Cancer cells oxidize organic substances in the presence of oxygen and ferment sugar when oxygen is lacking; in these respects the metabolism of the cancer cell does not seem to differ from the metabolism of normal body cells. The disturbance in the metabolism of the cancer cell lies in its fermentation in the presence of oxygen, its aerobic glycolysis, which was discovered by Otto Warburg (1) fourteen years ago. In order to suppress the pathological metabolism of cancer cells and change their course to normal, we must therefore try to check the aerobic glycolysis.