Page:The New International Encyclopædia 1st ed. v. 18.djvu/215

* SILKWORM. 171 SILL. most attention in Europe, however, are An- ihcrna ynma-mai. from .Japan, commonly known as tlic ■yaina-mai' silkworm: Anlheriid pcnii/i, from Cliina; and P/iilosumia cynthia, from Japan, China, the Himalayas, Assam, and Java, which has been introduced into Europe and which has been acclimatized in the Eastern United States. Its larva is commonly known as the ailanthus silkworm, while the yamamai and periiyi silkworms are commonly known as oak silkworms. The yamamai silkworm is commonly raised in Japan and its cocoon is large, hea'y, and hand- soiiip. and of a yellowish-green color. It is readily reeled, and its silk ranks commercially next to that of the domestic silkworm. The silk is strong and valuable. It bleaches well and may then be dyed. Fewer threads are required to make a strand than with Bombyx mori, and the cocoons unwind with perfect ease by the ordi- nary process. The life of the worm lasts from 50 to 80 days, and it feeds on all kinds of oak, but prefers those of the white oak group. The pernyi silkworm has been cultivated in Europe with better success than the yamamai. It develops more rapidly, is double-brooded, and passes the winter in the chrysalis state. The cocoon is not so valuable, though ranking proba- bly third best among the diiTerent silkworm cocoons. The ailanthus silkworm is utilized extensively in North China. It has been known in Europe since the middle of the last century, and has been cultivated there as well as in the United States with perfect success. The cocoons, how- ever, cannot be reeled successfuHy, and their silk is utilized principally by carding processes. In the United States several species of silk- worm moths occur, and their caterpillars spin an abundance of silk of a strong and durable quality. The 'American' silkworm {Telea Poly- phemus) is a large moth of a buflf color, whose caterpillar feeds upon the leaves of many trees, including oak, willow, hickory, maple, apple, sycamore, and many others. The cocoon is formed of strong silk, which when unwound has a, glossy fibre. It is oval and closed at both ends, dense, and generally fastened to a leaf or leaves with which it sometimes falls to the ground. The fibres are intermixed and cemented ■with a gummy substance which when dry gives the cocoon a chalky appearance. The principal difficulty in reeling the cocoon is in the hard matter which binds the threads. This, however, may be softened, and no doubt the cocoon could be improved by a process of continued selection. The insect lias one generation each year in the Northern States and two in the Southern States, and passes the winter in the chrysalis state. The large luna moth (Tropwa lima) is a beau- tiful species of a delicate green color, with long tails to the hind wings, whose larva feeds on several forest trees and -nhose cocoon is less dense than that of the polyphemus moth. The cocoons of these two species have the same gen- eral characteristics as those of the yamamai silk- worm. Another native North American silkworm {CaUosfimia proniclhia) resembles in many re- spects the ailanthus worm. Its cocoon, like that species, is open and is in the same way diflicult to reel. It feeds on ash, sassafras, wild cherry, maple, lilac, birch, and other trees. The largest Vol. XVIII.— 12. of the American silkworms is the larva of Samia cccropia, a beautiful moth of a grayish brown color marked with reddish and yellowish spots and bands. The large green larva, which bears six coral-red tubercles on its thorax and smaller blue tubercles on its abdomen, feeds upon the apple and other rosaceous plants, as well as upon hazel, hickory, maple, willow, and honey-loeu.st. The cocoon is peculiar in being apparently double. There is a thick, wrinkled outer Layer which re- sembles strong brown paper and which covers an inner oval cocoon composed of the same kind of silk, but closely woven like that of the mulberry silkworm. Nearly related to this species are fiamia Gloreri, of the Eocky Mountain region; ^amia cohonha, of the North Atlantic States; and Samia rubra, from the Pacific States. In Mexico there are several large silkworm moths of the Saturnian group which produce quantities of silk, but it has not been commercially utilized or experimented with. There is another" group of moths belonging to the family Psychidie, in which the larva makes a large bag"of silk which it car- ries about with it to protect its soft body from the attacks of birds. A common American ex- ample is the bagworm (q.v.) or basket-worm. This silk has not been utilized except in China. BiBLiOGR.PHY. Consult: Riley, I'ourlh Annual Hcport folate Entomologist of Missouri (Jetl'cr- son City, 1872) ; Riley, "The JIulberry Silk- worm," in Bulletin No. 9, Division of Entomol- oyy. United States Department of Agrieulture (Washington, 1886) ; Kelly, "The Culture of the ilnlberry Silkworm," in Bulletin No. 39 (ib., 1003): Villon, La Soie (Paris, 1890); Verson and Quajat, // filugello e I'arte sericola (Padova, 189C). See Silk. SILKWORM GUT. A material used by anglers to form the hook end of a fish-line. Its advantages are its extreme tenacity and its trans- parency or invisibility in w-ater. " It is prepared from the viscid secretion to be found in the silk- worm (q.v.) just before it is ready to begin to spin. The grub is inmiersed in strong vinegar for several hours and the substance which, if it had lived, would have been spun into a cocoon, is forcibly drawn out from the dead worm. This thread is first soaked in cold water and then in a caustic solution. This loosens the outer covering, which is next removed. The silk is then dried in a shady place. If simply dried it will be of a yellowish hue; the pure white thread is produced by bleaching in sulphur fumes. The manufac- ture of gut strings is carried on in Italy and Greece, and other silk-growing coimtries. but particularly in Spain, the principal market being Valencia. It takes from 20,000 to 30,000 threads to make a pound, the first price for a pound being from .$25 to $30. SILL, Edward Rowland (1841-87). An American poet and essayist, born at Windsor, Conn. He graduated at Yale in 1801, resided till 1806 on the Pacific Coast, studied theology at Harvard, and after several years of teaching and literary work in the East was made principal of the Oakland, Cal.. High School (1871) and in 1874 professor of English in the University of California. He returned to the East in 1882. He wrote: Hermionc, and Other Poems; The Hermitage, and Other Poems (1807); The TVhhs of Milo, and Other Poems (1882). A posthumous selection embracing most of his bet-