ty of new circumstances, are
most serviceable to man. These only can be carried by him into different
climates, and can have their properties or instincts variously
diversified by differences of nourishment and habits. If the resources
of a species be so limited, and its habits and faculties be of such a
confined and local character, that it can only flourish in a few
particular spots, it can rarely be of great utility.

We may consider, therefore, that in the domestication of animals and the
cultivation of plants, mankind have first selected those species which
have the most flexible frames and constitutions, and have then been
engaged for ages in conducting a series of experiments, with much
patience and at great cost, to ascertain what may be the greatest
possible deviation from a common type which can be elicited in these
extreme cases.

_Varieties of the dog--no transmutation._--The modifications produced in
the different races of dogs exhibit the influence of man in the most
striking point of view. These animals have been transported into every
climate and placed in every variety of circumstances; they have been
made, as a modern naturalist observes, the servant, the companion, the
guardian, and the intimate friend of man, and the power of a superior
genius has had a wonderful influence not only on their forms, but on
their manners and intelligence.[803] Different races have undergone
remarkable changes in the quantity and color of their clothing; the dogs
of Guinea are almost naked, while those of the arctic circle are covered
with a warm coat both of hair and wool, which enables them to bear the
most intense cold without inconvenience. There are differences also of
another kind no less remarkable, as in size, the length of their
muzzles, and the convexity of their foreheads.

But, if we look for some of those essential changes which would be
required to lend even the semblance of a foundation for the theory of
Lamarck, respecting the growth of new organs and the gradual
obliteration of others, we find nothing of the kind. For, in all these
varieties of the dog, says Cuvier, the relation of the bones with each
other remains essentially the same; the form of the teeth never changes
in any perceptible degree, except that, in some individuals, one
additional false grinder occasionally appears, sometimes on the one
side, and sometimes on the other.[804] The greatest departure from a
common type--and it constitutes