CHOLERA: GENERAL CONSIDERATIONS. 333 



three hours. In the moist condition, 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 dimin- 

 ished. 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 destiny of 

 pathogenic micro-organisms in the dead body, Von 

 Esmarch" found that, when the cadaver of a guinea- 

 pig dead from the introduction of cholera organisms 

 into the stomach, was immersed in water and decom- 

 position allowed to set in, after eleven days, when de- 

 composition 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 FraenkeP has shown that an atmosphere of 

 carbonic acid is directly inhibitory to the development 

 of the cholera spirillum, and Percy Frankland * states 

 that in an atmosphere of this gas it dies in about 

 eight days. In an atmosphere of carbon monoxide its 

 vitality is lost in nine days, and in general the same 

 may be said for it when under the influence of an 

 atmosphere of nitrous oxide gas. 



1 Zeitachrift fiir Hygiene, Bd. v. p. 134. 2 Ibid., Bd. vii. p.l. 



3 Ibid., Bd. V. p. 332. * Ibid., Bd. vi. p. 13. 



15* 



