TORPIDITY. 63 



attend to those other causes which are concerned ui the pro- 

 duction of torpidity. 



From the consideration, that this state of torpidity com- 

 mences with the cold of winter, and terminates with the 

 heat of spring, naturahsts, in general, have been disposed 

 to consider a reduced temperature as one of the principal 

 causes of this lethargy. Nor are circumstances wanting to 

 give ample support to the conclusion. 



When the temperature of the atmosphere is reduced, as 

 we have already seen, below 50°, and towards the freezing 

 point, these animals occupy their torpid position, and by 

 degrees relapse into their winter slumbers. When in this 

 situation, an increase of temperature, (the action of the sun, 

 or a fire), rouses them to their former activity. This expe- 

 riment may be repeated several times, and with the same 

 result, and demonstrates the great share which a diminish- 

 ed temperature has in the production of torpidity. If mar- 

 mots are frequently disturbed in this manner during their 

 lethargy, they die violently agitated, and a htemorrhage 

 takes place from the mouth and nostrils. 



The circumstance of torpid animals being chiefly found 

 in the colder regions, is another proof that a diminished 

 temperature promotes torpidity, And, in confirmation of 

 this, Dr Barton states, that, in the United States of 

 America, many species of animals which become torpid in 

 Pennsylvania, and other more northern parts of the coun- 

 try, do not become torpid in the Carolinas, and other 

 southern parts of the continent. 



But while a certain degree of cold is productive of this 

 lethargy, a greater reduction of temperature produces revi- 

 viscence, as speedily as an increase of heat. Mangili placed 

 a torpid marmot, which had been kept in a temperature 

 of 45°, in a jar surrounded with ice and muriate of lime, so 

 that the thermometer sunk to 16°. In about half an hour 



