? Has the little variability of the ass or
guinea-fowl, or the small power of endurance of warmth by the rein-deer,
or of cold by the common camel, prevented their domestication? I
cannot doubt that if other animals and plants, equal in number to our
domesticated productions, and belonging to equally diverse classes and
countries, were taken from a state of nature, and could be made to breed
for an equal number of generations under domestication, they would
vary on an average as largely as the parent species of our existing
domesticated productions have varied.

In the case of most of our anciently domesticated animals and plants, I
do not think it is possible to come to any definite conclusion, whether
they have descended from one or several species. The argument mainly
relied on by those who believe in the multiple origin of our domestic
animals is, that we find in the most ancient records, more especially on
the monuments of Egypt, much diversity in the breeds; and that some of
the breeds closely resemble, perhaps are identical with, those still
existing. Even if this latter fact were found more strictly and
generally true than seems to me to be the case, what does it show, but
that some of our breeds originated there, four or five thousand years
ago? But Mr. Horner's researches have rendered it in some degree
probable that man sufficiently civilized to have manufactured pottery
existed in the valley of the Nile thirteen or fourteen thousand years
ago; and who will pretend to say how long before these ancient periods,
savages, like those of Tierra del Fuego or Australia, who possess a
semi-domestic dog, may not have existed in Egypt?

The whole subject must, I think, remain vague; nevertheless, I may,
without here entering on any details, state that, from geographical and
other considerations, I think it highly probable that our domestic dogs
have descended from several wild species. In regard to sheep and goats
I can form no opinion. I should think, from facts communicated to me by
Mr. Blyth, on the habits, voice, and constitution, etc., of the humped
Indian cattle, that these had descended from a different aboriginal
stock from our European cattle; and several competent judges believe
that these latter have had more than one wild parent. With respect to
horses, from reasons which I cannot give here, I am doubtfully inclined
to believe, in opposition to several authors, that all the races have
descended from one wi