140 Elements of Water Bacteriology. 



the amount of pollution, the authors above quoted have 

 proved beyond reasonable cavil. It may safely be said 

 that when the colon bacillus, as denned by the tests above, 

 is found in such abundance as to be isolated in a large 

 proportion of cases from i c.c. of water, it is reasonable 

 proof of the presence of serious pollution. 



