With the purpose to elucidate the mechanism of recuperating power of polysaccharides extracted from the bone marrow aoting on anemia, the author conducted a series of bone-marrow tissue culture of rabbits with experimental bone-marrow dysfunction and of patients with aplastic anemia, adding the polysaccharides to the culture medium; and obtained the following results: 1. In the bone-marrow tissue culture of rabbits with kolargol-anemia the addition of the polysaccharides accelerates the hone marrow function. 2. In the bone-marrow tissue culture of rabbits with acute bone-marrow dysfunction by X-ray irradiation the addition of such polysaccharides gives benefitial effects on the bone marrow function. 3. In the case of bone-marrow tissue culture of patients with aplastic anemia the addition of such polysaccharides promotes the tissue growth, the wandering velocity of cells, and induces an increase in the hemoglobin content and erythrocyte count. 4. However, in the above-mentioned experiments if the bone marrow function is extremely disturbed, the addition of these substances can not reactivate the lost function. 5. In other words, polysaceharides extracted from the bone marrow act directly as to stimulate the disturbed bone marrow so as to reactivate the hematopoietic function so long as the degree of the dysfunction still retains some possibility of recovery, but these substances can not reactivate the function of the bone marrow in the case where the function is so highly disturbed as to be completely obliterated.