62 INTERNAL ANATOMY OF INSECTS. 
laminated structure shows itself very clearly in old spe- 
cimens, and in such as have been immersed in boiling 
water 3 . 
ii. Trachea and Bronchia*. Parallel with each side 
of the body of most insects and extending its whole 
length, run two cylindrical tubes c , which communicate 
with the spiracles d , and from which issue, at points op- 
posite to those organs, other tubes which ramify ad in- 
fantum, and are distributed to every part of the body. 
The first of these tubes are called the trachea and the 
latter the bronchia. This structure appears, however, 
not to be universal : it is to be found in caterpillars and 
many Dipterous larvae ; but in that of the rhinoceros- 
beetle and other Lamellicorns, the bronchia branch di- 
rectly from the spiracle, the bottom or interior mouth 
of which is lined by a membrane from which they pro- 
ceed 6 : something similar has been observed to take 
place in many insects in other states, as the common 
cockchafer f ; in the pupa of Smcrinthus Populi s ; in the 
Cicada h ; in the Locust tribe ' ; and many others. In 
the Cossus, or larva of the great goat-moth, the trachea 
commences with the first spiracle, and finishes a little 
beyond the last, after which it diminishes considerably 
in diameter, and terminates in several branches or bron- 
chia, which proceed to the anal extremity of the body k . 
The bronchia which originate from the trachea in the 
a Treviranus Ibid. 24. Plate XXIX. Fig. 1. 
b Plate XXI. Fig. 3. a b. c Ibid. a. 
d Ibid. b. e Sprengel Coram entar. t. \.f. 1. 
f Ibid.f. 10. 8 Ibid.t.W.f. 15. 
h Malpigh. De Bombt/c. t. in./. 3. ' Ibid. t. \s.f. I. 
k Lyonet Anat. 101. 
