350 BACTERIOLOGY. 



same time the common saprophytic bacteria increased in 

 number. Relatively the same process occurs at a lower 

 temperature, from 22 to 25 C., but the process is 

 slower, the maximum development of the cholera organ- 

 isms being reached at about the fifteenth hour, after 

 which time they were overgrown by the ordinary sapro- 

 phytes present. 



From this it would seem that the vitality of the 

 cholera spirillum in milk depends largely upon the 

 reaction : the more quickly the milk becomes sour the 

 more quickly does the organism become inert, while 

 the longer the milk retains its neutral, or only very 

 slightly acid reaction, the longer do the cholera organ- 

 isms that may be present in it retain their power of 

 multiplication. 



According to Laser, 1 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. 



In regard to the antagonism between the cholera 

 spirillum and other organisms with which it may come 

 in contact, the experiments of Kitasato 2 led him to 

 conclude that no organism has been found which, when 

 growing in the same culture medium with it, possessed 

 the power of depriving it of its vitality within a short 

 time. On the other hand, the experiments showed that 

 there were quite a number of other organisms the devel- 

 opment of which was checked, and in some cases their 

 vitality was completely destroyed, when growing in the 

 same medium with the cholera spirillum. 



1 Zeitschrift fur Hygiene, Bd. x. p. 513. 



2 Ibid., Bd. vi. p. 1. 



