SPIRILLUM CHOLEILE ASIATICS. 435 



Among other noxious influences the following have Relation to 

 been investigated hy Koch, and by Nicati and Rietsch. 

 Low temperatures did not interfere with the vitality of 

 the comma bacilli, (even 10 C.,) the cultivation having 

 been completely frozen. On the other hand, high tem- 

 peratures were very active ; exposure for half an hour to 

 a temperature of 60 C. caused death with certainty, as 

 did also boiling of the fluid for a short time. Their 

 growth is also hindered when, for example, 10 per 

 cent, of alcohol is added to the nutrient substratum ; 

 or 2 per cent, of sulphate of iron ; or J per cent, of 

 carbolic acid ; or ^V P er cent, of hydrochloric acid ; or 

 r,Y,- per cent, of quinine ; or ^rjW P er cen ^ of bichloride 

 of mercury ; the presence of 2 per cent, of common salt 

 does not interfere with development. With the excep- 

 tion of bichloride of mercury, these organisms are most 

 certainly killed by carbolic acid, which renders the 

 comma bacilli incapable of development when employed 

 in 3 per cent, concentration for a few minutes. 



In order to demonstrate with certainty the etiological Experiments 

 significance of the comma bacilli it was desirable, if 01 

 possible, to set up the choleraic process in animals by 

 inoculation of pure cultivations. Nevertheless from the 

 first there was but little expectation that this mode of 

 direct experimentation could be employed with success. 

 For it has been distinctly demonstrated that no animal 

 of any species is ever naturally attacked with symptoms 

 similar to those of human cholera, even although they 

 live in intimate association with mankind and come in 

 contact with the infective material of cholera in all sorts 

 of ways and in places where the disease is endemic or 

 epidemic. 



Numerous experiments on animals made formerly 

 and also in recent times with the dejecta and vomit of 

 cholera patients, with the intestinal contents of cholera 

 bodies, &c., led to no noteworthy result. On some 



