The viral materials isolated from the spleen of C58 strain mice with myelogenous and lymphocytic leukemia were inoculated on the chorio-allantoic membrane, in the allantoic cavity and in the yolk sac of embryonated eggs. Purification of the viral materials was done by filtration through Berkefeld N filters or emulsification with fluorocarbon. From the observations on the changes of the chorio-allantoic membrane and on the influence of the inoculation to chick embryos, the following results are obtained. 1) Inoculation on the chorio-allantoic membrane. Inoculation of the filtered viral materials caused slight thickning, hyperemia, opacities and edema of the inoculated areas of the chorio-allantoic membrane. but no changes were observed in other embryonic organs. Histologically, the chorio-allantoic mambrane showed proliferation of fibroblasts and epithelial cells and infiltration of monocytoid cells and eosinophils in the interstitial tissue. In the inoculation of the fluorocarbon-purified viral materials from myelogenous and lymphocytic leukemia, the changes of the chorioallantoic membrane were almost the same as findings described above. But in the case of mammary cancer, changes such as thickning, opacities, hyperemia and edema of the inoculated areas of the chorioallantoic membrane were more remarkable and sometimes hemorrhages and tumor-like nodular swellings were also observed. Histologically, proliferation of epithelial cells, fibroblasts and infiltration of eosinophils, lymphoid and monocytoid cells were much more prominent. No pathologic changes of other embryonic organs were observed following inocuration of the viral materials isolated by either method. 2) Inoculation in the allantoic cavity. In all cases, no significant organ changes were observed and no death of the embryos occurred. 3) Inoculation in the yolk sac. Inoculation of the filtered viral materials caused 100 % desth of the embryos by the ninth day after inoculation in the case of myelogenous leukemia, by the twelfth day in lymphocytic lukemia and by the fifth day in mammary cancer.
On the other hand, in the inoculation of the fluorocarbon-purified viral materials, 100 % mortality occurred by the fifth day in myelogenous leukemia and mammary cancer and by the ninth day in lymphocytic leukemia. These varied experimental results are considered to be related to the differences in strains and virulencies of the viruses.