122 INSECTS LEPIDOPTERA DIAGRAM 6. 



except the outer floss silk, is generally formed of one single 

 uninterrupted thread. It may measure 300 yards in length. If 

 the body of a silkworm is opened when it is about to spin, we can 

 easily perceive two long sacs, folded on themselves. They are 

 yellow, and are filled with a sticky substance, which is nothing 

 else than silk. It becomes solid, and winds off, as it issues into 

 the air. In some countries, these sacs are taken from the body of 

 the silkworm, unfolded, and allowed to dry. They thus obtain 

 strips of a true silk, which are much thicker than ordinary silk, 

 but these strips are always very short, and are chiefly used for 

 fishing-lines. 



When the cocoons are allowed to remain in the branches 

 where the worm has spun them, the moth emerges at the end of 

 about a fortnight, pushing aside and breaking the threads. Its 

 legs are furnished with hooks, with which it clings to objects. It 

 cannot fly ; though if a few generations of them are reared in the 

 open air, they recover the power of flight. It eats nothing, and soon 

 begins to lay its eggs. It is placed on sheets of paper or 

 cardboard, where it lays its eggs near each other, and then dies. 

 These eggs are the provision for the following year, and are 

 called seed in commerce. Great quantities are annually sold and 

 bought in all countries which produce silk, and they go to fetch 

 them from the most distant countries, where the silk is finer than 

 in Europe. 



But the moth, in emerging from the cocoon, spoils the silk and 

 breaks it. To prevent this, only a certain number of cocoons 

 are allowed to produce moths, and the chrysalides of the others 

 are killed by exposing them to heat. The cocoon can then be 

 reeled off entire, like a ball of silk, just as it has been spun 

 entire from a single end. For this purpose, it is put into boiling 

 water, after having rid it of the floss silk which surrounds it ; it 

 is rubbed with a soft brush to find the end, and when this is 

 found, there is nothing more to do than draw it gently off by 

 means of a winder, which generally winds off a great number of 

 cocoons at once. Several of these threads are put together to 



