540 APPLICATION OF METHODS OF BACTERIOLOGY 



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

 is slower, the maximum development of the cholera organ- 

 isms being reached at about the fifteenth hour, after which 

 time they were outnumbered by the ordinary saprophytes 

 present. 



From the foregoing it would seem that the vitality of 

 microspira comma in milk depends largely upon the reac- 

 tion; the more quickly the milk becomes sour the more 

 quickly does the organism become inert. 



According to Laser,' the cholera organism retains its 

 vitality in butter for about seven days; it is therefore 

 possible for the disease to be contracted by the use of butter 

 that has in any way been in contact with cholera material. 



When dried microspira comma retains its vitality for 

 from about three to twenty-four hours, according to the 

 degree of desiccation. In moist conditions vitality may be 

 retained for many months; though repeated observations 

 lead us to believe that under these circumstances virulence 

 is diminished. 



Carbon dioxide, carbon monoxide and nitrous oxide gases 

 kill this germ in from seven to ten days. 



From what has been said, we see that the spirillum of 

 Asiatic cholera, while possessing the power of producing 

 in human beings one of the most rapidly fatal diseases with 

 which we are acquainted, is still one of the least resistant 

 of the pathogenic organisms known to us. Under conditions 

 most favorable to its growth its development is self -limited; 

 it is markedly susceptible to acids, alkalies, other chemical 

 disinfectants, and heat; but when partly dried upon cloth- 

 ing, food, or other objects, it may retain its vitality for a 

 relatively long period of time, and it is more than probable 



1 Zeitschrift fiir Hygiene, Bd. x, S. 513. 



