Although an infusion of tea contains no more than the one-tenth of a grain of theine, still, if it contribute in point of fact to the formation of bile, the action even of such a quantity cannot be looked upon as a nullity. Neither can it be denied, that in the case of an excess of non-azotised food, and a deficiency of motion, which is required to cause the change of matter of the tissues, and thus to yield the nitrogenised product which enters into the composition of the bile, that in such a condition the health may be benefited by the use of compounds which are capable of supplying the place of the nitrogenised substances produced in the healthy state of the body, and essential to the production of an important element of inspiration. In a chronical sense, and it is this alone which the preceding remarks are intended to show, caffeine, or theine, &c., are, in virtue of their composition, better adapted to this purpose than all nitrogenised vegetable principles. The action of these substances in ordinary circumstances is not obvious, but it unquestionably exists. Tea and coffee were originally met with among nations whose diet was chiefly vegetable. Considerable discussion has taken place regarding the tea plants; some say that there is only one species; others that there are two or three. Mr. Fortune, who visited the tea districts of Canton, Fokien, and Chekiang, asserts that the black and green teas of the northern districts of China are obtained from the same species or variety, known under the name of _Thea Bohea_. Some make the Assam tea a different species, and thus recognise three: _T. Cantoniensis_ or _Bohea_, _T. Viridis_, and _T. Assamica_. The quality of the tea depends much on the season when the leaves are picked, the mode in which it is prepared, as well as the district in which it grows. The green teas include Twankay, Young Hyson, Hyson, Gunpowder, and Imperial; while the black comprise Bohea, Congou, Souchong, Oolong, and Pekoe. The teas of certain districts, such as Anhoi, have peculiar characters.