4 

 4.14 THE POPULAR SCIENCE MONTHLY. 



Such arc the effects on animals of the elevation of temperature. 

 Let us now see what becomes of them when immersed in cold media. 

 Some curious facts with respect to the freezing of certain animals have 

 long been known. During his voyage to Iceland, in 1828 or 1829, 

 Gaimard, having exposed in the open air a box filled with earth in 

 which toads were put, opening it after a certain time, found the rep- 

 tiles frozen, hard and brittle ; but they could be restored to life when 

 put in warm water. Many ancient authors cite similar cases, and we 

 can almost bring ourselves to understand how a great English physi- 

 ologist might for a moment have given them the whimsical interpreta- 

 tion that he did. John Hunter fancied it might be possible to prolong 

 life indefinitely by placing a man in a very cold climate, and there 

 subjecting him to periodical freezing. The man, he said, would per- 

 haps live a thousand years, if, at the end of every ten years, he were 

 frozen for a hundred, then thawed out at the end of the term for ten 

 years more, and so continuously. " Like all inventors," Hunter adds, 

 " I expected to make my fortune by this scheme, but an experiment 

 completely undeceived me." Putting carp into a freezing mixture, he 

 observed, in fact, that, after being entirely frozen, they were dead, 

 past recovery. The case is the same with all other animals, as the 

 late and very remarkable experiments of F. A. Pouchet have proved. 



The influence of cold on organized beings varies, according as we 

 regard superior animals or the inferior species. In general, it may be 

 said that it requires a very low surrounding temperature to chill many 

 animals, because the vital heat they develop resists the process with 

 energy. Yet the mammals of arctic regions, in spite of their thick coat 

 of fur, can only brave the temperature of the pole (sometimes equal to 

 40 (cent.) below zero, the freezing point of mercury) by living under 

 the snow where they make their lair. The Esquimaux, too, dig huts 

 in it, where they pass their wretched days. When the organism can 

 neither react nor protect itself against temperatures so low, death by 

 freezing quickly overtakes it. The body is stiffened, and retains after- 

 ward a state of remarkable incorruptibility. Every one knows the 

 story of the antediluvian mammoths, discovered in the polar ice, where 

 they had been buried, as fresh as animals just dead. While heat 

 destroys the tissues, cold preserves them. 



Through what mechanical means does cold become mortal ? It 

 seems to act on the nervous system. Travellers relate that in polar 

 regions an unconquerable disposition to sleep overcomes men attacked 

 by very low temperatures. On the icy shores of Terra del Fuego, 

 Solander said to his companions, " Whoever sits down falls asleep, 

 and whoever falls asleep never wakes again." This inclination is so 

 overpowering that many of his attendants gave up to it, and he 

 himself sank down for a moment on the snow. It is said that, during 

 the winter of 1700, two thousand soldiers of Charles XII.'s army 

 perished in the sleep to which they surrendered, under the influ- 



