394 ZOOLOGY. 



metamorphosis. They may be seen then to climb the branches 

 of small fagots placed intentionally and carefully above the 

 hurdles in which they had hitherto remained. Their bodies 

 become soft, and there springs from their mouth a thread of 

 silk which they draw after them. Soon they fix themselves, 

 throwing around them a multitude of threads of extreme 

 fineness, called bane or banne, and, suspended in the middle 

 of this network, spin their cocoon, which they construct by 

 continually turning on themselves in different ways, and thus 

 rolling around their body the thread which leaves the winder 

 with which their lip is pierced. The thread thus formed is 

 produced by glands which have much analogy with the 

 salivary glands of other animals, and the matter of which 

 it is composed is soft and viscous at the moment of its leaving 

 the mouth, but soon hardens in the air. From this it results 

 that the different turns of this single thread become agglu- 

 tinated together, and form an envelope whose tissue is firm 

 and whose shape is ovoid. The colour of this silk varies ; 

 sometimes it is yellow, sometimes pure white, according to 

 the variety of the worm which has produced it, and the 

 length of each thread often exceed^ six hundred metres, 

 (somewhat more than six hundred yards), but it varies much, 

 as well as the weight of the cocoons. The worms produced 

 from a single ounce of seed may produce as much as one 

 hundred and thirty pounds, but such a harvest is rare, and 

 often they obtain only from seventy to eighty pounds from the 

 cocoons. 



In general, from three days and a half to four days suffice 

 for the larvae to finish their cocoon, and if we afterwards open 

 this kind of cellule we may see that the animal (Fig. 373), 

 no longer offers the same appearance as before its seclusion ; 

 it has acquired a brown colour, its skin resembles old leather, 

 and its form is ovoid, a little pointed at its posterior rxtiv- 

 mity. Neither head nor jaws are to be any longer distin- 

 tinguished, but its posterior portion is occupied by moveable 

 rings, whilst anteriorly an oblique band may be observed, 

 disposed like a scarf, and representing the future rings of the 

 perfect animal. The time during which the bombyces re- 

 main thus shut up in a state of chrysalis, varies according to 

 the temperature. If the heat be from 15 to 18 (from 59 

 to 65 Fahrenheit), they come out in the perfect state from 

 the eighteenth to the twentieth day. To pierce their cocoqn, 

 they moisten one extremity with a particular liquid which 



