74 INTERNAL ANATOMY OF INSECTS. 
larva or perfect states. Lyonnet, however, Musschen- 
broek, Martinet, and some other physiologists, have 
doubted whether quiescent pupz breathed*; but Reau- 
mur and De Geer seem to have proved that they do?: 
and if thrown into water, the same proof of respiration, 
by the emission and retraction of a bubble of air takes 
place, as in the larvee; and De Geer found that if one 
be transferred under water from one spiracle to another, 
it will be absorbed by it®. Indeed, unless these pupz 
had breathed, where would have been the necessity for 
the spiracles with which all are furnished? It is remark- 
able, however, that all these spiracles do not seem of 
equal importance in this respect. Reaumur found that 
if the posterior spiracles only were closed with oil, the 
insect suffered no injury; but that if the anterzor ones 
were similarly treated, it infallibly died*. ‘The respira- 
tion however of pupz seems more perfect in those that 
have recently assumed that state, than in those that are 
more advanced towards the imago; in which at first, from 
Reaumur’s experiments‘, it appears that the posterior 
spiracles were stopped; and in others still older, from 
Musschenbroek’s‘, even the anterior ones. Those quies- 
cent pupz that during that state remain submerged, re- 
spire air. De Geer has given an interesting record of 
this, in the case of Botys stratiolaris. This insect spins 
a double cocoon, the outer one thin, and the inner one 
of a close texture. In the pupa there are three pair of 
conspicuous spiracles on the second, third, and fourth 
segments of the abdomen, which are placed on cylindri- 
* Lesser, L. i. 124. note *, Lyonnet Anatom. pref. xii. De Geer ii. 
132. » Reaum. i. 399—. De Geer i. 37—. 
© Ibid. 40. “* Reaum. i. 400. © Ibid, £ De Geer ii. 129. 
