Since the Japanese pond frogs (Rang nigromaculata and R. brevipoda) are known to be very closely allied with each other in morphological, ecological, physiological or immunological characters, the phylogenetical relationships between the Japanese pond frogs and other 10 species of Japanese amphibians were investigated by means of immunoelectrophoretic analysis of liver extract. The results obtained are as follows: (1) There are conservative antigens which are commonly found in all species of Anura. (2) The Japanese pond frogs have specific antigens. (3) R. nigromaculata and R. brevipoda are very closely allied with each other. (4) Four species of the genus Rana (R. rugosa, R. catesbeiana, R, ornativentris and R. japonica) are closely related to the Japanese pond frogs. (5) Two species of the genus Rhacophorus (Rh. arboreus and Rh. buergeri) are related to the Japanese pond frogs. (6) R. limnocharis is related to the Japanese pond frogs at the same extent as the genus Rhcophorus is. (7) Two species of the suborder Procoela (Hyla arbored and Bufo bufo) are only partially related to the Japanese pond frogs. (8) Cynops pyrrhogaster pyrrhogaster of Urodera had only a few common antigens with the Japanese pond frogs.

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The Learning behavior on a water maze was observed in Wistar-JCL rats which were 10 weeks of age at the beginning of tests. Each rat was given five swimming trials in a straightway on the first day, as well as daily five trials to escape from a water maze on the 2nd to 4th day of the tests. In the first trial of the straightway, the harmonic means of the swimming time were 12.0 and 17.4 seconds in the male and femals, respectively. In each trial of the water maze, there were no significant differences between the female on the spent time and the number of errors. During the test days, the median of total of errors were 25.2 and 24.3 times in the male and female, respectively. Error response entered into a blind alley occurred beside the starting point more frequently than the goal.

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A lightweight stainless steel autoclavable pentagon isolator was designed for experiments using gnotobiotic mice. The chamber, 400×450×350 mm, has an entry port 200 mm in diameter at the back and a window at the ceiling. The globes and two filters were equipped at the front and each side, respectively. An inner stainless steel cap of the entry lock was sealed by a seamless silicone band. It was possible to ventilate this isolator by either free-flow or blower operation. After autoclaving the isolators 10 to 16 times for a year, none of them was repaired. Five mice can be kept in this isolator for about 1 month without supply of diet, water and wood shaving after the first setting.

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Serological surveys on several infections were performed on the inbred mouse strains maintained at the Central Institute for Experimental Animals. In the first survey, 11 strains of mouse, which were 8 weeks of age or older and were kept in separate cages in the same animal room, were tested for antibodies to Salmonella en teritidis, Corynebacterium kutscheri, Tyzzer's organisms, Mycoplasma pulmonis, mouse hepatitis virus (MHV), Sendai virus (HVJ), pneumonia virus of mice (PVM) and minute virus of mice (MVM) . Positive results were obtained in MHV, HVJ, PVM and MVM. Positive rates for these viruses except for MVM were different among mouse strains. In the second survey, 5 strains of mouse kept together in the same cage for 4 weeks after weaning were examined for MHV and HVJ antibodies. Positive rates to MHV were different among mouse strains as observed in the first survey. For HVJ antibody, no difference was demonstrated in positive rates unlike in the first survey, but the titers varied between the strains. These results suggest the difference in antibody response to natural infections dependent on mouse strains.

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A survey on the number of animals used in experiments including bioassay, diagnosis, education and preparation of biological agents such as vaccines between April 1975 and March 1976 was conducted by the support of a grant-in-aid for the specific research, “Purification and Development of Experimental Animals”, from the Ministry of Education, Science and Culture of Japan. Of 933 universities, institutes, hospitals, testing laboratories and companies, 648 replies were received. As shown in the table, a total of 57, 107, 553 animals were used for various experiments in Japan in 1975. The distribution of the number to animal species is also shown in the table. Comparing with the similar surveys in 1956, 1960, and 1970 (Exp. Anim., 7, 3-8, 1958, 12, 145-168, 1963, and 22, 307-340, 1973), the number of animals used in Japan seems to have reached a roughly constant level. Periodic surveys should be continued as a nation wide project for medical and biological sciences.

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