CHAPTER XI. 



PEINOIPIES MB PEACTIOE OF BEEEDIKG. 



Bebbding, in its technical sense, as applied to the 

 reproduction . of domesticated animals imder the direction 

 of man, is the art of selecting such males and females to 

 procreate together as are best adapted, in conjunction, to 

 produce an improved and uniform offspring. The first and 

 most important fact to be kept in view, in pursuing the object 

 of breeding, is that result of a fixed natural law which is 

 expressed in the phrase, " like produces like." The painted 

 oriole now fiashing among the apple blossoms before my 

 window wears the same bright dyes that were worn by the 

 oriole ages ago. But the breeding maxim just quoted, is 

 xmderstood to assert more than that species and varieties 

 continue to reproduce themselves : it implies that the special 

 individual characteristics of parents are also transmitted to 

 progeny. This is the prevailing rule, but it has a broad 

 margin of exceptions and variations. Animals are oftentimes 

 more or less unlike their parents, yet inherit a very distinct 

 resemblance to remoter ancestors — sometimes to those 

 several generations back. This is termed " breeding back." 

 And, moreover, where the resemblance is to the immediate 

 progenitors, the mode of its transmission is not imiform. 

 Sometimes the progeny is strongly like one parent and 

 sometimes like the other ; sometimes, and perhaps oftenest, it 

 bears a modified resemblance to both. 



The physiological causes or laws which control the 

 hereditary transmission of physical forms and properties — 

 which determine the precise structure which the embryo shall 

 assume in the womb, and give to each animal a distinct 

 individuality which will accompany it through life and 

 distinguish it from every other animal of the same breed and 

 family — have not yet been, and probably never will be, 

 fully understood. Nor can we, by the closest study of 

 analogies or precedents, learn to anticipate their action with 



