NATURAL BREEDING. 127 



ing; but the former point is the more impor- 

 tant of the two, inasmuch as the evidence is 

 more decisive. The evil results from close inter- 

 breeding are difficult to detect, for they accu- 

 mulate slowly and differ much in degree with 

 different species ; while the good effects which 

 almost invariably follow a cross are from the 

 first manifest." And again Mr. Darwin says: 

 "The benefit from a cross, even when there 

 has not been any very close interbreeding, is 

 almost invariably at once conspicuous. * * * 

 That evil directly follows from any degree of 

 close interbreeding has been denied by many 

 persons, but rarely by any practical breeder ; 

 and never, so far as I know, by one who has 

 largely bred animals which propagate their 

 kind quickly. * * * Almost all men who 

 have bred many kinds of animals, and have 

 written on the subject, such as Sir J. Sebright, 

 Andrew Knight, etc., have expressed the 

 strongest conviction on the impossibility of 

 long -continued close interbreeding. Those 

 who have compiled books on agriculture and 

 have associated much with breeders, such as 

 the sagacious Youatt, Low, etc., have strpngly 

 declared their opinion to the same effect. Pros- 

 per Lucas, trusting largely to French authori- 

 ties, has come to a similar conclusion. The 

 distinguished German agriculturist Hermann 

 von Nathusius, who has written the most able 



