^ Hereditary Diseases of Horses. 107 



themselves to every one as most apposite examples. Although 

 exposed for centmies to the powerfully modifying influences of 

 external circumstances of climate, country, association with 

 nations of very different customs and habits, these remarkable 

 races still retain their identity, and remain distinct and peculiar 

 people. But it is not alone their face or figure that remains 

 unaltered, their manners, habits, and customs are also uniform 

 and permanent : a most striking proof of the hereditary trans- 

 mission of almost every bodily and mental character and quality. 



As regards intellectual ability, it is observed that certain races 

 are remarkable for intelligence and aptitude in the acquirement 

 of knowledge, and others for stupidity and narrowness of 

 capacity ; that the children of such races, although reared and 

 educated with equal care, always show much difference in intel- 

 lectual attainments ; and that it is only after educating several 

 generations of the less-gifted race that they attain the natural 

 capacity of the more gifted. Both ancient and modern history 

 afford many striking instances of analogous temperaments and 

 dispositions being transmitted from father to son through many 

 generations ; of some families remarkable during centuries for 

 virtue, honour, and liberality, and of others notorious during an 

 equally long period for every sort of wickedness, vice, and 

 oppression. 



But diseases, as well as physical and mental qualities, descend 

 from parent to children. Many of the most wide-spread and 

 fatal maladies affecting the human subject are hereditary. Under 

 this category we may include pulmonary consumption, which 

 destroys so many of the inhabitants of these islands, frequently 

 decimating, and sometimes completely sweeping away, entire 

 families ; scrofula, gout, gravel, and rheumatism, which, like 

 consumption, occur chiefly in predisposed subjects, and in the 

 progeny of those who have themselves suffered from them ; most 

 nervous diseases, especially palsy, epilepsy, and insanity, which 

 rarely attack any individual without also affecting many of the 

 same family; and many imperfections of the external senses, 

 as deafness and blindness. These are the most common here- 

 ditary diseases incident to man ; most of them have their 

 analogues in the lower animals, in which they are also here- 

 ditary. 



Amongst horses and cattle we find, as in the human subject, 

 ample illustration of the hereditary tendency of external forai, 

 disposition, habit, and disease. The parent transfers to its 

 offspring size, shape, and general conformation similar to its 

 own ; and the aphorism " like produces like " is as applicable 

 to faulty and disproportioned as to beautiful and symmetrical 

 form, to diseased and debilitated as to healthy and vigorous 



