386 BACTERIOLOGY. 



the cholera spirillum frora mixed cultures and from the 

 evacuations in so short a time as has been mentioned, 

 is due more to unfavorable nutritive conditions than to 

 the direct action of the other organisms present. 



When completely dried, according to Koch's experi- 

 ments, the cholera spirillum does not retain its vitality 

 for longer than twenty-four hours, but by others its 

 vitality is said to be destroyed by an absolute drying of 

 three hours. In the moist conditions, as in artificial 

 cultures, vitality may be retained for many months, 

 though repeated observations lead us to believe that, 

 under these circumstances, the virulence is diminished. 

 According to Kitasato,^ they retain their vitality when 

 smeared upon thin glass cover-slips and kept in the 

 moist chamber for from 85 to 100 days, and for as long 

 as 200 days when deposited upon bits of silk thread. 



In the course of his studies upon the destiuy of path- 

 ogenic micro-organisms in the dead body von Esmarch^ 

 found that, when the cadaver of a guiuea-pig dead from 

 the introduction of cholera organisms into the stomach 

 was immersed in water and decomposition allowed to 

 set in, after eleven days, when decomposition was far 

 advanced, it was impossible to find any living cholera 

 spirilla by the ordinary plate methods. 



A similar experiment resulted in their disappearance 

 after five days. In another experiment, in which de- 

 composition was allowed to go on without the animal 

 being immersed in water, none could be detected after 

 the fifth day. 



Carl FrankeP has shown that an atmosphere of car- 

 bonic acid is directly inhibitory to the development of 



1 Zeitschrift fur Hygiene, Bd. v. p. 134. - Ibid., Bd. vii. p. 1. 



» Ibid., Bd. V. p. 882. 



