CRYPTOBIOTIC STAGES IN BIOLOGY 1 3 



release of these substances is a necessary prerequisite for the 

 activation of the enzymes. They believe that the enzymes are 

 rendered dormant by incorporation into a complex. This 

 complexing not only makes them inactive but also renders them 

 resistant to heat and chemicals. 



In bacterial spores we find a number of phenomena that are 

 common to other dormant systems. Aging simplifies the germi- 

 nation requirements. This is comparable to the after-ripening 

 process that goes on in certain seeds. Many fresh spores require 

 heat shock in addition to the presence of the germination 

 nutrients. Upon aging, the need for heat may disappear. Also, 

 whereas fresh spores may require a number of substances to 

 trigger the germination, after aging, some of the nutrients may be 

 needed in reduced amounts or not at all. We beheve that these 

 changes are due to autolytic enzymes which slowly release 

 substances that can function as germination nutrients. In fact, 

 we, as well as others, have shown that during aging, small 

 amounts of alanine are released from the spore, and that this is 

 one of the key substances needed for germination. 



In the study of bacterial spores, we are making progress 

 toward an understanding of the mechanisms that are involved 

 in conferring dormancy on cells. We are also learning how to 

 break this dormancy. Further advances in this area may help us 

 to better understand the mechanisms involved in dormancy in 

 other areas of biology. 



REFERENCES 



1 D. Keilin, Proc. Roy. Soc. ( London), B, 150 (1958) 150. 



2 W. Preyer, Biol. Zentr., II (1891) 1. 



3 P. Schmidt, SSSR Academy of Science, Moscow, 1948. 



^ H. Proom, Symposium on Freezing and Drying, (R. J. C. Harris, Editor) 



Institute of Biology, London, 1951. 

 5 M. Rhodes, J. Gen. Microbiol., 4 (1950) 450. 



** A. S. Lund, Ann. Kept. Hormel Inst. Univ. Minnesota, 1949-50, p. 47. 

 ' A. S. Lund, Ann. Kept. Hormel Inst. Univ. Minnesota, 1950-51, p. 70. 

 ^ J. A. Ulrich, Ann. Kept. Hormel Inst. Univ. Minnesota, 1947^8, p. 25. 

 9 E. W. Flosdorf and S. Mudd, /. Immunol., 29 (1935) 389. 



