

 isted between domestic races and species, this source of 

 doubt could not so perpetually recur. It has often been 

 stated that domestic races do not differ from each 

 other in characters of generic value. I think it could 

 be shown that this statement is hardly correct ; but 

 naturalists differ widely in determining what characters 

 are of generic value ; all such valuations being at 

 present empirical. Moreover, on the view of the origin 

 of genera which I shall presently give, we have no 

 right to expect often to meet with generic differences 

 in our domesticated productions. 



When we attempt to estimate the amount of struc- 

 tural difference between the domestic races of the 

 same species, we are soon involved in doubt, from not 

 knowing whether they have descended from one or 

 several parent species. This point, if it could be 

 cleared up, would be interesting ; if, for instance, it 

 could be shown that the greyhound, bloodhound, 



