1 6 Elements of Water Bacteriology. 



Certain bacteriologists have held that the toxic waste 

 products of the bacteria themselves may render water 

 unfit for their own development. Horrocks (Horrocks, 

 1901), Garr^ (Garre, 1887), Zagari (Zagari, 1887), and 

 Freudenreich (Freudenreich, 1888) have shown that an 

 "antagonism" exists when bacteria are grown in artificial 

 culture media such that the substratum which has 

 supported the growth of one form may be rendered anti- 

 septic to another. Frost (1904) has exhaustively studied 

 the phenomenon of antagonism by exposing typhoid 

 bacilli in collodion sacs to the action of certain soil and 

 water bacteria growing in broth. Artificial culture 

 media, however, offer conditions for bacterial development 

 which are scarcely paralleled in natural waters. It is 

 difficult to believe that under ordinary conditions poisons 

 are produced of such power as to render a stream or 

 lake specifically toxic for any particular type of bacteria. 

 It appears indeed from the experiments of Jordan, 

 Russell and Zeit (1904), and Russell and Fuller (1906), 

 which will shortly be referred to more fully, that the life 

 of typhoid germs is shorter in water containing large 

 numbers of other bacteria than in that of greater 

 purity. Horrocks (1899), too, found freshly isolated 

 typhoid bacilli alive in sterile sewage after sixty days; 

 while they disappeared in five days when B. coli was 

 also present. These phenomena may be due, however, 

 to a struggle for oxygen, or for food, rather than to the 

 assumed presence of highly toxic bacterial products of 

 which there is no independent evidence. 



