292 TORPIDITY OF ANIMALS. 



they take some food. It is remarkable, that although the or- 

 dinary cold of the season keeps them in the torpid state, yet 

 exposure to a much lower temperature than that to which they 

 are commonly subjected, rouses them from it. Thus a mar- 

 mot which had remained in its natural lethargic state in an at- 

 mosphere of 45, upon being exposed to one of 16, soon 

 gave signs of returning animation, and in sixteen hours was 

 completely revived ; it shivered with cold, and made attempts 

 to escape. The same has been found true of bats. If this di- 

 minished temperature be continued, the animal is frozen to 

 death. The benevolent object of this singular provision is ob- 

 vious. It prevents the destruction of life which might arise 

 from the occurrence of uncommonly cold weather, or from the 

 accidental exposure of the habitations of torpid animals to the 

 access of cold, by rousing them from their lethargy, and ena- 

 bling them to seek protection from the danger which threatens 

 them. 



' Animals come out of their torpid state diminished in weight, 

 but not with any considerable diminution in strength, or vigor 

 of constitution. They enter immediately with great alacrity 

 upon the business of the season, the collection of food, and 

 preparation for the reception of their young. It is not improb- 

 able that this winter lethargy acts in some measure like sleep, 

 in refreshing and invigorating the system, and may be neces- 

 sary to the constitutions of some animals. 



' It has been frequently supposed, that many birds, as well 

 as quadrupeds, become torpid during the winter ; and instances 

 have been related in particular of swallows which have been 

 found at the bottom of ponds, or rivers, and have revived on 

 exposure to air and warmth. That birds have been sometimes 

 found in a torpid state, is barely possible, but the facts which 

 have come to light are not sufficient to authorize the belief, 

 that any species pass the winter in a torpid state as a substitute 

 for the annual migration, by which they are usually enabled to 

 avoid the extremes of cold. 



' All the reptiles of cold climates become torpid during the 

 winter, and the phenomena they exhibit do not differ essen- 

 tially from those of quadrupeds. Below the temperature of 

 50 they soon fall into a state of lethargy, which continues till 

 spring ; and by exposing them in an ice-house, where the 

 atmosphere remains constantly below that degree of heat, rep- 

 tiles have been kept in a torpid state for three years and a 

 half, and have, at the end of that time, readily revived. No 

 limits can be set to the time during which they might thus be 



