When any portion of the earth is colonized by civilized man, an era of change and readjustment at once begins. The untilled plain, the primeval forest, the bridgeless river, the malaria-breathing swamp, and the jungle—lurking place for beasts of prey—are all obstructions which must be removed from the highway of social and industrial progress. Until a new environment had been created, the colonists of Virginia and New England were like helpless children, compared with the Indians whom they had come to disinherit. The hills were soon cleared, and the water-courses dried up, swamps were drained, and lakes were made in the valleys, the plains were plowed and planted with exotic vegetation, and great regions of land were entirely changed in character by irrigation and the use of manure. The New World has in two centuries become in very truth a new world, for its physical features have been entirely reconstructed. The aboriginal man retreated before the advancing strides of civilization, and has now been practically exterminated, at least east of the Mississippi River. The manner in which the man of European descent has eliminated and replaced the son of the soil is fairly typical of changes which have occurred in the animal and vegetable life of the continent. Bear, moose, caribou, deer, wolf, beaver, and all other large animals have been entirely destroyed in many parts of the country, and the time is not far remote when they will exist among us only in a state of partial or entire domestication. The prairie chicken once reared its brood in Massachusetts, but is now never seen east of the Alleghenies. The alligator is fast being exterminated in Florida and Mississippi, and the buffalo is now rarely to be seen except in captivity. The sea cow of the north Pacific, the great auk of New England and Newfoundland stand with the dodo, the moa, and the zebra in the list of animals which have become extinct within the memory of man, and the list will continue to increase. A similar story might be told for birds, reptiles, and plants. The rattlesnake is retreating to the mountain tops, the turkey, the pigeon, the woodpecker and hosts of others are disappearing, the medicinal plant ginseng, once so important in the Alleghenies, is almost a rarity to botanists.