260 BACTERIOLOGICAL EXAMINATION OF WATER. 



recently been investigated by Houston. Ten c.c. of Crossness 

 sewage were poured into a sterile test tube, and then inoculated 

 with a loopful of a recent agar culture of the cholera vibrio. 

 The tube was kept in the dark at the room temperature, and 

 from time to time a loopful of the contents was transferred to a 

 peptone and salt solution tube. The peptone tube was incu- 

 bated at 37 C., and in less than twenty-four hours a loopful 

 was taken from the surface and a cover-glass preparation made. 

 The results obtained were as follows : Immediately after the 

 inoculation the cholera vibrios were present in great abundance, 

 and almost pure cultures were obtained. On the following day 

 the vibrios were demonstrated with difficulty. On the third 

 and fourth days, however, the vibrios were present in abundance. 

 From this date up to the eleventh day the vibrios were demon- 

 strated with difficulty. On the sixteenth day a few typical 

 vibrios were found, but on the twenty-fifth day many vibrios 

 were isolated which were longer and thicker than the normal 

 microbes. On the forty-second day the vibrios completely 

 disappeared. 



The experiment was repeated, but now a whole agar-slope of 

 the spirillum, instead of one loopful, was added to the sewage. 

 Again, the same difficulty was experienced in isolating the 

 vibrios the day after the inoculation. On the eighth dav they 

 were found without difficulty ; but after the fourteenth day the 

 result was negative. From these experiments it appears that 

 cholera spirilla may lose their vitality in less than a fortnight, 4 

 or remain viable for nearly four weeks, in crude sewage. 



THE RELATION OF CHOLERA VIBRIOS TO OTHER PATHOGENIC AND 

 NON-PATHOGENIC MICRO-ORGANISMS. 



Many experiments have been made on this important subject. 

 Garre grew B. fluorescens putridus on agar, and having removed 

 the growth of this organism planted out Sp. cholerae on the 

 medium. He found that the products of B. fluorescens putridus 

 were only slightly antagonistic to the growth of the cholera 

 microbe. Freudenreich filtered a broth culture of B. pyocyaneus 

 through a Chamberland bougie, and then planted out Sp. 

 cholerae in the filtrate ; the organism, however, refused to grow. 

 He also found that broth, in which the cholera spirillum 



