224 moderator: s. hestrin 



the day germinate readily while those collected at night 

 germinate poorly or not at all. 



The mechanism underlying these phenomena deserves further 

 elucidation. 



Halvorson: I have no pet experiment to suggest, but I do 

 want to make a general suggestion, applicable perhaps to all the 

 fields. It is generally agreed that the study of bacterial spores 

 has arrived at a rather ideal technique. The reason for this is, 

 that the investigations were centered for a Ions time on the 

 initial changes rather than on the phase of outgrowth. In doing 

 so only germination triggering was studied. Therefore some 

 similar techniques would have to be found in the other fields 

 before some real progress could be registered. 



(VIII) Purpose of Dormancy 



Moderator: There is one further aspect we can still touch on 

 briefly: the purpose of dormancy. This is of course teleological, 

 but I think this is permissible on the last day of the conference. 

 Do we have dormant stages which are useful as distinct from 

 resistant stages? 



Halvorson Jr. : I would like to quote some work done by 

 Dr. Knight and his colleagues at Wisconsin University on the 

 enzymatic oxidation of sterols. They found that this reaction 

 takes place only in the spore and is absent in vegetative cells. 

 The presence of specific antigens in bacterial spores, of cysteine- 

 rich structures as shown by Vinter, of heat-resistant enzymes and 

 of compounds such as dipicolinic acid, all attest to distinctive 

 features of the dormant state in bacterial endospores. 



Lees: I accept the invitation to become teleological! I have 

 emphasized that the diapause state does not necessarily go hand 

 in hand with resistance to adverse environmental factors such 

 as low temperature and water lack. Diapause should rather be 

 regarded as a timing device which ensures that the actively 

 developing feeding stages appear at a time when these factors 

 are favourable. When this delicate adjustment is upset by 



