From this experiment it became evident that strain N4 inoculated into mice and guinea pigs intraperitoneally caused death of the animals by bacteraemia, but strain EB102 did not. Fujino et al.⁽³⁾ reported that 0.01 mg of EB102 caused the death of mice within 12 hours after intraperitoneal inoculation. The difference between our result and Fujino's would be attributed to the decrease in pathogenicity of the strain caused by successive transfers. The heated suspension (100°C, 30 minutes) or the Seitz-sterilized broth culture of strain N4 had no fatal effect on mice after intraperitoneal injection. Takikawa⁽²⁾ observed that cats administered per or with the heated suspension of strain N4 showed fever and leucocytosis, but he could not prove exotoxin.
Although strain N4 showed almost similar growth pattern on every agar slant examined, it was observed that the organism grown on synthetic nutrient agar was less toxic than those cultivated on medium which were enriched with peptone or meat infusion. According to Ogasawara et al.^{(4, 5)} Salmonella enteritidis maintained on a synthetic medium containing no vitamin had antigenicity to produce the infection-preventing antibody in immunized animals but had no communicability (a factor of pathogenicity). Communicability was recovered by culturing the organism on a synthetic medium containing vitamin B group. Although an experiment using organisms maintained on the synthetic medium was not performed, a result similar to Ogasawara's was observed in this study. The fact that mice were not killed with intraperitoneal inoculation of normal meat infusion broth culture of strain N4 might be due to their poor multiplication in this medium. However, the effect of sodium chloride may be expected.
From this experiment it may be suggested that the injection of viable cells of strain N4 gives an incomplete immunization to prevent the infection of the organism, but injection of EB102 cells does not provide the immunity. However, a definite conclusion can not be drawn because the extended survival period was short.

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Genetic studies have been made on the kanamycin resistance system of Mycobacterium avium, R-type Jucho strain, by population analysis method. It has been indicated that kanamycin resistance system of Mycobacterium avium has multiple genotypes. It has been suggested that there are multiple genes, each of which is instrumental for kanamycin resistance but differs in their potency. It is notewothy that the range of resistance development of this organism is very narrow, unlike the case of M. tuberculosis.

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In order to understand the presence of the ribonucleoprotein particles (RNP) bound to the cytoplasmic membrane ("ghost") of Pseudomonas fluorescens A3-12, ultracentrifugal separation was applied to the disintegrated ghosts.
The release of RNP from the membranous structures into the cytoplasm during the preparation of ghosts was quantitatively studied, and the relationship between the magnitude of osmotical lysis in protoplasts and the incorporation of the "broken protoplast" for S³⁵-methionine were investigated.
It could be summarized that (1) the RNA-rich particles (RNP), regarded as the incorporation sites of amino acids, associate relatively firmly with the membranous structures preparable as the ghost, and (2) the incorporation of amino acid into a mildly broken protoplast is more prominent than that vigorously disrupted.
With reference to the results obtained in the previous paper⁽¹⁹⁾, it can be concluded that the bacterial membranous-structures are the incorporation site of amino acids and which plays an important role in protein synthesis.

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The cellular localization of the antigens of Salmonella enteritidis in the mouse tissues after intravenous and intraperitoneal injections of the killed organisms was investigated, using the double-layer method of fluorescein-labeled antibody technique (Coons). The heat-killed organisms and the chrome-vaccine were comparatively studied. In the liver, the antigens of Salmonella enteritidis were observed to fill the cytoplasms of the Kupffer cells, and those of the leukocytes (monocytes and granulocytes) infiltrated around the sinusoids and other vessels. When the granulomas were formed, the antigens were demonstrated in their cells in various amounts; some contained a large amount of the antigens and the others small. The epitheloid and other cells, which constituted the granulomas, contained the antigens in their cytoplasms. In the spleen, the antigens were localized in the cytoplasms of the large round mononuclear cells (chiefly reticulum cells) of the red pulp. Using heatkilled vaccine, the antigens accumulated in a few layers of cells lining the lymphoid follicles. However, after administering chrome-vaccine, it was found in the cells of the red pulp. The other differences in the distribution of the antigens between the heat-killed vaccine and the chrome-vaccine were described. The localization of antigenic particles of the killed organisms was markedly different from that of the endotoxin (the soluble antigen). Biological significance of the distribution of the antigens was discussed, particularly the role of antigen and antibody in the formation of the granuloma.

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1) Hα-proteinase was purified eight times from Trimeresurus flavoviridis venom using successive ammonium sulfate fractionation and calcium phosphate gel treatment. The preparation thus obtained was electrophoretically homogeneous.
2) The purified Hα-proteinase was activated two folds by manganese chloride, although the crude venom was not affected, and inhibited by EDTA and cysteine.
3) Hα-proteinase showed both lethal and necrotizing effects.

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The DNA and RNA phosphorus content of 32 strains of B. anthracis and 10 strains of B. cereus were determined using the method of Schmidt and Thannhauser(1).
Wide variation was found in the nucleic acid content of both species. Virulent strains of B. anthracis contained significantly more DNA than avirulent strains.

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1. The fish-killing factor produced in peptone solutions by Proteus vulgaris was not adsorbed by either kaolin or animal charcoal.
2. Absolute alcohol could not precipitate the factor from the culture solution, similarly with tannin and picric acid.
3. Both AgNO₃ and phosphotungstic acid could form a precipitate, leaving the culture solution non-toxic, but no active factor was liberated from the precipitate.
4. Simultaneous addition of Ba(OH)₂ and absolute alcohol produced a precipitate with which the factor was completely precipitated. The precipitate thus obtained was found to be a Ba-salt of a polypeptide present in the peptone preparation.
5. A similar precipitate was produced even when an uninoculated peptone solution was used. The polypeptide whose Ba-salt was precipitable by the addition of alcohol was presumably changed into the toxic factor by the action of the bacteria, whereby a portion of NH₂-group was dissociated from the polypeptide.
6. Sometimes the polypeptide seemed to become non-precipitable after a long duration of incubation without losing the toxic activity.
7. When CaCl₂ was used instead of Ba(OH)₂ the same result was obtained.

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Two types of temperate phage causing lysogenic conversion were obtained from certain toxigenic strains which were recently isolated from diphtheria cases or healthy carriers in Japan. Strains were not restricted to any biological type of Corynebacterium diphtheriae, while there seemed to be a certain relationship between the type of phage and the area of origin of the strains from which the phages were obtained. Although the sti ains were obtained at different times, same type of phage resulted from strains obtained from the same area. Inquiry in the clarification of the relationship between lysogenization and the outbreak of diphtheria has been performed without success.
One of the two types thus obtained is identical with β phage in all its properties, while the other, designated κ, a new one in regard to its host range, is not significantly distinguishable from type β in other properties.

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Listeria monocytogenes was isolated in pure culture from the cerebrospinal fluid of a child with symptoms of meningitis, and the disease was diagnosed as Meningitis listeriosa. This case is believed to be the first case of human listeriosis in Japan.

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The successful demonstration of NDV multiplication in cultured human cells by hemagglutination and fluorescent antibody technique was presented. The immunohistochemical findings of the virus antigen correlated fairly with the growth curve of hemagglutinating virus, determined from companion cultures. The first appearance of the virus antigen was limited to the perinuclear region of the cytoplasm. There were two different processes of the virus antigen formation in the late stage. In 12 hours, the first accumulation of NDV antigen in detectable amounts was found in the form of a few small particles in the perinuclear region of the cytoplasm. The number and density of the antigen particles increased. They fused to each other, some of them occurred in the other parts of the cytoplasm. In most cells the next outstanding localization of the antigen was found in the surface region of the cytoplasm. It occurred in the form of a band and was getting denser and thicker. The virus seemed to be released into the medium from the surface of the cell, judging from the growth curve of virus. In this case cytolysis did not occur. In some of the cells, however, another process of the virus antigen formation took place in the later period. At 48 to 72 hours, large and dense granules of the virus antigen appeared in the cytoplasm. Their number and size were getting larger and the virus antigen filled the most part of the cytoplasm. Finally it caused the lysis of cells and the synthesized virus was released into the medium. The virus antigen, observed by the method employed, appeared to be limited to the cytoplasm of the cell and never occurred in the nucleus. Binuclear or multinuclear cells were observed in virus-containing cells. It indicated that mitosis or division occurred in virusmultiplying cells.

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