162 PRINCirLES OF STOCK-BREEDING. 



without question, too often the case, that high-bred 

 animals have one or more of the defects in question, 

 to an extent that seriously impair their value for any 

 useful purpose ; and it is undoubtedly the interest of 

 the breeder to ascertain the true causes of their prev- 

 alence, and the best methods of counteracting them. 



If an imaginary cause is mistaken for the real 

 one, the breeder may, by avoiding it, rest in fancied 

 security, while the unsuspected agencies that he has 

 overlooked may be acting with undiminished energy. 

 We have already observed that, in the highest devel- 

 opment of special characters by artificial treatment, 

 particularly in the meat-producing breeds, a delicacy 

 of constitution is produced that renders the animal 

 more susceptible to the influence of modifying agen- 

 cies. 



When this impressibility of the organization is in 

 excess and becomes a marked characteristic of a fam- 

 ily, it will be fixed, and perhaps intensified, by in-and- 

 in breeding ; or, in other words, if a delicacy of con- 

 stitution is produced by the system of management to 

 which animals are subjected, it will readily be made 

 a prominent characteristic by in-and-in breeding. 



That the close breeding in this case is not the 

 cause of the impaired condition of the organization, 

 but rather the means of its being perpetuated, cannot 

 be doubted. The following cases, in connection with 

 a number of a similar character that have already 

 been cited, will show that in-and-in breeding is not 

 necessarily associated with a delicacy of constitution, 

 and it does not, as a matter of course, produce it. 



In the first volume of the " Hereford Herd-Book " 



