• The Zoologist— June, 1868. 1227 



hooked feet are far too feeble to tear such a dense structure. But the 

 moth must have some means of exit from the cocoon : in fact, they 

 are provided with two glands opening into the mouth, which secrete, 

 during' the last few days of the pupa state, a fluid which is a dissolvent 

 for the gum so firmly uniting the fibres of the cocoon : this liquid is 

 composed in great part of bombycic acid. When the insect has 

 accomplished the work of transformation which is going on under the 

 pupa-skin, it manifests a great activity, and soon the chrysalis-covering 

 bursts open longitudinally upon the thorax ; the head and legs are 

 soon disengaged, and the acid fluid flows from its mouth, wetting the 

 inside of the cocoon. The process of exclusion from the cocoon lasts 

 for as much as half an hour. The insect seems to be instinctively 

 aware that some time is required to dissolve the gum, as it does not 

 make any attempt to open the fibres, and seems to wait with patience 

 this event. When the liquid has fully penetrated the cocoon the 

 pupa contracts its body, and pressing the hinder end, which is fur- 

 nished with little hooks, against the inside of the cocoon, forcibly 

 extends its body; at the same time the head pushes hard upon the 

 fibres, and a little swelling is observed on the outside. These con- 

 tractions and extensions of the body are repeated many times, and 

 more fluid is added to soften the gum, until under these efforts the 

 cocoon swells, and finally the fibres separate, and out comes the head 

 of the moth. In an instant the legs are thrust out, and then the whole 

 body appears; not a fibre has been broken, they have only been 

 separated. To observe these phenomena 1 had cut open with a razor 

 a small portion of a cocoon in which was a living chrysalis nearly 

 ready to transform. The opening made was covered with a piece of 

 mica, of the same shape as the aperture, and fixed to the cocoon with 

 mastic so as to make it solid and air-tight : through the transparent 

 mica I could see the movements of the chrysalis perfectly well. 



When the insect is out of the cocoon it immediately seeks for a 

 suitable place to attach its claws, so that the wings may hang clown, 

 and by their own weight aid the action of the fluids in developing and 

 unfolding the very short and small pad-like wings. Every part of the 

 insect on leaving the cocoon is perfect, and with the form and size of 

 maturity, except the pad-like wings and swollen and elongated abdo- 

 men, which still gives the insect a worm-like appearance : the abdomen 

 contains the fluids which flow to the wings. When the still immature 

 moth has found a suitable place it remains quiet for a (ew minutes, 

 and then the wings are seen to grow very rapidly by the afflux of the 



