22O THE INSECT WORLD. 



francs, and even more. The value of manufactured silks represents 

 annually about 8,000,000 francs ; and we find by official statistics 

 that France exported in 1863 silk stuffs to the value of 384,000,000 

 francs. This immense trade shows how much silk is now-a-days 

 everywhere appreciated ; in those numerous tissues called taffeta, 

 satin, and velvet, each of which seems to have a charm a peculiar 

 attraction. The consistency of the stuff, the smoothness, the softness 

 of surface, the manner in which silk receives colours, the brightness, 

 fineness, power of reflecting, the rustling, the light or heavy folds, 

 all these are beauty, elegance, and luxury, in whatever way these 

 words are understood. 



The Bonibyx mori has, however, nothing alluring in its appear- 

 ance. Other caterpillars of the genus Bombyx have brilliant liveries ; 

 they are adorned with spots, blue as sapphires, green as emeralds, red 

 as rubies, but produce threads without brightness and fineness. The 

 humble silkworm, in a white blouse, like a workman, has nothing 

 brilliant in its dress, and yet it gives to the whole world its most 

 beautiful and gorgeous array. The body of the silkworm is composed 

 of thirteen distinct segments. In front are three pairs of articulated 

 legs, which will become later those of the moth. In the middle and 

 towards the posterior part, are five pairs of membranous legs, furnished 

 with a circle of very fine bristles, which assist the animal to hook 

 itself on to leaves and stalks. On the two sides of its body are 

 eighteen stigmata, or respiratory mouths. 



The head of the silkworm is remarkable ; it is scaly, horny, and 

 formed of one single piece. The mouth is provided with six small 

 articulated pieces. Below is a simple blade, the upper lip, having in 

 its middle a hollow, into which the animal causes the edge of the 

 leaf it is gnawing to enter, and holds it thus without any exertion. 

 Underneath the lip are inserted two large jaws, which cut the leaf as 

 a pair of scissors. Underneath, some weaker jaws divide the 

 fragments, and a little organ, articulated on to each jaw, that is to 

 say, a palpus, pushes them back towards the mouth, and prevents the 

 smallest particle of the leaf from falling. And lastly, in the space 

 comprised between the two jaws, is an under-lip, which completely 

 closes the mouth below. At the extremity of this piece may be seen 

 a little prolongation, a sort of papilla, pierced with a hole, which is 

 the orifice that gives issue to the silky thread. 



The organs which serve for the elaboration and emission of the 

 silk have a peculiar interest for us. If we dissect a silkworm under 

 water, we succeed, sooner or later, after having removed the outer 

 parts, in laying bare a double apparatus, placed along the two sides 



