the maximum of variation as yet known in
the animal kingdom--is exemplified in those races of dogs which have a
supernumerary toe on the hind foot with the corresponding tarsal bones;
a variety analogous to one presented by six-fingered families of the
human race.[805]

Lamarck has thrown out as a conjecture, that the wolf may have been the
original of the dog; and eminent naturalists are still divided in
opinion on this subject. It seems now admitted that both species agree
in the period of gestation, and Mr. Owen has been unable to confirm the
alleged difference in the structure of a part of the intestinal
canal.[806] Mr. Bell inclines to the opinion that all the various races
of dogs have descended from one common stock, of which the wolf is the
original source.

It is well known that the horse, the ox, the boar, and other domestic
animals which have been introduced into South America, and have run wild
in many parts, have entirely lost all marks of domesticity, and have
reverted to the original characters of their species. But dogs have also
become wild in Cuba, Hayti, and in all the Caribbean islands. In the
course of the seventeenth century, they hunted in packs from twelve to
fifty, or more, in number, and fearlessly attacked herds of wild boars
and other animals. It is natural, therefore, to inquire to what form
they reverted? Now, they are said by many travellers to have resembled
very nearly the shepherd's dog; but it is certain that they were never
turned into wolves. They were extremely savage, and their ravages appear
to have been as much dreaded as those of wolves; but when any of their
whelps were caught, and brought from the woods to the towns, they grew
up in the most perfect submission to man.[807]

Many examples might be adduced to prove that the extent to which the
alteration of species can be pushed in the domestic state depends on the
original capacity of the species to admit of variation. The horse has
been as long domesticated as the dog, yet its different races depart
much less widely from a common type; the ass has been still less
changed, the camel scarcely at all; yet these species have probably been
subjected to the influence of domestication as long as the horse.

_Mummies of animals in Egyptian tombs identical with species still
living._--As the advocates of the theory of transmutation trust much to
the slow and insensible changes which time may work, they are accustomed
to lament the