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464 high authorities regard it as a necessary concomitant and even as the actual germ and true cause of Asiatic cholera, the vibrio acquires an importance of the first rank.

Description of the comma bacillus.—The comma bacillus (Fig. 77) is a very minute organism, 1.5 to 2 μ in length by 0·5 to 0·6 μ in diameter—about half the length and twice the thickness of the tubercle bacillus. It is generally slightly curved, like a comma; hence its name. After appropriate



staining, at each end, or at one end only, flagella can be distinguished—sometimes one, sometimes (though less frequently) two. These flagella, though of considerable length—from one to five times that of the body of the bacterium—owing to their extreme tenuity are difficult to see in ordinary preparations. They are not always present during the entire life of the parasite. In virtue of this appendage the bacillus exhibits very active spirillum-like movements. The individual bacilli when stained show darker parts at the ends or at the centre, suggesting spore formation. Sometimes in