1. The neoplastic changes induced by the feeding tests could be recognized merely as leukemoid changes of mesenchymal as well as mesothelial tissues. A typical malignant ascites tumor appeared. first in the second generation of transplantation of the leukemoid tissue.
2. Even though a rat died early without showing neoplastic change, remarkable granulative proliferation was recognized in the viscera. The transplantation of the affected tissue into a healthy mix-bred rat was able to induce a malignant tumor.
3. Neoplastic change seemed to occur in mesenchymal and mesothelial cells over the whole body, and especially in the lung, liver, and spleen earliest and most conspicuously. If a rat was fed with tumor tissue more than seven times, the transplantation of pieces of its visceral tissue into a mix-bred rat often was able to induced a malignant tumor even though definite neoplastic changes had not been recognized in the tissue histologically.
4. The new tumor is characterized by a) formation of specific tumors in Harder's glands and the petrous bone, 9) b) formation of nuclear inclusion bodies belonging to type B after Cowdry, and c) non-formation of the second type10) of tumor cells (unlike the Yoshida tumor). Nevertheless, after intra-abdominal transplantation over ten generations differentiation of the new tumor from Yoshida tumor is impossible.
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