Experiments will be performed aimed at elucidating why the transplantable reticulum cell sarcomas of SJL mice grow only in normal but not in x-irradiated syngeneic mice. The studies include transfers with labeled cells to determine the fate of this B-lymphocyte tumor in comparison with normal B-lymphocytes. Similar experiments are planned in histocompatible chickens, either using the transplantable Olson leukosis or carcinogen-induced lymphoid tumors. Cell surface characteristics and the ability of lymphoid tumors in mice and chickens to synthesize immunoglobulin will also be determined. Some aspects of the immune response to lymphoid tumors, particularly with respect to in vitro interactions between lymph node and tumor cells, and concerning the influence of bursectomy (agammaglobulinemia) on tumor growth in chickens will be examined. Experiments on sites of synthesis of soluble group-specific mammary tumor and leukemia virion proteins will be continued in a few mouse strains and in chickens, including the effect of drugs such as bromodesoxyuridine and carcinogens in vivo on such protein synthesis by subsequently cultured tissues in vitro.