68 THE ORIGIN OF SPECIES 



vailed by any mechanical < ontrivance, is only a variety 

 of the wikl Dipsacus; and this amount of change may 

 have suddenly arisen in a seedling. So it has probably 

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

 been the case with the ancon sheep. But when we com- 

 pare the drayhorse and racehorse, the dromedary and 

 camel, the various breeds of sheep fitted either for cul- 

 tivated 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 gamecock, so pertinacious in battle, with 

 other breeds so little quarrelsome, with "everlasting lay- 

 ers" which never desire to sit, and with the bantam so 

 small and elegant; when we compare the host of agricul- 

 tural, culinary, orchard, and flower-garden races of plants, 

 most useful to man at different seasons and for different 

 purposes, or so beautiful in his eyes, we must, I think, 

 look further than to mere variability. We cannot sup- 

 pose that all the breeds were suddenly produced as per- 

 fect 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 almost nec- 

 essary to read several of the many treatises devoted to 



