HISTORY OF THE SILK-WORM. 17 



SECTION II. 



HISTORY OF THE SILK-WORM. 



The silk-worm or Bombyx mori, is a caterpillar ; its 

 body formed of twelve membranous rings, which sup- 

 port the legs, which are sixteen in number and in pairs. 

 Six of these are in front and inflexible, and situated be- 

 neath the three first rings, and are each covered with a 

 scale. The other ten are flexible, and membranous, 

 their positions beneath the rings ; these are called climb- 

 ers or holders, and are provided with sharp hooks or 

 claws, to aid in climbing. The head has a horny cov- 

 ering, like a scale ; the jaws are very strong, the teeth 

 sharp, serrated, or indented like a saw. The mouth is 

 vertical and peculiar, and not horizontal as in most other 

 beings; two broad objects in its forehead, which might 

 be mistaken for eyes, are but bones of the skull. The 

 eyes are small, fourteen in number, seven on each side 

 of the head and near the mouth. The organs of respi- 

 ration are eighteen in number ; equi-distant, and situated 

 along the body are the holes or openings, nine on each 

 side, which serve for breathing. 



The substance of which the silk is composed is a li- 

 quid transparent gum, of a fine yellow color, and is con- 

 tained in two separate sacks, of slender dimensions. Each 

 of these vessels is about ten inches in length, and 

 wound in the stomach in spiral folds : near the jaws two 

 ducts convey the silken fluid ; these uniting in one serve 

 to compose the silken thread, which is usually from 400 

 to 1200 feet in length. 



The eggs of the silk-worm are of a dark lilac or slate 

 color. The silk-worms are at first black and extremely 

 small ; as they advance in age and size, they cast off 

 their outer covering or skin, usually from three to four 

 times at different periods, according to the variety. 

 These successive changes are called mountings ; and the 



