Measurements of Cesium-137 content in rain water in Yamagata have been made in 1958 by gamma scintillation spectroscopy.
The average monthly quantity of Cesium-137 in rain water in 1958 was estimated as 0.99 me/km² per month while it was 0.3 mc/km² per month in 1957.
Despite the amount of precipitation in 1958 was 1.7 times that of precipitation in 1957, the content of Cesium-137 increased more than 3 times during the same period.

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Enhancement of radiation lethal effect on microorganisms by NaCl action during irradiation is observed. The effects of radiation dose, dose rates, cell concentration and pre-irradiation on this phenomenon are investigated. This enhancing action of NaCl appears to have no direct correlation to NaCl tolerance of cells. Its possible mechanism is discussed from a viewpoint of free radical hypothesis.

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The difference in the behavior of cesium and potassium in the waterfish relation was investigated. The uptake ratio of these two chemical elements from water into fish bodies varied remarkably by the concentration of these elements in water. The ratio Cs/K taken into fish was approximately proportional to the square of the ratio in water.

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Recent variation on the atmospheric radiocarbon was measured using tree ring samples grown at. three different places in Honshu Island of Japan. These three series of measurements on the annual variation of radiocarbon content showed good agreement each other. The observed increase of radiocarbon content in these samples indicates a remarkable increase after 1954. The percentage increase of the atmospheric radiocarbon is 8% in 1957 and 24% in 1959.
The evaluation of the variation of radiocarbon content in the surface layer of the ocean water was done assuming the observed variation of radiocarbon in the atmosphere. The relation between the variation of C-14 in the atmosphere and the sea water gives a way to evaluate the residence time of carbon dioxide in the atmosphere and the sea water. The detailed examination on this problem leads to the conclusion that the observed variation of C-14 content in the atmosphere and the sea water gives rather poor results of the numerical informations on the residence times of carbon dioxide in the atmosphere and the sea water. However if we have some exact knowledge on one of the residence times of carbon dioxide in the atmosphere or the sea water, we can get a reliable knowledge on the mean depth of the mixed layer of the ocean sea water.
Using the residence time of 7 years of a carbon atom in the atmosphere and the mean depth of 75 meters of the mixing layer, the expected increase of radiocarbon in the surface water of the ocean is 1.7% in January 1958 and 4.7% in January 1960.

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The succinoxidase system and each component enzyme, i.e. succinic dehydrogenase and cytochrome oxidase, which are obtained from liver of mice and rats, and from beef heart, were irradiated in vitro with cobalt-60 γ-rays. Inactivation of the enzyme systems was observed to occur by relatively large does of γ-irradiation. Succinic dehydrogenase was found to be more radio-sensitive than cytochrome oxidase in all preparations.
Effect of gamma irradiation on the enzyme systems localized in mitochondria and nuclei of rat liver was compared. The enzyme systems in the nuclear fraction were relatively more radio-sensitive to γ-ray inactivation than those in the mitochondrial fraction.

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The sensitivity of the chick embryo to radiation hazard was investigated. Retinal anomalies were chosen for subjects, because it was revealed that the central nervous system including the retina showed the highest sensitivity against radiation. Various degree of abnormalities from the discontinuities of the outer nuclear laver to the severe rosette formations were observed, and the dose-effect relationship in different irradiation stages were investigated. It was concluded that the most sensitive stage is 6 days old embryo, and it's minimal effective dose is 350 r. It was observed also that the situation of retinal anomaly in the eye globe depends on the embryonic stages irradiated.

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Yttrium administered to mouse has been found in relatively higher amount among soft tissues like liver and spleen. Our investigations were carried on the effect of internal exposure with β-radiation from ⁹¹Y distributed in spleen and liver.
The rate of retention of ⁹¹Y in spleen and liver after intravenous injection was about 20 times higher than after intraperitoneal injection, but the distribution pattern was similar in both cases, i.e., ⁹¹Y was retained homogeneously in liver, but predominantly in the red pulp region in spleen.
When mice were administered intravenously with ⁹¹Y at the rate of 3 μc/g. body weight, the splenic weight was reduced exponentially with absorbed energy, and similarly, DNA content of spleen was decreased with tissue dose. These effects could be understood from consideration of disappearance of lymphocytes. RNA content of spleen was sensitively decreased. On the other hand, both the tissue weight and the nucleic acid content in liver showed scarcely any change. These studies indicate that liver and spleen result in different response against internal β-radiation from ⁹¹Y, and thus, the general information that liver is radioresistant and spleen is radiosensitive can be fully accepted.

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In this paper, the distributions of ¹³⁷Cs in the pregnant rats and the parent rats during lactation are studied and discussed in comparison with the distribution in normal rats.
The percentage of retention was observed to be lower with the pregnant rats than with the non-pregnant normal ones. The transfer of ¹³⁷Cs to the fetus after the administration of ¹³⁷Cs to the pregnant mother and the transfer of ¹³⁷Cs to the baby from the parent during lactation after the administration of ¹³⁷Cs to the parent are also studied.
The fetus showed relatively low concentrations as compared with the pregnant mother. The tissue concentrations of the organs except blood were higher with the normal in the ratio roughly about two to one as compared with the parents during lactation. However, the concentration in blood was much higher with the rats during lactation than with the normal. Therefore it may be inferred that the tissue concentrations of the baby rats tend to be in equilibrium with those of the parent during lactation, if the baby is continuously fed with the milk of the parent that is receiving a continuous supply of ¹³⁷Cs.

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A chemical technique has been developed for concentrating traces of fallout Cesium-137 in sea water (and in sewage) so that assay can be made rapidly with a gamma ray spectrometer. Measurements have been made of Cs-137 in surface waters of the eastern Pacific, especially near shore, and data are compared with fallout contamination reported elsewhere. Also a contemporary vertical profile of Cs-137 activity in the Pacific is given. The behavior of fallout activity in a large modern sewage treatment plant and in its oceanic outfall are discussed, and estimates are made of the probable effects in coastal areas.

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Contrasting properties of the classical and the balance hypotheses as applied to quantitative characters were examined in the light of existing data in human genetics. It was concluded that among the loci concerned with a quantitative character in man, overdominant loci are in minority as compared with loci in which genetic variability is maintained by mutation and selection, though the former loci may contribute a large fraction to total genetic variability in the quantitative character.

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Since the first case of atom-bomb leukemia described in 1951 by Misao et al., numerous reports have followed and their statistical data have confirmed a significantly high incidence of leukemia among survivors compared with that seen among non-exposed subjects. This paper described all cases of leukemias and allied diseases hitherto experienced at our Department of Medicine, Kyushu University.
Case 1 was an acute monocytic leukemia which developed about 2 months after A-bomb explosion in Nagasaki—the first case of A-bomb leukemias in the world. Case 2, a chronic, myelocytic leukemia, developed about 7 years after the explosion in Hiroshima. Both patients showed an immediate, acute symptom, such as fever, epilation, etc., after the explosion, once recovered from it and then developed a leukemia. In these 2 cases, it might be considered that there was certain relationship between radiation damage of hematopoietic organs by A-bombing, followed by their over-regeneration, and development of leukemia. Case 3, an acute myelocytic leukemia, case 4, an acute lymphocytic leukemia and case 5, a reticulosarcomatosis, developed 9, 11, and 12 years after the A-bombing, respectively. Cases 4 and 5 were thought to be due to secondary irradiation, because the patients had entered Hiroshima, walking around the hypocentric area for several to 20 hours.

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