THE SIGNIFICANCE OF B. COLI IN WATER. 77 



nople, but the only characters which these "colon bacilli" 

 exhibited in common were the "classical growth" upon 

 potato, the possession of less than 8 cilia, and the power 

 of active development on certain media upon which the 

 typhoid -bacillus did not grow. A more careful and sig- 

 nificant piece of work on the same line was published by 

 Poujol in the succeeding year. This author reported 

 (Poujol, 1897) the isolation of B. coli from 22 out of 34 

 waters studied by him in relation to their use as public 

 supplies. The waters were from various sources — springs, 

 wells, and rivers — but all were of fair quality and many 

 quite free from any possibility of contamination. Samples 

 of 100 c.c. were used for analysis; in the only case in which 

 a smaller amount was also tested, broth inoculated with 

 10 drops of the water and placed at 45 C. remained 

 sterile. The author concluded that " fecal contamination 

 can only exceptionally be invoked to explain the presence 

 of B. coli in water. As the bacteria of the subterranean 

 water are contributed to it from the surface of the earth 

 by the water which filters downward, I am rather inclined 

 to believe in a general diffusion of B. coli either on the 

 surface of the earth, where it might be deposited with 

 the dust of the air, or in the superficial layers of the earth, 

 which may form one of its normal habitats." Therefore, 

 the author considered that caution should be exercised 

 in condemning a water on account of the presence of B. 

 coli, except, as he added, "for those cases where it exists 

 in considerable quantity." 



Certain Italian observers appear to have come to even 



