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This consists in an eruption of pustules common to the head, trunk, and extremities, pea-sized, flattened at the top, in clusters, often uniting; discharge, fetid; scabs, honey-combed; the cells filled with fluid. It occurs both in early and adult life. Modern researches have satisfied some observers, that the crusts of favus are of vegetable nature, and formed of a parasitic plant, belonging, according to Gruby, to the obsolete genus mycoderm'a. MM. J. Muller and Lebert refer it to the genus Oidium, and call it Oid'ium Schonlei'ni, whilst Remak assigns it to a now genus under the name Achorion Schouleinii. The point is not, however, settled. The treatment of this variety must consist in the exhibition of laxatives and the mildest stimulating ointments, such as the Ung. Zinci, Ung. hydrargyri praecipitat. alb., &c. Eczema of the hairy scalp is often confounded with Porrigo.