1356 



ARBORETUM AMD FKUTICETl'M. 



PART III. 



to Count Damlolo, a hundred trees, great and small, will furnish 7,000 Ib. of 

 . and these will be sufficient for 200,000 silkworms. 



t of the Silkwoi-m. The silkworm is the popular name for the larva, or caterpillar, of 

 the inotii known'to entomologists as the/fombyx mori Fab. ; a native of China, which was introduced 

 into Kurope, as we have before seen, in 5:10. Fig. 12-2-1. represents this insect, in its various stages, 



1224. 



of the natural size: a, the eggs, which, when good, arc of a pale slate or dark lilac colour; b 

 is the larva, or caterpillar, when full grown ; c is the insect in its chrysalis state, after the silk has 

 been removed ; d is the male imago, or perfect insect; and e, the female. When full grown, the 

 larva is nearly Sin. long, of a yellowish grey colour, with a horn-like process on the last joint of the 

 body. The eggs, in Britain, may be purchased in Covent Garden Market, at 105. per oz. ; and can- 

 should be taken that they are of the proper colour; because those that are of a pale yellow 

 colour are imperfect. They are preserved in a cool place, that is, in a temperature of from 10 to 12 

 Reaumur (55 to 59 Fahr.), till wanted for use, and will retain their vitality upwards of a year. 

 To hatch them, a temperature of 86 Fahr. is required ; for which purpose, in most parts of 

 Europe where the silkworm is cultivated, the rooms used for that purpose are heated by stoves; 

 though in the East Indies, in the Islands of France and Bourbon, c., and in the southern 

 parts of the United States, the natural temperature of the air is found sufficient. The houses in 

 which the insects are kept are built with numerous windows, for the admission of air; and fur- 

 nished with tables or shelves, on which the insects are kept. These shelves have movable ledges, 

 of 1 in. or more in height, on each side, to confine the insects ; and several stages of them may bo 

 formed one above the other, if care be taken that they are not attached to the wall, in order to admit 

 a free circulation of air on every side. When the mulberry begins to unfold its leaves, it is time to 

 commence the hatching of the eggs. These should be placed on the shelves in the temperature 

 mentioned ; and when they begin to turn white, which will be in about ten days, they should IK- 

 covered with sheets of writing paper, turned up at the edges, and pierced full of holes with a large 

 knitting needle. On the upper side of the paper should be laid some young twigs of mulberry, 

 which the insects will smell ; and, crawling through the holes in the paper, will begin to eat as soo'n 

 as they are hatched. As fast as these twigs become covered with insects, they are carefully taken 

 up and removed to another shelf, where they are placed on whity-brpwn or any absorbent paper, 

 about one to every square inch. The silkworm changes its skin four times before it spins its cocoon. 

 Its life is thus divided into five ages ; during t lie first of which it is fed with chopped or young 

 leaves, fresh ones being given as soon as it has eaten what it had before. At this time it frequently 

 appears to sleep, when it should on no account be disturbed. When the silkworm is in its second 

 age, it may be fed with young leaves entire, or old ones chopped small ; a great part of this age also 

 is passed in sleep. During the third age the silkworms become more lively and vigorous, and they will 

 devour full-grown leaves without cutting. In the fourth age the silkworm changes to a flesh colour, 

 and eats greedily. In the fifth age the silkworm will eat the coarsest leaves, and it should be fed 

 abundantly night and day, and have plenty of air and warmth. Each change is preceded by a day or 

 two's apparent sickness and want of appetite in the insect, which becomes torpid before the change 

 of its skin takes place. During the whole period of the silkworm's life, the litter made by the waste 

 leaves, &c., must be frequently removed, the insects being attracted toonecorner of their shelves with 

 some fresh leaves, while the other parts are cleaned. When the caterpillars cease to eat, and run to and 

 fro, frequently looking up, it is an indication that they are preparing to make their cocoons. They 

 will now have become transparent, of a clear pearly colour, and the green circles round their bodies 

 will have assumed a golden hue. Twigs of oak, tufts of dandelion, rolled up shavings from the 

 cabinet-maker, cornets of paper, or sprigs of alaternus, phillyrea, heath, or broom, as may be most 

 convenient, are then placed on the tables or shelves, to serve as a support for the insects ; the tables 

 or shelves having been previously cleared of all litter, and the branches, or other materials, having 

 been so arranged as to give the insects a feeling of security. They then immediately begin to make 

 their cocoons, which are exuded in threads from the mouth, and which are generally completed in 

 from four to seven days. When the insects have done working, the cocoons are taken from the 

 twigs, and sorted : those that are double, or in any way imperfect, are thrown aside ; a certain num. 

 bcr are selected to breed from, and the rest are set apart for reeling the silk. The first operation 

 with these last is to kill the insects enclosed. This is performed, in Italy, by exposing the cocoons to 

 the heat of the sun for three days, from 10 o'clock A. M. to 5 o' clock p. M., when the thermometer 

 stands at 88 Fahr. In France they are put into bags or baskets, and enclosed for half an hour in 

 ovens heated to 88 ; but in America they are generally placed in sieves or boxes, having perforated 

 bottoms; these are covered very closely with a woollen cloth, and then placed over the steam 

 either of boiling water, or boiling whiskey or rum. (See New York Fnrm. t vol. vi. p. ITi. ) The in. 

 sects being killed, and the cocoons cleared of the external floss (which is manufactured under the 

 name of floss, or spun, silk), they are thrown by handfuls into basins of pure soft water, placed over 

 small furnaces of charcoal fires. When the water is almost at the boiling point, the cocoons are sunk 

 with a whisk of broom or peeled birch under water for two or three minutes, to soften the gum and 

 loosen the fibre. This, however, is unnecessary when they have been killed by the steam of boiling 



