Success in therapy for diseases of the skin demands a more intimate knowledge of the histology, physiology and function of the healthy skin. With this in view, the need for a careful study of the various dermal systems becomes apparent. Mumford1emphasized the fact that constant changes are taking place in the superficial vascular system in response to various stimuli, and he expressed the belief that similar alterations are undoubtedly occurring in the activity of the sudoriparous glands, the output of which is subject to wide variations not only in different persons examined under similar circumstances but also in the same person examined at different times. These variations apparently depend on certain inherent physical and mental characteristics and on the metabolic requirements of the moment, resulting from altered internal or external physical influences or from both. Steno2in 1683 seems to have been the first to mention the