SILK CULTURE. 907 



have not this natural gum. As the hatching point approaches, the egg becomes lighter in 

 color, which is due to the fact that its fluid contents become concentrated, as it were, into 

 the central, forming worm, leaving an intervening space between it and the shell, which is 

 semi-transparent. Just before hatching, the worm within becoming more active, a slight 

 clicking sound is frequently heard, which is, however, common to the eggs of many other 

 insects. After the worm has made its exit by gnawing a hole through one side of the shell, 

 this last becomes quite white. Each female produces on an average from three to four 

 hundred eggs, and one ounce of eggs contains about 40,000 individuals. It has been 

 noticed that the color of the albuminous fluid of the egg corresponds to that of the cocoon, 

 so that when the fluid is white the cocoon produced is also white, and when yellow the cocoon 

 again corresponds. 



The Larva or Worm. The worm goes trough from three to four moults or sicknesses, 

 the latter being the normal number. The periods between these different moults are called 

 &quot;ages,&quot; there being five of these ages, including the first from the hatching and the last from 

 the fourth moult to the spinning period. The time between each of these moults is usually 

 divided as follows: The first period occupies from five to six days, the second but four or 

 five days, the third about five, the fourth from five to six, and the fifth from eight to ten. 

 These periods are not exact, but simply proportionate. The time from the hatching to the 

 spinning of the cocoons may, and does vary all the way from thirty to forty days, depending 

 upon the race of the worm, the quality of the food, mode of feeding, temperature, etc. ; but 

 the same relative proportion of time between moults usually holds true. 



The color of the newly-hatched worm is black or daik gray, and it is covered with long, 

 stiff hairs, which, upon close examination, will be found to spring from pale-colored tubercles. 

 Different shades of dark gray will, however, be found among worms hatching from the same 

 batch of eggs. The hairs and tubercles are not noticeable after the first moult, and the worm 

 gradually gets lighter and lighter until, in the last age, it is of a cream-white color. When 

 full grown, it presents the appearance as indicated in the cut. It never becomes entirely 

 smooth, however, as there are short hairs along the sides, and very minute ones, not notica- 

 ble with the unaided eye, all over the body. 



The preparation for each moult requires from two to three days of fasting and rest, during 

 which time the worm attaches itself firmly by the abdominal prolegs (the 8 non-articulated 

 legs under the 6th, 7th, 8th, and 9th segments of the body, called prolegs in contradistinction 

 to the 6 articulated true legs under the 1st, 2d, and 3d segments), and holds up the fore part 

 of the body, and sometimes the tail. In the operation of moulting, the new head is first dis 

 engaged from the old skin, which is then gradually worked back from segment to segment 

 until entirely cast off. If the worm is feeble, or has met with any misfortune, the shriveled 

 skin may remain on the end of the body, being held by the anal horn; in which case the 

 individual usually perishes in the course of time. It has been usually estimated that the 

 worm in its growth consumes its own weight of leaves every day it feeds; but this is only an 

 approximation. Yet it is certain that during the last few days before commencing to spin, it 

 consumes more than during the whole of its previous worm existence. It is a curious fact, 

 first noticed by Quatrefages, that the color of the abdominal prolegs at this time corresponds 

 with the color of the silk. 



Having attained full growth, the worm is ready to spin up. It shrinks somewhat in 

 size, voids most of the excrement remaining in the alimentary canal ; acquires a clear, trans 

 lucent, often pinkish or amber-colored hue; becomes restless; ceases to feed, and throws out 

 silken threads. The silk is elaborated in a fluid condition in two long, slender, convoluted 

 vessels, one upon each side of the alimentary canal. As these vessels approach the head, they 

 become less convoluted and more slender, and finally unite within the spinneret, from which 

 the silk issues in a glutinous state and apparently in a single thread. The glutinous liquid 

 which combines the two, and which hardens immediately on exposure to the air, may, how 

 ever, be dissolved in warm water. The worm usually consumes from three to five days in the 

 construction of the cocoon, and then passes, in three days more, by a final moult, into the 

 chrysalis state. 



The f/OCOOn. The cocoon consists of an outer lining of loose silk, known as &quot;floss,&quot; 

 which is used for carding, and is spun by the worm in first getting its bearings. The amount 

 of this loose silk varies in different breeds. The inner cocoon is tough, strong, and compact, 

 composed of a firm, continuous thread, which is, however, not wound in concentric circles as 

 might be supposed, but irregularly, in short figure of eight loops, first in one place and then 

 in another, so that in reeling several yards of silk may be taken off without the cocoon turn- 



