24 SELECTION BY MAN. 



and apples, shows how utterly he disbelieves that the several 

 sorts, for instance a Ribston-pippin or Codiin-apple, could 

 ever have proceeded from the seeds of the same tree. In- 

 numerable other examples could be given. The explanation, 

 I think, is simple : from long-continued study they 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 

 differences, yet they ignore all general arguments, and refuse 

 to sum up in their minds slight differences accumulated dur 

 ing many successive generations. May not those naturalists 

 who, knowing far less of the laws of inheritance thai) does 

 the breeder, and knowing no more than he does of the inter- 

 mediate links in the long lines of descent, 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 species 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 domestic 

 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 ac- 

 count 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, fo: 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 case 

 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 breec 1 for another purpose j when we 



