The observation that exudates in a tuberculous lung might completely resolve was apparently first made by French clinicians1 in the nineteenth century. These reports, though frequently mentioned in the literature, had little influence on the views concerning the pathogenesis of pulmonary tuberculosis. In 1922 Assmann2 and in 1923 Wessler and Jaches3 described the infraclavicular infiltration as a typical early form of adult pulmonary tuberculosis. Haudek and Fleischner4 soon pointed out that these early lesions had remarkable powers of resolution. In the year previous to Assmann's publication Eliasberg and Neuland5 had reported the complete resolution of lobar exudates in tuberculous children, and Kleinschmidt6 in 1919 had called attention to the resolution of extensive exudates which he had observed in several children suffering from pulmonary tuberculosis. The first cases in the American literature were published by Gerstenberger and Burhans7 in 1927 in their report on the