EXPANSION OF PERFECT INSECTS. 341 



destroyed by external injuries, but might grow strong 

 and ripen.'* 



While the httle creature remains in this condition, 

 there is produced, as Swammerdam tells us, a violent 

 agitation in its fluids, so that they are driven from the 

 internal vessels through the tubes in the wings, which 

 are likewise supphed with air from the windpipe. The 

 insect, besides, labours violently with its legs, and all 

 these motions concurring with the growth of the wings, 

 it is impossible that the tender skin which covers it 

 should not at length give way, which it does by burst- 

 ing in four distinct and regular pieces. When the legs 

 become disengaged they much assist in freeing the body 

 and other parts that are yet bound up; at the same time, 

 the skin on the back flies open and uncovers the wings 

 and shoulders. The insect, after this, remains for 

 some time in a state of rest, with its wings drooping 

 down like wet paper, and its legs fixed in the skin 

 which it has just cast oft', together with the lining of 

 the windpipe and breathing spiracles. This latter cir- 

 cumstance enables the insect to take more air into its 

 body, and thereby renders it the letter able to fly, and 

 perform the other functions dependant on a good sup- 

 ply of air. In consequence of this the wings expand 

 so rapidly, that it is by no means easy to trace their 

 unfolding; for in the space of a few minutes, they in- 

 crease in dimensions about five-fold. Their spots and 

 colours at the same time, previously so small as to 

 be scarcely discernible, become proportionally extend- 

 ed, so that what but a few minutes before appeared as 

 a number of confused and indistinct points, acquires 

 many varied beauties of colour and form. From the 

 wings extending themselves so suddenly, their soft 

 wrinkled appearance is, in less than half an hour, 



* Slalpighi, De Bombyce. 

 VOL. VI. 29* 



