ils; so that a tailless race might have been formed like
the tailless races of dogs and cats. A Russian breed of horses is said to
have frizzled hair, and Azara[123] relates that in Paraguay horses are
occasionally born, but are generally destroyed, with hair like that on the
head of a negro; and this peculiarity is transmitted even to half-breeds:
it is a curious case of correlation that such horses have short manes and
tails, and their hoofs are of a peculiar shape like those of a mule.

It is scarcely possible to doubt that the long-continued selection of
qualities serviceable to man has been the chief agent in the formation of
the several breeds of the horse. Look at a dray-horse, and see how well
adapted he is to draw heavy weights, and how unlike in appearance to any
allied wild animal. The English race-horse is known to have proceeded from
the commingled blood of Arabs, Turks, and Barbs; but selection and training
have together made him a very different animal from his parent-stocks. As a
writer in India, who evidently knows the pure Arab well, asks, who now,
"looking at our present breed of race-horses, could have conceived that
they were the result of the union of the Arab horse and African mare?" The
improvement is so marked that in running for the Goodwood Cup "the first
descendants of Arabian, Turkish, and Persian horses, are allowed a discount
of 18 lbs. weight; and when both parents are of these countries a discount
of 36 lbs."[124] It is notorious that the Arabs have long been as careful
about the pedigree of their horses as we are, and this implies great and
continued care in breeding. Seeing what has been done in England by careful
breeding, can we doubt that the Arabs must likewise have produced during
the course of centuries a marked effect on the qualities of their horses?
But we may go much farther back in time, for in the most ancient known
book, the Bible, we hear of studs carefully kept for breeding, {55} and of
horses imported at high prices from various countries.[125] We may
therefore conclude that, whether or not the various existing breeds of the
horse have proceeded from one or more aboriginal stocks, yet that a great
amount of change has resulted from the direct action of the conditions of
life, and probably a still greater amount from the long-continued selection
by man of slight individual differences.

With several domesticated quadrupeds and birds, certain coloured marks are
either stro