OF INSECTS IN GENERAL, ^^^ 



Thefe ftigmata are commonly 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 firft began to attra£l: the attention of naturalifts, 

 it was imagined, that by means of them the infeci: only 

 infpired, and that the air was ejected by the pores in the 

 common manner, by perfpiration. 



This opinion was adopted by Af. de Reaumur * ; but 

 fubfequent experiments have proved, that the air is both 

 introduced into the lungs, and emitted from them by 

 the fpiracies : 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 funftions on that part 

 are impeded, and the fide becomes paralytic f . Nor is it 

 in their winged and a£live ftarte alone, that infects breathe. 

 The cruflaceous fliell, by which the chryfaiis is covered, 

 is alfo provided with lateral ftigmata, by which refpiration 

 is carried on during the period of their pupa Hate. In 

 the breathing of infe£ts, there is Hill another peculiarity; 

 they thrive in air tainted by putrifying fubftances, and 

 are capable of fubfiiling in phlogiilicatcd air, the infpi- 

 ration of which is fo fatal to other animals. 



From the limbs of infefls are obtained the moft per- 

 manent and flrlking generic charafters ; thefe are moil 

 commonly taken from the tail, the legs, or the wings, 

 in ftich fubje^ls as are furnifhed with them. The tail 

 terminates the abdomen ; and fometimes has two horns, 

 and fometimes none : It is eitlier fimplej or armed with 

 a forceps, a brifllc, a clav/, or a fling t. 



Vol. hi. U u Thr 



• Vide Memoir pour fcrvir a V hlfl. des infe<5les. 



-f Bonr.Gt. \ Barbut's genera infcdlorum* 



