<t>F INSECTS IN GENE&AE; 
337 
Thefe fligmata are comtnonlj fituated on the fides both 
of the thorax and abdomen and their number is various* 
being from eight to twelve. When the ufes of thefe or- 
gans at firfl began to attraffc the attention of naturalifls* 
it was imagined, that by means of them the infect only 
infpired, and that the air was ejected by the pores in the 
common manner, by perfpiration. 
This opinion was adopted by M. de Reaumur * ; but 
fubfequent experiments have proved, that the air is both 
introduced into the kings, and emitted from them by 
the fpiracles : If the fligmata are covered with oil, re- 
fpiration totally ceafes, and the animal dies ; if they are 
covered only on one fide, the vital functions on that part 
are impeded, and the fide becomes paralytic f. Nor is it 
in their winged and aftive fiate alone, that infe£ts breathe* 
The cruflaceous fliell, by which the chryfalis is covered, 
is alfo provided with lateral fligmata, by which refpiration 
is carried on during the period of their pupa ftate. In 
the breathing of infects, there is Hill another peculiarity; 
they thrive in air tainted by putrifying fubftances, and 
are capable of fubfifting in phlogifticatcd air, the infpi- 
ration of which is fo fatal to other animals. 
From the limbs of ihfefts are obtained the molt per- 
manent and ftriking generic characters ; thefe are mod 
commonly taken from the tail, the legs, or the wings* 
in fuch fubjedts as are furnilhed with them. The tail 
terminates the abdomen ; and fometimes has two horns, 
and fometimes none i It is either fimple, or armed with 
a forceps, a briftle, a claw, or a fling t- 
Vol.UL U u The 
* Vide Memoir pour fervir a 1’ hlft. des infe&es. 
f Eonnet. 1 Barimt’s genera infedtorum. 
