SPIRILLACE^ AND THE DISEASES CAUSED BY THEM 367 



opsonins for the cholera vibrio are increased. Practically such 

 vaccination has resulted in a reduction in case incidence to about 

 one-half and in mortality rate to about one-fourth that observed 

 among the unvaccinated. 



Spirillum (Vibrio) Metchnikovi. — This curved organism was 

 found by Gamaleia in 1887 in the feces and in the blood of chickens 

 suffering from enteritis. Morphologically and in cultures this 

 organism resembles Sp. cholera very closely. It has a single 

 fiagellum. The growth and liquefaction of gelatin seems to be 

 somewhat more rapid in the case of Sp. metchnikovi, and it usually 

 produces a larger amount of indol. Accurate differentiation is 

 possible only by animal experimentation and by testing with 

 anti-sera. A minute quantity of culture of Sp. metchnikovi in- 

 troduced into the skin of a dove or chicken is sufficient to cause 

 general bacteremia and death, whereas even large doses (4 rhg.) 

 of true cholera organisms introduced into such a skin wound are 

 without effect. Sp. metchnikovi is also much more virulent for 

 guinea-pigs. Agglutination and bacteriolytic tests with specific 

 sera also differentiate the two organisms. 



Spirillum (Vibrio) Finkler-Prior. — Finkler and Prior in 1885 

 isolated this organism from the feces in cholera nostras. Morpho- 

 logically it resembles the cholera vibrio very closely.' Indol is 

 not produced. It is apparently non-pathogenic. 



Spirillum 3^ogenum (Vibrio Deneke).^ — This organism was 

 isolated from old cheese. It resembles the cholera vibrio but 

 does not form indol and appears not to be pathogenic. 



A large number of other cholera-like organisms have been 

 isolated in the various examinations for the cholera germ. Some 

 of these can be differentiated morphologically, as they possess 

 more than one fiagellum. Others fail to produce indol or show 

 other cultural difference -from the true cholera organism. In 

 some instances differentiation depends almost altogether upon 

 the agglutination test. This latter has come to be regarded as 

 most important in the accurate recognition of the cholera organ- 

 ism and its differentiation from other vibrios. 



