SIGNIFICANCE OF COLON GROUP IN WATER 161 



colon bacilli, and the greater the amount of sewage 

 in water, the nearer this ratio will be approached. 



Colon Bacilli in Ground- waters. With ground-waters 

 the story is the same. Even in sources of excellent 

 quality we should expect to find, and we do sometimes 

 find, colon bacilli in large volumes of water. Abba, 

 Orlandi, and Rondelli (1899) showed by experiments 

 with B. prodigiosus at Turin that when bacteria are 

 present in great numbers on the surface of the ground, 

 a few may penetrate for a considerable distance and 

 ultimately reach the sources of ground-waters. The 

 chance that disease germs could survive this process in a 

 soil so impervious as to allow colon bacilli to appear 

 only in large samples of water, is infinitesimal. 



An interesting contribution to the bacteriology of 

 ground-waters was made by the Massachusetts State 

 Board of Health (Massachusetts State Board of Health, 

 1901) in connection with the examination of the spring- 

 waters bottled for the sale in the State. Ninety-nine 

 springs were included in this study, and in almost every 

 instance 4 samples were examined, 2 taken directly 

 from the spring by the engineers of the board and 2 

 from the bottles as delivered for sale to the public. In 

 the water of one spring B. coli was found twice, once 

 in a sample from the spring and once in the bottled 

 sample. This spring was situated in woodland, but 

 was unprotected from surface drainage, and the method 

 of filling bottles subjected it to possible contamination. 

 In 5 other cases B. coli was found once in the sample 

 from the spring; all were subject to pollution from 

 dwellings or cultivated fields, and 4 of the 5 were shown 



