THE CATERPILLAR. 



295 



third, and the laft. Thcfe oval openings may be confidered as fo many 

 mouths, through which the infect breathes into its lungs, which are con- 

 fequently eighteen. They appear at firft view to be hollow cartilaginous 

 tubes, mother-of-pearl colour. They often unite with each other ,- fomc 

 open into the inteftines, and fome go to different parts of the furface of the 

 body. That thefe convey air, appears from the experiment of Malpighi ; 

 "who by (lopping up the mouths of thefe ftigmata with oil, quickly fuffo- 

 cated the animal. Oil on other parts of the body, leaving the ftigmata free, 

 feemcd innocent; the infedt continued to move and eat as ufual : he rubbed 

 on the ftigmata of one fide, and it underwent a partial convulfion, but re- 

 covered foon after. Caterpillars will live in an exhauftcd receiver feve- 

 ral days. 



The inteftines run ftraight from the mouth to the anus. They refem- 

 blc a number of fmali bags opening into each other j ftrengthened on 

 both fides by a fieftiy cord, by which they are united. Caterpillars often 

 caft the internal €oat of their inteftines with their food, in their frequent 

 changes. But the inteftines take up a fmall part of the body, compared 

 to the fatty fubftance in which they are involved. This fubftance 

 changes its colour when the infed's meramorphofis approaches, and from 

 white ufually becomes yellow. All caterpillars fpin at onetime or other, 

 like the filk-worm. 



Many caterpillars change their /kins five or fix times in a feaibn ; and 

 this caft-off covering feem.s fo complete, that it might be miftaken for 

 the real infed. Among hairy caterpillars, the caft fkin is covered with 

 hair j the feet, as well griitly as membranous, remaining ; even the 

 parts which nothing but a microfcope can difcover, are vifible in it; all 

 the parts of the head ; not only the fkuii, but the teeth. As the time 

 approaches for the caterpillar to caft its ikin, its colours become more 

 feeble, and the fkin feems to wither and dry like a leaf no longer fupplied 

 with moifture. A day or two before the critical hour, the infect ceafes 

 to eat, lofes its ufual adivity, and feems immoveable : it feeks fecurity ; 

 and. no longer timorous, feems regardlefs of the touch. It often bends it- 

 felf, elevates its back, ftretches itfeif to its utmoft extent : lifts up its head, 

 and lets it fall, waves it three or four times from fide to fide, and then 

 remains quiet. At length, fome of the rings of its body, particularly the 

 firft and lecond, fwell confiderably, the old fkin diftends and burfts ; till, 

 by repeated fwellings and contra6tions in every ring, the animal difen- 

 gages itfeif, and creeps from its inconvenient covering, in the fpaceof a 

 minute ; and feems to enjoy new vigour, as well as colouring and beaurv. 

 The hairy preferve their hair j for every hair appears to have been drawn, 



3^2 A new 



