THE PENYCUIK EXPERIMENTS. . 135 



experiments, as far as they have gone, afford no evidence in support of 

 the telegony hypothesis." Nothing has occurred which is not ex- 

 plicable on the theory of reversion. 



There is no factor in breeding of more importance than prepotency, 

 and none which 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 char- 

 acters, 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. Pre- 

 potency 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 inbreeding is much commoner among wild 

 animals than has usually been conceded, and he holds the opinion that 

 the prepotency so induced has played a considerable part in the origin 

 of species. This, if true, would to some extent take the place of 

 Eomanes' 'physiological selection'; for Eomanes also thought that, 

 though of great importance, variation and natural selection were in- 

 sufficient 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 'regression toward mediocrity.' 



In inbreeding the great difficulty of the breeder is to know when 

 to stop. Carried too far it undoubtedly leads to degeneracy. In the 

 'Domesticated Animals of Great Britain,' Low records the case of a 

 gentleman who inbred foxhounds to such an extent that "the race 

 actually became monstrous and perished." Hogs, if too closely inbred, 

 grow hair instead of bristles; their legs become short and unable to 

 support the body; and not only is their fertility diminished, but the 

 mothers can not nourish the young. 



So far as is known, no direct investigations have been made to 

 test how far inbreeding may be carried in the Equidae; but, on the 

 other hand, the breeding of race-horses may perhaps be looked upon 

 as a gigantic experiment in this direction. Our English thorough- 

 breds can be traced back to a few imported sires — the Byerly Turk, 

 imported in 1689; the Darley Arabian, in 1710; and the Godolphin 



