688 



SILKWORM. 



numerous trials, it was found that the climate of the 

 British Isles was too humid for the production of 

 useful silk, and the company was finally broken up. 

 It has been observed, by way of accounting for the 

 failure of this and other undertakings of a similar 

 nature in this country, that although " the mulberry- 

 tree is found in different climates; yet the juice of 

 the leaves grown in the north is much less suitable 

 for the production of good silk than that of the south. 

 In this respect the mulberry-leaves and silk differ as 

 much as wines according to the climate and soil in 

 which they are produced. In general, every cli- 

 mate and soil that will grow good wheat will pro- 

 duce large succulent mulberry-leaves ; but these 

 leaves will, in many cases, be too nutritive ; that 

 is, they will have too much sap and too much sub- 

 stance and succulency. The wild mulberry with 

 smooth leaves answers better for such a soil than the 

 grafted mulberry with large leaves. A general rule, 

 and one to be depended on is, that the mulberry, to 

 produce the best silk, requires the same soil and ex- 

 posure that the vine does to produce the best wine. 

 Experience has proved that silk-worms nourished by 

 leaves gathered from a dry soil succeed much better, 

 produce more cocoons, and are less subject to those 

 diseases which destroy them, than those which have 

 been nourished by leaves produced by an extremely 

 rich soil." (Journ. d'Agric. des Pays Bas, quoted in 

 Arboretum Britannicum, from which some of the pre- 

 ceding historical details have been abridged.) How 

 far these objections are entitled to full weight, and 

 how far any other plans (such as those suggested by 

 the Rev. F. W. Hope in a Memoir upon Silk Insects, 

 contained in the first volume of the Transactions of 

 the Entomological Society) may succeed in this 

 country, must be determined by future experiments ; 

 in the mean time it is certain that the severity of the 

 climate cannot be an obstacle : even the climate of 

 Pekin or China is much severer than that of Scotland ; 

 and that in America not only has the growth of the 

 silk been effected, but double crops in the course of 

 a single season have been obtained. It is objected, 

 however, that the number of hands requisite, and the 

 high rate of wages in this country, would be an ob- 

 stacle ; but children and old persons might be em- 

 ployed, especially in the rearing houses, which should 

 be kept at a certain temperature. 



A short account of the plans adopted in rearing 

 the silk-worrns in an artificial state will close our ac- 

 count of the Bombyx mori. Instead of the eggs being 

 allowed to hatch at their own fixed time, they are 

 preserved in a temperature of from 55 to 60 Fahr. 

 To hatch them a temperature of 86 Fahr. is required, 

 so that heated rooms are necessary ; but in the 

 southern parts of China, the East Indies, &c , the 

 natural temperature of the air is sufficient for this 

 purpose. The houses in which the insects are kept 

 are built with numerous windows for the admission of 

 air, and furnished with tables or shelves on which 

 the insects are kept ; these shelves have moveable 

 ledges of an inch or more in height to secure the 

 insects, and several stages are arranged one above 

 another, care being taken to place them at a distance 

 from the wall, so as to ensure a free current of air, 

 which is essentially requisite, as well as great clean- 

 liness in the removal of dead and unconsumed leaves 

 and other litter. Indeed, the great care required to 

 preserve them clean and warm is curiously shown in 

 the following extract from an old Chinese work upon 



the subject : " The place where their habitation is 

 built must be retired, free from noisome smells, cattle, 

 and all noises ; a noisome smell.or the least fright, makes 

 great impressions upon so tender a breed ; even the 

 barking of dogs and the crowing of cocks are capable 

 of putting them in disorder when they are newly 

 hatched. For the purpose of paying them every 

 attention an affectionate mother is provided for the 

 worms, who is careful to supply their wants ; she is 

 called Isan-mon, mother of the worms. She takes 

 possession of the chamber, but not till she has washed 

 herself, and put on clean clothes which have not the 

 least ill smell ; she must not have eaten any thing 

 before, or have handled any wild succory, the smell 

 of which is very prejudicial to those tender creatures ; 

 she must be clothed in a plain habit without any 

 lining, that she may be more sensible of the warmth 

 of the place, and accordingly increase or lessen the 

 fire; but she must carefully avoid making a smoke or 

 raising a dust, which would be very offensive to these 

 tender creatures, which must be carefully humoured be- 

 fore the first time of casting their slough." During the 

 first twenty-four hours of the creatures' existence, the 

 patient Chinese feeds the objects of her care forty- 

 eight times a day, or once in every half hour; during 

 the second day and night thirty times, and so on, 

 reducing the number of meals as the worms grow 

 older. 



According to Count Dandolo, 39,000 eggs weigh 

 an Italian ounce: five ounces produce from 150,000 

 to 195,000 silk-worms. These require 8-JoOlbs. of 

 grafted mulberry -leave?, and will produce b'OO Ibs. of 

 cocoons, which in common years will sell for 1000 

 Milan livres. In Persia silk-worms are permitted to 

 feed upon the boughs of the trees as well as the 

 leaves ; and it is asserted, though perhaps too loosely, 

 that in some countries of the south of Asia, no less 

 than twelve crops of cocoons are obtained in a year; 

 whereas in Europe only one crop is capable of being 

 produced. That crop, however, is so much more 

 abundant, that Count Dandolo is of opinion that one 

 good European crop equals in point of produce all 

 the crops of Asia. 



Soon after the cocoons are completed, a certain 

 quantity is set apart for breeding, and the rest are used 

 for silk, the enclosed insects being first destroyed, 

 either by exposing the cocoons to the sun for three 

 days when the temperature is not below 86 Fahr., or 

 bv being placed in ovens heated to the same tem- 

 perature, or by placing them over the steam of boil- 

 ing water or spirit. The floss silk is then removed, 

 and the cocoons thrown into water, which then is 

 almost suffered to boil, by which process the gum is 

 dissolved, and the fibres of the silk loosened, so that 

 the reeling of the silken thread is rendered very 

 easy. 



The following short estimate of expenses occurring 

 in the produce of five ounces of eggs will give an idea 

 of the proceedings of the silk-grower : 



Five ounces of silk-worms' eggs 

 Fuel wood for hatching them 

 8250 Ibs. of leaves . . 4ftl 

 Expense of gathering the leaves . 

 Shavings . ';"" 'V r '' : "-'*' 



Faggots and broom . .-n- il ' 

 Paper . . > ' : ' ''".1 

 Oil for lamps . '*&'M J %W*?ifl 



Milan 



Liv. Sou 



15 



1 15 



385 



90 5 



J6 



22 10 



J8 



9 



