36 L. LEON CAMPBELL, JR. 



which they define as the emergence of the bacillus from the spore case. 

 However, demonstration by Mandels, Levinson, and Hyatt (1956) of the 

 rapid increase in respiratory activity coincident with stainability has re- 

 cently led Levinson and Hyatt (1956) to accept the validity of the latter 

 as a criterion of germination. 



It is interesting to note that nearly all of the investigators who have pro- 

 posed new criteria (or definitions) of germination have always attempted 

 to correlate their techniques with loss in heat resistance of the spore. Thus, 

 for practical purposes, loss in heat resistance has been the standard for com- 

 parison of other methods of studying germination. This is not surprising 

 when one considers that the most outstanding physiological difference be- 

 tween spores and vegetative cells of any one organism is the heat stability 

 of the former in contrast to the heat lability of the latter. Since a spore 

 after loss of heat resistance can no longer be considered as being in the 

 spore state, germination may be defined in terms of loss of heat resistance. 

 Thus, spore germination may be regarded as the change from a heat resist- 

 ant spore to a heat labile entity ivhich may not necessarily be a true vege- 

 tative cell. The excellent correlation of other physiological and morpholog- 

 ical changes with loss in heat resistance makes this definition sound from 

 both the morophological and physiological viewpoint. 



If we accept the definition proposed above for germination, what term 

 should be used to designate the transition of the germinated form to the 

 vegetative cell? In our studies (O'Brien and Campbell, 1956) we have used 

 the term "outgrowth" to designate the stages occurring subsequent to ger- 

 mination. This general term includes the various steps listed by Levinson 

 and Hyatt (1956) as swelling, emergence, elongation, and cell division. 



References 



Church, B. D., H. Halvorson, and H. 0. Halvorson. 1954. Studies on spore 

 germination. Its independence from alanine racemase activity. J. Bact. 

 68: 393-399. 



Cook, R. P. 1932. Bacterial spores. Biol. Revs. 7: 1-23. 



Evans, F. R. and H. R. Curran. 1943. The accelerating effect of sublethal 

 heat on spore germination in mesophilic aerobic bacteria. J. Bact. 46: 

 513-523. 



Fischoeder, F. 1909. Beitrage zur Kenntnis des Milzbrandes. Zentr. Bakt., 

 Abt. I. Orig. 57 : 320-417. 



Fitz-James, P. C. 1954. The duplication of bacterial chromatin. Interpreta' 

 tions of some cytological and chemical studies of the germinating spores 

 of Bacillus cereus and Bacillus megatherium. J. Bact. 68: 464-473. 



Fitz-James, P. C. 1956. The phosphorus fractions of Bacillus cereus and 

 Bacillus megatherium. II. A correlation of the chemical with the cyto- 

 logical changes occurring during spore germination. Can. J. Microbiol. 

 1: 525-548. 



