TOKPIDITY. 53 



the surrounding medium, in whatever circumstances they 

 are placed. Even in this torpid state, the energies of hfe, 

 though feeble, are still sufficient to the production of a cer- 

 tain quantity of heat. 



2. Diminished Respiration. — In this, as in all the other 

 departments of this curious subject, accurate and varied 

 experiments are still wanting. The following are the prin- 

 cipal facts which we have been able to collect. 



The hedgehog, according to Professor Mangilt, who 

 has bestowed more attention on this part of the subject 

 than any of his predecessors, respires only from five to seven 

 times in a minute during ordinary repose. When it be- 

 comes torpid, the process of respiration is periodically sus- 

 pended and renewed. Thus a hedgehog, procured after it 

 had revived naturally from its winter lethargy in April, was 

 placed in a chamber the temperature of which was about 54*. 

 It refused vegetable food, and became torpid, and continued 

 in that state to the 10th of May. At first, after every 

 fifteen minutes of absolute repose, it gave from thirty to 

 thirty-five consecutive signs of languid respiration. In the 

 beginning of May, when the thermometer was about 62", 

 it gave from seven to ten consecutive respirations, after an 

 interval of ten minutes of absolute repose. Upon lowering 

 the temperature, the intervals of repose became greater, 

 while the number of respirations increased to eighteen or 

 twenty. 



Marmots, according to the same author, when in health 

 and activity, perform about five hundred respirations in an 

 hour, but when in a torpid state, the number is reduced to 

 fourteen, and these at intervals of four minutes, or four 

 minutes and a half, of absolute repose. 



Bats, when kept in a chamber from 45" to 50", were ob- 

 served at the end of every two, three, or four minutes of 



