THE REPOSE OF NATURE. 207 



marked a temperature of thirty-six degrees, one whose 

 bulb was within the stomach only marked thirty-nine. 

 A similar phenomenon was observed by Dr. Jenner with 

 a hedgehog, when the internal temperature was a little 

 over three degrees above that of the air. 



The reader must bear in mind that experiments of 

 this nature require the very greatest care, for the hiber- 

 nating state is of so delicate a nature, and so easily 

 disturbed, that a heedless footstep on the floor will 

 awaken the creature, set it breathing, and increase the 

 temperature some twenty degrees in a minute or two. 



During the true hibernation the breath is almost 

 entirely suspended. Bats while sleeping have been 

 gently immersed in water kept carefully at the same 

 temperature as their bodies, have been sunk below the 

 surface for a space of sixteen minutes, and found to be 

 none the worse for their bath. A hedgehog has been 

 subjected to the same test for more than twenty minutes, 

 and although it moved slightly under water, and expelled 

 a little air from his lungs, it was not at all injured by 

 the experiment. 



Hibernating animals have also been placed in car- 

 bonic acid gas for a space of several hours, without suf- 

 fering from its effects, while rats and sparrows placed in 

 the same gas fell lifeless to the bottom of the vessel and 

 did not recover. 



In order to ascertain with accuracy the rate of re- 

 spiration and pulsation during this curious state, a hiber- 

 nating bat was placed in an ingenious instrument which 



