The susceptibility of Meriones unguiculatus to infection with several species of Leptospira was studied.
It was found that L. icterohaemorrhagiae were virulent for Mer. unguiculatus and 4 to 10 week old gerbils challenged with more than 10⁵ cells developed always lethal infections with hemorrhages in subcutaneous tissue and lungs and occasionally with jaundice. L. autumnalis proved also to be virulent, but both L. hebdomadis and L. australis A were avirulent in gerbils.
The protective effect of homologous immune rabbit serum and the immunizing potency of vaccine in gerbils against infection with L. icterohaemorrhagiae were studied and the availability of gerbils in these experiments was demonstrated.

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The determination of 50% lethal time in mice under the decreased atmospheric pressure (140, 161, 183, 205, 249mmHg) was performed.
The experiment revealed the fact that the lethal time is shorter under the lower atmospheric pressure and the lethal time is most markedly shortened between 249mmHg and 205mmHg.

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[in Japanese]

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It has been recognized that CS₂, when injected to laboratory animal, may combine with a group of amino acids and protein in serum to forming thiocarbamate and thiazolidone, which are known to be a chelating agent, and might, therefore, affect trace metal metabolism in the animal body. In this experiment, by repeated subcutaneous injections of CS₂ to rabbits, body weight, hematocrit, hemoglobin, serum copper, serum caeruloplasmin, urinary copper and, serum and urinary iron were observed sequentially for 368 experimental days. Rabbits were divided three groups of three animals each; first group was injected olive oil 2-diluted CS₂ 0.8cc per 10 days, second group 0.4cc per 10 days, and control group was given olive oil alone. Results obtained are as follows:
1. Neither CS₂ rabbits nor cotrol showed loss of body weight through the whole period of the experiment (Fig. 1).
2. Hematocrit and hemoglobin of the CS₂ rabbits showed lower values than the control at the later period of the experiment (Fig. 2, 3).
3. Marked decrease of serum copper concentration was observed in the first and second groups according to repeated injections of CS₂ as shown in Fig. 4. After 6 months recess of CS₂ administration, however, this copper values were gradually recovered to a preexpeimental level. Serum caeruloplasmin, a copper enzyme bound to serum ∝-globuline, showed on meaningful change. It may, therefore, be suggested that the decreased serum copper would probably be derived from free copper faction in the blood. Increased excretion of copper in urine was noted as shown in Fig. 6; concentration curve of urinary copper showed the adverse parallelism with serum copper. Behavior of serum and urinary iron in the CS₂animals was identical to of copper.
Based on these findings, it may be concluded that a chelating compound would be formed in the blood when CS₂ is administered and this agent would affect the body metal metabolism by acting as a secondary metabolite toxin.

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In this report it was tried to discriminate the dead from the live eggs of trematodes (Paragonimus westermani and Clonorchis sinensis) by means of fluorescence microscopy.
In the beginning, the attitude of the eggs of the trematodes toward the acridine orange vital staining was examined comparing with that of nematodes eggs (Ascaris, Ancylostoma etc.). As the result, it was recognized that the eggs of the both trematodes had two characters seemed to be inconsistent each orther: (1) They were liable to be injured by acridine orange solution in contrast to the eggs of nematodes, because the contents (germs and yolk cells or miracidium) of the live eggs, immersed in aqueous solution of acridine orange for several days, emitted secondary fluorescence in yellowish green. (2) On the other hand, the trematodes eggs were more resistant to the staining with acridine orange than the nematodes eggs, because by the treatment with acridine orange in short time the contents of the dead eggs did not emit secondary fluorescence. These characters, differed from that of nematodes, were more remarkable in the eggs of Paragonimus westermani than Clonorchis sinensis.
As a result of the experiments, the condition of the acridine orange vital staining, suitable for the discrimination of the dead from the live eggs of the trematodes, was decided as follows:
In case of acridine orange concentration in 1:5, 000 and temperature at 26°C, the time for the staining was in need of 5∼6 hours for the Paragonimus eggs, and (10∼) 60 minutes for the Clonorchis eggs.
When the trematodes eggs were killed by various methods (boiling, drying, action of chemicals etc.) and then observed under the fluorescence microscope after the treatment with acridine orange according to the above mentioned condition, the contents of the live eggs did not fluoresce, but the most of the dead ones emitted secondary fluorescence in yellowish green.
Therefore, it was proved that on the eggs of the trematodes it was able to discriminate the dead from the live ones according to the observation whether their contents fluoresce or not. And the observation of autofluorescence in the contents of eggs was also helpful for the discrimination.

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