sical characteristics, among the most flexible of our
domesticated animals. They may by selection readily and rapidly be made
to vary as regards the character of their wool, the size and proportion
of their muscles, and the quantity and placing of the fat. In all these
features they may be fairly blown to and fro by the wind of favor.
Between the meagre-bodied merino, with its skeleton-like frame and
heavily wrinkled skin bearing a vast burden of long wool, and the heavy
Hampshire-downs or South-downs, there is really an immense difference in
bodily quality; yet these variations represent only a century or two of
careful experiment on the part of the breeders. It seems not improbable
that in the present state of this developing art it would be possible,
in a hundred years, to reverse the conditions of these two varieties.

Sheep and goats, like the other herbivorous species which are the
common tenants of our fields and forests, belong to the great class of
dull-witted mammals in which the intellectual processes appear to be
almost altogether limited to ancient and simple emotions, such as are
inspired by fear or hunger. They are characterized by little
individuality of mind, and although the needs of men have not led to
any experiment in developing their wits, as in the case of dogs, there
is no reason to believe that they afford much foundation for such
essays. The present rapid variations in the physical characteristics of
our sheep which are induced by the breeder's skill, make it evident
that we are far from having attained the maximum profit from these
creatures. The goats also give promise, when selective work is
carefully done upon them, of giving much more than they now afford to
the uses of mankind; but from neither of these forms is there reason to
hope, at least on our present lines of experiment, for any considerable
gain in the intellectual qualities.

[Illustration: The Great Caravan Road--Central Asia]

We have already noted the fact that the sheep is especially adapted to
serve man in high latitudes, where he has to provide against the
winter's cold. The camel is an even more striking instance in which the
value of the creature depends upon climatal peculiarities. It is
peculiarly fitted, by its ancestral training and development, for the
use of men who dwell in arid countries. In the olden days of the later
Tertiary epoch, creatures akin to the camels appear to have been widely
distributed, and were