It is scarcely necessary to insist that the primitive nature of the sensory function of the skin with the derivative nature of the other senses, is a well ascertained and demonstrable fact. The lower we descend in the animal scale, the more varied we find the functions of the skin to be, and if in the higher animals much of the complexity has disappeared, that is only because the specialization of the various skin regions into distinct organs has rendered this complexity unnecessary. Even yet, however, in man himself the skin still retains, in a more or less latent condition, much of its varied and primary power, and the analysis of pathological and even normal phenomena serves to bring these old powers into clear light. Woods Hutchinson (_Studies in Human and Comparative Pathology_, 1901, Chapters VII and VIII) has admirably set forth the immense importance of the skin, as in the first place "a tissue which is silk to the touch, the most exquisitely beautiful surface in the universe to the eye, and yet a wall of adamant against hostile attack. Impervious alike, by virtue of its wonderful responsive vitality, to moisture and drought, cold and heat, electrical changes, hostile bacteria, the most virulent of poisons and the deadliest of gases, it is one of the real Wonders of the World. More beautiful than velvet, softer and more pliable than silk, more impervious than rubber, and more durable under exposure than steel, well-nigh as resistant to electric currents as glass, it is one of the toughest and most dangerproof substances in the three kingdoms of nature" (although, as this author adds, we "hardly dare permit it to see the sunlight or breathe the open air"). But it is more than this. It is, as Woods Hutchinson expresses it, the creator of the entire body; its embryonic infoldings form the alimentary canal, the brain, the spinal cord, while every sense is but a specialization of its general organic activity. It is furthermore a kind of "skin-heart," promoting the circulation by its own energy; it is the great heat-regulating organ of the body; it is an excretory organ only second to the kidneys, which descend from it, and finally it still remains the seat of touch. It may be added that the extreme beauty of the skin as a surface is very clearly brought out by the inadequacy of the comparisons commonly used in order to express its beauty. Snow, marble, alabaster, ivory, milk, cream, silk, velvet, and all the other conventional similes furnish surfaces which from any point of view are incomparably inferior to the skin itself. (Cf. Stratz, _Die Schönheit des Weiblichen Körpers_, Chapter XII.)