408 M. R. SMIRNOW 



broth media. B. coli no. 3 is markedly changed from its control, 

 which itself appears weaker in its cultural characteristics than 

 controls carried in broth. The changes in the other strains 

 need but little comment. When compared with the glucose 

 action as seen in the previous tables, a similar action may be 

 noted here. 



Too much stress cannot be placed upon so few experiments 

 with proteid-free media, but the writer feels confident that in- 

 hibitory action of other sugars than glucose does occur, and 

 can readily be demonstrated. It may be well in passing, to 

 note that indol production is invariably completely suppressed. 

 Next to indol, the greatest amount of inhibition is manifest upon 

 gas production, then, on lab enzyme and the characteristic 

 growth on potato and finally on acid production. This sequence 

 is not always adhered to, but holds good in a general way. All 

 of these activities seem to correspond very well indeed with 

 the action of glucose in broth media. 



Peckham in a series of experiments along similar lines prefers 

 to regard the changes as not. due to any direct carbohydrate, or 

 chemical effect, but rather to what she terms exhaustion, sheer 

 inability to produce normal biological effects on account of 

 previously expended energy. She describes numerous experi- 

 ments carried out with a number of strains of B. coli, in which 

 she claims that proteolytic activities were suspended when these 

 organisms were grown in fresh peptone sugar broth. The index 

 she took for determining proteolysis was the amount of indol 

 produced by those subjected to carbohydrate as compared to 

 control cultures. She concluded that this suppression of pro- 

 teolytic activities was due to the preference of the B. coli for 

 carbohydrate, a more readily assimilated food, to proteins, 

 with a subsequent exhaustion on the part of the bacteria by the 

 time they reached the protein material. That this "exhaustion 

 of energy" was not due to the amount of lactic acid produced 

 was proven by her in another series of tests in which quantities 

 of lactic acid were added to similar peptone solutions without 

 carbohydrate, and in which indol was produced as in the control 

 cultiu*es. 



