The original concept of Warburg,1 that defective respiration is characteristic of and indeed is the cause of tumors, has undergone a great deal of modification. Extended debate has given rise to considerable confusion in the literature concerning the differences in the respiration and glycolysis of tumor tissue and normal tissue. Much of the difficulty arises from the fact that comparisons have been made of normal tissue and tumors derived from different tissues. The metabolism of sarcoma or epithelioma is compared with the metabolism of normal liver or kidney, for example, instead of with that of the normal tissue from which the tumors arise. There are few experiments reported in which a direct comparison is made between the tumor and the normal tissue from which it arose.
These facts have led to the recent discussion by Boyland,2 Dickens and Weil-Malherbe3 and Berenblum, Chain and Heatley4 on tumor