A diminution in cellular concns. within the peritoneal fluid of rats follows the admn. of cortisone or epinephrine. The percentage changes of eosinophils in peripheral blood are correlated positively to those for eosinophils in peritoneal fluid. Both hormones lead to degenerative processes in the eosinophilic leukocyte, followed by their uptake by macrophagic cells. This mechanism may form the basis for the eosinopenic state that follows the admn. of adrenal hormones.