Cell-free extracts of lymphatic cells from rabbit appendix and cells from Gardner's mouse lymphosarcoma contained active enzymes for the metabolism of glucose via the glycolytic and the phosphorylated oxidation pathways. Utilization of glucose, lactate formation, and oxygen consumption were inhibited by iodoacetate to a closely parallel extent in the lymphatic cells; in lymphosarcoma cells inhibition was less complete. With the use of variously labeled glucose and lactate, and measurement of the activity of labeled lactate and C14O2, it was concluded that the pathway of glucose metabolism in lymphatic cells is almost exclusively via the glycolytic pathway, whereas in lymphosarcoma cells phosphorylated oxidation plays an important role. The ascitis fluid in Ehrlich ascitis tumor contained measurable amounts of ribose, and on incubation with glucose it produced ribose and fructose. © 1957.