During the progress of research dealing with the etiology of psoriasis and exfoliative dermatitis it appeared advisable to investigate certain phases of the chemical composition of the scales of psoriasis and of exfoliative dermatitis with the hope of disclosing variations of such a character as to furnish some causative clue. From time to time various theories of the etiology of psoriasis have been proposed, but at present no theory has been sufficiently well supported to clarify the problem. Although the microbic theory of psoriasis probably has the greater number of adherents, recent work on the rôle of sulphur in metabolism suggests that if the etiology of psoriasis is not metabolic, some metabolic change in the skin may be a factor.
The results presented in this paper are the analyses of scales from patients with psoriasis and exfoliative dermatitis. In only a few instances was it possible to secure samples