The imm mimmBJ: 



A Penny Weekly Magazine of Natural History. 



No. 115. JANUAEY 21st, 1882. Vol. 3. 



DARWINISM. 



Third Paper. 



WE have found it so impossible to 

 condense what we have to say, on 

 variation under domestication and re- 

 version to the original form, into one 

 paper, that we have been reluctantly 

 compelled to make two of it, and to-day 

 will speak of variation under domesti- 

 cation only. 



If what has already been said has 

 been made clear enough, our young 

 readers will be enabled now to under- 

 stand why much greater change can be 

 obtained under domestication, and in a 

 much shorter time than in a state of 

 nature. In the first place all the natu- 

 ral restrictions are removed. If the 

 argument in previous papers be correct, 

 the normal form of an animal is exactly 

 that most fitted for its p]ace in nature. 

 Such being the case, any departure from 

 that form in any direction will produce 

 an animal less fitted to hold its own in 

 the great struggle for existence. Thus 

 extensive variation is kept down in 

 nature, and no changed form can become 

 permanent that is not in harmony with 

 existing conditions. As these conditions 

 change but slowly, so the change in the 

 form must be very slow also ; any mark- 



ed divergence M'ould either cause the 

 animal to die out or be killed ofi* quicker 

 than its congeners, the original form 

 alone surviving. In domestication no 

 such cause is in operation. An animal 

 whose safety is assured and whose food 

 is provided for it may vary in any 

 direction without suffering from the 

 change. Yet even in domestication 

 change would be exceedingly slow if 

 man did not interfere and further it for 

 his own ends. Let us illustrate our 

 argument by a reference to wild and 

 domestic rabbits. In nature how rarely 

 we see a rabbit of any other colour than 

 grey. Occasionally we may see a black 

 one in a dealer's shop, but in all the 

 many thousands that are weekly sent to 

 market how very seldom any other 

 variety is seen. The reason for rabbits 

 being grey is obvious, it is the hue most 

 in harmony with their surroundings. 

 ''A white rabbit," says Wallace, would 

 be more surely the prey of the hawk or 

 buzzard." This very fact prevents the 

 continuance of a light-coloured variety 

 — they are not in harmony with their 

 surroundings, and are killed ofi" because 

 they are easier seen. This restriction 

 not obtaining under domestication, a 

 white variety would be as likely to 



