During the last 12 years the water-soluble organic components of human horny layers have attracted steadily increasing attention. In early reports Rothman, Bolliger, and their co-workers1,2pointed out that in horny structures these components were always present. While originally thought to be derived at least in part from sweat,1the later fundamental works of Szakall, Spier, and others3-18definitely established that the water-soluble compounds were formed by the epidermal cells during the development of the horny layer. These authors and subsequent investigators brought growing evidence that these compounds are not merely by-products of keratinization, but may occupy a central role in the physiology and chemistry of normal and pathologic epidermis. "In faulty keratinization, disturbances of the cellular decomposition are probably at least as important as anomalies of keratin formation."19 Experiments with isolated psoriatic epidermis, freed of horny layer, present formidable technical difficulties. Therefore the common approach