1) When 0.5 gram per body weight kilogram of bone marrow was embedded to normal rabbits at the inner part of thigh, the histological influence of it upon the bone marrow, the spleen, the liver, the hypophysis and the adrenal glands was observed as follows: The bone marrow……the functional acceleration remarkably appeared on image for a few weeks after imbedding, particularly of homogeneous bone marrow. Other internal organs……no notable change was noticed. Beside, in the case whea the muscles were embedded as a contrasting experiment. no remarkable influence upon the bone marrow could be seen either. 2) A embedded bone marrow, in both cases of homogeneous and of heterogeneous imbedding, was found to get absorbed by degrees into the embedded part, without any hemato poietic function. 3) Between the embedded bone marrow particle and the embedded body, no direct connection through blood vessel was perceived, in both cases of homogeneous and heterogneous imbedding. 4) Judging from above experiences, the following is concluded: The function of embedded bone marrow in promoting the formation of blood does not mean that it produces blood outside of embedded bone marrow when the imbedding is successful, but it means that some peculiar substance to promote the formation of blood, which is contained in bone marrow, is gradually absorbed into the body and directly stimulates the hematopoietic organs in the embedded body.