sticated
animals, the difference is great. A good cow with us daily yields more
than five gallons, or forty pints of milk, whilst a first-rate animal,
kept, for instance, by the Damaras of South Africa,[742] "rarely gives
more than two or three pints of milk daily, and, should her calf be
taken from her, she absolutely refuses to give any." We may attribute
the excellence of our cows, and of certain goats, partly to the
continued selection of the best milking animals, and partly to the
inherited effects of the increased action, through man's art, of the
secreting glands.

It is notorious, as was remarked in the twelfth chapter, that
short-sight is inherited; and if we compare watchmakers or engravers
with, for instance, sailors, we can hardly doubt that vision
continually directed towards a near object permanently affects the
structure of the eye.

Veterinarians are unanimous that horses become affected with spavins,
splints, ringbones, &c., from being shod, and from travelling on hard
roads, and they are almost equally unanimous that these injuries are
transmitted. Formerly horses were not shod in North Carolina, and it
has been asserted that they did not then suffer from these diseases of
the legs and feet.[743]

{301}

Our domesticated quadrupeds are all descended, as far as is known, from
species having erect ears; yet few kinds can be named, of which at least
one race has not drooping ears. Cats in China, horses in parts of Russia,
sheep in Italy and elsewhere, the guinea-pig in Germany, goats and cattle
in India, rabbits, pigs, and dogs in all long-civilised countries, have
dependent ears. With wild animals, which constantly use their ears like
funnels to catch every passing sound, and especially to ascertain the
direction whence it comes, there is not, as Mr. Blyth has remarked, any
species with drooping ears except the elephant. Hence the incapacity to
erect the ears is certainly in some manner the result of domestication; and
this incapacity has been attributed by various authors[744] to disuse, for
animals protected by man are not compelled habitually to use their ears.
Col. Hamilton Smith[745] states that in ancient effigies of the dog, "with
the exception of one Egyptian instance, no sculpture of the earlier Grecian
era produces representations of hounds with completely drooping ears; those
with them half pendulous are missin