For the purpose of a comparative study on the influences of various anti-leukemic agents on the erythropoietic function of bone marrow, a roller culture method was performed to culture the cell suspensions of human and rabbit bone marrow. In the course of the incubation, the author observed the changes in the erythrocyte counts, number of nucleated cells, hemoglobin content, percentage of orthochromic erythroblasts, and increment index of orthochromic erythroblasts. As the results, it has been recognized that in this culture method bone marrow erythroblasts mature and differentiate in the same fashion as in in vivo. Therefore, it is assumed that, when human or rabbit bone marrow is cultured by this method in the media containing chemical substances or sera, it is possible to observe their direct influences on the erythropoietic functions of bone marrow
