INTERNAL ANATOMY OF INSECTS. 79 
so difficult to kill the larva of Stratyomis Chameleon, 
which he first immersed twenty-four hours in spirits of 
wine, and then put them several days in water, without 
killing them,—that he lost his patience, and dissected 
them alive. He tried to drown them also in vinegar, in 
which they held out more than two days?. 
That the suspended animation and subsequent death 
of most terrestrial insects when thrown into water is 
caused by the want of azr, is evident from this,—that the 
same effect ensues if the spiracles be covered with any 
oily or fatty matter. In this case too, their vital powers 
soon become suspended: they revive, if the suffocat- 
ing matter be soon removed ; and if this be not done, in- 
fallibly perish. This fact was known to the ancients, 
for Pliny observes that bees die if dipped in oil or ho- 
ney’. One exception to this law has been before men- 
tioned‘: a similar contrivance secures the cheese maggot 
from having its respiration interrupted by its moist and 
greasy food; the grub also of Muscacarnaria, and of other 
Muscide probably, has its posterior spiracles placed in a 
plate at the bottom of a kind of fleshy pouch, which has 
the shape of a hollow, truncated, and reversed cone. 
This pouch the grub can close whenever it pleases, so 
as to cover its spiracles?. And numerous other larve, 
both of Diptera and Coleoptera that devour unclean and 
oily food, have doubtless some protection of this kind for 
their spiracles and respiratory plates. 
2 Swamm. Bibl. Nat. ii. 48. a. > Hist. Nat. 1. xi. c. 19. 
© Swamm. Bibl. Nat. ii. 64. a. 
¢ Reaum. iv. 428. ¢. xxix. fi 2. ¢, 5. 
