FORMING THE COCOON. 43 



shelves, and the insects mount them and form 

 their cocoons among the twigs. 



Supposing the worm to be left to itself on the 

 tray, without either of these precautions, it at 

 last selects some corner or hollow place which will 

 conveniently hold the cocoon it is about to spin, 

 and begins by throwing out a number of irregular 

 threads, which are intended to support its nest. 

 Upon these it forms, during the first day, a loose 

 structure of floss silk of an oval shape, within 

 which, during the next three days, it winds the 

 firm, hard, yellow ball, remaining, of course, all 

 the time within it. In this operation the insect 

 does not greatly change the position of the hinder 

 part of its body, but continues drawing its thread 

 from various points and attaching it to others, so 

 that after a time the body becomes to a great 

 extent enclosed by the thread. " The work is 

 then continued from one thread to another, the 

 silkworm moving its head and spinning in a zigzag 

 way, bending the fore part of the body back to 

 spin in all directions within reach, and shifting 

 the body only to cover with silk the part which 



