Page:Geological Evidences of the Antiquity of Man.djvu/440

420 which it may have lost when under domestication. If these faculties are so much enfeebled as to be irrecoverable, it will perish; if not, and if it can adapt itself to the surrounding conditions, it will revert to the state in which man first found it; for in one, two, or three thousand years, which may have elapsed since it was originally tamed, there will not have been time for such geographical, climatal, and organic changes, as would only be suited to a new race, or a new and allied species.

But in regard to plants, Dr. Hooker questions the fact of reversion. According to him, species in general do not readily vary, but when they once begin to do so, the new varieties, as every horticulturist knows, show a great inclination to go on departing more and more from the old stock. As the best marked varieties of a wild species occur on the confines of the area which it inhabits, so the best marked varieties of a cultivated plant, are those last produced by the gardener. Cabbages, for example, wall fruit, and cerealia, show no disposition, when neglected, to assume the characters of the wild states of these plants. Hence the difficulty of determining what are the true parent species of most of our cultivated plants. Thus the finer kinds of apples, if grown from seed, degenerate and become crabs, but in so doing they do not revert to the original wild crab-apple, but become crab states of the varieties to which they belong.

It would lead me into too long a digression, were I to attempt to give a fuller analysis of this admirable essay; but I may add, that none of the observations are more in point, as bearing on the doctrine of what Hooker terms 'creation by variation,' than the great extent to which the internal characters and properties of plants, or their physiological constitution are capable of being modified, while they exhibit