50 



H. O. HALVORSON 



succinate, diethyl L-glutamate, ethyl formate, and ethyl pro- 

 pionate did not. 



Fig. 8 shows the effect produced by ethyl malonate. It is 

 obvious from this that ethyl malonate behaves differently than 

 a-picolinic acid. This inhibitor prevents sporulation whether it 

 is added before the pH begins to rise or afterwards. This 

 inhibitor, therefore, probably does not interfere with the forma- 

 tion but instead interferes with the function of some essential 

 enzyme. With this inhibitor the pH rises for a while as if the 

 culture were normal but finally falls to the low level produced 

 with a-picolinic acid. We know from other carefully controlled 

 experiments that the interference with sporulation in this case 

 is not due to a drop in the pH but rather to a specific effect of 

 ethyl malonate. 



Fig, 9 shows the effect produced with diethyl succinate as an 



8 



pH 







8 



12 16 



Time in hours 



Fig. 9. The effect of diethyl succinate (2 : 10"- M) on the pH and sporu- 

 lation of B. cereus T. 



inhibitor. Here again, the inhibition occurs whether the inhibitor 

 is added before or after the pH begins to rise. Here also, as in the 

 case of the ethyl malonate, the pH rises for a while and then 

 drops. Fig. 10 shows the effect produced with ethyl pyruvate. 

 Here also, the inhibitor functions whether it is added before or 

 after the pH begins to rise, indicating that this inhibitor, as well 



