Total lipid content in Ehrlich ascites carcinoma cells decreased gradually with considerable fluctua tions in the course of cell growth. There was also remarkable fluctuation in individual lipid component. A gradual decrease in the quantity of phospholipid during tumor growth was responsible for a decrease of total lipid. 2) The main components of phospholipids in mitochondria and microsome were lecithin and phosphatidyl ethanolamine. A fairly large quantity of sphingomyelin was found in

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... mal fraction. 3) In fatty acid composition of individual lipid frac tions, there was a tendency for C 18:0 to be high in phospholipid. The content of C 18:0 in simple lipid of subcellular fractions from Ehrlich ascites carcinoma cells exceeded that of the corresponding subcellular fraction from other tissues. This tendency was especially remarkable in mitochondrial fraction. 4) From the results mentioned above, considerable differences in lipid metabolism between normal tissues and cancer were noted. Analysis of lipid metabolism in cancer cells may offer helpful suggestions for cancer chemotherapy. Ehrlich ascites carcinoma cell; fatty acid composition; lipid fluctuation during the tumor growth Numerous investigations have been made on carbohydrate metabolism in cancer cells, but few on lipid metablolism.