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 5 , 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. Sur le Vol des Ins. c. i . 423, 452. Addend. 30 1 . 

 b See above, p. 83. c Lyonet Anat. t. xiii,/. 1, 2. 



VOL. IV. O 



