By injecting 3 mc/kg of radio isotope P(32) once only and observed for the periods of 1-14 days and to other group 800 μc/kg once and observing for the periods of 1-30 days, the author performed cultures of the bone marrow from these rabbits in coverslips and obtained the following results. 1) In the group irradiated with P(32) 3 mc/kg, the relative growth rate, cell density and the wandering velocity of pseudoeosinophils all decreased strikingly; while in the group receiving P(32) 800 μc/kg, these values were found all increased. Namely, in the case receiving a large dosage of P(32) irradiation, the white corpuscle series of the bone marrow show marked disturbances while in the case subjected to a small dosage of the irradiation it is stimulated. 2) The increase in the cell proliferation in the case irradiated with such an amount of P(32) as to cause stimulation seems to precede the increase in the cell functions. 3) Therefore, judging these results along with those in report Ⅰ, the cell proliferation seems to be more sensitive to the irradiation than the cell functions. 4) As the cell proliferation tends to be affected prior to the cell functions in the both irradiations so far described, the influences of P(32) irradiation on the bone marrow seem not to differ essentially to any great extent from those of X-ray irradiation.