THE SILKWORM. 



509 



into silk. The feeding these worms, the 

 gathering, the winding, the twisting, and the 

 weaving their silk, is one of the principal 

 manufactures of Europe ; and, as our luxuries 

 increase, seems every day to become more and 

 more necessary to human happiness. 



ring. These feet may be termed holders. There is also 

 a kind of tail on the upper part of the last ring but one. 



At the end of the period above stated, the worm's 

 desire for food begins to lessen, though it continues to 

 nibble the leaves, which it scatters about; its colour is 

 now of a light green ; it is very restless and uneasy, 

 erects its head, and moves from side to side in a circular 

 manner, seeking a corner where it can commence its 

 labour of forming its cocoon, before which, however, the 



body becomes firmer, more glossy, and somewhat trans- 

 parent towards its head ; it also lessens in size. 



It may not be out of place to mention here from 

 whence the silk proceeds ; The silk is secreted in the 

 form of a fine yellow gum, in two long slender vessels, 

 one on each side of the body. This silky material, when 

 drawn from the orifices beneath the mouth, appears to be 

 one thread, but is, in fact, composed of two fibres, which 

 are extracted from the orifices, and brought together by 

 means of two hooks placed in the mouth. 



The worm, having fixed upon some corner that will 

 suit its purpose, commences the labour by spinning thin 

 and irregular threads, so as to support its future dwel- 

 ling ; it then forms upon these a loose structure of an 

 oval shape, which is called floss silk ; in the three fol- 

 lowing days it forms a firm and consistent yellow ball, 

 the anterior of which is smeared with a peculiar gum, 

 so as to shield it against the rain and various changes 

 of temperatures. The filament is not spun in regular 

 concentric circles, but in stops, going backwards and 

 forwards with a sort of waving motion, which the 

 worm effects by means of its fore feet while it remains in 

 the interior. 



Isnard, an old author, affirms, that the length of the 

 silk of one cocoon, when drawn out, will measure six 

 miles, that is, 10,565 yards ; but Count Dandolo says, 

 the probable length is 625 yards ; other authors state it to 

 be about 400 yards, while Pullein says the average length 

 is 300 yards. The latter author thus writes ; " There 

 is scarcely anything among the various wonders which 

 the animal creation affords, more admirable than the 

 variety of changes which the silkworm undergoes ; but 

 the curious texture of that silken covering with which it 

 surrounds itself, when it arrives at the perfection of its 

 auimal life, vastly surpasses what is made by other ani- 



There are two methods of breeding silk- 

 worms ; for they may be left to grow, and to 

 remain at liberty upon the trees where they 

 are hatched ; or they may be kept in a place 

 built for that purpose, and fed every day with 

 fresh leaves. The first method is used in 



mals of this class. All the caterpillar kind do, indeed, 

 undergo changes like those of the silkworm, and the 

 beauty of them in their butterfly state greatly exceeds it j 

 but the covering which they put on before this change 

 into a fly is poor and mean, when compared to that 

 golden tissue in which the silkworm wraps itself. They, 

 indeed, come forth in a variety of colours, their wings 

 bedropped with gold and scarlet, yet are they but the 

 beings of a summer's day; both their life and beauty 

 quickly vanish, and they leave no remembrance after 

 them, but the silkworm leaves behind it such beautiful, 

 such beneficial monuments, as at once record both the 

 wisdom of their Creator and his bounty to man." 



The worm, having finished its cocoon, rests awhile 

 from its labour, and at the same time decreases in size 

 and bulk ; it then throws off its last skin, and undergoes 

 its metamorphosis into a chrysalis, which is of a chest- 

 nut colour, and smooth. The time during which the 

 insect remains in this state of lethargy is generally from 

 fifteen to thirty days, as it is influenced by the tempera- 

 ture of the climate in which this metamorphosis is about 

 to take place, viz. in England it requires thirty days, in 

 France twenty-one, in Spain and Italy eighteen to twenty, 

 and in India only eleven days. 



After the above stated periods the insect breaks through 

 the upper end of the cocoon, by emitting a liquid from its 

 mouth, which moistens the gum with which it has lined 

 the interior of its chamber. After this operation, it ap- 

 pears as the perfect insect, with four wings of a grayish 

 white colour, with two transverse undiriated bands on 



the fore and wings. The stationary arid sluggish habits 

 of these moths are not entirely owing, as is generally 

 supposed, to the insect being confined within certain 

 limits during the period of several generations ; as these 

 habits are also common to others of the same family, 

 which are only found in certain local districts ; and thus 

 proves that this valuable insect partakes of the same 

 mode of life in the domestic as in the wild or natural 

 state. Their life continues for the short period of two or 

 three days, in which time they are wholly occupied in 

 securing the continuance of their kind. Various ac- 

 counts are given as to the number of eggs which the 

 female lays, some stating 250, while others mention 400 

 to 500 as the usual number. Natural History of Insects, 

 London, 1835. Vol. If. 



