322 



L. A. ROGERS 



THE EXAMINATION OF INDIVIDUAL SAMPLES OF SURFACE WATER 



In the course of this work about 30 samples of water from a 

 great variety of sources have been examined. These have 

 included samples from grossly polluted streams such as Rock 

 Creek and the Anacostia river and from springs in the Maine 

 woods in which the chance of pollution was remote. With a 

 few exceptions bacteria of the colon-aerogenes type were isolated 

 from these samples without difficulty. The exceptions were a 

 Maine lake without pollution except from a few camps on the 

 shores, a small stream flowing into this lake and which at no 

 point was near a habitation or a highway, a spring flowing out 



TABLE 5 

 Comparison of cultures from grain, water and feces 



of the gravel on the shore of the lake and a well protected spring 

 in Rock Creek Park, Washington. In all other cases at least 

 2 or 3 colon cultures were obtained by direct plating. 



A total of 134 cultures were isolated from these samples. In 

 table 5 the characters of these cultures as a group are compared 

 with those from grains and from human feces. There will be 

 noticed a general tendency for the water cultures to agree with 

 those of fecal origin rather than with those isolated from grains. 



In making this comparison it should be remembered that the 

 grain cultures included some which were very probably of fecal 

 origin while the water cultures included some evidently not of 

 fecal origin. The 12 per cent of the B. aerogenes cultures from 



