The Colorof the Skin as Analyzed by Spectrophotometric Methods

Variation in the superficial blood supply undoubtedly plays a more important r6le in the production of changes in the color of the skin than does an increase or decrease in the pigment. This accounts for the difference in subjects who are fairly well matched otherwise with regard to content of cutaneous pigment. In general, the pigment, in proportion to its amount, prevents the superficial blood from attaining visibility. Changes in color in the brunet, attributable to alterations in the circulation in the skin, are less noticeable than the same changes in the blond, and in the negro they are practically negligible. This holds true for the skin of the same thickness, it being quite obvious that the skin of the palms or soles or other hyperkeratotic areas will permit less light to penetrate than will the thin covering of the malar prominence or the dorsum of the hand. The color which the blood imparts to the skin is directly related to the amount or quality of the blood present in the peripheral vessels. The size of the arteries, capillaries, and venules varies with the degree of pressure behind them and with the volume of blood to be accommodated. In conditions of hypertension one would expect more force to be exerted peripherally than normally. In the dependent areas of the body, such as the legs and hands, the elements of gravity and stasis of sluggish flow are added. In cases in which the total blood volume