iS 



SILKWORMS. 



the body and holding on firmly with its claspers, and assisting its 

 grasp with some silken threads run backwards and forwards across 

 the object to which it is clinging. In this position it remains (Fig. 

 i) perfectly immovable, and hence its condition is described by the 

 French as "sleep," the caterpillar being said to "go to sleep." 

 When in this state, it is highly irritable, and resents any touch 

 by petulant jerkings of its fore-part. A slight change in the 

 appearance of this part is perceptible ; it seems to become more 

 swollen and misshapen than usual, and the head appears to be 

 thrust forward beyond its natural position (Fig. 2). After the worm 



Fig. i. Position of Silkworm before moulting. 



Fig. 2. Head of Silkworm about 

 to moult. 



has remained in this position some time, perfectly regardless of all 

 that is going on around it, the skin by the head begins to split, 

 the split extends, and presently, by means of working its head 

 from side to side, the front part of the body is dragged through 

 the opening, the legs being drawn out of their skins like fingers 

 from a glove. By muscular contractions and contortions the old 

 skin is gradually pushed backwards off the whole body, and is 

 left in a collapsed condition in the spot previously occupied by 

 the caterpillar, being retained there by the skin of the prolegs and 

 the silken threads. 



When the grub has thus wriggled out of its skin, it shows that 

 it was fully prepared for such a remarkable performance, by 

 appearing clad in a new skin, which had been gradually formed 

 beneath the old one at the expense of some of the food that had 

 been ravenously devoured during the last few days of its first age. 

 This second skin is really larger than the first, though it was 

 contained within that, and thus, as the pressure of 

 the old tight-fitting garment is removed, the body 

 expands, and we have the curious spectacle of a 

 creature, bereft of its skin, larger than when it had 

 Fig. 3 . silkworm it on. It has, however, considerably altered in 

 appearance by passing through this crisis (Fig. 3). 

 It is paler, of a greyish colour, and much less hairy, only the 

 merest trace of hairs remaining, and we can now see clearly, 

 at the end of the body opposite the head, a prominent object, 

 curving upwards and backwards, in the form of a central horn. 



