GENERAL PRINCIPLES OF BREEDING. 59 



he meets in the farmer's mixed stock, gives a 

 produce of greatly increased value for every- 

 thing except the purposes of reproduction. All 

 intelligent breeders agree in condemning close 

 in-breeding; but they are not agreed as to what 

 constitutes close in-breeding. May we not, upon 

 the theory herein advanced, base a rule which 

 will safely govern our practice? With purely- 

 bred stock, or well-established breeds, keep as 

 far from in-breeding as is compatible with uni- 

 formity of type and purity of blood; but in the 

 formation of a breed from heterogeneous ma- 

 terials, use it as the most potent of all agents, 

 without fear of bad results, provided the par- 

 ents are healthy, vigorous, and well formed, 

 until a considerable degree of uniformity has 

 been reached; bearing in mind the cardinal 

 fact that in proportion as unity of form and 

 organism is attained, constitutional vigor and 

 fertility is endangered by such a course of 

 breeding. May we not, also, find in this theory 

 an explanation of the well-known fact that in- 

 bred animals which are barren when coupled 

 with each other frequently prove fruitful when 

 united with individuals of a different breed? 



THE VALUE OF PEDIGREE. 



A pedigree is the genealogy of an animal. As 

 usually understood it consists of the names of 

 the ancestors for a greater or less number of 



