42 LECTURES ON BIOLOGY 



inside a solid block of ice. It was dead at last, but since it 

 seemed befitting to preserve its body in spirit, the piece of ice 

 was placed in a pot on an oven to thaw and forgotten. When 

 at last some one went to take the newt for its final funeral it 

 was trying its hardest to escape from what seemed very much 

 like a Turkish bath. None the worse for being nearly frozen 

 and nearly boiled to death, the little animal lived in the best 

 of health until it died of natural causes. 



I have personally repeatedly observed that fishes, in par- 

 ticular the mud-fishes (Cobitis fossilis) and frogs, may be several 

 times successively frozen and thawed without suffering any fatal 

 injuries, provided that the thawing is done very slowly and 

 carefully. 



It was formerly believed that as soon as the interior of the 

 body of animals had cooled down to zero death was inevitable, 

 but numerous experiments made with various animals by Power, 

 Preyer, Pictet, myself and many .others contradict this belief. 

 Preyer, for instance, slowly froze two frogs, gradually lowering 

 the temperature to 2J C. One frog was then opened, and it 

 was shown that all organs, even heart and blood, were frozen 

 to ice. The frog was then carefully taken into a warm room, 

 when the heart began to beat and drive the blood which had 

 again become liquid through the artieries. (On account of its 

 extraordinary resistance the frog is a favoured object for experi- 

 ments of this kind, for its heart will continue to beat long 

 after the animal is dead, even when it has been removed from 

 the body.) When the second frog, which had been exposed to the 

 same conditions, had been thawed, it revived and did not appear to 

 have in any way suffered. Pictet's recent experiments prove 

 that frogs and snakes are not adversely affected by a tempera- 

 ture of 28 C., and that snails can successfully withstand a 

 temperature of 120 C., even when exposed to it for several 

 days. As at such low temperatures all chemical processes cease, 

 we have here another proof that life has temporarily come 

 to an absolute standstill. 



What we attained by artificial means Nature performs 

 regularly year after year in all countries with a cold climate, 

 for a large number of mammals, such as the bat, hedgehog, 

 badger, hamster, and brown bear, become torpid as soon as the 



