This report deals with the results of investigations of material obtained from the blood serum and blisters of patients with pemphigus, dermatitis herpetiformis and other dermatoses. The neurohistologic studies of Urbach1 and Riehl2 of tissue removed at autopsy from patients dying of pemphigus failed to demonstrate any etiologic possibilities. Kartamischew3 regarded a disturbance of chloride metabolism as the cause of pemphigus, but Urbach4 and others demonstrated this as untenable. Evidence in support of an endocrinologic etiology is insufficient. An infectious cause has long been suspected. Lipschütz5 found some protozoan-like formations in both blister contents and skin, but we believe that they are products of cellular degeneration, for they have been observed in bullae due to other causes. A number of pyogenic organisms have been incriminated as etiologic agents in pemphigus. Riecke6 recently reviewed the literature on this subject and concluded that none