REGULATING FACTORS IN BACTERIAL METABOLISM 



669 



glucose (0.3 per cent and 0.4 per cent, respectively), and varying 

 amounts of phosphate salt, (0.2 per cent, 0.3 per cent and 0.4 

 per cent, respectively). As nearly as possible the methods of 

 preparation of media, inoculation, incubation, etc., were kept 

 uniform. Tests were made on the first, third, and fourth days, 

 respectively, with the results given in table IV. 



TABLE IV 

 Effect of different concentrations of acid phosphate on the utilization of glucose by 



bacteria 



To avoid the confusion that might result from unnecessary 

 detail only the four-day tests are tabulated. The effect of the 

 phosphate is strikingly shown in both the A and B section 

 of the Table. The significant results are italicized. The low 

 figures represent high hydrogen ion concentrations — or the acid 

 phase — while the high figures represent low hydrogen ion con- 

 centrations or the alkaline phase. The progressive change pro- 

 duced in carbohydrate media by members of the colon-typhoid 

 group, excepting certain types, is from the alkaline to acid and 

 back. So long as there remains unutilized carbohydrate the 

 acid phase persists. With the complete consumption of the 



