CLASS INSECTS. 



433 



hundred and thirty pounds, hut 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. 455) 

 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 extre- 



Fig. 453. Silkworm of the Ailantus.* 



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

 guished, 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 



* Silkworm of the Ailantus from India and the extreme East. All these 

 various kinds of silks have their peculiar qualities or properties. R< K. 

 F F 



