We wish, in this article, to discuss general principles associated with the operation of closed intrapleural pneumonolysis. Our observations are based on a two-year experience with the procedure employed on 109 patients, representing a total of 132 thoracoscopic examinations, with or without severance of the adhesions. All of the work was done on Negroes and, with the exception of one patient, all were performed at the Maryland Tuberculosis Sanatorium (Colored Branch), Henryton, Maryland. Artificial pneumothorax, as a collapse measure, is widely employed. It is almost proverbial where pneumothorax is induced, adhesions will be encountered. Adhesions between the parietal and visceral pleurae may vary from a single cord adhesion to a widespread symphysis of the two pleurae completely obliterate the pleural space. In between these two extremes are encountered adhesions whose number, size, location, and appearance are truly protean. The adhesions, naturally, assume paramount importance since, in a large majority of the cases, they interfere with a satisfactory collapse. Figures showing the percentage of pneumothorax cases in which adhesions offer a barrier to an effectual collapse are given by Alexander as 4250 per Jones states that only 50 per cent become effective, and a successful end result was obtained in less than 50 per cent. Our experience shows a much higher percentage than the figures just quoted. A review of the records of 100 consecutive cases in which pneumothorax was induced shows in 26 per cent there was either complete obliteration of the pleural space, or adhesions so widespread only extremely insignificant collapse was obtained, and in 62 per cent adhesions prevented a satisfactory collapse. This brings clearly to the fore the fact pneumothorax, unless supplemented by some other collapse procedure, is an inadequate therapeutic measure in the treatment of pulmonary tuberculosis. To us it has become inconceivable a pneumothorax program can operate, with any appreciable degree of success, without facilities for performing, at the optimum time, some additional collapse measure. The extra hazards follow the maintenance of a pneumothorax, rendered ineffective due to adhesions, are an increase in the amount of spontaneous pneumothorax, an increase in the incidence of tuberculous empyema, and a greater frequency in contralateral or homolateral infection due to bronchogenic spread from uncollapsed cavities. In addition, a fair number of patients complain of pain due to the tug of adhesions on the parietal pleura. If the pain is not considered an important enough indication for relieving the pull of the adhesion, the potential danger of spontaneous rupture is. The purpose of inducing a pneumothorax is the closure of cavities and when, due to adhesions, the closure does not occur within a reasonable period of time, some supplementary procedure must be employed. In the vast majority of cases a closed pneumonolysis is the procedure of choice. There are other supplementary collapse measures can be employed, the most frequently used being surgery of the phrenic nerve. Some prefer to do the phrenic first, which if unsuccessful, is followed by a closed pneumonolysis. We never consider other supplementary surgery until it has been proven the adhesion cannot be severed. Our insistence upon performing a closed pneumonolysis as a primary supplementary measure is due to the fact we consider a closed pneumonolysis less of a hazard and less liable to produce complications than the maintenance of a poor pneumothorax beyond a reasonable time. Surgery of the phrenic nerve rarely causes sufficient rise of the diaphragm or relaxation of the lung in these cases to effect cavity closure; and this is all the more true when the adhesions are horizontal. Too much time is consumed in determining whether this measure will work. The possibility of a complication arising during this interval might cause the abandon-