CLIMATE AND HYBERNATION 



103 



the coldest 46°. The lowest point to which the thermometer 

 fell was 41^.5, and occasionally in the middle of the day it 

 rose to 69'' or 70^. Yet with this high temperature almost 

 every beetle, several genera of spiders, snails, and land-shells, 

 toads and lizards, were all lying torpid beneath stones. But 

 we have seen that at Bahia Blanca, which is four degrees south- 

 ward, and therefore with a climate only a very little colder, 



SKINXIXG UJI OR WATER SERPENTS. 



this same temperature, with a rather less extreme heat, was 

 sufficient to awake all orders of animated beings. This shows 

 how nicely the stimulus required to arouse hybernating animals 

 is governed by the usual climate of the district, and not by the 

 absolute heat. It is well known that within the tropics the 

 hybernation, or more properly aestivation, of animals is deter- 

 mined not by the temperature, but by the times of drought. 

 Near Rio de Janeiro, I was at first surprised to observe that, 

 a few days after some little depressions had been filled with 

 water, they were peopled by numerous full-grown shells and 

 beetles, which must have been lying dormant. Humboldt has 

 related the strange accident of a hovel having been erected 

 over a spot where a young crocodile lay buried in the hardened 



