348 
gree, affect the quality of the surrounding air ; but 
if the temperature was raised a few degrees, the ves- 
sel soon became dim from the exhalation of fluid, the 
animals revived, and the oxygenous portion of the 
air was then, as usual, converted into carbonic acid. 
We have before related examples of snails (48.) 
which, like the rotifer, were rendered torpid by the 
abstraction of water ; and, since they remained in 
that condition for years without exhibiting any ma- 
terial change, it may be safely inferred, that, during 
the same period, they effected no change in the air 
that surrounded them. 
655. In the insect class, Spallanzani found that 
caterpillars, which were in full vigour, consumed 
more oxygen and produced more carbonic acid than 
others; and when about to change into chrysalides, 
they consumed less than in their caterpillar state *. 
A caterpillar, confined in air at temperature 2 Reau- 
mur, consumed, in five hours, only O.02 of its oxy- 
gen gas, while a similar caterpillar, kept for the same 
time in a temperature varying from 16 to 17, con- 
sumed O.08 of oxygen gas. When several cater- 
pillars were kept for a whole night in a vessel of air, 
preserved in a temperature at and below zero, the 
air, on examination, contained its usual quantity of 
oxygen, so that no portion of that gas had disappear- 
ed. When, however, the temperature was raised to 
11 above zero, the animals then, in a small degree., 
consumed the oxygen gas of the air f. 
* Rapports de 1'air avcc les etrcs organise-, torn. i. p. 25. 
f Ibid, p, 30, 31. 
