36 THE DARWINIAN THEORY 



over his fences, it occurred to him that, if he could 

 produce a breed of sheep with short bandy legs, he 

 would lose none of them, as they would be unable to 

 jump his fences. He therefore bred entirely from 

 the short-legged ram when it had reached maturity, 

 and after a few years succeeded in raising a consider- 

 able flock of this variety, which was known as the 

 Ancon sheep. 



The power of artificial selection is almost 

 unlimited, and breeders of animals speak with the 

 utmost confidence of being able to produce any 

 desired result in the form of the body ; and, in the 

 case of poultry and pigeons, in the length of beak, 

 the number of feathers, and even in the markings on 

 particular feathers. Lord Spencer says : "It is 

 therefore very desirable before any man commences 

 to breed either cattle or sheep, that he should make 

 up his mind as to the shape and qualities he wishes 

 to obtain, and strictly pursue this object." And 

 speaking of Leicester sheep Lord Somerville re- 

 marks : " It would seem as if they had just chalked 

 on the wall a form perfect in itself, and then had 

 given it existence." So also with plants ; enormous 

 changes are effected bycultivation — i.e., by selec- 

 tion, in fruits and flowers. 



Natural Selection. 



The theory of Natural Selection teaches that 

 there are in Nature causes which act in much the 

 same way as man acts when selecting artificially the 

 best animals for breeding purposes ; causes which 



