1 1 8 Elements of Water Bacteriology. 



that head all bacilli of medium size, which formed grape- 

 vine-leaf colonies on gelatin and gas in sugar agar, which 

 were more or less motile, or rarely non-motile, and which 

 were decolorized by the Gram method. As regards 

 coagulation of milk and formation of indol, " the bacteria 

 isolated differed." In the second place it is difficult to see 

 how the author could possibly have believed that his 

 experiments proved the isolation of the colon bacillus to be 

 " useless as an aid in the sanitary examination of water," 

 as the title of the paper runs. Even his own work fur- 

 nishes strong evidence to the contrary. In 24 of the 26 

 samples from bad sources, he isolated his imperfectly 

 defined colon bacilli from i c.c. of the water, while in 

 only 8 of the 30 samples of good waters could he find such 

 organisms in that quantity. 



The work of certain recent observers has suggested 

 the possibility that the colon bacillus may live in a sen;i- 

 parasitic fashion on plants as well as on animals. Of 

 a series of 47 cultures of lactic-acid bacteria, recently 

 examined by one of ourselves (Prescott, 1902*; Prescott, 

 1903; Prescott, 1906), 25 were found to give the reactions 

 of B. coli. These organisms were isolated chiefly from 

 cereals and products of milling, such as flour, bran, corn- 

 meal, oats, barley, etc., while others were in technical use 

 for producing the lactic fermentation. There is no evi- 

 dence that any of these organisms were of intestinal origin, 

 and yet they possessed all the characters of typical colon 

 bacilli, even to the pathogenic action when inoculated 



