32 * CATTLE-BREEDING. 



this sort, and Darwin cites from a German 

 authority the very strong case of a cow which, 

 having lost a horn by disease, produced three 

 calves which in lieu of a horn on the same side 

 of the head as that from which their dam had 

 lost her horn had only a "bony lump merely 

 attached to the skin." Darwin suggests that 

 this case approaches "the doubtful subject of 

 inherited mutilations," but it is to be clearly 

 noted that the mutilation arose from disease 

 and not from mechanical means a distinction 

 of the highest importance. 



Passing on to the class of cases where the 

 cause is active and in the nature of disease we 

 find such well-authenticated cases as the inher- 

 itance of ringbone, spavin, navicular disease, 

 and similar affections in horses. These diseases 

 are most frequently latent at birth, and only 

 begin to develop as the horses reach maturity. 

 Of this sort Miles, in his work on stock-breed- 

 ing, cites the case of a mare that was affected 

 with ringbone and incapacitated by it for work, 

 but from which a number of colts were bred. 

 Her colts at two and three years old showed no 

 signs of the disease, but at five to six years they 

 had all of them developed the disease. 



Another well-known disease which is well 

 recognized as hereditary among horses is roar- 

 ing, and even more so ophthalmia. The Irish 

 horse Cregan, of considerable celebrity, is re- 



