With the bone marrow of normal human sternum the author performed the bone-marrow tissue culture in fluid medium and further observed the stained pictures of granulocytes, and arrived at the following conclusions. 1. For the medlum to be used in the bone-marrow tissue culture mainly for the purpose of observing granulocytes, the medium that the author devised, namely, E. E. I. + Tyrode's solution+serum, proves to maintain the life of cells for a lon er period of time and also enable cells to multiply best, within the author's experience. 2. It has also been found that the culture conducted at rest can keep the life of cells for a longer period of time rather than by shaking culture. 3. From the observations conducted in the medium mentioned above it has been clarified that the bone-marrow granulocytes in fluid medium mature and undergo cell division.