A study of syringoma and eccrine poroma by methods which detect phosphorylase, leucine aminopeptidase, and indoxyl esterase revealed the functional relationship of the tumors to the eccrine gland. The term "adenoacanthoma of sweat glands" is not favored because these tumors are adenoid squamouscell carcinoma and do not contain the typical enzymatic activity of the sweat glands. Basalcell carcinoma and seborrheic keratoses are notable for minimal phosphorylase activity and distribution of this activity in areas of squamoid differentiation. Glycogen content and phosphorylase are usually concurrent in adnexal tumors. Histogenetic studies must include histochemical analysis.