58 



H. O. HALVORSON 



TABLE XII 



EFFECT OF DPA ON THE PRODUCTION OF HEAT SENSITIVE SPORES BY ETHYL 



OXAMATE OR DIETHYL PIMELATE 



Both of these inhibitors can be reversed by dipicolinic acid 

 added from the outside. The results are shown in Table XTL It 

 can be observed from this that reversal can be obtained with 

 dipicolinic acid when added from the outside, as much as seven 

 to nine hours later. In the presence of DPA, the spores produced 

 are heat resistant. A similar experiment cannot be made with 

 diethyl pimelate because this substance cannot be added to the 

 cultures at the beginning. But, if this is added to the culture at 

 seven hours, we find that most of the spores are heat sensitive; 

 whereas if we add dipicolinic acid at the same time, all of the 

 spores are heat resistant. 



To summarize our data, it indicates that the glyoxylic acid 

 shunt is involved in the synthesis of spore material and dipico- 

 linic acid. Some of the enzymes that are needed in this shunt 

 appear not to be present in vegetative cells but are produced as 

 adaptive enzymes after the sugar has been used up. Succinic 

 acid appears to be important as an intermediate in the synthesis 

 of the spore material, and perhaps also in the synthesis of 

 dipicolinic acid. The synthesis of spore material and the produc- 

 tion of a spore-like structure can occur, independent of the 



