For clothing man depends partly upon such plant-products as Cotton and Flax and partly on plant-fed animals which yield him silk, wool and leather. The great plant structures of the forest give him the chief materials which go into the construction of his ships and houses, with all their appurtenances. The bodies of plants, recently alive or the bodies of plants long since dead furnish fuel for cooking, heating and power. Drugs are very largely of vegetable origin. In brief, the plants feed, clothe, shelter, and warm mankind. Man has made many plants his servants. His first attention was naturally given to such species as he could use for food. Two thousand years ago, the ancients were growing practically all the food plants that are known today. Maize, Potatoes, Rice, Beans, Dates and Bananas have been cultivated for an even longer period. Fodder plants, calculated to furnish food for man’s domestic animals, were the next to receive attention, and following those, medical plants, edible fruits, garden vegetables and aromatic leaves and seeds, such as Tea and Coffee, came to the fore. When we consider that plants display superior powers in so many directions and, as F. L. Sargent says, “do to perfection so many things we cannot do at all,” it is really remarkable that man has so completely subjected them to his will. Because of their static condition, they are quite helpless in his hands. He levels their grandest forests and burns their widest prairies. Certain plants he makes his pets, fighting their enemies and nurturing them in the most careful way. The tender Wheat would never be able to occupy the vast stretches it does through its own strength. Under man’s guidance and protection, its volume is increased a thousand fold. The vast changes which human efforts make in the surface of the earth have a correspondingly important effect on vegetation. Every time a tract of woods is cut down, every time a lake is drained, every time a field is plowed--whenever any alteration is made in the landscape--the vegetation is affected. Sometimes this disturbance of the natural order of things becomes a serious menace, as in the case of deforestation. The welfare of the world is bound up with the welfare of the plants. About a hundred years ago, a certain section of forest in France was levelled. It contained Oak, Beech, and Ash. The new trees to spring up were Birch and Poplar. After thirty years they too were felled and young shoots of the same species immediately came up, with a few descendants of the original growth reappearing. It was not until the third clearing or ninety years after the original cutting that the Oaks and Beeches began to regain their lost prestige. This is a good example of the effect that human operations have on the plant world. Wholesale cuttings tend to change the chemical composition of the soil by withdrawing certain elements, thereby causing other species to flourish which do not need this material.