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 1-3rd 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 
