28 PRINCIPLES OF STOCK-BREEDING. 



were hereditary. In 73 cases given by Trelat, 43 are 

 represented as due to heredity. " From a report made 

 to the French Government in 1861, it appears that, in 

 1,000 cases of persons of each sex admitted to asy- 

 lums, 264 males and 266 females had inherited the 

 disease. Of the 264 males, 128 inherited from the 

 father, 110 from the mother, and 26 from both. Of 

 the 266 females, 100 inherited from the father, 130 

 from the mother, and 36 from both." * 



Dr. Hammond remarks that the hereditary ten- 

 dency to insanity is shown " not only by the fact that 

 ancestors have been insane, but that insanity in the 

 descendants may have resulted from hysteria, epi-. 

 lepsy, catalepsy, or some other general nervous affec- 

 tion in them." a 



Bone-spavin, curbs, ring-bone, navicular disease, 

 and other similar affections of the bones and joints, 

 are of frequent occurrence in the hereditary form. 



Many cases are on record illustrating the heredity 

 of this class of diseases, which we need not quote, as 

 the fact of their transmission is familiar to every one. 

 But a single case will be given, that came under my 

 observation several years ago. 



A mare affected with ring-bone, that unfitted her 

 for farm-work, was kept as a breeder for several years. 

 Her colts were quite uniform in form and color, and, 

 as they showed no indications of the disease when two 

 or three years old, they found ready buyers at good 

 prices. 



At the age of five or six years, however, they all 



1 Ribot, " Heredity," p. 131. 



2 " Diseases of the Nervous System," p. 376. 



