CRYPTOBIOTIC STAGES IN BIOLOGY 



H. ORIN HALVORSON 



School of Life Sciences, University of Illinois, Urbana, III. (U.S.A.) 



The term cryptobiosis was first introduced by Keilin^ in his 

 Leeuwenhoek Lecture given at the University of Cambridge. 

 He intended this term to include all forms of latent life, such as 

 the anabiosis suggested by Preyer- and the abiosis introduced 

 by Schmidt-*^. In his discussion of this pseudo-lifelessness, he 

 treated the dormant state as though it were synonymous with 

 cryptobiosis; but in his classification of the related terms he 

 differentiated between them regarding the dormant state as 

 encompassing hibernation, diapause, and quiescence, states 

 where there is no growth but some metabohc activity. It would 

 appear to me that, in many areas of biology, the term dormancy 

 has been used to denote latent life, a state that shows metabolic 

 activity only when a suitable environment arises. I can agree 

 with Keilin that hibernation is not the same as cryptobiosis, in 

 that in the former there is a positive metabolism even though it 

 may be reduced to a low level, whereas in the latter no positive 

 metabolism is perceptible. In this discussion, however, I shall 

 use the term dormancy as it has been used in the past — by 

 bacteriologists to describe bacterial spores and by zoologists to 

 describe protozoan cysts. In these cases it is really analogous to 

 cryptobiosis. As indicated in Keilin's outline, among various 

 forms that exhibit reduced metabolism to a marked degree, 

 there is no sharp dividing line between a state of 'hypometabo- 

 lism' and 'ametabolism'. In dealing with the state of cryptobiosis. 

 therefore, one must necessarily refer to some of the borderline 

 cases. 



A state of cryptobiosis is certainly not limited to any single 

 area of biology. One can find good examples among plants, 

 animals and micro-organisms. Among these, one needs to 

 mention: the seeds of plants; plant buds; the dehydrated forms 

 of all kinds of micro-organisms, such as protozoa; bacteria, 



References p. 13 



