BACTERIAL SFORK GERMINATION 43 



onset of the first visible germination changes and the emergence of new 

 vegetative bacilli from ruptured spore cases ought not to be subdivided into 

 at least two periods with different sensitivity to damaging influences. 



The other matter concerns the advisability or otherwise of dating germi- 

 nation of any kind of spore, the conidia of molds, for example, or those of 

 bacteria, from (a) the moment of rupture of the spore case, or (b) from the 

 completion of the first cell division. Concerning (a) one wants to remind 

 oneself that vegetative spores such as the conidia of Penicillium or other 

 imperfect fungi germinate directly without rupture of their wall. There is 

 continuity here between the spore wall and the wall of the outgrowing hypha. 

 It is different with ascosphores of Penicillium and with the endospores of 

 bacteria. Here a new cell wall forms beneath the spore coat. On germina- 

 tion the coat bursts open and is later discarded by the growing organism. 

 As to cell division (b) it must be pointed out that what in life appears as 

 a single bacillus emerging from a spore case is, at least in B. megatherium 

 and B. subtilis, often already fully divided into two cells with two, if not 

 four, nuclear equivalents. The transverse septum separating the two cells is 

 readily seen after suitable staining but not easily during life. 



Mandels: I would like to comment briefly on that. It seems to me that 

 biologically the significant point of germination is a transition from a state 

 of low metabolism to one of high. It seems to me that the germination of a 

 bacterial spore should be considered to be those changes that occur along 

 with this initial loss of heat resistance that occurs very rapidly along with 

 an increase in respiratory activity. The fundamental thing seems to me 

 to be this increase in metabolic activity. This is followed by swelling and 

 rupture of the spore coat. 



SussMAN: It seems to me that these experiments point to one of the de- 

 ficiencies in the use of loss of heat stability as a criterion of germination. 

 I should like to recount just briefly a few experiments with Neurospora. If 

 one takes spores of this organism and treats them with a variety of poisons, 

 one finds that none of these materials penetrate the intact spore as measured 

 by techniques like manometry. Although these materials are removed from 

 solution, they penetrate only at the time when a visible protrusion appears, 

 signalizing the start of germination. With reference to the work that Dr. 

 Halvorson's group is doing, Neurospora ascospores can be activated by heat, 

 but if exposed to anaerobic conditions for an hour, the respiratory stimula- 

 tion is lost and the rate diminishes to that of the dormant cell. The point is 

 that although you get some of the types of metabolic stimulation that seem 

 to bfe associated with the whole germination process, it can only go so far 

 and no further. This means to me that the whole of the germination process 

 has not really been accomplished and that there is only "partial" germination 



