LIFE, ITS PHYSICAL BASIS AND SIMPLEST EXPRESSION 39 



into fine icy powder. But a temperature of —20° C. killccl the 

 fisli. According to L. J. Turner, tlie Alaska nuid-fi.sli (Dallia), 

 was fed frozen to Esquimaux dogs. One of these thawing in 

 tlie stomach of the animal made its escape alive. Frogs lived 

 after being kept at a temperature of —28° C, centii)etles, at 



Fig. 29. — ^The piddock, Zirphosa crisputa, a rock-boring mollusk. "(Natural size, from 



life.) 



a temperature of —50° C, and certain snails endured a temjiera- 

 ture of —120° C. without dying. 



At the other extreme, instances are known of animals living 

 in water (hot springs or water gradually heated with the organ- 

 isms in it) of a temperature as high as 50° C. Experiments with 

 Amoebse show that these simplest animals contract and cease 

 active motion at 35° C, but are not killed until a temperature 

 of 40° to 50° C. is reached. 



Variations in pressure of the atmosphere also constitute 



