Introduction
In clinical medicine the most readily available biopsy material, the blood, has become the major source for quantitative chemical determinations in the diagnosis and treatment of disease. In dermatology the skin, another accessible tissue for biopsy, has not yet been utilized for clinical chemical measurements. The development of the skin biopsy as a source for clinical chemical study awaits the elimination of two obstacles. The first is the small size of the biopsy tissue ordinarily available. Unlike the blood, chemical determinations of the skin must be measured in specimens considerably smaller than 0.1 cc. in volume. In order to overcome this difficulty it is necessary to employ microchemical methods. Numerous micromethods have been devised, and, in fact, have been applied to chemical determinations of the blood in hospital laboratories.1 The second obstacle to the use of skin biopsy specimens is the heterogeneity of the skin. The human skin,