INTERNAL ANATOMY OF INSECTS. 35 
speedily perish in air altogether deprived of its oxygen, 
or placed in situations to which all access to this essential 
element is excluded. Their respiration too of atmo- 
spheric air produces the same change in it with that of 
the vertebrate animals, the oxygen disappearing, and 
carbonic acid gas being produced in its place. Bayle 
had long since ascertained, that when bees, flies, and 
other insects were placed under an exhausted receiver, 
they often perished?: and the same effect was even ob- 
served by the ancients to ensue, when their bodies were 
by any means coyered with oil or grease, which necessa- 
rily closed the orifices of their respiratory organs?. 
But for the first series of experiments ascertaining the 
necessity of a supply of air to insects, and their conver- 
sion of it into carbonic acid, we are indebted to the illus- 
trious Scheele‘ ; and his experiments have been repeated 
and confirmed by Spallanzani, Vauquelin, and other 
chemists. The former found, that when caterpillars and 
maggots were confined in vessels containing only about 
eleven cubic inches of atmospheric air, though furnished 
with sufficient food, they soon died, and sooner when the 
space was more confined’. He ascertained too, that a 
larva weighing only a few grains consumed, in a given 
time, as much oxygen as an amphibious animal a thou- 
sand times as voluminous®. A male grasshopper (Acrida 
viridissima K.) in six cubic inches of oxygen lived but 
eighteen hours, and the female placed in eight cubic 
inches of atmospheric air, only thirty-six hours. The 
4 Philos. Trans. v. 2011. Works, 4to. i. 79, 112. 
6 Aristot. Hist. Animal. 1. vill. c. 27. 
© On Air and Fire, 148, 155. 4 Tracts, 208. 
* Mem. on Respirat. 75. 
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