70 The Philippme Journal of Science isie 



followed, except that meat extract was used in making the media. 

 The fermentation tubes (bouillon or bile) contained 1 per cent 

 of lactose. No peptone was added to the bile. Plates were 

 counted and production of gas was determined after twenty-four 

 hours' incubation. When the presumptive test for Bacillus coli 

 was positive, 1 cubic centimeter of the medium in the fermenta- 

 tion tube was plated, lactose litmus agar and Endo medium 

 being used for the confirmatory tests. 



Besides these media, which are customarily used to show 

 acid and gas producers, Congo red ^* agar was also tried. This 

 shows the presence of coli-like organisms by a darkening of the 

 medium, the acid produced causing a dark blue or black precipi- 

 tate, which can be more readily seen than the changes of color 

 on lactose litmus agar plates. 



This medium was found at times to give positive results when 

 litmus lactose agar did not show the presence of B. coli, 

 although the fermentation tube and the subsequent attempts to 

 isolate B. coli on litmus lactose agar were positive. Although, 

 as was to be expected, litmus lactose agar plates gave smaller 

 counts at 37°C. than agar at 25°C., Congo red agar at 37°C. 

 gave the highest counts. For the confirmatory tests for B. coli, 

 Endo medium seemed to be more suitable than Congo red or 

 litmus lactose agar. 



In making the presumptive test for B. coli, the bile medium 

 used was found less efficient than lactose bouillon or neutral red 

 lactose bouillon. The fermentation tubes, into which 10 cubic 

 centimeters of the water to be tested were inoculated, contained 

 30 cubic centimeters of the medium. The results of these tests 

 are summarized in Table XIII. 



TESTS MADE AND DISCUSSION OF RESULTS 



Before trying to determine the effect of disinfectants on the 

 swimming-pool waters, preliminary tests were made to get an 

 idea of the biological condition of the pools and of the variations 

 which occur during use. The results obtained showed that the 

 bacterial content of the swimming pools was not excessive. The 

 plates incubated at blood heat showed a lower count than those 

 kept at the temperature of the room (29°C.). The average 

 count for pool I was highest; this pool had been used by the 

 largest number of persons. 



As the tanks were used most extensively in the afternoon, it 



" Liebermann, L., and Acel, J., Deutsche Med. Wochenschr. (1914), 51, 

 2093. 



