The sense and scope of the affinities between black tongue and trichomycosis cannot be fully unfolded without at least some discussion of the two diseases. It would be superfluous for this paper to re-record the more or less ancient history of either; that of black tongue was sufficiently unfolded before the section on Dermatology and Syphilology in June, 1928, by Heidingsfeld.1 He found only 100 cases reported in the literature, but rightly stated that there were, of course, many others which were not reported because they added nothing to the knowledge. Almost nothing of importance has been added since that time. Indeed, he still appears to be the only author who has ever made a study of histologic sections of the entire lingual mucosa; although Vollmer's2 article intimated that he had employed histologic methods, they were confined to avulsed "hairs." Trichomycosis, too, while a comparatively recent subject, particularly