TORPIDITY OP ANIMALS. 291 



themselves in their subterranean retreats, and when they first 

 feel the approach of the torpid state, shut the passages to their 

 habitations, in such a manner, that it is more easy to dig up 

 the earth any where else than in the parts they have thus forti- 

 fied. At the time of becoming torpid, animals are generally 

 very fat ; this fat, during the winter, is absorbed for the purpose 

 of nutrition, and they become quite lean. 



' During the torpid state, the temperature becomes very 

 much diminished. The natural heat of these animals is gene- 

 rally a little above that of man; but during torpidity it de- 

 scends to 30 or 40 of Fahrenheit, as has been ascertained 

 by accurate observation, but still generally continues above 

 that of the surrounding atmosphere. The quantity of respi- 

 ration is also very much lessened. The animal has long in- 

 tervals of complete repose, during which it does not breathe 

 at all, and then performs a number of respirations in imme- 

 diate succession. Sometimes this function is for a considera- 

 ble time entirely suspended, and the degree in which it is di- 

 minished, is in proportion to the more or less complete state 

 of torpidity of the animal. 



* Connected with this diminution of temperature and respi- 

 ration, there is a corresponding diminution in the force and 

 rapidity of the circulation. The heart beats -feebly and with 

 less force. In the hamster, whose pulse, in its active state, 

 amounts to 150 in a minute, it is, when the animal is torpid, 

 reduced to only 15 in the same period. The pulsations of 

 the heart in dormice, under common circumstances, from their 

 great frequency, can scarcely be counted ; but as soon as they 

 begin to pass into the torpid state, the pulse is reduced grad- 

 ually to thirty, twenty, and sixteen, and becomes finally im- 

 perceptible from feebleness. Whilst this lethargy continues, 

 these animals remain entirely insensible to external objects. 

 They do not feel, when wounded or deprived of their limbs ; 

 they are not roused by the electric spark. The functions of 

 the digestive organs cease, and they are not only without the 

 appetite for food, but without the power of digesting it. Th 

 stomach and bowels are found empty and collapsed. There 

 seems to be only just so much of vital action going on in the 

 system, as is sufficient to keep the spark of life from becoming 

 entirely extinguished. 



* Torpidity is brought on by the first cold weather in the 

 autumn, and is probably principally produced by cold. Tor- 

 pid animals, however, sometimes revive a little, during the 

 warm days which occur during the winter ; and in this case 



