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shown that within certain limits and with certain exceptions carcinomatous tissue has a unique and characteristic metabolism. They and Warburg (1925) found that normal tissues have a relatively high rate of oxygen consumption and a low aerobic glycolysis. Embryonic tissue has high respiration and, under anaerobic conditions, a high glycolysis, but it has only a slight destruction of sugar under aerobic conditions. Neoplastic tissue, on the other hand, has a rather low respiration rate and a high glycolysis under both aerobic and anaerobic conditions. These broad generalizations have been corroborated by Murphy and Hawkins (1925), Rona and Deutsch (1926), and others. The subject is more fully reviewed by Jackson (1929). Neither glycolysis nor oxygen consumption, however, proved to be an infallible guide to the nature of a given living tissue, so that Warburg (1927) resorted to a new value by which to differentiate neoplastic from normal tissue. He points out that when the Pasteur reaction functions at its maximum, the formation of exactly two molecules of lactic acid is suppressed when one molecule of oxygen is consumed, and on this basis he suggests a new value "U, " which may be regarded as the