A crude lipopolysaccharide fraction was obtained from the methylcholanthreneinduced spindle cell sarcoma (MS) of inbred Wistar rats by means of a modified Westphal's method. The intravenous injection of the fraction (MS-LP) into rabbits produced antibody. The rabbit antisera showed specific cytotoxic action to the MS cells in tissue culture with the intervention of isologous complement. The antisera did not react to the six kinds of culture cells of normal and malignant origin from rats, mice, and humans. The lytic activity of the antiserum can be absorbed with tumor-lipopolysaccharide (MS-LP) or tumor homogenates, but not with normal tissue homogenates and tissue lipopolysaccharide (N-LP) of rats. These findings suggest that there would be a qualitative difference in the antigenic structure of lipopolysaccharides between the tumor and normal tissue of the rat.
The injection of MS-LP intravenously into Wistar rats susceptible to MS induced antibody which showed a peak of hemagglutinin titer 7th day after the injection. This protected animals from the tumor. N-LP gave no sign of such an isologous immunity in rats.

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Immunization of Donryu rats was performed by the inoculation of Yoshida ascites sarcoma attenuated with nitrogen mustard or ⁶⁰Co-ray irradiation.
The animals were pretreated with tumor cells which had been attenuated with 0.01mM nitrogen mustard solution or with ⁶⁰Co-ray irradiation. They showed a marked resistance, after a few weeks, to subsequent transplanting of a small dose of Yoshida sarcoma cells, whereas no resistance was observed in animals similarly pretreated with tumor cells which had been lyophilized or treated with 0.1mM nitrogen mustard solution.
A direct relationship was observed between the viability of attenuated tumor cellls and the immunizing activity.

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Peritoneal exudate cells of rats immune to Yoshida sarcoma showed a marked inhibiting effect on the growth and survival of Yoshida sarcoma cells in vivo and in diffusion chambers.
Rats injected intraperitoneally with the peritoneal exudate cells from rats immune to the Yoshida sarcoma rejected the growth of a challenged Yoshida sarcoma cells and survived. The antitumor effect of the peritoneal exudate cells disappeared after cytolysis. Although Yoshida sarcoma cells survived in diffusion chambers in the immunized animals, they were destroyed when they were placed in the chambers with the peritoneal exudate cells from immune animals.
Inoculation of peritoneal exudate cells of immune rats who were bearing tumor masses in their organs but no tumor cells in the peritoneal fluid prolonged the survival time of recipient animals that were transplanted simultaneously with Yoshida sarcoma cells.

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A small number of Yoshida sarcoma cells grew successfully in vitro when an appropriate amount of rat blood was added to the basal culture medium. In this series of experiments, the rôle of blood in the culture medium was investigated. The results obtained here indicated that the factor(s) sustaining the growth were attributable neither to the plasma nor to the leucocytes but to the "living" or "metabolizing" erythrocytes of the added blood. Furthermore, the blood could be replaced with either pyruvate, α-ketoglutaric acid, or oxalacetic acid. Considering the metabolism of erythrocytes and the data obtained, it seemed reasonable to conclude that the medium was conditioned by pyruvic acid leaking from the erythrocytes. Difference of the nutritional requirements between large and small cell populations in vitro was also discussed.

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The hexosamine content of tissue hydrolysates of mice was determined at varying intervals after inoculation of Ehrlich ascites carcinoma. The hexosamine contents were significantly influenced by tumor development. Restoration of the changed hexosamine levels to normal was not always parallel to the carcinostatic effect of the anticancer agents used.
Hexosamine synthesis in ascites tumor cells exceeded that observed in other tissues. On the other hand, a weak depolymerizing enzyme of mucopolysaccharide, hyaluronidase, has been found in ascites tumor cells. β-Glucuronidase activity in tumor cells was also lower than that of other tissues.
It is suggested that ascites tumor cells might be the source of hexosamine substances in ascites fluid.

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Mouse uterine tumors were induced 12-20 weeks after insertion of 20-methylcholanthrene-impregnated threads into the cervical canal. A group of mice was given 8μg of estradiol benzoate per week. For autoradiographic purpose, ³H-thymidine was administered 1 hour prior to sacrifice of the animals. Estradiol did not apparently promote cancerization. Furthermore, it seemed likely to suppress malignant cell division.
The cell division was observed only in the basal layer in the case of normal squamous epithelium and epithelioma. However, when the malignant changes were observed histologically, the uptake of ³H-thymidine into DNA was found even in the inner part of the epithelial alveolar structures. These results suggest that the pattern of cell division is quite different in the malignant proliferation.

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Bovine liver was fractionated for the carcinostatic factor active in vitro, using the original assay method of Nakahara and Fukuoka. Starting with 75% ethanol extract, from which basic components were removed by acidic resin column chromatography, further fractionations by means of acetone extraction and DEAE-cellulose chromatography showed that the activity may be due not to a single substance but to any one of several common constituents of normal liver, and the results of thin-layer chromatography with active fractions strongly indicated that they consist of simple sugars. Several hexoses and other sugars were then tested and many were found to show the expected activity.

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A spontaneous tumor was found in a male Donryu rat. The tumor has been successfully transplanted as solid and ascites forms up to date of writing (October 1964). The chromosome number of the ascites tumor cells showed a wide range of distribution, ranging from 24 to 78, with a peak at 40 (58%).

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New-born Swiss mice were injected subcutaneously with 50-200μg 4-nitroquinoline 1-oxide. In 98% of mice sacrificed after 6 months, adenomas were found in the lung, and 34.8% had well-developed adenocarcinomas.

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Mammary cancer developing in a high leukemic strain C58 mouse was examined by electron microscopy. Numerous C particles were observed in extracellular spaces, but no A or B particles were present in this tumor. This finding suggested that the mammary cancer could have been induced by leukemia virus.

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Crystalline 4-hydroxyaminoquinoline 1-oxide was prepared by the reduction of 4-nitroquinoline 1-oxide in ethanol solution with sodium borohydride, and this preparation was found to be as active a carcinogen as the hydrochloride of 4-hydroxyaminoquinoline 1-oxide, prepared by the catalytic reduction of 4-nitroquinoline 1-oxide.

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Several relevant liver fractions were tested for their effect on tumor growth in vivo. With the exception of the whole extract, which promoted tumor growth, none showed any recognizable effect, and tumor-inhibiting effect of liver factor was not confirmed.

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