the latter are found upon a square inch of the palm of the hand, and at least 500 on an equal space upon other parts of the body.
Perspiration is the watery matter "breathed out" from the system through the pores described. It is more copious than the exudation from the lungs by respiration, but the quantity discharged varies greatly, and is affected by the heat or the dryness of the atmosphere, by liquids drunk, by exercise, and by the relative activity of the kidneys. Sensible perspiration is that which is perceptible in the form of small drops, but by far the larger portion exuded is of the insensible or nonvisible kind. Solid matter is carried to the surface of the skin in the sweat, and authorities all agree that a considerable proportion of the total waste of the body is evacuated in this manner. Hence, besides keeping the skin in a healthy, moist condition, and acting through evaporation as a refrigerator regulating body temperature, perspiration takes its share in the elimination of useless material.
Close sympathy exists between the skin and the lungs, the kidneys, the liver, and the bowels, and this is evidenced in the fact that, when one or other of these organs becomes affected by disease, the perspiratory function
