^30 A SYMPOSIUM ON RESPIRATORY ENZYMES 



the preface to the Enghsh edition of The Metabolism of Tumors ( 1), 

 which should be consulted for details of Warburg's work on tumors, 

 Warburg stated that "interference with the respiration in growing 

 cells is, from the standpoint of the physiology of metabolism, the 

 cause of tumors. If the respiration of a growing cell is disturbed, as a 

 rule the cell dies. If it does not die, a tumor cell results. This is no 

 theory, but a comprehensive summary of all the measurements at 

 present available." 



At present, however, the idea that respiration itself rather than 

 the presence of oxygen inhibits glycolysis is frequently questioned. 

 High anaerobic glycolysis is not a property of growing tissue alone, 

 since it is found, for instance, in adult brain and in glycogen-rich 

 livers. More important, the high aerobic glycolysis is not found in 

 tumors alone. Warburg himself showed that mammalian retina 

 glycolyzes very rapidly, aerobically as well as anaerobically, though 

 he considered that some sort of damage occurred to this delicate 

 tissue in preparing it for in vitro work. Gyorgy and co-workers (2) 

 and Dickens and Weil-Malherbe (3) found high aerobic glycolysis 

 in kidney medulla, and the latter authors (4) have recently found 

 the same for jejunal mucous membrane. Testis and several other 

 non-cancerous tissues are now known to show a moderately high 

 aerobic glycolysis, and my co-workers and I have found that a 

 fairly high rate of aerobic glycolysis occurs during the first few 

 minutes of an experiment with various other normal tissues. Murphy 

 and Hawkins (5), on the other hand, reported little or no aerobic 

 glycolysis with some spontaneous tumors occurring in mice. Con- 

 cerning the normal tissues which show continuous aerobic glycolysis, 

 that is, an "anaerobic type of metabolism" by which energy is pro- 

 duced by the anaerobic method even in the presence of oxygen, 

 Dickens (3) considered that "the cause of an anaerobic type of 

 metabolism is in all such cases merely a disparity between blood 

 supply, i.e., oxygen supply, and energy requirements in vivo." Con- 

 sideration of aerobic glycolysis as opposed to anaerobic glycolysis 

 does not enter into the following theory of Dickens. 



Dickens' Theory.— Dickens and Simer (6) arranged the normal 

 tissues into three groups. One group, which included kidney cortex 

 and liver, showed little anaerobic glycolysis and respired with a 

 rather low respiratory quotient and so apparently metabolized little 

 carbohydrate. Another group, including brain, retina, chorion, and 

 embryo tissue, showed high anaerobic glycolysis and a respiratory 

 quotient of unity in glucose-containing medium. These tissues appar- 



