"The finiteness of nature in all her proportions, and the necessity of finiteness and fixedness for the very existence of a kingdom of life, or of human science its impress on finite mind, are hence strong arguments for the belief that hybridity can not seriously trifle with the true units of nature, and, at the best, can only make temporary variations.

"It is fair to make the supposition that, in case of a very close proximity of species, there might be a degree of fertile hybridity allowed, and that a closer and closer affinity might give a longer and longer range of fertility. But the case just now alluded to, seems to cut the hypothesis short; and, moreover, it is not reasonable to attribute such indefiniteness to nature's outlines, for it is at variance with the spirit of her system.

"Were such a case demonstrated by well-established facts, it would necessarily be admitted; and we would add, that investigations directed to this point are the most important that modern science can undertake. But until proved by arguments better than those drawn from domesticated animals, we may plead the general principle against the possibilities on the other side. If there is a law to be discovered, it is a wide and comprehensive law, for such are all nature's principles. Nature will teach it, not in one corner of her system only, but more or less in every part. We have, therefore, a right to ask for welldefined facts, taken from the study of successive generations of the interbreeding of species known to be distinct.

"Least of all should we expect that a law which is so

rigid among plants and the lower animals should have its main exceptions in the highest class of the animal kingdom, and its most extravagant violations in the genus Homo; for if there are more than one species of Man, they have become, in the main, indefinite by intermixture. The very crown of the kingdom has been despoiled; for a kingdom in nature is perfect only as it retains all its original parts in their full symmetry, undefaced and unblurred. Man, by receiving a plastic body, in accordance with a law that species most capable of domestication should necessarily be most pliant, was fitted to take the whole earth as his dominion, and live under every zone. And surely it would have been a very clumsy method of accomplishing the same result, to have made him of many species, all admitting of indefinite or nearly indefinite hybridization, in direct opposition to a grand principle elsewhere recognized in the organic kingdoms. It would have been using a process that produces impotence or nothing among animals for the perpetuation and progress of the human race.

"We have, therefore, reason to believe, from man's fertile intermixture, that he is one in species; and that all organic species are divine appointments, which cannot be obliterated unless by annihilating the individuals repre-senting the species."

We regard it, then, as a settled truth, no longer capable of being controverted, that the human family, throughout all its varieties, constitutes one species.

And if so, then they may, at least, have all de scended from a single parental pair. However great. the diversities between them, or of however long standing, there is nothing in this fact to disprove the Bible doctrine of the unity of the race, or to make necessary the hypothesis of one, or any number of races, different from and perhaps older than that which descended from Adam.

We have said that they may have all descended from one pair; and this is all that my argument requires in this place. But we might go further, and insist that the unity of species requires the idea of such a descent; that it is given, indeed, in the very nature of a species. "We unite," says Candolle, " under the designation of a species all those individuals who mutually bear to each other so close a resemblance as to allow of our supposing that they may have proceeded originally from a single being or a single pair." Professor Dana's definition appears to amount to the same thing. says, "A species corresponds to a specific amount or condition of concentrated force, defined in the act or law of creation. The species in any partic

He

ular case began its existence when the first germ-cell or individual was created. But the germcell is but an incipient state in a cycle of changes, Physiologie Végétale, ii. p. 689.

and is not the same for two successive instants; and this cycle is such that it includes, in its flow, a reproduction after an interval of a precise equivalent of the parent germ-cell. Thus an indefinite perpetuation of the germ-cell is in fact effected, yet it is not mere endless being, but like evolving like in an unlimited round. Hence, when individuals multiply from generation to generation, it is but a repetition of the primordial type-idea; and the true notion of the species is not in the resulting group, but in the idea or potential element which is at the basis of every individual of the group; that is, the specific law of force, alike in all, upon which the power of each, as an existence and agent in nature, depends." This is but saying, in exact, scientific language, that all the individuals of a species are developed by this law of force from one "parent germ-cell." If, then, all the individuals of the human family are of one species, their descent from one pair is, by that very fact, established.

But we are aware that this idea of a species, as including the element of descent from a single pair or individual, is not conceded by polygenists. Agassiz, as we have seen, though asserting the specific unity of mankind, holds such an idea of species as to permit their descent from eight origi

Bib. Sac. October, 1857, p. 861.

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nal centers. We will not, therefore, insist on the argument here, though we still claim that, on this point, he and all pluralists depart from the estabished usage of science, inventing definitions of their own for the sole purpose of maintaining preconceived theories.*

2. Not only are the diversities in the human family consistent with the unity of the species, but changes are even now constantly taking place, analogous, both in kind and degree, to those which originated those diversities. Nor are these changes confined to any race or country. They are seen in all cases where there is any considerable change in the condition and circumstances under which they live...

er

Says the writer of the article "Man," in the Cyclopædia of Natural History," "What may be the precise influences which have caused so much difference to exist between the individuals of the human race, we are unable to say; but instances are constantly occurring which seem to show us how possible it is that all the varieties in human beings have occurred in a common family. Even amongst the races of our own island, when exposed to circumstances which deprive them of their usual nutriment and means of developing the civilized

*See Bachman's "Examination,” etc.