GENERAL PRINCIPLES OF BREEDING. 45 



produce, if a female, when of proper age is cou- 

 pled with her own sire, and this produce again, 

 if a female, is bred to the same male, that was 

 her sire as well as her grandsire. This process 

 is sometimes resorted to for three or four suc- 

 cessive generations, with a view of intensifying 

 or perpetuating a quality for which the sire is 

 especially noted, and which it is found he trans- 

 mits with certainty; for it is a well-known, 

 although inexplicable fact, that of two animals 

 bred precisely alike, and manifesting the same 

 spontaneous variation, one will transmit the 

 peculiarity with considerable certainty, while 

 not a trace of it will appear in the produce of 

 the other. The same principle often finds its 

 application in coupling tho son with his own 

 dam, and then, if the produce be a female, 

 using upon her the same male, that is at once 

 her brother and her sire. This process of cou- 

 pling near relatives, which is generally termed 

 breeding in-and-in, is unquestionably very ef- 

 fectual, and is frequently the only available 

 source from which breeding- stock can be 

 obtained that possess and transmit the desired 

 quality. But there is always danger that such 

 a course of breeding will result in a loss of 

 constitutional vigor and fertility in the prod- 

 uce, and it should be practiced with great 

 caution. Should any constitutional defect or 

 weakness be noticed as tho result of breeding 



