110 NATURAL HISTORY READER. 



scientiougly of its task, it does nothing but eat, digest, and 

 sleep. In about five days this devouring appetite ceases ; 

 the little worm becomes almost motionless, hangs itself by 

 its hind feet, raising and holding a little inclined the 

 anterior part of its body. This repose lasts twenty-four, 

 thirty-six, or forty-eight hours, according to temperature ; 

 then the dned-up skin splits open behind the head, and 

 soon along the length of the body. The caterpillar comes 

 out with a new skin, which has been formed during this 

 sleep. 



3. The process of insects shedding their old skin and 

 emerging in a new one is usually termed moulting, but in 

 silk-culture it is termed sickness; for this is a critical 

 period in the life of a silk-worm, and many of the weaker 

 ones do not survive it. Before reaching maturity, the skin 

 is changed four times, in periods varying from three to 

 eight days, the worm eating voraciously after each moult- 

 ing, and becoming nearly dormant for a brief period before 

 the next change. After the skin is shed for the last time, 

 the growth becomes very rapid, and maturity is reached in 

 about ten days, giving the insect a life of about thirty-two 

 days in the larva state. 



4. At this point it ceases to eat, and the alimentary 

 canal is entirely emptied of food ; it appears restless, 

 wanders about, and seeks to climb. When furnished with 

 a proper kind of branch, it mounts upon it, and, choosing 

 a convenient place, it hangs itself by its hind feet, and 

 soon through its spinner a thread of silk makes its appear- 

 ance. This is at first cast out in any direction, and forms 

 a collection of cords, which 'shall attach the cocoon to be 

 spun to the surrounding twigs. Next the form of the co- 

 coon is outlined, and then for some hours we can see the 

 worker performing his task through the transparent gauze 

 with which he surrounds himself. Little by little this 

 gauze thickens and grows opaque, until finally it becomes 



