Seeds of small sylvan plants, too deeply buried by successive layers of forest foliage and the mould resulting from its decomposition to be reached by the plough when the trees are gone and the ground brought under cultivation, may, if a wiser posterity replants the wood which sheltered their parent stems, germinate and grow, after lying for generations in a state of suspended animation. Darwin says: "On the estate of a relation there was a large and extremely barren heath, which had never been touched by the hand of man, but several hundred acres of exactly the same nature had been enclosed twenty-five years previously and planted with Scotch fir. The change in the native vegetation of the planted part of the heath was most remarkable--more than is generally seen in passing from one quite different soil to another; not only the proportional numbers of the heath-plants were wholly changed, but TWELVE SPECIES of plants (not counting grasses and sedges) flourished in the plantation which could not be found on the heath." [Footnote: Origin of Species, American edition, p. 60.] Had the author informed us that these twelve plants belonged to species whose seeds enter into the nutriment of the birds which appeared with the young wood, we could easily account for their presence in the soil; but he says distinctly that the birds were of insectivorous species, and it therefore seems more probable that the seeds had been deposited when an ancient forest protected the growth of the plants which bore them, and that they sprang up to new life when a return of favorable conditions awaked them from a sleep of centuries. Darwin indeed says that the heath "had never been touched by the hand of man." Perhaps not, after it became a heath; but what evidence is there to control the general presumption that this heath was preceded by a forest, in whose shade the vegetables which dropped the seeds in question might have grown [Footnote: Writers on vegetable physiology record numerous instances where seeds have grown after lying dormant for ages. The following cases are mentioned by Dr. Dwight (Travels, ii., pp. 438, 430). "The lands [in Panton, Vermont], which have here been once cultivated, and again permitted to lie waste for several years, yield a rich and fine growth of hickory [Carya Porcina]. Of this wood there is not, I believe, a single tree in any original forest within fifty miles from this spot. The native growth was here white pine, of which I did not see a single stem in a whole grove of hickory." The hickory is a walnut, bearing a fruit too heavy to be likely to be carried fifty miles by birds, and besides, I believe it is not eaten by any bird indigenous to Vermont. We have seen, however, on a former page, that birds transport the nutmeg, which when fresh is probably as heavy as the walnut, from one inland of the Indian archipelago to another.