"The construction of these two membranes may easily inform us, without having recourse to fanciful hypotheses, how disease, affecting any part of this membrane, either internally or externally, may pass to any other part and affect the whole; and thus how a faulty digestion in a lady, a disease of the investing or mucous membrane of the stomach, may show itself in eruptions on the face. We see at once, too, how it happens that, calling into more active action the shower bath and flesh brush, dyspepsia may be avoided or cured. It serves also to explain the circumstance noticed by Fourcroy and Vauquelin, that the skin, with all its products, 'is capable of supplying the office of the kidneys,' and carrying off, as we know it to imbibe nourishment, the indispensable excretions for which the proper organs may be deficient. "In explanation of this circumstance, we must remark, that the skin, internal or external, in which terminate all the arteries and commence the veins, in which too, the nerves of sensation commence, and the nerves of volition terminate, not only envelopes the whole body internally and externally, but is also the secretory organ of every part, and the immediate means of communication with the external world. "The skin is the organ of contact with the external world, and the means of making us acquainted with every part of the universe. The senses of touch, of hearing, of smell, of taste, are all exercised by the skin. "By the vessels terminating in the skin, or of which it is formed, all the phenomena of nutrition, and decay of appetite, and sensation, health and disease are produced. "Whatever may be the climate or temperature in which the body is placed, it is kept at nearly one uniform and vital heat by the varying and adapting operations of the skin. "The skin is the organ by which electricity is conducted into and out of the body. "Its functions are, in short, proportioned to its vastness; and as it envelopes every part, so manifold are its purposes. "The structure of the skin is highly curious; it consists of two layers; the one horny and insensible, guarding from injury; the other highly sensitive, the universal organ of feeling, which lies beneath; the latter feels, but the former dulls the impression. "The following will show how, by the perspiratory organs, excess of water is removed from the blood, and the uniform temperature of the body preserved. "Taken separately, the little perspiratory tube with its appended gland, is calculated to awaken in the mind very little idea of the importance of the system to which it belongs; but when the vast number of similar organs composing this system are considered, we are led to form some notion, however imperfect, of their probable influence in the health and comfort of the individual; the reality surpasses imagination and almost belief.