PREPOTENCY 91 



There is no factor in breeding of more importance 

 than prepotency, and none which it is more difficult 

 to estimate. The term is necessarily a relative one, 

 and, further, it may affect some characters and not 

 others. Often it must go undetected, as in the case 

 of the leader of a herd of wild cattle, who may be 

 highly prepotent, but whose prepotency, unless he 

 is mated with members of another herd displaying 

 different characters, may pass unnoticed. Breeders 

 claim to be able to produce cattle so prepotent that 

 they will produce their like however mated. A well- 

 known dealer in highly-bred ponies used to boast that 

 he had a filly so prepotent that, though she were sent 

 to the best Clydesdale stallion in Scotland, she would 

 throw a colt showing no cart-horse blood. Prepotency 

 is usually obtained by inbreeding, which up to a 

 certain point fixes the character of a race, and in all 

 cases tends to check variation and reversion — the 

 Jews, for instance, as a race are strongly prepotent — 

 but there is no doubt that it may also arise as a sport, 

 and this is probably its more usual origin in a state of 

 nature. Professor Ewart, however, believes that in- 

 breeding is much commoner among wild animals than 

 has usually been conceded, and he holds the opinion 

 that the prepotency so induced has played a con- 

 siderable part in the origin of species. This, if true, 

 would to some extent take the place of Romanes' 

 'physiological selection'; for Romanes also thought 

 that, though of great importance, variation and natural 

 selection were insufficient to account for the origin of 

 species without some factor which would help to 

 mitigate the swamping effect of intercrossing — some 

 such agency as the fences of modern farms and cattle- 

 ranches — without which the famous cattle breeds of 

 the world would soon disappear in a general ' regres- 

 sion towards mediocrity.' 



In inbreeding the great difficulty of the breeder is 



