HEREDITARY DISEASES OF HORSES. 
525 
tions this pace becomes a natural one, young untrained horses 
adopting it without compulsion. But what is still more cu- 
rious is the fact, that, if these domesticated stallions breed with 
mares of the wild herds which abound in the surrounding 
plains, they “ become the sires of a race to which the ambling 
pace is natural and requires no teaching. 55 “ The hereditary 
propensities of the offspring of Norwegian ponies,” says Mr. 
T. A. Knight, in a paper read before the Royal Society in 1837 5 
“whether full or half bred, are very singular. Their ancestors 
have been in the habit of obeying the voice of their riders , and 
not the bridle, and the horsebreakers complain that it is im- 
possible to produce this last habit in the young colts ; they 
are notwithstanding exceedingly docile and obedient when 
they understand the commands of their master. It is equally 
difficult to keep them within hedges, owing, perhaps, to the 
unrestrained liberty to which the race may have been accus- 
tomed in Norway. 55 * 
Much of what has been already stated concerning the 
hereditary nature of the external conformation and other 
qualities of the horse is also applicable to cattle. The progeny 
of a common stock bear a close resemblance to their parents 
and to each other in general appearance, length of limb, 
development of chest, shape of carcase, position and size of 
the udder, adaptation for the dairy, thickness of skin, and 
length and texture of the hair. In some of the hot provinces 
of South America there are cattle “ noted for an extremely 
rare and fine fur. . . . The variety is reproduced or descends in 
the stock. 55 1 In the same localities is also found another 
race with an entirely naked skin, which peculiarity is also 
hereditary. In our own country, too, there are great dif- 
ferences in the length and texture of the hair of various sorts 
of cattle — differences which, as in the South America animals, 
are transmitted to the progeny. The existence or non- 
existence of horns, their size, shape, and curvatures, are cha- 
racters the hereditary nature of which is generally admitted. 
But defects and deformities may also become permanent in a 
stock. We are informed by a friend that he has seen several 
cattle with a small portion of skin covered with short hair 
situated on the eye, just within its outer canthus ; and that 
this peculiarity had been traced back for five or six genera- 
tions, and had occurred in every case in exactly the same 
spot of the right eye. 
We have deemed it advisable thus far to consider the 
hereditary tendencies of external form, of habit, and of con- 
* See Prichard’s ‘ Natural History of Man/ 2d edition, p. 72. 
f Ibid., p. 33. 
