DYSENTERY AND ALLIED BACILLI 



Inoculation was made with 0.1 cc of a 24-hour broth culture with incuba- 

 tion at body temperature. 



H-ion concentration was determined daily for 4 days by withdrawing Ice 

 of the culture into 4 c c of neutral distilled water (Pn 7.0) in a clean, flat 

 bottomed test tube, and after adding the required amount of an appropriate 

 indicator, the color was matched with H-ion standards. Great difficulty was 

 encountered in obtaining neutral distilled water in the laboratory in France. 

 It was found, however, that the error introduced by the neutralization of 

 ordinary distilled water with a small amount of sodium hydroxid was only 

 about 0.1, which was within the limits of error in reading. Such neutralized 

 water had to be freshly prepared and quickly utilized. 



&/JYS. 



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Chart 1. Effects of peptone, dipotassium phosphate and glucose on the rate of acid pro- 

 duction and reversion. 



It was concluded (1) that with 1.0% peptone and 0.4% dipotassium phos- 

 phate, the employment of 0.3% or more glucose was undesirable for the purpose 

 of differentiating B. alkalescens and B. dispar from the true dysentery bacilli ; 

 (2) that in the absence of glucose B. alkalescens and B. dispar form alkali 

 more rapidly than the true dysentery strains (Shiga and B. flexneri) ; (3) that 

 with 0.1% glucose there is reversion among the true dysentery strains, but 

 B. alkalescens and B. dispar revert much more rapidly; (4) that with 0.2% 

 glucose reversion among the true dysentery cultures was greatly inhibited, 

 whereas B. alkalescens and B. dispar showed a marked alkali production after 

 the primary acidity, as is shown in chart 1. 



