PATHOGENIC BACTERIA IN DIFFERENT WATERS 301 



In the following table are recorded more in detail the 

 results obtained by Kraus on introducing cholera bacilli 

 into three different unsterilised waters at Munich : 

 Cholera Bacillus 



(1) Munich water s apply j 



(Mangfall) 30 \ 400 j 70,000 1,400,000 j 2,040 



(2) Well-water, Munich . ! 80 900 ! 85,000 innumerable 8,100 



(3) 250 2,000 100,000 innumerable 4,100 



In connection with the vitality of the cholera 

 bacillus in water, some recent investigations made by 

 Trenkmann 1 are of considerable interest. In these re- 

 searches varying doses of different salts were added to 

 a particular well-water kept at from 21-24 C. ; the 

 cholera bacillus was introduced, and its subsequent 

 behaviour carefully watched by means of plate- cul- 

 tures. In some experiments the water was sterilised, 

 whilst in others it was used in its natural condition, 

 and the competition between the ordinary water bac- 

 teria with the cholera bacilli was noted. 



One, two, or three drops, as the case might be, of a 

 10-per-cent. solution of sodium chloride, sodium nitrite, 

 sodium nitrate, sodium carbonate, disodium phosphate, 

 also potassium chloride, potassium nitrate, sodium sul- 

 phide, were added to 10 c.c. of the water contained in 

 test-tubes. 



These salts were selected as being those which 

 might normally be present in waters of different kinds, 

 although even the lowest proportions in which they 



1 ' Beitrag zur Biologic des Kommabacillus,' Ccntralblatt fur Eak- 

 teriologic, vol. xiii., 1893, p. 313. 



