In the previous paper, a report was made of the effect of oxygen on two normal individuals and seven cases of cardiac insufficiency. This paper represents a continuance of the studies in oxygen therapy in ten cases of lobar pneumonia and two cases of bronchopneumonia. The theoretical indications for giving oxygen, the methods employed, and the recent pertinent literature have been outlined in the beginning of the first paper. The plan of investigation has been maintained, namely, the correlation of the clinical condition of the patient with the oxygen saturation of the arterial and venous blood before and after treatment. REPORT OF CASES The individual cases follow: Case 101(Table 3).—M. W., white, male, driver, 36 years. Diagnosis.—Lobar pneumonia; chronic pulmonary tuberculosis; edema of the lungs. History.—Mother and sister died of tuberculosis. Patient has suffered from a chronic productive cough for five years. Three days before entry, tiredness, headache, and