242 



Microscopical Essays, 



fpiracula in .the air ; during this time he obferved, that when the 

 infect moved itfelf, little ftreams of bubbles ilfued from the ante- 

 rior fpiracula on the left fide ; from this and many other experi- 

 ments it appeared to him, that among!! all the eighteen fpiracula, 

 the two anterior and the two pofterior are of the greateft ufe in 

 refpiration.* Sometimes, when the mouths of thefe have been 

 flopped with oil, the caterpillar has fell into convulfions. If the 

 pofterior part has been oiled, that part will become paralytic. 

 Notwithstanding thefe experiments, and many more which have 

 been made, the fubjefl: is far from being decided, and many ftill 

 doubt whether there is any refpiration in infects fimilar to ours, 

 at leaf! at certain periods of their life. 



This opinion feems to be further confirmed by the experiments 

 of M. Lyonet. He placed feveral of the large mufk beetle, 

 probably the cerambyx mofchatus, under a glafs, where he had 

 been burning fulphur, and which he kept burning while they 

 were there; and though the vapour was fo thick that he could 

 not fee them, and that he kept them therein more than half am 

 hour, they did not feem in the leaft incommoded, t 



When we confider the great folidity of the cafes, or cones, of 

 the pupas of different infects, it is not eafy to conceive how they 

 can live feveral months under the earth, in /paces fo confined,, 

 and almoft impervious to the air. If refpiration was abfolutely 

 neceflary to their exiftenee, and indeed if they did refpire, the 

 fame fituation feems to preclude a continuance of the operation, 

 as the air would foon be corrupted, and unfit for the offices of 



life. 



* Philof. Tranf. vol. xlv. p. 300. 



f Letter Theologie des Infe&es, torn, t, p. 124. Ibid,. p< i»6* 



