ives: thus the ptarmigan, inhabiting snowy
regions, is white; the grouse has the colour of heath; the hare that of
dry fern or furze--a provision which has the effect of protecting the
weaker tribes from the stronger and predatory ones. In domesticated
animals, from causes apparently not as yet traced, the colour is
variegated and various. Closely connected with the colour and nature of
the skin, are the size and shape of the horns, their presence and
absence. Great as is the apparent variety of appearance effected by
horns, changes in these appear to be easily induced: they are connected
with the epidermic structure, generally the most easily modified; and we
need not cite instances to prove that different breeds of the same
tribe, and occasionally different individuals of the same breed, differ
materially as to horns. According to Azara, horned horses are sometimes
seen in Paraguay.

Very little appears to be known, at least scarcely any intimation is
given in the work before us, of the proximate or final cause of these
changes. Great as they are, certainly, as far as we can judge, no _nisus
formativus_ can account for the enormous horns of the Spanish sheep;
nor, looking to the final cause; does there appear any reason why
domestic animals should need such overgrown instruments of defence.
When, however, we come to the more important anatomical modifications,
such as the length and shape of the legs, the bones of the pelvis or of
the jaw, the object is more apparent. A greyhound, with the muzzle of a
bull-dog, would be an obvious natural inconsistency.

We now pass to the physical distinctions of the different races of men.
Here we may observe that a much greater importance is to be attached to
comparatively slight variations. Considering the surprising external
differences that exist in domesticated animals of the same species, the
wonder rather is, that the different races of men differ physically so
little as they do, than that they differ so much. Here we will take
first, the least important shades of difference--the texture of the
skin, hair, and complexion; and then pass on to the more prominent
diversities of the bony fabric, cranium, &c.

"The texture of the body, in which all these varieties have their
seat, is the extracorial or exodermal structure, constituting, if I
may so speak, the outer coating of the body, external to the true
skin, which corresponds to the cuticular and corneous