VARIATIONS IN TYPHOID BACILLI 



295 



by cultivation at various degrees of temperature, by long cultivation, 

 by the addition of chemical substances, or by passing through the ani- 

 mal body. Saisawa (1913) tried in the same way to separate daughter 

 colonies and mother colonies on plating typhoid bacilli but in vain. 



It seemed to us that similar studies made with typhoid bacilli 

 in regard to the separation of rapid and slow xylose fermenters 

 from a single original strain might prove of great interest. Ac- 

 cordingly we made subcultures of two xylose slow fermenters 

 two or three times on plain plates, each time fishing a single 

 colony and planting from the single colony in 1 per cent pepton 

 water. Then from the last suspension of a single colony we 

 plated on 1 per cent xylose plates containing china blue or 

 methylene blue-eosin. At the same time, a loopful of suspension 

 was inoculated to 1 per cent xylose broth containing china blue 

 indicator as a control. Repeated subcultures were made by 

 this method in the hope that after some generations we might 

 get a strain of non-xylose fermenters. We did not obtain such 

 results, however. Charts of the subcultures obtained from the 

 two strains follow : 



Strain 57 



This strain was always plated on 1 per cent xylose containing 

 methylene blue and eosin. 



O — Original 



• = quick xylose fermenter in twenty-four hours. 

 O = slow fermenter. 



JOURNAL OP BACTEHIOLOQT, VOL. VI, NO. 3 



