THE CHEMISTRY OF COFFEE AND TEA. 361 



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 nerv- 

 ous effort upon all the muscles, and so impresses the brain as to pro- 

 duce 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 observa- 

 tion 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 generali- 

 zation 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 exhilara- 

 tion and wakefulness. In final result, the excretion of carbonic-acid 

 gas is diminished, and the flow of blood through the capillaries is re- 

 tarded. 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 experi- 

 mental purposes. As to the effects of the habitual use of small por- 

 tions of theine, the tea-drinking peoples of the world ought to be com- 

 petent 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, Mubia- 

 cece) 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 caf- 

 feine, 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 



