74 NATURAL HISTORY. [CH. Ill 



efFortb of their flies to effect an escape, had pur 

 posely arranged themselves with their heads aL' 

 pointing to one end of the cocoon. 



In the preceding instances the escape is effected 

 by the perfect insect from a cocoon, the substance 

 of which is of an equal consistence throughout; 

 but there are numerous instances in which the cat- 

 erpillar provides for the more easy extrication of 

 the moth, by various peculiarities in the construc- 

 tion of the cocoon. 



Of these we shall only notice the mode of escape 

 of the emperor moth, of which Reaumur has given 

 a complete account. On examining one of these 

 cocoons from which the moth has escaped, and 

 another which still contains the chrysalis, both ap- 

 pear perfectly alike, the place from which the moth 

 has escaped not being observable. The cocoon is 

 of an oval shape, with its upper end produced al- 

 most into a point, like a Florence flask ; at this end 

 the hairs of the cocoon are longitudinally gummed 

 together, converging like so many bristles to a blunt 

 point, in the middle of which is a circular aperture 

 forming a kind of clastic funnel, through which the 

 insect does not experit^nce much difficulty in ma- 

 king its exit, but which immediately closes again 

 when the insect has escaped. So easy a mode of 



extrication would however afford an equally easy 

 entranoe to minute parasites or other voracious 



