[HARRISON & vanderleck] ANALYSES OF OTTAWA RIVER WATER 



2S 



medium was employed instead of œsculin bile-salt-agar plates. When 

 negative results were obtained vith 50 c.c. of watej" from the flasks we 

 assumed that B. coli had died out. 



On December 23rd, bile salt, peptone and œsculin Avere added ta 

 flask 11 and incubated at 37° C. The contents of the flask were black 

 in 24 hours, and subcultures gave black colonies on œsculin agar plates. 



On March lOtli, 1909, flasks 12 and 15, and on April 15th, 1909, 

 flasks 14 and 16 were treated in the same manner as flask 11. No change 

 oceurred and no black colonies developed on the subcultures. 



Presence of B. Coli in Flasks 11 to 16, Tested with Liquid Aesculin Media 

 WITH AND Without Bile Salt. 



A = without bile salt. B = with bile salt. Figures indicate amount of water 

 tested. + = B. coli. — = B. coli absent. 



These j-esults 'seem to show that B. coli may remain alive in Ottawa 

 River water for a considerable time, for after one hundred and thirty- 

 'five (135) days we isolated the colon bacillus from flask 11, and in all 

 6 flasks it survived for eighty-flve days. 



Our results also show that prolonged life in water weakens this 

 bacillus, for in many of the later experiments it was unable to grow in 

 the presence of bile salt, a substance which does not restrain the growth 

 of vigorous individuals. 



