SILK 101 



lar gets its growth in four or five weeks. Then the 

 screens are set with sprigs of heather, on which the 

 worms climb when the time comes for them to spin 

 their cocoons. They settle themselves one by one 

 amid the sprigs and fasten here and there a multi- 

 tude of very fine threads, so as to make a kind of net- 

 work which will hold them suspended and serve them 

 as scaffolding for the great work of the cocoon. 



"The silk thread comes out of the under lip, 

 through a hole called the spinneret. In the body of 

 the caterpillar the silk material is a very thick, 

 sticky liquid, resembling gum. In coming through 

 the opening of the lip, this liquid is drawn out into 

 a thread, which glues itself to the preceding threads 

 and immediately hardens. The silk matter is not 

 entirely contained in the mulberry leaf that the 

 worm eats, any more than is milk in the grass that 

 the cow browses. The caterpillar makes it out of 

 the materials of its food, just as the cow makes milk 

 of the constituents of her forage. Without the cat- 

 erpillar's help man could never extract from the 

 mulberry leaves the material for his costliest fabrics. 

 Our most beautiful silk stuffs really take birth in 

 the worm that drivels them into a thread. 



"Let us return to the caterpillar suspended in the 



midst of its net. Now it is working at the cocoon. 



Its head is in continual motion. It advances, re- 



9, ascends, descends, goes to right and left, \vhilr 



1< -it ing escape from its lip a tiny thread, which rolls 



itself loosely around the animal, sticks itself to the 



ad already in place, and finishes by forming a 



continuous envelope the size of a pigeon's egg. The 



