INTERNAL ANATOMY OF INSECTS. 193 
as it rises or falls in flight a , which seems to require the 
action of constrictor and laxator muscles. 
iv. The Viscera. Having before had occasion suffi- 
ciently to notice the muscles by which the systole and 
diastole of the dorsal vessel of insects is maintained b , I 
shall now only mention those that are woven round their 
alimentary canal, by which the peristaltic motion of that 
organ, causing its contractions and the propulsion of 
its contents, takes place. One would at first think that 
a view of the intestines of any animal could under no 
circumstances afford any very pleasing spectacle to the 
eye of any but a scientific spectator ; but any lady who is 
fond of going to Disons to be tempted with an exhibi- 
tion of fine lace, would experience an unexpected grati- 
fication could she be brought to examine those of a ca- 
terpillar under a microscope : with wonder and delight 
she would survey the innumerable muscular threads that 
in various directions envelope the gullet, stomach, and 
lower intestines of one of these little animals ; some run- 
ning longitudinally, others transversely, others crossing 
each other obliquely, so as to form a pattern of rhom- 
boids or squares; others again, surrounding the intestine 
like so many rings, and almost all exhibiting the appear- 
ance of being woven, and resembling fine lace, — one pat- 
tern ornamenting one organ ; another, a second ; and an- 
other, a third. This will suffice to give some idea of this 
part of the muscular structure of these little animals . 
Lyonet counted the muscles contained in the body 
of the caterpillar of the Cossus. In the head he found 
228; in the body, 1647 ; and enveloping the intestines, 
a Chabr. Analyse 25. Surle Vol des /ws. c. i. 423, 452. Adclend.30]. 
b See above, p. 83. c Lyonet Anat. t. xiii./. 1, 2. 
VOL. IV. O 
