This article is only available in the PDF format. Download the PDF to view the article, as well as its associated figures and tables.
The authors review the literature and present the results of their researches on the sulphydryl compounds of the epidermis and its appendages. They studied epidermis, hair, feathers, scales, nails, hoofs, etc., of several vertebrates. The sulphydryl reaction is positive in the stratum mucosum of both the epidermis and the appendages, but it is especially marked just within the cornified structure of the appendages. The authors conclude that a free form and a fixed form of glutathion exists, which constitutes the plastic substance of the keratin. They distinguish two forms of keratin, a soft form found in the epidermis and a hard form found in the appendages. Only the soft form is accompanied by keratohyalin. The epidermal keratin is poor in sulphur content, and the keratin of the appendages is rich in sulphur, which exists in both instances as cystine.