Today most people give the skin too great protection, and thus weaken it. The result is that it degenerates and partly loses its function with consequent detriment to the individual's health. A normal skin has a very soft feel, imparting to the fingers a pleasant, vital sensation. It either has color or suggests color. An abnormal skin pleases neither the sense of seeing nor feeling. It may feel inert or it may be inflamed. The skin is a beautiful and complex structure. It is made up of an outer layer called the epidermis and an inner layer, the true skin or corium, which rests upon a subcutaneous layer, composed principally of fat and connective tissue. The epidermis is divided into four layers. It has no blood-vessels and no nerves, but is nourished by lymph which escapes from the vessels deeper in the skin. It is simply protective in nature. The true skin is made up of two indistinct layers, which harbor a vast multitude of nerves, blood-vessels and lymph-vessels. In the skin there are two kinds of glands, the sebaceous and the sweat glands. The sebaceous glands are, as a general rule, to be found in greatest numbers on the hairiest parts of the body and are absent from the palms of the hands and the soles of the feet. They throw off a secretion known as sebum, which is made up principally of dead cells that have undergone fatty degeneration and of other debris. The sebum serves as lubricant. It is generally discharged near or at the shaft of a hair. The sweat glands discharge on the average from one and one-half to two pounds of perspiration per day, more in hot weather and much less when it is cool. They are distributed over the whole external surface of the body. According to Krause there are almost 2,400,000 of them. They carry off water and carbonic acid gas chiefly. The functions of the skin are: To protect the underlying structures; to regulate the heat; to serve as an organ of respiration; to serve as an organ of touch and thermal sensation; to secrete and eliminate various substances from the body; to absorb. The heat regulation is quite automatic. When the external temperature is high there is a relaxation of the skin. The pores open, the perspiration goes to the surface and evaporates, thus cooling the body. When the surface is cool the skin contracts, closing the pores and conserving the heat. Radiation always takes place, except when the temperature is very high. The sensation of touch and the ability to feel heat and cold protect us from untold numbers of dangers. They are a part of the equipment which enables us to adjust our selves to our environment. The secretions and excretions are perspiration and sebum. These contain water, carbonic acid, urea, buturic acid, formic acid, acetic acid, salts, the chief being sodium chloride, and many other substances. The respiratory function consists in the absorption of a small amount of oxygen and the giving off of some carbonic acid.