Two cages of different size, with capacities of 1: 2 in ratio were prepared, and a litter of 4 newborn ss strain of mice was reared in the smaller cage and 2 such litters in the larger cage together with their mothers. The sex ratio was kept at 2: 2 in all the three litters. The growth and the reproductive ability of the animals in the two cages were studied in comparison and the results may be summarized as follows:
Growth: No difference was apparent in the two cages.
Age of the first conception of female mice: The female inmates of the smaller cage attained the age somewhat earlier.
Age of descent of testis: No difference observed.
Reproductive ability: The litter produced in the smaller cage tended to be somewhat larger in size, total weight and the birth weight of its members.

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The genealogy of wistar strain of rats being bred by sib-mating in which cryptorchidism accidentaly occurred was studied and it was concluded that the anomaly is inherited through recessive genes.

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These studes are based upon the postmortem examination in 39 monkeys obtained at Nagoya Zoo during the period from Jan. 1952 to March 1955.
1) Principal causes of death in 39 monkeys appeared as follows: Tuberculosis 2, Pseudotuberculossis 3, Amoebiasis dysentery 4, Acute and chronic enteritis 12, Parasitic infection 2, encephalitis 2, Tumor formation 4, Inadaptable environment 1, Injury 7, Dermatitis 2.
2) Conspicuous changes due to gastro-entero cattahralis containing cause of bacteria and Strongiloides parasitism marked simple chronic inflamation.
3) Judging from histologic finding, simple chronic inflamation cases were atrophic of mucouse membrane and these cases contained inadaptable environment and malnutrition.
4) In breeding of captive monkey monkey habitation and conditions on the import are also of great matter.

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