Each cell count was averaged in each group and plotted on the graph, and thus we got the curve which is shown in Figure 3. The number of viable tumor cell decreases up to the point of the second week rapidly. After that, curve changes very slowly, until the cell counts reaches 0 at the point of the third week.
The possibility of transplantation of irradiated tumor cells was positive until 2 weeks but negative at 3 weeks after irradiation.

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[in Japanese]

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[in Japanese]

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In this paper, 155 cases of skin cancer, experience during the year from 1946 to 1956, were analysed. The cure rate of skin cancer depends chiefly upon its size.
Although small tumors can be cured easily, in most cases of skin cancer in Japan, tumor has grown too large before the patient asks for the treatment. Consequently, radiotherapy of skin cancer in Japan is more difficult problem than other kinds of cancer. Moreover, it is definite fact that many cases with metastases are difficult to cure completely. It is important for cancer treatment that we should study more about the treatment of metastasis.

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We analysed 97 cases of thyroid carcinoma which were treated by radiation during 1946-1955 and tried to reinvestigate it on the standpoint of the following facts:
A) There exists a close relationship between histological figure of tumor and its prognosis, and we must use different treatments for different types of tumor. It is imperative that we take biopsy before the treatment, in order to determine the most suitable form of treatment.
B) The tumor which has higher radiosensitivity is rather worse in its prognosis than the one with lower sensitivity.
C) Although the cases in the first stage are fit for the treatment by operation with radiation, we would rather use the treatment by radiation alone for the cases in II or III stages.

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Sarcoma was produced at the site by repeatedly injecting 2gdl solution in tween 80 of scarlet red subcutaneously into normal rats. Injections were made in doses of 0.2cc at as nearly the same site as possible on the back, and at the rate of once a week for about 13 months, and sarcoma developed in 4 of 8 rats that survived this period. In these tumors, a considerable amount of the scarlet red was seen in the center.

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In continuation of our previous experiment which demonstrated the powerful carcinogenic activity of 4-nitroquinoline N-oxide, we tested the carcinogenicity of eight closely related derivatives, based on the classical Tsutsui method. It was found that 2-ethyl, 2-methyl, and 6-chloro derivatives of 4-nitroquinoline N-oxide were about as potent as the original compound, but that quinoline Noxide, 4-nitroquinoline and 6-nitroquinoline were non-carcinogenic.
An important conclusion was therefore arrived at that NO₂ radical at the position 4 and O atom at the position 1 are both essential to the carcionogenicity of this class of molecules.
The respective role of these two components of the molecule in determining the cacinogenicity was reserved for consideration in our future investigation. The known biochemical and biological actions of 4-nitroquinoline N-oxide were discussed in connection with the carcinogenicity of this substance.

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The correlation between the electronic structure and the auxin activity of the plant growth compound is discussed. The strong resemblance between the carcinogenic compounds such as polycondensed aromatic hydrocarbons and the plant growth compounds such benzoic acid derivatives is pointed out and its meaning is discussed.

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1. When a pellet of nicotinamide (10mg) with or without Carbowax is intransplenically implanted in rats after partial removal of the liver, PN (or presumably DPN) content of the regenerating liver is invariably increased after 24 hours, and at the same time the numbers of mitoses are greatly reduced.
2. In rats receiving a pellet of 10mg of nicotinamide without hepatectomy, the PN content of the intact liver differs little from that of the control animals, although the mitotic activity is much reduced.
3. It was suggested that there is a correlation between the PN content of a given tissue and the rate of mitosis.

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1) Using a spontaneous mammary cancer arisen exceptionally rarely among the leukemic strain of SL mice, the electron microscopic observation of ultra-thin sections of tumor tissue was made.
2) The cancer tissues contain abundant viral particles (50-70mμ×75-100mμ) in their lumen of the duct which are similar to the viruses described in the tissues of mammary cancer strains C₃H, DBA and RIII by many authors. However, in the present case, neither viral matrix nor inclusion body in cytoplasm were found.
3) Predominant foci of the virus proliferation are the ectoplasm just under the cellular membrane facing the duct including epithelial microvilli. Therefore, the type of proliferation is almost similar to that of the influenza virus described recently by Morgan et al.
4) However, in our case, the virus producing microvilli have central filaments in the axial region. After the production of the viral particle at the top of the microvilli a small piece of the central filament is involved there and the separation of the virus takes place. The finding suggests the dual origin of external and internal structures of the virus.
5) The fact that the mammary cancer tissue of non-mammary cancer strain mice such as SL mice contains viral particles allows us to further expect that the other sporadic mammary tumors may also contain such viral particles.

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This communication records osteogenic fibroma from Wallago attu. A trilobed hard knob-like big tumour was situated at the tip of the premaxilla and was covered with thick skin. Near the basal portion of the tumour hard pointed teeth-like structures were present at the anterior side while the remaining sides had small warty projections. Irregular structures were observed internally after cutting the tumour in the middle. Spherules of multiple bone spicules, laminated in appearance, embedded in a fibrous matrix were observed on histological examination. Cartilage, multinucleated and spindle shaped cells were absent throughout in the section. The connective tissue did not show any sign of malignancy. Probable histogenesis and comparison of the tumour are discussed.

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