By observing the bone marrow obtained from the femur of rabbits with kollargol-induced anemia in bone-marrow tissue culture by cover-slip method, the following results were obtained. 1) When kollargol is added to normal bone marrow in culture, kollargol acts directly on the bone marrow and inhibits its tissue growth. 2) The bone marrow which has become hyperplastic the tissue growth has been found better than control; the bone marrow in which parenchymal cells have decreased in number does not necessarily show a decline in the tissue growth or in the cell function; and the bone marrow in which parenchymal cells have markedly decreased show a marked fall both in the tissue growth and in the cell function. 3) The following may be assumed from the foregoing: Although kollargol acts directly on bone marrow, thus inhibiting the tissue growth, in the continuous injections it promotes the tissue growth of bone marrow at first, and later inhibiting it, gradually decreases the number of parenchymal cells; and finally presents the tissue-culture picture similar to that of bone marrow which is completely damaged. 4) However, because the number of fat cells are decreased in tissue culture of the bone marrow which is completely damaged, tissue-culture of such bone marrow presents a picture differing from that observed in human hypoplastic anemia.