Until recently the word pemphigus has referred to a conglomerate of diseases between which the only common bond of relationship seemed to be the occurrence of bullae. In fact, it is not long since every dermatosis displaying blebs or bullous lesions was likely to be classified as a form of pemphigus. Pusey states that Martius, for example, with scholastic zeal, enumerated ninety-seven varieties. At present the term is limited in its application to a few more clearly defined types of acute and chronic affections of the skin characterized "by the formation of one or several well defined, oval, rounded blebs, elevated or not above the level of the general surface, the lesions developing in successive cycles of eruption, and which may or may not be associated with general symptoms." Such, at least, is Ormsby's characterization of the malady.
Admittedly, little has been definitely ascertained about the etiology of pemphigus. There