198 CLINICAL BACTERIOLOGY. 



ing to the method first described by Haffkine. This ob- 

 server injects first -^ of an agar-culture, twenty-four 

 hours old, carefully devitalized by chloroform, and five days 

 later y 1 ^ of a living virulent culture, and, again, after the 

 lapse of five days, y& of the last. Each inoculation is fol- 

 lowed by an insignificant, slight, painful infiltration and 

 mild fever, which, however, soon recede. The serum of 

 persons thus inoculated acquires, as Kolle has shown, 

 lysogenic properties at least equal to those of the serum of 

 convalescents from cholera. This bactericidal activity be- 

 gins on the fifth day, attains its maximum on the twentieth 

 day, and then gradually diminishes. It is, however, still 

 demonstrable after the lapse of a year. Kolle has shown, 

 further, by experiments on human beings, that a single 

 introduction of living or carefully devitalized vibrios is at- 

 tended with the same success, so that repeated inoculation 

 is not at all necessary to attain marked bactericidal activity. 

 Little of a positive nature can yet be said with regard to 

 the results of Haffkine's protective inoculations ; but they 

 are at least quite encouraging. 



CHOLERA NOSTRAS AND SUMMER DIARRHEA. 



Cholera nostras includes all of those cases of severe 

 diarrhea presenting symptoms similar to those of Asiatic 

 cholera, but with an absence of the comma-bacilli of Koch 

 from the feces, and without epidemic distribution. In by 

 far the larger number of cases the bacterium coli commune 

 is found in the stools and in the vomited matters. Under 

 these conditions the bacterium cpli manifests a considerable 

 degree of virulence ; and in cultures from a case of cholera 

 nostras it proves far more malignant in experiments on 

 animals than in cultures from normal feces. In severe 

 cases of cholera nostras the bacterium coli is often present 

 in the dejections in pure culture. In some cases strepto- 

 cocci have been found in the feces in overwhelming number, 

 or in pure culture, and in isolated instances also vibrios 

 presenting a superficial resemblance to Koch's bacilli, with- 

 out, however, agreeing perfectly with these as, for instance, 

 the vibrio Lisbon, in Appendix. 



As the necessity for bacteriologic examination in cases 

 of cholera nostras arises only in the presence of suspicious 



