THE SILKWORM ITS FORM AND LIFE HISTORY. 2/ 



to be in the form of a six-legged four-winged creature, whose 



wings, however, are soft and wet, and extremely small. But 



though the insect has escaped the confines of the hard brown 



case that so closely invested it, it is still a prisoner ; it is cut off 



from the outer world by the compact walls of the cocoon, through 



which there is no passage, and which certainly will not, in their 



present condition, yield to any amount of pressure that the poor 



limp thing within can exert upon them. Moreover, the moth has 



no jaws with which to bite its way through ; how, then, is it to 



escape? The problem seems difficult, and yet it is solved in a very 



simple way, though naturalists were for a long time puzzled as to 



the means employed. From two glands in the head the moth 



pours out upon the end of the cocoon against which its fore part is 



placed, a small quantity of an alkaline liquid which possesses a 



solvent power, not upon the silk itself, but upon that gummy 



substance which invested the threads at their extrusion and 



caused them to adhere to one another. In this way the threads 



at this point are in time loosened, and can then be pushed aside 



from within by the moth, which thus wc r ks a hole sufficiently large 



to permit of its escape, without intenuonally breaking any of 



the threads, though possibly some few of them may get broken 



during the struggle. In squeezing its way out, it is greatly 



assisted, if it can find any rough objects near at hand to which it 



may cling with its fore-legs, and thus obtain leverage to aid it in 



dragging its body out. 



It now seeks the nearest possible projection from which to hang 

 with its minute limp wings depending vertically behind its back. 

 This is to facilitate the passage of fluid from the body into the 

 minute tubes which form, as it were, the framework of the wings ; 

 the latter are thereby distended and speedily assume their proper 

 dimensions, not long after which they dry and harden. Shortly 

 after its emergence, the moth discharges a quantity of a thick 

 reddish fluid, which irretrievably stains everything it touches, and 

 on drying leaves a considerable deposit of a pale reddish powder 

 compacted together. The old pupa case is of course left empty 

 within the cocoon, which therefore now contains two cast-off 

 vestments the shrivelled larva skin, and the broken pupa case. 



The moth is a pale cream-coloured creature with a tolerably 

 stout body, covered with closely-lying creamy hairs, and with four 

 not very large creamy wings, the upper pair rather hooked at the 

 tip, and crossed by faint brownish markings in the shape of wavy 

 lines and bands (Figs, n and 12). When fully spread out, they 

 measure a little over an inch from tip to tip ; but they are never 

 naturally found in this position ; the insect always carries them 



