34 SELECTION BY MAN. [Chap. 1 



Principles of Selection anciently folloived, and their 



Effects. 



Let us now briefly consider the steps by which 

 domestic races have been produced, either from one or 

 from several allied species. Some effect may be at- 

 tributed 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 race- 

 horse, a greyhound and bloodhound, 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, but to man's use or 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 rivalled 

 by any mechanical contrivance, is only a variety of the 

 wild Dipsacus ; and this amount of change may have 

 suddenly arisen in a seedling. So it has probably been 

 with the turnspit dog ; and this is known to have been 

 the ease with the ancon sheep. But when we compare 

 the dray-horse and race-horse, the dromedary and 

 camel, the various breeds of sheep fitted either for 

 cultivated land or mountain pasture, with the wool of 

 one breed good for one purpose, and that of another 

 breed for another purpose ; when we compare the 

 many breeds of dogs, each good for man in different 

 ways ; when we compare the game-cock, so pertinacious 

 in battle, with other breeds so little quarrelsome, with 

 " everlasting layers " which never desire to sit, and 

 with the bantam so small and elegant ; when we 



