1. Male Wistar rats were immunized with BGG and the effects of X-radiation on the nucleic acids in their spleen were studied during the period of primary immune response.
2. Amount of DNA increased on the 9th day of immune response reaching twice as much as the unimmunized rats. DNA was markedly reduced by the irradiation with 500r of X-ray.
3. RNA increased also on the 10th day and it was reduced considerably by X-ray.
4. Particular changes caused by the administration of antigen were found in the chromatographic pattern of RNA by DEAE-cellulose columm, and X-ray diminished such changes ascribed to an immune response.

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Artemia dry eggs irradiated with γ-rays showed the biological after-effect; the hatchability of the eggs decreased with increased storage time. Such effect can be modified by various treatments applied after the irradiation. In this paper, the effects of water content and temperature upon storage after irradiation on Artemia dry eggs were examined.
Artemia dry eggs were γ-irradiated and then stored for one, three and seven days in various conditions. The hatchability was examined for each treatment to assess the biological damage.
Radiation damage after irradiation was considerably increased by the water content in highly dried eggs (water content, 7.4%). On the other hand, in the moistened eggs (9.6%, 18.5% and 35.1%) the damage was not so pronounced as compared to the highly dried eggs, and no appreciable difference in the after-effect was found among them.
The after-effect was temperature dependent; the dry eggs kept in dry ice did not reveal the decrease of hatchability. The possible mechanism of the biological after-effect on Artemia eggs was discussed.

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The effects of half lethal dose (600r) of whole-body X-irradiation on the concentration of oxidized (TPN) and reduced triphosphopyridine nucleotide (TPNH) in liver, spleen, kidney adrenal and testis of rats were studied. There was no significant change observed in both coenzymes of liver while the TPNH concentration of spleen decreased markedly following the irradiation. In kidney and testis of the irradiated animals, the gradual increase of the TPNH concentration was observed. The concentration of both TPNH and TPN in adrenal was elevated on 1st and 3rd day after irradiation and returned to normal levels by day 5 th. The physiological implications of these findings were discussed.

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Deep water samples collected in 1963 and 1964 in the adjacent seas of Japan were analyzed radiochemically.
Sr-90 and Cs-137 were detected in the deep layers down to 6, 000 meters deep and showed approximately uniform vertical distributions below 1, 000 meters. Mean concentrations of Sr-90 in deep waters were 0.028 μμc/l in the Pacific and 0.035μμc /l in the northern Japan Sea, and those of Cs-137 were 0.034 and 0.075 μμc/l respectiviely.
The mean Cs-137/Sr-90 ratios in deep layers of the Pacific showed uniform distribution and the mean value of 1.4, but in the northern Japan Sea, remarkably higher value of 5.5 due to the Sr-90 depletion was found in 1, 000 to 2, 600 meters layer.
Vertical distribution of Ce-144 suggests strong biological retention within the surface layer, and from the apparently uniform distribution in deep layers, 400 meters per month was estimated as the sinking rate of Ce-144.

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Japanese soil and rice collected at 15 localities have been analyzed for cesium-137 since 1959 through 1963. The time trend of rice-levels indicates the minimum in 1960 and 1961 and the maximum in 1963, showing more than threefold value of the minimum. A higher dependency was observed of the level of cesium-137 in rice on the fallout rate than either of the cumulative ground deposit or the N-ammonium acetate extractable cesium-137 in soil. Variation with locality is great and the highest rice-level is observed on the northern Japan Sea side, the lowest in the central and southern parts, and intermediate on the northern Pacific side.

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Kinetic investigations for reduction of cytochrome c in aqueous solution induced by cobalt-60 gamma rays have been carried out. Initial reduction yield of cytochrome c is about 5 as limiting value.
The decrease in initial reduction yield in presence of thallous ion as a radical scavenger with ferricytochrome c provides some evidences that OH radicals can contribute to reduction through some possible intermediate.
The effects of concentration ratio in ferro-ferricytochrome c and thallous ion-ferricytochrome c systems on initial reduction yield were investigated.
The results can be explained on the basis of some reaction scheme based on the contribution of OH radicals to reduction of ferricytochrome c. The following rate constants were determined by kinetic treatment of the results.
k_{OH+RH2Fe¹⁺}=5 × 10¹⁰M^-1 sec^-1
k_{OH+RH2Fe²⁺}=4.1 × 10¹⁰M^-1 sec^-1.

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