454 



SILK 



domesticity, it U capable of being reared anil 

 managed in a way which would otherwise be 

 impossible. 



Rearing of Silkworms. It is of the first conse- 

 quence in the production of silk that one of the 

 s|H-cies of mullierry should be cultivated, and that 

 it should he .-ci favourably situated as to climate 

 that it is in readiness for feeding the worms. The 

 species best adapted is the white mulberry, Mortis 

 alba. The extreme lateness of season at w hich the 

 black mulberry produces its leaves prevents its 

 employment generally, besides which it will not 

 bear the loss of its leaves BO well. It is said that 

 in some parts of China the silkworm is easily 

 reared upon the trees in the open air. So little 

 has it a tendency to wander far from the place of 

 its birth, if foot! be at hand, that it only requires a 

 warm, dry atmosphere to bring it to perfection ; 

 but usually, even in China, and in all other 

 countries, it is thought desirable to raise the silk- 

 worm in properly arranged buildings, and to supply 

 it with mulberry leaves gathered from day to day. 

 In India, China, and other tropical countries the 

 eggs hatch readily at the proper time by the 

 natural heat; hut in southern Kurope artificial 

 heat is almost always required ; formerly the heat 

 of fermenting dung was found serviceable, and the 

 warmth of the human body was also used, the 

 eggs being carried in little bags in the bosom of 

 tne cultivator; but now they are regularly hatched 

 by stove-heat, beginning with a temperature of 64 

 F 1 ., which is gradually increased through ten days 

 to 82, at which it is maintained until the eggs are 

 hatched. Experience has shown that the o|>eration 

 is facilitated by washing the eggs in the tirst place 

 with clean water ; and some cultivators also wash 

 them in wine, the value of which is very question- 

 able. Washing is found to remove a certain gum- 

 niiness and other impurities from the eggs which 

 would otherwise impede the hatching. When the 

 silkworms have been regularly developed as above 

 described, it is usual to place above tne trays con- 

 trivances for the caterpillar to spin within. In feed- 

 ing the worms care is taken so to distribute the food 

 on tin- shelves or in the trays that the insects shall 

 not crowd together ; and for this reason the most 

 careful cultivators chop the leaves small, and strew 

 them very evenly about. Great care is taken not 

 to let tin; worms of one hatch mix with those of 

 another, unless of exactly the same age, otherwise 

 the stronger insects would deprive the younger of 

 their food. Many other niceties of attention are 

 required, which altogether render the successful 

 rearing of silkworms a matter of much anxiety and 

 lalxmr. 



Silkworms ura subject to various 

 diseases. In nil about fifteen have been defined, 

 but the most ini|Kirtiint., which only need mention 

 here, me Mnxi-nnliiie, I'ebrine, Flac.herir. iliittim; 

 and '.'/.% vi , ,, . Miumrdine is the result of the 

 growth on the silkworm of a microscopic fungus 

 named BotrytitbtutiaiM, Thesporesof tlris minute 

 fungus are not larger than the two milliemes of a 

 millimetre. They are carried by the air, and fall- 

 ing on the niiillMTry leaves or on the worms cause 

 the di-ea-c. \\orins all'cctcdwith mnscardine die 

 before arriving at the moth. In the magnaneries 

 where the disease, is present or is suspected they are 

 daily fumigated with sulphurous acid gas (fumes of 

 snlphuri, which kills the spires, lint doe- not hurt 

 the worm. 1'ilirim- is the most im|>ortant disease. 

 Worms affected with it are without ditlienlty de- 

 tec ted ; amongst other well known signs by the 

 iinee of blackish spots on the skin. 'This 

 - i- the consequence of a cm pn-de or bacillus, 



which. 01 having entered the worm, multiplies 



rapidlv. The interior of the liody of a moth is 

 often found to be quite full of corpuscles. Pebrine 



is found in all the life-stages of the insect. Preven- 

 tion is the remedy laid down by M. 1'asto'iir, and in 

 all well-managed rearing- houses the microscope U 

 employed to examine the eggs, when those found 

 to be pebrinispd are rejected. This method, com- 

 bined with greater cleanliness, dessication, and 

 fumigations of chlorine, has been so successful l\ used 

 since 1865 that pebrine has nearly disappeared in 

 a number of localities in France ami Italy where 

 previously sericulture had l>ecome almost extinct, 

 and it now only exists where these precautions 

 are not sufficiently observed. Flacherie is a deadly 

 and contagious disease, and is the result of bac- 

 terial growth of a vibrionic nature. The worms 

 are attacked in their last stage, having arrived at 

 their full size; they languish, die, and decom|K>se 

 rapidly, a whole chamber sometimes perishing in a 

 day. Pasteur has fully studied this disease, and 

 has jxnnted out preventive remedies. It is gener- 

 ally the result of other diseases and the want of 

 proper precaution, especially as to the careful con- 

 servation of the eggs from the lining of them to 

 the time they are hatched. Hultinf is a disease 

 of the same character, and is probably only a 

 modification of flacherie. Gratserie is of less 

 importance than the other diseases; but it is 

 interesting and not very well understood. A 

 few worms will frequently be found in the midst 

 of healthy ones, which are evidently ailing, crawl- 

 ing slowly, with a glossy skin, becoming thinner 

 and longer. In the yellow races the colour becomes 

 bright, and in the wnite races an unhealthy milky- 

 white appearance, and through the skin there 

 exudes a dirty liquid which under the microscope 

 is seen to contain a multitude of many-sided 

 globules, probably albuminous. A cold, stagnant, 

 or damp atmosphere, or a too crowded chamber, 

 favours the commencement of this disease, which 

 is neither hereditary nor contagious. 



Preparation of Silk. When the cocoons are com- 

 pleted, which is known by the absence of any 

 sound within, they are carefully sorted, and a 

 certain number are kept for breeding. The sexes 

 are readily known by the difference of shape as 

 well as of size. The French growers sort them 

 into several varieties ; those which are less coin- 

 pact, or in which the worm has died a fart known 

 by external indications being separated from the 

 good ones. When the sorting is finished, the 

 cocoons are placed in an oven with a gentle heat, 

 which kills the enclosed chrysalis otherwise they 

 would all Income perforated by the insect eating 

 through; they are then prepared for winding by 

 first removing the flossy covering, which is often 

 somewhat hard and compact. The cocoons are 

 placed in basins of water, keiit warm by charcoal 

 fires, or in the larger establishments by steam. 

 This softens the natural gum which coats the silk, 

 and loosens the \arious coils of silk adhering 

 together in the cocoon. The operator then takes 

 :\ small bat (age brush made of I wigs and stirs 

 them alxmt irr the water. This catches the outside 

 portions of the cocoon, from which the reelahl 

 thread is gradually unwound. From three to five 



of the nds are taken and united into one tin end, 



which is passed through a polished metal or; 

 eye in the reeling machine. In large filatures or 

 silk establishments complex machinery is used for 

 winding: hut iceling apparatus of greater sim- 

 plicity is used by the Chinese, East Indians, and 

 others. In all cases, however, the principle is the 

 same. The plan most generally adopted in Italy 

 is shown in fig. 'J. 



(Jreal care and skill are- required ill reeling silk 

 from the cocoons, liecause, although the reeler 

 starts with four or five or six cocoons, not orrh 

 their individual threads apt to break. l>ut they am 

 not all of the same length, so that one will run ou* 



