EVOLUTION IN NATURE AND UNDER DOMESTICATION. 231 



the largest variability, those groups in which some forms are 

 adapted to some, and others to very different uses, or different 

 climates. 



Perhaps the goose and the turkey can be kept more economic- 

 ally than domestic chickens, yet chickens are more of a suc- 

 cess than either geese or turkeys as domestic animals, and it 

 may be that the oil- palm gives a greater return per acre than 

 corn, yet corn is a greater success as a cultivated plant. 



Where, as in nature, the variable off-spring of an occasional 

 cross goes under into the multitude, under cultivation aber- 

 rant individuals are apt to be noticed and given a chance to 

 show their value. 



Under cultivation both processes in evolution, on one hand 

 heightening of variability by crossing, and on the other hand 

 reduction of variability by isolation, selection and colonization 

 are exaggerated far beyond anything we can ever hope to find 

 in nature. 



Propagation of plants and animals under domestication is 

 essentially different from propagation in nature, as the former 

 is essentially a continued system of colonization. 



The history of the domestic breeds is one of repeated colon- 

 ization, of isolation of small groups. It is very instructive to 

 note how a breed of dogs is introduced into a new country, 

 speedily becomes popular and is propagated, and to note from 

 how few individuals the multitude of animals of a new popular 

 breed is derived. 



The result is, that such a breed in its new home is very much 

 purer than in the country where it originated, and this very 

 fact may be part of the reason for its popularity. The Airedale 

 terrier in America, is purer and different and better as a breed, 

 than the same breed in Scotland. The Schipperke in America 

 and England can hardly be compared with the original dogs, 

 asthey were kept by barge-men in Holland and Belgium. 



Evolution in plants and animals under cultivation is certainly 

 moie intense and often more accelerated than evolution in 

 nature. Whereas the origin and establishing of a new species in 



