For many years one of us (E. U.)1 has pointed to the fact that in the study of the physiology and pathology of the skin a chemical analysis of the skin excised from the living organism gives a far better insight into the metabolic processes of that organ than does a study of the blood alone. With regard specifically to the carbohydrate metabolism of the skin, the blood sugar tolerance test, which is generally so dependable, has been found unreliable in a number of instances.2 Urbach3 has introduced the electric punch biopsy method, with which skin can be removed almost painlessly, without anesthetics of any kind, even when the procedure is performed repeatedly for a series of studies. At the same time, microchemical methods have been perfected which make it possible to carry out an accurate determination of sugar in minute tissue particles. This method