146 ELEMENTS OF WATER BACTERIOLOGY 



tions be considered, furnish 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. 



Colon Bacilli on Plants and Plant Products. The 

 work of certain recent observers has suggested the 

 possibility that the colon bacillus may live in a semi- 

 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, i902 a ; 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, 

 cornmeal, oats, barley, etc., while others were in technical 

 use for producing the lactic fermentation. There is 

 no evidence that any of these organisms were of intesti- 

 nal origin, and yet they possess all the characters of typi- 

 cal colon bacilli, even to the pathogenic action when 

 inoculated into guinea pigs. In Germany, Papasotiriu 

 (Papasotiriu, 1901) was meanwhile carrying on almost 

 exactly similar investigations to Prescott's, with identi- 

 cal results. 



Other testimony is somewhat conflicting with regard 

 to the occurrence of B. coli on plants. Klein and 

 Houston (1900) reported the finding of typical colon 

 bacilli in only 3 out of 24 samples of wheat and oats 

 obtained from a wholesale house; rice, flour, and oat- 

 meal bought at two different retail shops gave B. coli 

 in all three cereals in one case and on none in the other. 

 Clark and Gage (1903) were unable to isolate B. coli 



