62 H. O. HALVORSON 



Halvorson: With growth. Growth is reduced. 



Grossowicz: Is the dipicoHnic acid found inside the spore or 

 on its coat? 



Halvorson: I think Dr. Gerhardt of the University of 

 Michigan claimed that it is inside the spore? 



Halvorson, Jr. : Robinowmade very thin sections and noticed 

 that the cortex region between the outer spore wall and the 

 inner membrane had about a third of the volume of the spore. 

 It showed a well defined striated structure which disappeared on 

 germination. It is suggested that the dipicolinic acid lies within 

 this region. Gerhardt showed, however, that dipicolinic acid 

 could be removed from the cell without injuring the cortex. 



Grossowicz: You mentioned a few inhibitors of some 

 energy-yielding reaction inside the spore. Is there any evidence 

 of necessity for protein synthesis in order that sporulation may 

 take place? 



Halvorson: Joan Powell of Porton showed that there were 

 special kinds of peptides when spores germinated, and I have 

 assumed all along that these represent breakdown products of 

 proteins, special proteins presumably. But we have not done 

 any work on this, and I am not sure that the evidence is suffi- 

 cient. 



Grossowicz : What is known about chemical transformations 

 occurring during the ripening or the aging of spores? 



Halvorson: We have mostly speculations. The evidence 

 found in our laboratory shows that L-alanine is found in aged 

 spores, but not in the supernatant of fresh spores. Krask working 

 at Camp Detrick found proteolytic enzymes present in the 

 intact spores. These enzymes seemed to be heat resistant. This 

 would be evidence that something happens during aging and 

 perhaps the same during heat shock. I assume that there is a 

 small breakdown of materials necessary for germination or 

 alteration of the spore walls, so that things can get in more 

 easily. We do know that with aging the germination require- 

 ments become simplified and the need for heat shock is reduced. 



