As a fundamental study on the relation between micrococci and animals, the biological characteristics of micrococci from laboratory animals were investigated.
Following tests, e. g., KNO₃ reduction, growth on ammonium phosphate medium, gelatine liquefaction, hemolysin production, coagulase production, and fermentation of mannitol, were carried out with 822 strains, of which 689 originated from the oral cavity, skin and feces of laboratory animals and 133 from cattle and human being.
Most of the micrococci from laboratory animals were coagulase-negative, although 50 per cent of the organisms from the oral cavity of monkey were positive.

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“Falter” (fa) is a recessive mutant which appeared spontaneously in 1958 in a sib-mated stock (DBA/Ms-c^e) bred in author's laboratory. In homozygous condition, falter can be recognized by its abnormal walk from side to side, slowly swaying walk. The mutant was found at the age of approximately 10 days. The abnormality was becoming more pronounced with advancing development, and all of those mice died when about 20 days old.
By the mating of two heterozyotes (fa/+), 81 offspring were obtained. Among them 59 were normal, and 22 were abnormal which indicates that the falter is due to a simple recessive mutation.
Reeler (rl) reported by FALCONER (1951) is very similar to falter and has been proved to belong to the 3rd linkage group. From the data of the segragation ratio in respect to s in the 3rd linkage group and fa, it seems to be that fa is independent from the 3rd linkage group.

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Experiments were performed to investigate the changes of lumbar vertebral numbers caused by reciprocal crosses between two inbred strains of mice which have different lumbar vertebral numbers and to analyse the influence of two different feeding conditions upon such changes. As‘interfrontal bones’ were found in the same materials, the distribution of these bones among the two strains and their hybrids F₁ was also examined.
The animals used in this study were two inbred strains of mice, dd, rr and their reciprocal hybrids F_l. They were divided soon after their birth into two groups namely, with high and low protein feeding conditions thus have been fed during 60 days.
1) The lumbar vertebral numbers of dd, rr were predominantly 6 in the former and 5 in the latter. Their numbers of the hybrids F₁ had a tendency of resembling those of rr.
2) As for the lumbar vertebral numbers of dd, rr and of their hybrids F₁, there was little difference in the two feeding conditions.
3) The investigation of the distribution of‘interfrontal bones’ showed that the ratio of these bones to those of normal dd was the same as that of rr, and the ratio in hybrids F₁ was slightly higher than those in inbreds dd, rr.
4) No changes were found in the distribution of‘interfrontal bones’between two studied groups with different feeding conditions.

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The roentgenological techniques for the giography of monkey were described. The techniques were proved to be useful either for stereotypic analysis of the cardiovascular system or in a magnificating studies with the organ slice following the administration of the contrast media.
A live monkey should be examined by arteriopuncture under the intravenous anesthesia with pent- barbitulate. In the case of dead monkey, it was recommended to leave the body in 5°C for 48 to 72 hrs. before the application of contrast media.
The emulsified contrast media was introduced slowly into the femoral artery under a fluoroscopy.
Bucky was necessary for the better results in the roentgenography of a whole body or the trunk.
No screen expose technique was used for the better result to the individual organs.
In order to obtain a sharp picture, an enough distance for focal spot, low voltage and waek current were recommended since the exposure has not any limitation for the still object.

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