. Pathogenic microörganisms; a practical manual for students, physicians, and health officers . ed with diarrheal symptoms buthad shown no clinical evidences of cholera. These strains are calledEl Tor strains. They give the serum reactions of cholera vibriosbut produce a strong hemolysin. Kraus and Ruffer believed them notto be true cholera, as hemolysin production was considered by theformer as an attribute possessed only by non-cholera types. Furtherinvestigations have shown that cholera vibrios may develop, lose, orshow wide variations in their ability to produce hemolysins. It isapparentl
. Pathogenic microörganisms; a practical manual for students, physicians, and health officers . ed with diarrheal symptoms buthad shown no clinical evidences of cholera. These strains are calledEl Tor strains. They give the serum reactions of cholera vibriosbut produce a strong hemolysin. Kraus and Ruffer believed them notto be true cholera, as hemolysin production was considered by theformer as an attribute possessed only by non-cholera types. Furtherinvestigations have shown that cholera vibrios may develop, lose, orshow wide variations in their ability to produce hemolysins. It isapparently a potential power of all vibrios and of no value in differen-tiation. For this reason the El Tor strains must be considered ascholera vibrios. Resistance and Vitality.—Development Outside of Body.—If a cultureis spread on a cover-glass and exposed to the action of the air at roomtemperature the spirilla will be dead at the end of two or three hours,unless the layer of culture is very thick, in which case it may taketwenty-four hours or more to kill all the spirilla. This indicates that. 458 CHOLERA SPIRILLUM infection is rarely if ever produced by means of dust or other driedobjects contaminated with cholera spirilla. The transmission of theseorganisms through the air, therefore, can only take place for shortdistances, as by the spray from infectious liquids. The cholera bacillus is also injuriously affected by the abundantgrowth of saprophytic bacteria. It is true that when associated withother bacteria, if present in large numbers, and if the conditions forth;eir development are particularly favorable, the comma bacillus mayat first gain the upper hand, as in the moist linen of cholera patients,or in soil impregnated with cholera dejecta; but later, after two orthree days, even in such cases, the bacilli die off and other bacteriagradually take their place. Thus, Koch found that the fluid contentsof privies twenty-four hours after the introduction of comma bacillino lo
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