At the end of this time the silkworms change to a clear pink or flesh colour, and look semi-transparent; they refuse food, become restless, and prepare to spin their cocoon. Care should be taken to raise the walls of their tray or they will climb over and be lost. The cocoon nest should now be prepared by twisting the corners of a piece of writing-paper, and raising its edges into the form shown in the illustration. A number of these should be prepared and fixed to a piece of tape, with their pointed ends downwards; and into each one a single worm should be placed when it refuses its food, and seems inclined to spin: it will then weave its web so as to leave a space within.
The cocoon consists of three layers of silk: the first is loose and flossy, and is of no use for the silk manufacture; the second is closer, the silk crossing from side to side; and the third is still finer, and is stuck firmly together, so as to form a compact inner coating.
When the cocoon is completed, the enclosed caterpillar once more casts its skin, with its head and jaws attached to it. It is now a conical chrysalis of the ordinary shape. At first the chrysalis, when opened, contains only a yellow fluid, but by degrees the parts of the moth appear, and in a fortnight or three weeks a swelling of the chrysalis indicates the approach of another change. A rupture down its back comes next, and the moth bursts through its coating into the hollow of the cocoon, and if left to itself would soon eat its way through.
The chrysalis, however, must be stopped from eating through the cocoon; and the silk must be wound. When, by shaking the cocoon, it is found to rattle, then it is time to wind the silk. The cocoon is placed in a cup of warm water, after the loose outward silk has been removed, and then, an end being taken, the whole filament may be wound off on a piece of card. The length of the thread of a cocoon varies from 600 to 1,000 feet.
When the silk is wound off the aurelia presents itself, and being put in a separate case, it remains motionless for about twenty days, when it appears as a pale yellow moth. The male soon dies; the females lay their eggs on the slips of paper provided for that purpose. They then soon die.
CHAPTER XIX.
THINGS BOYS CAN MAKE
A Way to Bind Magazines.—First, we must have a frame in which to stitch the sheets together. Here is mine in Fig. 1. I made it myself, and any handy lad can make one. The frame shown has an opening a foot long, so it is big enough to bind a book as long as that, or any smaller magazine. I have drawn it fitted with five strings, which would be the right number for a full-sized magazine; more or less strings are required according to the size of the book. They are, as may be seen, passed through holes bored opposite to each other above and below, and fixed tight with pegs. These strings are tapes ¼ inch wide, which mother or sister will supply.