VARIATIONS IN TYPHOID BACILLI 283 



Dulcitol 



We could not obtain uniform fermentation results with this 

 sugar, despite many attempts. Some strains gave rise to acid 

 at one time and failed to do so at others. On the other hand 

 certain strains gave rise to alkalinity at the first test and in later 

 tests gave an acid reaction. Usually they produced acid in 

 from one to three weeks. 



Number of 

 strains 



First series. Meat infusion broth (litmus) 115 



Second series. Meat infusion broth (litmus) 57 



Third series. Nutrose broth (phenol red, china blue) 21 



Fourth series. Meat infusion broth (phenol red, china blue) 29 



Fifth series. Meat infusion broth (phenol red, china blue) 139 



The results were as below: 



Positive on the fourth day 1 



Positive on the sixth day 26 



Positive on the seventh day 15 



Positive on the ninth day 31 



Positive on the tenth day 2 



Positive on the eleventh day 7 



Positive on the twelfth day 11 



Positive on the thirteenth day 9 



Positive on the fourteenth day 11 



Positive on the fifteenth day 11 



Positive on the sixteenth day 3 



Positive on the seventeenth day 3 



Positive on the nineteenth day 1 



Positive on the twenty-third day 12 



Positive on the twenty-sixth day 3 



Positive on the thirtieth day 9 



Positive on the thirty-first day 1 



Total positive on or before the thirty-first day 186 



Negative on thirty-first day 175 



The proportion of positives is 51.51 per cent against 48.49 per cent of negatives. 



In all of these tests there was a greater tendency for the indi- 

 cators (litmus, or china blue-phenol red) to become reduced than 

 was evident in arabinose or xylose broth cultures. For this 

 reason it is possible that the percentage of positives may be too 

 low, as all tubes showing reduction were recorded as negative. 



