Trench National institute, 145 



Messrs. Herholdt and Rafn, of Copenhagen, M. Saissy, 

 a physician of Lyons, and M. Prunelle of Montpelier, 

 have successively presented memoirs of great merit to the 

 Institute, on the torpidity of animals; and we think it right 

 to give here a detail of some of the phsenomena, with some 

 hasty conjectures respecting the cause. 



Cold is the most necessary accessory to sleep ; but it is 

 not the only one: there must also be an absence of irritating 

 causes, such as noise, food, &c. Several of these animals, 

 when domesticated, do not sleep, notwith»t:inding the cold. 

 An atmosphere deficient in oxygen is also favourable, and 

 frequently necessary. This is the reason that most animals 

 roll themselves up before falling asleep. 



The degree of heat, although variable according to the 

 kind of animal and accessary circumstances, is always a 

 little higher than the freezing point : a too violent cold has 

 the effect of awakening animals when they are suddenly ex- 

 posed to it. 



Quadrupeds subject to lethargic sleep have not in general 

 their blood colder than other animals in the ordinary state, 

 nor do they consume less oxygen in respiration : it appears^ 

 Lowever, that their heat decreases a little with that of the 

 atmosphere, although it always remains sufficiently high 

 while they are awake. 



When once asleep, their breathing and circulation be- 

 come slower : the consumption of oxygen decreases in the 

 same proportion; they lose all feeling when the lethargy is 

 at its height. Irritability eeems to be the function which is 

 best preserved. 



Their animal heat decreases in the same interval to one 

 or two decrees above O' (Reaumur), but it does not become 

 lower; and if we gradually expose the animal to a more vio- 

 lent cold, and it becomes frozen, death ensues. 



Warmth is the most natural cause of the animal's awaking: 

 there are other causes, liowever, and cold is one of them. 

 When the animal awakes from any given cause, respiration 

 and circulation recommence with the usual degree of heat. 

 The profoundness of the sleep is different, according to the 

 species. Some animals awake several times in winter: the 

 bear and the badger are subject to a slight sleep only : the 

 tlormouse allows itself to be dissected without exhibiting any 

 signs of pain. 



They evacuate their bowels before going to sleep ; but they 

 cat duting the short times in which they are awake : they 

 transpire but very little. The above are such facts as have 

 been charlv ascertained. 



Vol. M.\No. 136. ^?^5«5M8Q9. K With 



