Liver Catalase Activity in Rat Leukemia^*

Liver catalase activity in rats bearing a transplanted lymphocytic leukemia showed progressive changes that were similar to those reported for solid neoplasms in a rodent. There was an initial drop in the recipient's liver catalase activity upon inoculation with blood from a leukemic donor. This was followed by a return to normal liver catalase activity levels and then by a further steady decline until the animal died. The early changes took place before there was any visible evidence of tumor growth either in the liver or elsewhere in the body.