There is no definite opinion on the reliability of the hemolysis test for differentiation between classical and El Tor biotypes of Vihrio cholerae, serotype 1, although several improved modifications of the test have been reported. In order to obtain consistent methods for determining hemolytic activity of V. cholerae, studies were carried out using 1, 222 strains of the vibrio. It was found, in a preliminary study, that peptone and extract produced from animal tissue stimulated hemolytic activity in culture and that heart infusion broth consisting of those two ingredients was one of the suitable basal media for the hemolysis test. No variation among several batches of dehydrated heart infusion broth of Difco products was observed.
Among plain heart infusion broth (HIB), heart infusion broth by Feeley and Pittman (FP-HIB), glycerolized heart infusion broth (HIGB) and glycerolized brain heart infusion broth, the largest number of hemolysispositive tubes were obtained with HIGB. The results given by two agar plates, an aerobic plate of brain heart-thioglycollate-cystine agar (BHTCA), devised by the authors during the course of this study, and an anaerobic plate of heart infusion agar with washed sheep red cells were also compared with those given by HIGB. It was demonstrated that BHTCA was also satisfactory for the hemolysis test of V. cholerae.
Thus, when 1, 124 strains resistant to polymyxin B and to Mukerjee's phage IV with one exception being sensitive to the latter were tested in HIGB and BHTCA, the hemolytic activity was demonstrated in 99% of the strains. Classical strains were consistently nonhemolytic in/on these media; no false positive was recognized in any of them.
However, some varying results were recognized between HIGB tube and BHTCA plate. Variation was also given even in the same medium among strains which revealed weakly or no hemolytic activity. From these results, in this paper the joint use of HIGB and BHTCA has been recommended for the determination of hemolytic activity of V. cholerae. The test should be repeated if a doubtful or negative result is obtained.
Role of glycerol in HIGB and of thioglycollate and cystine in BHTCA for detection of hemolytic activity was discussed.

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The O antigenic variation between Ogawa and Inaba variants of Vibrio cholerae was studied. It was demonstrated that Inaba form colonies were isolated from Ogawa cultures, but none of Ogawa form colonies from Inaba strains of V. cholerae.
In cross agglutinin-absorption tests using Ogawa and Inaba antisera, the Inaba specific antigen was not found in any of Inaba strains, whereas the Ogawa specific antigen was demonstrated in all strains of Ogawa and Hikojima variants. The results were interpreted to indicate that V. cholerae strains may produce three somatic antigens designated a, b, and c, and that Inaba strains are a loss mutant of the antigen fraction b which can be used as the specific factor for recognizing the Ogawa form.
It was discussed that the differentiation of Ogawa, Inaba and Hikojima forms is not significant in epidemics.

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Specific RNA synthesis induced in VERO cells by the infection with western equine encephalitis (WEE) virus or Chikungunya virus was studied by autoradiography in the presence of chromomycin A3 or actinomycin D allowing the viruses to propagate despite the suppression of cellular RNA synthesis. It was revealed that such virus-induced RNA pulse-labeled with ³Huridine after infection of WEE virus or Chikungunya virus appeared dispersedly in the cytoplasm of the infected cells. Chikungunya virus-induced RNA accumulated after chase in the restricted areas of the cytoplasm. This finding supports the general view that the loci of RNA synthesis induced by group A arboviruses are confined within the cytoplasm of the infected cells.

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The dye and three different hemagglutination tests for toxoplasmosis were compared and evaluated in regard to the sensitivity and specificity on a total of 228 sera from humans, dogs and cats.
Good agreements were obtained among the positive rates by the dye test, a modified Jacobs-Lunde's and the Lewis-Kessel' s hemagglutination tests. Such a high agreement rate as 94% was shown on human sera by these hemagglutination tests, but slightly lower rates, 88.5% and 82.8%, on dog sera. The dye test demonstrated the antibody in all sera from proven cases of toxoplasmosis (29/29), whereas both Jacobs-Lunde's and Lewis-Kessel's hemagglutination tests in 97% (28/29) . Higher titers were demonstrated on the sera by these hemagglutination tests than by the dye test. By Jacobs-Lunde's hemagglutination test, the titer was 2 to 3 tubes (16 to 64 times) higher than that by the dye test. The titer by Lewis-Kessel's technique was 4 tubes (256 times) higher than that by the dye test. The Hanaki-Nobuto-Sato's hemagglutination test was slightly inferior to the other tests although the pre-sensitized and lyophilized erythrocytes are available for the test.

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