CRYPTOBIOTIC STAGES IN BIOLOGY 1 1 



from a low to a high value before they can be made to hatch^o. 

 Hence, there are certain species of mosquitoes that may lay 

 their eggs in the spring or summer, but the eggs will not hatch 

 until they have been stored over the winter and then brought to 

 the proper temperature in the spring-^. To the best of my 

 knowledge, the biochemical changes that are involved are not 

 known. 



In addition to the dormancy that is exhibited with these eggs 

 of insects, it is also possible to get dormant forms in almost any 

 of the developmental stages of the insects. These can be pre- 

 served in a seemingly dormant state by a proper lowering of 

 temperature. Many insects, therefore, will survive the frozen 

 state. In general, however, there is a limit to how low the 

 temperature can be brought. According to Prosser'^"^, at the 

 University of Illinois, the temperature can be lowered until 

 about 70% of the body water is frozen; below that, the organism 

 dies. Depending upon the species, the temperature may be 

 brought considerably, below the freezing point of water before 

 a lethal temperature is reached. It is presumed that a consider- 

 able amount of organic material is dissolved in the remaining 

 water, so as to effectively lower the freezing point. In other 

 words, the organisms have a built-in antifreeze system. At these 

 low temperatures, the metabolism is reduced almost to, if not to, 

 zero, so that these also may be regarded as being in a state of 

 cryptobiosis. 



SPORES 



Among the bacteria, the spores are the best examples of a 

 cryptobiotic state, although vegetative cells, as indicated above, 

 can be brought into such a state through drying or freezing. 



The spores that are produced by some species of aerobes and 

 anaerobes are the most resistant dormant cells known. Freshly 

 produced and properly separated from their growth medium, 

 they are truly inert and perhaps the best examples of a crypto- 

 biotic state that can be found. Many studies have been made on 

 the respiratory activity of such cells, but the data are conflicting. 



References p. 13 



