SIGNIFICANCE OF COLON GROUP IN WATER 155 



NUMBER OF B. COLI PRESENT IN CERTAIN RIVER 

 WATERS 



(Jordan, 1901) 



These results harmonize rather closely with those 

 pre\iously recorded by Brown and Fuller and indicate 

 that in the larger rivers w^here the proportionate pollu- 

 tion is not extreme, colon bacilli may be isolated in about 

 half the i-c.c. samples examined. Such rivers are of 

 course inadmissible as sources of water-supply, accord- 

 ing to modern sanitary standards, unless subjected to 

 purification of some sort. 



Hunnewell and one of us (Winslow and Hunnewell, 

 1902^) examined a considerable series of normal waters 

 for B. coli, testing i c.c. from each by the dextrose- 

 broth method and a larger portion of 100 c.c. by incuba- 

 tion with phenol broth as described in Chapter VI. 

 The samples were obtained from the public suppHes of 

 Taunton, Boston, Cambridge, Braintree, Brookline, 

 Needham, and Lynn in ^Massachusetts, and Newport, 

 R. L, from the Sudbury River, from the ocean, from 

 the waters of springs bottled for the market, from 

 ponds, pools of rain and melted snow, springs, brooks, 

 shallow wells, and driven wells in various towns near 



