464 BACTERIOLOGY. 



guinea-pigs that had died of cholera induced by Koch's 

 method of inoculation contained no living cholera spir- 

 illa when exhumed after having been buried for nineteen 

 days in wooden boxes, or for twelve days in zinc boxes. 

 In a few that had been buried in moist earth, without 

 having been encased in boxes, when exhumed after two 

 or three months, the results of examinations for cholera 

 spirilla were likewise negative. 



Kitasato,^ in his experiments with the cholera organ- 

 ism, found that when mixed with the intestinal evacu- 

 ations of human beings under ordinary conditions it 

 lost its 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 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 

 serve as favorable materials for the development of 

 the cholera organisms. In his experiments upon its 

 behavior in milk Kitasato ' found that at a temperature 

 of 36° C the cholera sjiirillum developed very rapidly 

 during the first three or four hours, and outnumbered 

 the other organisms commonly found in milk. They 

 then diminished 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° 



• Zeitschrift fiir Hygiene, Bd. v. S. 487. 

 « Ibid., Bd. V. S. 527. 



•' Bolletino della E. Acad. Med. di Eoma, 1888. 



* Zeitschrift fur Hygiene, Bd. v. S. 491, 



