VARIATIONS IN TYPHOID BACILLI 285 



inoculation, but not sufficient to account for the inhibition of 

 growth of typhoid bacilli. We do not know what substance 

 caused this inhibitory action. 



In the second series 60 strains and in the third series 21 strains 

 were inoculated; all tubes became alkaline on the second day 

 and showed no fermentation after thirty days' incubation. Of 

 course both sets of media showed a neutral reaction before 

 inoculation. Subcultures from a few of these raffinose broth 

 cultures in raffinose broth again failed to produce fermentation. 



Rhamnose 



Rhamnose broth 



One per cent rhamnose meat infusion broth, with china blue 

 and phenol red as indicators was used for this experiment. One 

 set of tubes was inoculated with 144 strains of tj^Dhoid, and 

 another with 19 strains. Both produced alkalinity after twenty- 

 four to forty-eight hours' incubation. 



Salicin 



Salicin broth 



One per cent salicin meat infusion broth, containing china 

 blue and phenol red indicator, was used. Two series of experi- 

 ments, with 144 strains and with 21 strains were carried out, 

 but no fermentation resulted during thirty days' incubation. 



Xylose 



We used for the most part 1 per cent xylose meat infusion 

 broth, with china blue and phenol red indicator. During the 

 course of this study we carried on many fermentation experi- 

 ments, in which we found 8 per cent of 126 strains to be xylose 

 non-fermenters, while the remaining strains all fermented xylose 

 in twenty-four hours. Apparently these 10 negative strains, 

 and in addition 12 strains brought from France by Lieutenant 

 Colwell were found to be slow xylose fermenters. On carrying 



