WOOL AND OTHER ANIMAL FIBERS 251 it was introduced into India in the fourth century under the romantic circumstances of a marriage between Chinese and Indian royal families. At the request of Byzantine Emper- or Justinian in A.D. 552, two monks Wool and Other made the perilous journey and risked smuggling silkworm eggs out of China in the hollow of their bamboo canes, and so the secret finally left Asia. Animal Fibers Constantinople remained the center of Western silk culture for more than 600 years, although raw silk was also HORACE G. PORTER and produced in Sicily, southern Spain, BERNICE M. HORNBECK northern Africa, and Greece. As a result of military victories in the early 13 th century, Venetians obtained some silk districts in Greece. By the 14th century, the knowledge of seri- ANIMAL FIBERS are the hair, wool, culture reached England, but despite feathers, fur, or filaments from sheep, determined efforts it was not particu- goats, camels, horses, cattle, llamas, larly successful. Nor was it successful birds, fur-bearing animals, and silk- in the British colonies in the Western worms. Hemisphere. Let us consider silk first. There are three main, distinct A legend is that in China in 2640 species of silkworms—Japanese, Chi- B.C. the Empress Si-Ling Chi noticed nese, and European. Hybrids have been a beautiful cocoon in her garden and developed by crossing different com- accidentally dropped it into a basin of binations of the three. warm water. She caught the loose end The production of silk for textile of the filament that made up the co- purposes involves two operations: coon and unwound the long, lustrous Sericulture, or the raising of the silk- strand. She was eager to create a fabric worms, and the processing of the silk of the lovely fiber and prevailed on the filament from their cocoons. Emperor to let her try. She is said to The commercially cultivated silk- have developed the methods of reeling, worm species (which is actually a spinning, and weaving silk that form caterpillar—not a worm) is the Bom- the basis for the techniques used today. byx mori. The moths are made to lay Growing silkworms and producing their eggs on sheets of paper and, if silk were a Chinese monopoly for many they are to be for breeding, in cells. centuries. Death was the penalty for The eggs are kept cool and dry until trying to steal the secret. Silk fabrics spring, when mulberry trees have their are thought to have reached Europe leaves, on which the larvae feed. about 75 B.C., when a Roman general Then the eggs are hatched in an brought some home from China. By incubator or in the sun. A.D. 126, a ''silk road" nearly 6 thou- Villages of China and Japan have sand miles long was opened to enable community incubators, but the larger the transport of silk from China. At the silk farmers have their own facilities. end of the camel-train path was Da- Larvae are one-eighth to one-fourth mascus, the marketplace where East inch long and about as thick as a and West met. Silk cloth was in great hair when they emerge from the eggs. demand in Greece and Rome. During the 5 weeks to 2 months that By A.D. 300, the Japanese had the larvae eat, they grow about 70 learned about sericulture. Presumably times their original size, change skin 252 THE YEARBOOK OF AGRICULTURE 1964 4 times, and consume several thousand from the cocoons onto the reels. The times their own weight in mulberry number of filaments brought together leaves—perhaps 200 pounds to pro- depends on the fineness of the raw duce a pound of silk. silk thread desired. In their early stages, silkworms There may be 300 to 1,600 yards of must be fed five times during the day reelable filament on each cocoon. and twice a night. At full growth the They are so fine that a pound of silkworm may be 2 to 3.5 inches long. thread made of three to five filaments During this period, silk glands along together would reach a thousand miles. each side of the caterpillar's body are The amount of reelable silk and its filling with sticky fluid. When the quality depend on the care with larvae is full grown, it ceases to eat which the operations are conducted, and begins swinging its head about. the variety of silkworm, and the Then the silkworm farmer provides a region in which it is grown. cell for each in a framework, which The technology of silk produc- becomes the support for the cocoon. tion (except the reeling process) has Fluid issues from two spinnerets changed little over the centuries. In at the front of the silkworm's head, the beginning, reeling always was done forms into one strand, and is spun by hand. about the larvae in figure-8 patterns. Once the silk is removed from the At the end of this process, the silkworm cocoons, the remainder of the process- is about half of the weight that it ing at the filature consists of cleaning, was at the beginning. drying, and preparation into skeins A few carefully selected cocoons are for shipment to textile centers of the permitted to mature into moths that world. The product of the reeling are later to lay the eggs. Moths process is called by several names— develop from cocoons in 2 to 3 weeks. raw silk, silk yarn, silk thread, grege. Moths have no mouth and cannot eat An average batch of fresh cocoons and live only a few days. They mate, weighing i thousand pounds will yield and the female lays about 500 eggs. about 360 pounds of dried cocoons and Except for those selected to mature 137 pounds of filament, which in- for breeding, the life of the silkworm cludes raw silk and silk waste. is ended in the chrysalis stage by Something less than 10 percent of steam, boiling water, or dry heat. Japan's cocoon crop consists of double Cocoons are graded as to quality. cocoons, which produce dupion silk, The next step is reeling, which one cocoon produced by two larvae. usually is done by machinery at It is difficult to reel, although it pro- filatures, or reeling factories. duces a slubby yarn much in demand The cocoons are prepared for reeling for novelty fabrics. by the removal of an outer layer of The only other major type of silk floss by brushing after boiling in a produced commercially is the wild, tank. The equipment includes a uncultivated silk known as tussah. It reeling basin, a thread guide, a device comes from worms that feed on the for crossing the threads, and a reel, a leaves of oak, castor, cherry, and un- hexagonal drum of laths on which the cultivated mulberry. The filament is silk filaments are gathered. In the flat, hairy, and several times thicker reeling operation, a number of cocoons than silk from the Bombyx morí. are placed in warm water, which Several types of other wild silks are softens the gum that binds the tiny found in Japan, India, Asia, and in threads together. America and parts of Africa, but they The ends on several cocoons are are not of commercial significance. assembled, passed through a fine eye Attempts have been made to com- of glass, porcelain, or polished metal, mercialize production of spider silk. fastened to the reel, and so unwound It has been found to be not practical WOOL AND OTHER ANIMAL FIBERS 253 for textile uses, but is used for cross- 800 thousand pounds of thrown silk, lines for optical instruments. and about 7 million pounds of silk ^ea silk, sometimes called pinna silk fabrics and other goods. or fish wool, is obtained from certain Japan also exports silk cocoons, silk types of mollusks and is used in Italy waste, spun silk yarns (yarns made of and France for making braids. short silk fibers, usually waste) and Another silk product of commercial other types of made-up goods. It has importance is silk waste, which is been estimated that about 25 percent produced in the rearing of worms, the of the raw silk that is processed in reeling of raw silk thread, and the Japan eventually moves into inter- process of converting raw silk into national trade channels. yarn, thread, and fabric. Silk waste Japan's export trade in raw silk, may be 3.5 to 6.5 inches long and is silk fabrics, and silk products of other used for spun yarns. Lengths below kinds was valued at more than 100 3.5 inches are called noils, and are million dollars in 1962, about one- used mainly to mix with wool. half of which was raw silk. Other large Raw silk sometimes is used for weav- producers of raw silk also ship to ex- ing without further twisting, but it port markets. is generally advanced by throwing, The United States is the largest im- which consists of several operations: port market for raw silk, silk yarn, Cleaning, first twisting (also known as fabrics, and made-up goods. Other spinning), doubling (the twisting of leading silk-importing countries are two or more threads together), and the Italy, France, Switzerland, West Ger- second twisting. many, and Great Britain. Several of The first and second twistings are in these countries, particularly France opposite directions, and the number of and Switzerland, export large quanti- turns per inch is determined by the ties of made-up silk goods. use to which the silk yarn is to be put.