26 8BLJ£GTI0N B Y MAIT, 



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 di-ay 

 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 botauists, 

 for instance, believe that the fuller's teasel, with its hooks, 

 which can not be rivaled 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 culti- 

 vated 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 com- 

 pare 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, culi- 

 nary, orchard and flower-garden races of plants, most useful 

 to man at different seasons and for different purposes, or so 

 beautiful in his eves, we must, I think, look further than 

 to mere variability. We can not suppose that all the 

 breeds were suddenly j^roduced 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 

 breed ei's have, even within a single lifetime, modified to a 

 large extent their breeds of cattle and sheep. In order 

 fully to realize what they iiave done it is almost necessary 



