CHOLERA: GENERAL CONSIDERATIONS. 329 



for but twenty-seven hours ; and in the undiluted con- 

 tents of cesspools it is impossible to demonstrate them 

 after twelve hours. In the experiments of Nicati and 

 Eiietsch they retained their vitality in sterilized distilled 

 water for twenty days ; in Marseilles canal-water (sew- 

 age), for thirty-eight days ; in sea-water, sixty-four 

 days; in harbor-water, eighty-one days, and in bilge- 

 water, thirty-two days. 



In the experiments of Hochstetter, on the other 

 hand, they died in distilled water in less than twenty- 

 four hours in five of seven experiments ; in one of the 

 two remaining experiments they were alive after a day, 

 and in the other after seven days. 



In one experiment with the domestic water supply ot 

 Berlin the organism retained its vitality for 267 days ; 

 in another for 382 days, notwithstanding the fact that 

 many other organisms were present at the same time. 

 There is no single ground upon which these variations 

 can be explained, for they depend apparently upon a 

 number of factors which may act singly or together. 

 For example, in general it may be said that the higher 

 the temperature of the water in which these organisms 

 are present, up to 20° C, the longer do they retain their 

 vitality; the purer the water, that is, the poorer in 

 organic matters, the more quickly do the organisms die, 

 whereas the richer it is in organic matter the longer do 

 they retain their vitality. 



Still another point that must be considered "in this 

 connection is the antagonistic influences under which 

 they find themselves when placed in water con- 

 taining large numbers of organisms that are, so to 

 speak, at home in water — the so-called normal water 

 bacteria. 



