7 8 ELEMENTS OF WATER BACTERIOLOGY. 



less conservative conclusions. Abba (Abba, 1895) found 

 colon bacilli constantly present in certain unpolluted 

 waters near Turin. Moroni (Moroni, 1898; Moroni, 



1899) reported the examination of numerous deep and 

 shallow wells and unpolluted springs about Parma, as 

 well as of the public water-supply of the city, for the colon 

 bacillus and concluded that that organism was a water form 

 and had no sanitary significance. The characters used 

 for the identification of the species in this case were fairly 

 exhaustive, but both Abba and Moroni used liter samples 

 for analysis. 



Levy and Bruns (Levy and Bruns, 1899) gave a new 

 turn to the discussion by emphasizing the importance of 

 animal inoculation, already suggested by Blachstein (Blach- 

 stein, 1893) and others. They claimed that the existence of 

 numerous para-colon and para-typhoid organisms in air, in 

 dust, and in unpolluted water made it impossible to decide 

 by ordinary bacteriological methods whether true colon 

 bacilli were present in water or not. In no case, how- 

 ever, did representatives of the colon group isolated by 

 them from water kill a guinea-pig, even when i or 2 c.c. 

 were injected intraperitoneally; and the authors, there- 

 fore, considered pathogenicity as an attribute belonging 

 only to the true B. coli of the intestine. This paper 

 aroused Professor Kruse's pupil, Weissenfeld, to a pub- 

 lication, in which the position of the Bonn school was 

 carried to an extreme. Weissenfeld reported (Weissenfeld, 



1900) the analysis of 30 samples of water supposedly pure, 

 and of 26 samples considered to be contaminated. In 



