300 Dr.'Edw^dSy De VIvfluence 



the power of supplying heat at its maximum when first l)orn ; 

 they then part with it by degrees, and, as they advance in 

 age, their heat becomes gradually augmented again till it 

 reaches the adult standard. 



Dr. Edwards next proceeds to discuss the phenomena of 

 animal temperature more exclusively regarding adults, and 

 especially among those singular creatures of the mammiferas 

 wnich form an exception to the general law of nature 

 respecting the uniformity of temperature as to warm-blooded 

 animals. These beings are what are termed hybernants, 

 such as the dormouse^ the hedgehog, the bat, the marmot, 

 &c., natives of Europe, which remain dormant during winter 

 without any external signs of life and motion. The change 

 which these undergo reduces them from the state of warm- 

 blooded animals to that of cold. Unlike the rest of their 

 class, the autumnal season lowers their temperature by de- 

 grees, till in winter it reaches so low as to be scarcely higher 

 than the surrounding air. Their powers fail gradually, and 

 their losses of heat are not repaired, till at length their 

 respirations become slow and feeble, and the heart languidly 

 urges the blood through the arteries. In this state there is 

 an imperfect aerification of the blood, and a partial state 

 of asphyxia, producing continued repose of the nervous and 

 muscular system. But the temperature of these animals 

 sinks no lower than the air, and remains sufticient to main- 

 tain a passive existence, till the returning spring raises their 

 heat again, and they become lively and active till autumn ; 

 but even in spring these animals are characterised by pro- 

 ducing less heat than others of their class. 



If we seek to know the cause of this curious variety,' we 

 can only refer it to peculiarity of constitution, which is insti- 

 tuted by nature as adapted to animals placed in situations 

 of rigorous cold, and where they cannot procure sustenance 

 but in spring and summer. 



Our author imitated the process of hybernation by artifi- 

 cial cold, and produced the same effects; and when he 

 restored animation by gradual warmth, he found the animals 

 as lively as before. 



John Hunter and others have written on the natural his- 

 tory of hybernants, and Dr. Edwards regards only their 

 temperature. The experiments on hybernants by artificial 

 cold prove this fact, that hybernation is attributable to other 

 causes than to the reduction and deprivation of nutriment ; 

 for the animals submitted to the ordeal of cold were well 



