332 BACTERIOLOGY. 



while the longer the milk retains its neutral or only 

 very slightly acid reaction, the longer do the cholera 

 organisms that may be present in it retain their power 

 of multiplication. 



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. 



In regard to the antagonism between the cholera 

 spirillum and other organisms with which it may come 

 in contact, the experiments of Kitasato^ 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 experi- 

 ments showed that there were quite a number of other 

 organisms the development of which was checked, and 

 in some cases their vitality was completely destroyed, 

 when growing in the same medium with the cholera 

 spirillum. 



From this it would appear that the disappearance 

 of the cholera spirillum from mixed cultures and from 

 the evacuations in so short a time as has been men- 

 tioned, is due more to unfavorable nutritive condi- 

 tions 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 



1 Zeitschrift fUr Hygiene, Bd. x. p. 513. 1 1bid., Bd. Ti. p. 1. 



