MC-induced sarcomas produced under the skin on the back between　scapulas of C3H mice were transplanted　successively to the mice of the　same strain. Using the first and the second generation tumors, viable　tumor cells were prepared and with these tumor cells C3H mice were　inoculated. From these sensitized mice regional lymph　nodes were taken　out at certain intervals and lymph-node cells were prepared. These tumor　cells were mixed with regional lymph-node cells in the ratio of 1 : 10, and
the mixed cells were transplanted subcutaneously on the back of C3H　mice, and the development and growth of tumors were observed at intervals.　As a result it was found that the inhibitory effect of these regional　lymph-node cells on the tumor growth was strong one to two weeks after　the transplantation, but beyond 3, or 4 weeks no inhibition　was observable.　In connection with the present in vivo experiments, some comments　were made on the available literature, and it has been demonstrated that　even in the cancer-bearing animal destined to die of tumors, at certain
stage of cancer there is seen an inhibitory effect of the host on the tumor　growth by way of the lymphoid system and that such a response of the　host in vivo seems to be　correlated well with in vitro reaction.</p
