Note 91 — Chapter II

See Prof. Asa Gray in Foster’s Pre-Historic Races, p. 392; also Lyell’s Antiquity of Man, p. 41, where the opinion of President Harrison is quoted as follows: “We may be sure that no trees were allowed to grow so long as the earthworks were in use; and when they were forsaken, the ground, like all newly-cleared land in Ohio, would for a time be monopolized by one or two species of tree, such as the yellow locust and the black or white walnut. When the individuals which were the first to get possession of the ground had died out one after the other, they would, in many cases, instead of being replaced by other species, be succeeded, by virtue of the law which makes a rotation of crops profitable in agriculture, by other kinds, till at last, after a great number of centuries (several hundred years perhaps), that remarkable diversity of species characteristic of North America, and far exceeding what is seen in European forests, would be established.”