LEPIDOPTEEA. 223 



liveries ; they are adorned with, spots, blue as sapphires, green as 

 emeralds, red as rubies, but produce threads without bright- 

 ness 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 poste- 

 rior 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 silkworm is remarkable for its muzzle. This 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 trunk, articulated on to each jaw, that is to say, a palpus, 

 pushes them back towards the mouth, and prevents the smallest 

 particles of the leaf from falling. And lastly, in the space com- 

 prised 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 which 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 one dissects a silkworm 

 under water, one succeeds very soon, after having separated it 

 from the other parts, in laying bare a double apparatus, placed 

 along the two sides of the intestinal canal and below it. This 

 is the apparatus which secretes the silk ; it is the double seri- 

 cipary gland. Each one of these glands is composed of a tube 

 formed of three distinct parts (Fig. 201). The part which is 

 nearest to the tail of the worm is a sort of bent tube, ABC, of 

 a thirtieth of an inch in diameter, and about nine inches in length, 

 twisted a great many times into irregular zigzags. This part of 



