] 46 THE SILKWORM MOTH. 



firm and consistent yellow ball ; the labour always, 

 of course, remaining within the sphere of the cone 

 which it is forming. 



If at any time the threads intended for the sup- 

 port of the cocoon should be broken, the ball not 

 being properly poised, becomes unsteady, so that 

 the insect is unable perfectly to go forward with its 

 labours. Under these circumstances, the worm 

 pierces a hole in, and altogether abandons the un- 

 finished cocoons, and throws out its remaining 

 threads at random wherever it passes, by which 

 means the silk is wholly lost, and the caterpillar, 

 finding no place wherein to prepare for its change, 

 dies without having effected it. 



At the end of the third or fourth day, the worm 

 generally completes its task, and has formed its 

 cocoon, which, in size and shape, is like that of a 

 pigeon's egg. It is, however, but seldom that it 

 attains so large a size. The following figure repre- 

 sents the cocoon upwards of two-thirds the usual 

 size, with part of the floss silk removed : 



The operation of spinning, and the emission of so 

 large a quantity of silk, uncompensated by food. 



