The present study was undertaken to investigate the mechanisms of food poisoning by V. parahaemolyticus by the observation of the growth rate and deteriorating activity of food stuffs, and the following results were obtained.
1) When 10²/g cells were inoculated at 30-37°C in the food stuffs (horse-mackerel, squid and boiled octopus), the organism multiplied more rapidly within a short time, in comparison with other common contaminant bacteria.
2) In spite of the strong proteolytic activity of this organism, the deterioration of food stuffs was not detected after 6hrs. of inoculation. During this perind, however, the cell multiplication was observed at the magnitude of 10⁴-10⁵/g in 2-3hrs. and of 10⁷-10⁸/g in 6hrs.
3) The estimated generation times of this organism were 13min, at 37°C and 15-18min. at 30°C in horse-mackerel and squid, and 12min. at 30°C in boiled octopus.
4) It might be concluded from the results of this investigation that feeding raw fish and sellfish containing V. parahaemolyticus of 10⁴-10⁵/g was possible to cause the food poisoning even if the quality were fresh.

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“Whether the resistant factors of SM resistant Str. fecalis and multiple drug-resistant Str. fecalis are transmitted to E. coli, or not” was examined. The result is as follows:
1) In the test with E. coli K 12 sub-strain ML. 649 having the resistant factor of high transmissive frequency, the resistant factor is not transmitted to Str. fecalis BlO strain.
2) In the same way, each of the resistant factors of SM resistant Str. fecalis BlO-SMR strain and multiple drug resistant Str. fecalis BlO-4R strain is not transmitted to E. coli K 12 substrain 58-161 F-M-.

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By the well-known procedure of transferring cultures to media containing increasing concentrations of antibiotics, three variants of Streptococcus Faecalis, respectively resistant to 1, 000 units of penicillin (PN), 300γ of choloramphenicol (CM), or 250γ of tetracycline (TC) per ml., could be made after respective 27th, 111th, or 120th passage.
They were proved almost identical with their sensitive parent strain in many of physiological properties such as catalase reaction, nitrate reduction, indole production, hemolysis, and so on. However, they differed from the parent strain in several points.
They showed somewhat poorer growth and production of lactic acid. In nutrition, glycine was altered to stimulatory from non-essential, and serine, though only in the PN-resistant strain, was the same. The TC-resistant strain became to require vitamin B₂ strictly, and the PN-resistant one did not demand folic acid. Each variant indicated a tendency of poor utilization in trehalose and dextrin, and further the TC-resistant variant did likewise in mannose and lactose, too.
In serological aspect, all variants retained the similar antigenic specificity as that of the original strain.

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The phage sensitivity was tested on 129 strains of rapidly growing Mycobacteria employing 17 strains of Mycobacteriophage, and the schemes of phage typing of them, which were proposed by the present authors 4 years ago, were remodeled from the practical standpoint to a considerable extent.
For the rough classification Table 1 was proposed by which the Mycobacteria examined were classified into 6 groups with different phage patterns to the 6 bacteriophages. For the more detailed classification Table 2 was proposed in which 4 groups out of the six were grouped into 2 or 3 subgroups, respectively.
The classification of 129 rapidly growing Mycobacteria by the phage sensitivity coincided very well with that obtained by the growth temperature or the acid production patterns from carbohydrates.

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Mice immunized intraperitoneally with the particulate fraction obtained as the sediment after centrifugation at 92, 600g for 60 minutes from sonically disintegrated cells were challenged with the living cells through the same route, and the aspects of infection in the peritoneal cavity were investigated according to the lapse of time.
In the analysis of cells which appeared in the peritoneal cavity after the challenge, polymorphonuclear leucocytes seemed to play a leading role. The rates of phagocytosis and inhibition of intracellular colony formation in immunized mice were higher than those of respective control animals, and the number of extracellular living cells decreased markedly also in immunized animals. These tendencies were known to commence on the 24th hour after immunization.

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