THE SILK- WORM. 21 



days ; changing, four days ; from the fourth change to the 

 period of beginning to spin, eight days; spinning, five days. 



When the caterpillar is about to change its skin it ceases 

 to eat, holds its head up stiff, and appears ill and sulky ; 

 the new head is plainly to be discovered through the trans- 

 parent skin, behind the old one, and rather of a triangular 

 shape the apex of the triangle being uppermost ; after re- 

 maining in this state two or three days, as above stated, the 

 skin opens behind the head, which cracks longitudinally, 

 and is cast with the skin ; the caterpillar then twists itself 

 from side to side, and writhes about, while the skin gradu- 

 ally slips from the body and comes off at the tail. 



Whilst the silk-worms are feeding, they should be kept 

 very clean and abundantly supplied with fresh leaves; open 

 trays, made of pasteboard, are very convenient for holding 

 them; and from these, if supplied with food, they never 

 wander. Care should be taken to preserve silkworms from 

 birds and mice, both of which are excessively fond of them; 

 the influence of the sun is highly injurious to them, as are 

 also cold north and east winds ; but plenty of air, in warm 

 weather, is beneficial. The leaves should be given to the 

 caterpillars perfectly dry; if brought from a distance, they 

 preserve their freshness for many days in a tin box, or on 

 the cold bricks or stones of a cellar. After the fourth 

 change the silk-worms require constant watching ; twice a 

 day they should be carefully looked over, and those ready 

 to spin picked out and placed in little cells, made of writ- 

 ing-paper, about as large as one's thumb, open at one end 

 and closely screwed up at the other ; these paper cells may 

 be pinned to lines crossing a room, and placed touching 

 each other on the line. 



The period of a silk-worm's being ready to spin is plainly 

 indicated by its ceasing to eat, and becoming suddenly more 

 transparent and of a yellow colour; it will also begin to spin 



