Page:Popular Science Monthly Volume 20.djvu/375

Rh nature forms in plants but not in food-plants—bodies that include narcotics, stimulants, hypnotics, delyriants, poisons, antidotes, tonics; some of them affecting the whole nervous system, one to excite and another to depress, and others influencing only parts of the nervous system, for special functions of the body. There is an alkaloid that gives steady impulse to spinal nerves, causing continuous contraction of one set of the muscles of the body; another that diminishes nervous effort upon all the muscles, and so impresses the brain as to produce sleep along with dreamy activity of the mind; another that, among other effects, so controls certain muscles as to open wider the pupil of the eye, and another that promotes digestion by arousing force in the nervous supply of secretory functions. Again, in the observation of the effect of an alkaloid it is found that, while a small portion stimulates the nervous system, a large portion acts as a sedative, so that a difference in quantity of the potion causes a difference in kind of its effects. By far the greater number of alkaloids do exert some sort of specific effect on the nervous system, but even to this generalization there are exceptions, and we could really infer nothing from analogy as to the effect which theine should have on the system.

The administration of theine in small portions, to animals or to man, quickens the circulation and effects some degree of mental exhilaration and wakefulness. In final result, the excretion of carbonic-acid gas is diminished, and the flow of blood through the capillaries is retarded. Larger portions prove poisonous, causing painful restlessness, rigidity of the muscles, and general exhaustion. Not more than three or four grains at once can be properly taken for medicinal or experimental purposes. As to the effects of the habitual use of small portions of theine, the tea-drinking peoples of the world ought to be competent witnesses, and their testimony, pro or con, may be brought by any advocate before the judgment of the world.

But we have to ask whether the alkaloid theine is found elsewhere in the vegetable kingdom. The coffee-tree (Coffea Arabica, Rubiaceæ) appears to have been planted by Nature in the heart of tropical Africa. At present it grows wild in Liberia, and is cultivated in most regions of the tropical world. It is twenty to thirty feet high, though, like the tea-plant, in the course of culture it is cut down to the height of five or six feet. It has the general appearance of a cherry-tree. It is an evergreen, with leaves four or five inches long and one and a half or two inches wide, and bearing clusters of white and richly fragrant flowers, the fruit being dark-red when ripe, and each holding two seeds, the coffee-berries of commerce.

In chemical analysis coffee yields an alkaloid, at first named caffeine, but long since determined to be identical with the alkaloid of the tea-plant, so that while the terms theine and caffeine are both in use, chemists recognize them as synonyms. Theine is found not only in the seed—the "berry" of the coffee-plant but even more