The nails not only serve as a protection to the ends of the fingers, but also enable us to grasp more firmly, and to pick up small objects. Well-kept nails contribute much to the beauty of the hand. They are not only an indication of cleanliness but also a mark of refinement. =The Perspiratory Glands.=--The skin is provided with numerous sweat-glands which consist of very small tubes with globe-like coils at their deeper extremity. It is estimated that there are 2,800 of these glands to the square inch of the surface of the body. These glands or pores of the skin are, day and night, constantly excreting a watery fluid. Ordinarily this evaporates as rapidly as it is formed, and the process is called insensible perspiration. Under the influence of heat or exercise the flow is more abundant, and appears upon the surface of the body in the form of minute, colorless drops. This is known as sensible perspiration. This excretion consists of about ninety-eight parts of water and two parts of solid matter. The quantity of perspiration varies with the temperature, the occupation of the individual, and other circumstances. In an adult, the daily amount is about thirty ounces, or more than nine grains a minute. =Benefit of Perspiration.=--Besides freeing the blood of a large amount of water, with the effete matter it contains, perspiration serves to reduce the temperature of the body. This function is most active in hot weather, and the cooling process is proportionally increased, thereby contributing to the comfort of the individual. A partial or temporary check of this excretion is usually attended with headache, fever, and other unpleasant symptoms, and its total interruption is fatal. For the purposes of experiment, rabbits and other small animals have been covered with a coating of varnish, and death invariably ensued in from six to twelve hours. =Importance of Bathing.=--As the watery portion of the perspiration evaporates, the solid matter is left on the surface of the skin, and soon clogs the mouths of the pores. The scales of the worn-out cuticle also accumulate, and further impede the action of the skin. These impurities must be removed, not only from motives of cleanliness but also from considerations of health. =General Effects of the Bath.=--Bathing, in every form, increases the activity of the internal machinery. It increases the rate of respiration, the activity of the heart, the rapidity of the circulation, the combustion in the tissues, and the perspiration through the skin. This increased activity causes a degree of exhaustion, and makes demand upon the vital forces. The reaction that follows more than restores the depleted vitality, and the bath serves as a tonic to the system.