EXPANSION OF PERFECT INSECTS. 341 



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i destroyed by external injuries, but might grow strong 

 I and ripen."* 



While the little creature remains in this condition, 

 there is produced, as Swammerdam tells us, a vio- 

 lent agitation in its fluids, so that they are driven 

 from the internal vessels through the tubes in the 

 wings, which are likewise supplied 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 bursting in four distinct and regular 

 pieces. When the legs become disengaged, they 

 iimch 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 

 off^, together with the lining of the windpipe and 

 breathing spiracles. This latter circumstance enables 

 the insect to take more air into its body, and thereby 

 renders it the better able to fly, and perform the 

 other functions dependent on a good supply of air. 

 In consequence of this, the wings expand so rapidly, 

 that it is by no means easy to trace their unfold- 

 ing ; for in the space of a few minutes, they increase 

 in dimensions about five-fold. Their spots and 

 colours at the same time, previously so small as to 

 be scarcely discernible, become proportionally ex- 

 tended, so that what but a few minutes before ap- 

 peared 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 



I * Malpighi, De Bombyce. 



