After perfoming bone marrow tissue culture of various experimental anemias in rabbits, the follwing conclusions were drawn: 1. The accelerated bone marrow function in the anemic rabbit depleted of blood can not be maintained in culture. In the culture the mitotic index falls below that of normal rabbit, and also cell degeneration occurs earlier. 2. Mitosis of bone marrow from normal rabbit is accelerated in the serum of blood-depleted anemic rabbit. 3. The bone marrow function of anemic rabbit induced by collargol administration for a long period of time is highly deteriorated, while in the case given for a short time, disturbances of maturation and multiplication of cells, and inhibition of cells wandering out due to the proliferation of reticulo-endothelial cells in the outer region of the explant can be recognized. 4. In the bone marrow of the rabbit exposed to X-ray the start of mitosis is checked, and also maturation and migration of cells are disturbed. 5. In the bone marrow of the rabbit injected with P(32) mitotic disturbances can be recognized by the rate of acceleration of cell function, and in the case injected with a large doze of P(32) maturation and wandering capacity of cells are disturbed.