CuAr. I. UNDER DOMESTICATION. 29 



incstic varieties manifested a strong tendency to reversion — • 

 that is, to lose their acquired characters, while kept under the 

 same conditions, and while kept in a considerable body, so that 

 free intercrossin2^ mig-ht check, by blending together, any slight 

 deviations in their structure, in such case, I grant that we could 

 deduce nothing from domestic varieties in regard to species. 

 But there is not a shadow of evidence in favor of this view : to 

 assert that we could not breed our cart and race horses, long 

 and short horned cattle, and poultry of various breeds, and 

 esculent vegetables, for an unlimited number of generations, 

 would be opposed to all experience. 



Character of Domestic Varieties ; Difficult}/ of distinguish- 

 inff heticeen Varieties and Species y Origin of Domestic 

 Varieties from one or more /Sjjecies. 



When we look to the hereditary varieties or races of our 

 domestic animals and plants, and compare them with closely- 

 alUed species, wc generally perceive in each domestic race, as 

 already remarked, less uniformity of character than in true 

 species. Domestic races often have a somewhat monstrous 

 character ; by which I mean that, although differing from each 

 other, and from f)thcr species of the same genus, in several 

 trifling res]iects, they often differ in an extreme degree in some 

 one part, both when compared one with another, and more 

 especially when compared with the species under nature to 

 which they are nearest allied. With these exceptions (and 

 witli 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, only in most cases in a less de- 

 gree, in the same manner as do closely-allied species of the 

 same genus in a state of natiu-e. This must be admitted as 

 true, for the domestic races of many animals and plants have 

 •been rank(!d by some competent judges as the descendants of 

 aboriginally distinct species, and by other competent judges as 

 mere varieties. If any well-marked distinction existed be- 

 tween a domestic race and a species, this source of doubt 

 would not so perpetually recur. It has often been stated that 

 domestic races do not diffcT from each other in characters of 

 generic value. It can ])e shown that this statement is not cor- 

 rect ; but naturalists differ nuich in determining what char- 

 acters are of gimerio value ; all such valuations being at 

 present empirical. When it is explained how genera origi- 

 nate under nature, it will bo seen that we have no right to 



