This term is very conveniently introduced to explain all the difficulties which embarrass this discussion. Dr. Bachman insists that all the races of men are mere _varieties_, and sustains the opinion by a repetition of those analogies which have been so often drawn from the animal kingdom by Prichard and his school. It is well known that those animals which have been domesticated undergo, in a few generations, very remarkable changes in color, form, size, habits, &c. For example, all the hogs, black, white, brown, gray, spotted, &c., now found scattered over the earth, have, it is said, their parentage in one pair of wild hogs. "This being admitted," says Dr. B. "we invite the advocates of plurality in the human species to show wherein these varieties are less striking than their eight (alluding to Agassiz) originally created nations." Again-- "And how has the discovery been made that all the permanent races are mere varieties, and not 'originally created' species, or 'primitive varieties?' Simply because the naturalists of Germany, finding that the original wild hog still exists in their forests, have, in a thousand instances, reclaimed them from the woods. By this means they have discovered that their descendants, _after a few generations_, lose their ferocity, assume all colors," &c. The same reasoning is applied to horses, cattle, goats, sheep, &c., while many, if not most of the best naturalists of the day deny that we know anything of the origin of our domestic animals. Geoffroy St. Hilaire, in his work, just out, denies it in toto. We are, however, for the sake of argument, willing to admit all the examples, and all he claims with regard to the origin of endless varieties in domesticated animals.[201] Let us, on the other hand, "invite the advocates of _unity_ of the human species" to say when and where such varieties have sprung up in the human family. We not only have the written history of man for 2000 years, but his monumental history for 2000 more; and yet, while the naturalists of Germany are catching wild hogs, and recording in a thousand instances "after a few generations" these wonderful changes, no one has yet pointed out anything analogous in the human family; the porcupine family in England, a few spotted Mexicans, &c., do not meet the case; history records the origin of no permanent variety. No race of men has in the same country turned black, brown, gray, white, and spotted. The negroes in America have not in ten generations turned to all colors, though fully _domesticated_, like pigs and turkeys. The Jews in all countries for 2000 years are still Jews. The gypsies are everywhere still gypsies. In India, the different castes, of different colors, have been living together several thousand years, and are still distinct, &c. &c.