134 INSECTS. 



by filling the vessels which run through the wing-nerves 

 stretches the wing to its full size. 



Fig. 47. 



This explanation is partly guess-work, for nothing is 

 known of any internal arrangement by which the air may 

 be pumped into the wings instead of being forced out of 

 the body, but any one who has watched the simultaneous 

 reduction of the apparently inflated abdomen and the 

 apparent inflation, or at least expansion, of the wings, 

 could hardly fail to receive this impression. That blood 

 is forced into the wings during this period is proved by 

 the fact that insects of some kinds will bleed freely 

 through a prick inflicted on the wing whilst it is in the 



