264 DIMINUTION OF RESPIRATION IN TORPID STATE. 



the lapse of an hour, they had sunk to 58 ; and they sub- 

 sequently fell to 46. In the first hour of its confinement it 

 produced about l-3rd of an inch of carbonic acid (a quantity 

 many times greater, in proportion to its size, than that which 

 Man would have set free in the same time) ; and during the 

 whole twenty-four hours of the subsequent day, the insect 

 produced a less amount than that which it then evolved in a 

 single hour. In the Larva state, which is usually one of com- 

 parative inactivity, the respiration is not much above that of 

 the Worm tribes ; and in the Chrysalis state of those which 

 become completely inactive, the amount of respiration is still 

 lower. 



309. This chrysalis state, indeed, bears a strong resemblance 

 to the condition of. torpor in which many animals pass the winter. 

 Reptiles, and most Invertebrata that inhabit the land, become 

 (to all appearance) completely inanimate when the temperature 

 is lowered below a certain point ; yet retain the power of 

 exhibiting all their usual actions when the temperature rises 

 again. In this state, their circulation and respiration appear 

 to cease entirely ; or, if these functions are carried on at all, 

 they are performed with extreme feebleness ; and the animals 

 may be prevented from reviving for a long time, without their 

 vitality being permanently destroyed, if they be surrounded by 

 an atmosphere sufficiently cold. Thus Serpents and Frogs have 

 been kept for three years in an ice-house, and have completely 

 revived at the end of that period. Among Mammals there are 

 several species which pass the winter in a state of torpidity ; 

 but this is less profound than the torpidity of cold-blooded 

 animals, for the circulation and respiration never entirely 

 cease, though they become very slow. There are various 

 gradations between this condition and ordinary deep sleep. 

 Thus some of the animals which hybernate or retire to winter 

 quarters, lay up a supply of food in the autumn, and pass the 

 cold season in a state differing but little from ordinary sleep, 

 from which they occasionally awake, and satisfy their hunger. 

 But others, like the Marmot, are inactive during the whole 

 period, taking no food, and exhibiting scarcely any evidence 

 of life, unless they are aroused. The consumption of oxygen 

 and the production of carbonic acid, under such circumstances, 

 are extremely slight, as might be anticipated from the languor 

 of the circulation and the inactivity of the nervo-muscular 



