METAMORPHOSES OF INSECTS. SILKWORM. 107 



covered by a thin pellicle, which lies over the external organs, 

 follows all their inequalities of surface, and causes the insect to 

 appear as if closely wrapped in bandages. 



625. Before undergoing this metamorphosis, the Larva pre- 

 pares a defence for itself ; and shuts itself up in a case, which it 

 makes with silk^ secreted by salivary glands, and drawn out by 

 the aid of spinnerets^ hollowed in the lips. In other instances, 

 it suspends itself by means of threads, or conceals itself in some 

 hollow. It is, however, whilst the insect is in this state of appa- 

 rent repose, that active operations are going on within the body, 

 of which the result is the complete development of the entire 

 organisation. Its interior parts become soft, and by degrees 

 assume the shape that they will preserve ; the different organs, 

 with which the adult animal ought to be provided, are deve- 

 loped under the envelope which conceals them ; and when this 

 evolution is finished, it frees itself from this species of mask ; 

 spreads its wings, which are not long in acquiring firmness, and 

 becomes a perfect insect or Imago. 



626. As an example of this complete metamorphosis, we can- 

 not make a better selection, than by taking the Bomlyx Mori ; 



for this insect in 

 its larva state pos- 

 sesses for us an 

 immense interest ; 

 it is the silkworm, 

 the rearing of 

 which contributes 

 so powerfully to 

 the agricultural 

 prosperity of the 

 southern countries 

 of Europe, and the 



FIG. 330. SILKWORM. product of which 



gives origin to so much industry and wealth. This insect came 

 originally from the northern provinces of China, and was not 

 introduced into Europe until the sixth century. The Greek 

 Missionaries brought some of its eggs to Constantinople in the 



