85 



so in summer, when intense cold and frosty nights 

 occasionally prevail, is a sufficient refutation that cold 

 alone cannot be the exclusive agent. " We may say, 

 and truly, that the sensation of fatigue causes man to 

 lie down and sleep ; hut we should laugh at any one 

 who contended that this sensation forced him first to 

 make a four-post bedstead to repose upon."* 



" A continuance of life," says Dr. Reeve, " under 

 the appearance of death, a loss of sensibility and of 

 voluntary motion, or suspension of those functions 

 most essential to the preservation of the animal eco- 

 nomy these are the phenomena which accompany 

 the torpid state, and they constitute one of the most 

 singular problems in the whole range of natural philo- 

 sophy." f When we contemplate animals shut up in 

 their subterrene abodes during the brumal period of 

 the year, we shall find that, in those which become 

 torpid, the temperature of the skin is reduced to a 

 low ebb, the circulation of the blood is entirely sus- 

 pended, and respiration at an end ; the torpid animal 

 has contracted its limbs into the form of a ball, and 

 is generally rolled up in some substance dry and non- 

 ducting as to temperature : such nests are formed 

 of dried leaves, grass, and the like. The dormouse 

 we always found rolled up during the season of re- 

 pose, and it had carefully wrapped the dry moss 

 round itself. Perhaps one of the most extraordinary 

 phenomena of this description is exhibited in the 

 case of the dipus canadensis, or the Canada jumping 

 mouse, which has been found twenty inches beneath 

 the surface of the ground, completely enveloped in a 



* Ubi supra. 



f " An Essay on the Torpidity of Animals." Svo. London 

 1809. p. 6. 



