CHOLERA: GENERAL CONSIDERATIONS. 33 1 



Kitasato,' in his experiments with the cholera organ- 

 ism, found that when mixed with the intestinal evacua- 

 tions of human beings under ordinary conditions they 

 lost their vitality in from a day and a half to three 

 days. If the evacuations were sterilized before the 

 cultures were mixed with them, the organisms retained 

 their vitality up to from twenty to twenty-five days. 

 He was unable to come to any definite conclusion as 

 to the cause of these phenomena. 



It was demonstrated by Hesse ^ and by Celli* that 

 many substances commonly employed as food-stuffs 

 offer a favorable nidus upon which the cholera organisui 

 may develop. In his experiments upon its behavior in 

 milk, Kitasato* found that at a temperature of 36° C. 

 the cholera spirillum developed very rapidly during the 

 first three or four hours, and outnumbered the other 

 organisms commonly found in milk. They then dimin- 

 ished in number from hour to hour as the acidity of 

 the milk increased, until finally their vitality was lost ; 

 at the same time the common saprophytic bacteria 

 increased in number. Relatively the same process 

 occurs at a lower temperature, from 22° to 25° C, but 

 the process is slower, the maximum development of the 

 cholera organism being reached at about the fifteenth 

 hour, after which time they were overgrown by the 

 ordinary saprophytes present. , 



From this it would seem that the vitality of the 

 cholera spirillum in milk depends largely upon the 

 reaction : the more quickly the milk becomes sour, 

 the more quickly does the organism become inert, 



1 Zeitschrift fttr Hygiene, Bd. 9. p. 487. 2 Ibid., Bd. v. p. 527. 



3 Bolletino della E. Aocad. Med. di Koma, 18SS. 

 1 Zeitschrift f. Hygiene, Bd. v. p. 491. 



