By performing a series of bone-marrow tissue culture of patients with various blood diseases by simple method the author studied the tissue growht and the wandering velocity of mature neutrophils, and arrived at the following conclusions: 1. In the case of chronic myelogenous leukemia the tissue growth is excellent, but the wandering velocity of mature neutrophils is somewhat decreased. In the cases of acute myelogenous leukemia monocytic leukemia the rate of relative growht is somewhat lower than in the case of normal persons: and the wandering velocity of mature neutrophils shows a markedly low value. The boundary of the growth zone is sharply demarcated, and the cell density index is high, presenting the growth pattern chareteristic to leukemia. 2. In the case of hypoplastic anemia the tissue growth is extremely poor; and the wandering velocity of mature neutrophils is markedly low, showing an increase of fat cells in the explant. 3. In the case of Banti's disease the tissue growth is rather poor, and the wandering velocity of mature meutrophils is low. 4. In the case of essential hypochromic anemia both the tissue growth rate and the wandering velocity of mature neutrophils are identical with those of normal persons. 5. In the case of agranulocytosis the tissue growth is extremely poor, and showing no increase of fat cells in the explant, the treatment with ACTH, however, improves the bone marrow function strikingly. 6. In the case of pernicious anemia the wandering velociyt of mature neutrophils is accelerted by the presence of vitamin B(12) in the medium. These findings by this method of culture coincide almost exactly with those by the conventional method, and it is believed that this method can be widely used in clinics due to its simplicity manipulation.