Furthermore, the part played by the lungs in the maintenance of life and health cannot be underestimated. Impaired functioning of the lungs has an immediate and vital effect upon every other part of the body. It is through this channel that we secure the oxygen, without which the processes of life would terminate almost instantaneously. It is through this channel also that the elimination of carbonic acid gas is accomplished. Without the continuous and thorough elimination of carbonic acid our tissues would become choked up and poisoned in such a way that all cell activity and bodily function would come to an abrupt end. If the lungs are sound and healthy in every respect the supply of oxygen is abundant, and the elimination of carbonic acid, which may be regarded as the "smoke" of the human system, is carried on perfectly. Breathing is only one of the various functions that must be continuously carried on, but it is of such importance as to require special attention in building vitality. In the work of eliminating impurities and keeping the system clean the kidneys are to be classed with the lungs, although they have to do with poisonous wastes of a different type. Insufficient functioning of the kidneys is not so immediately fatal as the failure of the lungs to do their work, but proper action of the kidneys is none the less important. If the poisons which are normally eradicated from the system in this way are allowed to remain or to accumulate, they poison the body as truly as any external toxic element that could be introduced. Insufficient activity of the kidneys leads to the accumulation of those poisons, bringing on convulsions of the most serious nature, and unless the condition is relieved there will be fatal results. The requirements of health, therefore, demand that the kidneys should be strong and active, and that their functional capacity should be maintained at the highest degree of efficiency. In supplementing the work of the kidneys and the lungs, the excretory function of the skin is only secondary in importance. The skin has various functions. It is one of our chief organs of sense, the sense of touch being hardly second to those of sight and hearing. It is likewise a wonderful protective structure, and at the same time is a channel of elimination which cannot be ignored with impunity. To interfere with the eliminative function of the skin by absolutely clogging the pores for a period of several hours means death. One may say that we really breathe through the skin.