SINCE 1929, when I began to use artificial pneumoperitoneum systematically, I have had the opportunity to observe the effect of repeated injections of air and oxygen upon the position of the abdominal viscera. It was stated in a previous publication (1) that artificial pneumoperitoneum causes not only an elevation of the diaphragm but also a downward displacement of the liver and the spleen. The downward displacement of these organs can be explained, first, by the pressure of the injected gas, and, second, by the diminution of the negativity of the subdiaphragmatic pressure which normally exerts an upward pull upon the subdiaphragmatic organs. The purpose of this paper is to present a series of measurements made on roentgenograms of patients who were receiving artificial pneumoperitoneum for the treatment of pulmonary tuberculosis. A group of 54 unselected cases was studied. Of these, 12 had moderately advanced and 42 far-advanced tuberculosis, according to the classification of the National Tuberculosis ...