VARIATION UNDER DOMESTICATION 57 



frrm long-continued st'dy hey are strongly impressed 

 with the differences between the several races; and 

 though they well know that each race varies slightly, 

 for they win their prizes by selecting such slight differ- 

 ences, yet they ignore all general arguments, and refuse 

 to sum up in their minds slight differences accumulated 

 during many successive generations. May not those nat- 

 uralists who, knowing far less of the laws of inheritance 

 than does the breeder, and knowing no more than he 

 does of the intermediate links in the long lines of de- 

 scent, yet admit that many of our domestic races are 

 descended from the same parents — may they not learn 

 a lesson of caution, when they deride the idea of spe- 

 cies in a state of nature being lineal descendants of other 

 species ? 



Principles of Selection anciently followed, and their 



Effects 



' Let us now briefly consider the steps by which do- 

 mestic races have been produced, either from one or from 

 several allied species. Some effect may be attributed to 

 the direct and definite action of the external conditions 

 of life, and some to habit; but he would be a bold man ^ 

 who would account by such agencies for the differences 

 between a dray and racehorse, a greyhound and blood- 

 hound, a carrier and tumbler pigeon. One of the most 

 remarkable features in our domesticated races is that we ■ 

 see in them adaptation, not indeed to the animal's or 

 plant's own good, bat to_,,. man's use, -.ox_fancy. Some 

 variations useful to him have probably arisen suddenly, 

 or by one step; many botanists, for instance, believe that 

 the fuller's teasel, with its hooks, which cannot be ri- 



