The sputum of each patient at the Adirondack Cottage Sanitarium is carefully examined every six weeks. In this paper the results of these observations carried out at the sanitarium during the last two years have been made use of to determine the possible prognostic value of quantitative and qualitative changes in the tubercle bacilli occurring in the sputum of phthisis. Before giving the results of the observations it might be well to recall briefly a few facts which, though thoroughly familiar, are of sufficient importance to review at this time.
Pulmonary tuberculosis has no characteristic form of sputum. It may vary in quantity from almost nothing to even 1,000 c.c. in twenty-four hours. The absence of sputum is no better sign of the absence of pulmonary tuberculosis than is the absence of cough. An abundant, mucoid, more or less frothy sputum, which often contains no tubercle bacilli, at times marks