74 NATURAL HISTORY. [cH. III. 



efforts of their flies to effect an escape, had pur- 

 posely arranged themselves with their heads all 

 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 wliicli is a circular aperture 

 forming a kind of clastic funnel, through which the 

 insect does not experience 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 

 entrance to minute parasites or other voracious 



