22 THE ORIGIN OF SPECIES 



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 account by such agencies for the differ- 

 ences 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 sud- 

 denly, 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 case with the ancon sheep. But when we com- 

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

 various breeds of sheep fitted either for cultivated land or moun- 

 tain 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 compare the host of agricultural, culinary, orchard, and 

 flower-garden races of plants, most useful to man at different sea- 

 sons and for different purposes, or so beautiful in his eyes, we 

 must, I think, look further than to mere variability. We cannot 

 suppose that all the breeds were suddenly produced as perfect and 

 as useful as we now see them; indeed, in many cases, we know 

 that this has not been their history. The key is man's power of 

 accumulative selection: nature gives successive variations; man 

 adds them up in certain directions useful to him. In this sense he 

 may be said to have made for himself useful breeds. 



The great power of this principle of selection is not hypothetical. 

 It is certain that several of our eminent breeders have, even within 

 a single lifetime, modified to a large extent their breeds of cattle 

 and sheep. In order fully to realize what they have done, it is al- 



