338 Insect Architecture. 



be understood from examining the work after it is finished. 

 In order to complete the structure, it must draw out of the 

 gum-bag a more delicate silk, and then with a stronger gum 

 bind all the inner threads over one another. 



" Here, then, are three coverings entirely different, which 

 afford a succession of shelter. The outer loose silk, or floss, 

 is for keeping off the rain ; the fine silk in the middle pre- 

 vents the wind from causing injury ; and the glued silk, which 

 composes the tapestry of the chamber where the insect 

 lodges, repels both air and water, and prevents the intrusion 

 of cold. 



"After building her cocoon, she divests herself of her 

 fourth skin, and is transformed into a chrysalis, and subse- 

 quently into a moth (Bombyx won'), when, without saw or 

 centre-bit, she makes her way through the shell, the silk, and 

 the floss ; for the Being who teaches her how to build herself 

 a place of rest, where the delicate limbs of the moth may be 

 formed without interruption, instructs her likewise how to 

 open a passage for escape. 



" The cocoon is like a pigeon's egg, and more pointed at 

 one end than the other ; and it is remarkable that the cater- 

 pillar does not interweave its silk towards the pointed end, 

 nor apply its glue there as it does in every other part,* by 

 bending itself all around with great pliantness and agility : 

 what is more, she never fails, when her labour is finished, to 

 fix her head opposite to the pointed extremity. The reason 

 of her taking this position is, that she has purposely left this 

 part less strongly cemented, and less exactly closed. She is 

 instinctively conscious that this is to be the passage ' for the 

 perfect insect which she carries in her bowels, and has there- 

 fore the additional precaution never to place this pointed 

 extremity against any substance that might obstruct the moth 

 at the period of its egress. 



" When the caterpillar has exhausted herself to furnish 

 the labour and materials of the three coverings, she loses the 

 form of a worm ; her spoils drop all around the chrysalis ; 

 first throwing off the skin, with the head and jaws attached to 



* This is denied bv recent observers. 



