We now have to deal with a fiber which is very different in structure and physical characteristics from any other of those commonly used. In origin, although an animal fiber, silk differs from wool and hair in being the secretion of an internal gland of the silkworm, while wool is an epidermal appendage. Other worms and spiders produce a similar secretion, but only the silkworm has furnished us with a fiber strong enough to be spun into thread and of such a nature that it is prized above all other textile materials.
The use of silk by man does not, like the other textile industries, date back before the dawn of history. It has been a comparatively recent development. Chinese records tell us that in 2700 B.C. the Empress Se-ling-chi investigated the silkworm cocoon, reeled the silk filament from it, spun thread, and had it woven into garments. For many hundreds of years the Chinese carefully guarded their secret. At first only the royal family carried on the industry, but gradually it spread and became national. Chinese silks were carried all over Asia, but the process of making them was still kept secret, while to carry the eggs of the silkworm out of the country was punishable by death. As a result, although silk of some other varieties was produced in neighboring countries of the Far East by carding the fibers from the cocoon, it was not until about the fifth century A.D. that the process of reeling was known outside of China.
The Emperor Justinian, 555 A.D., is said to have bribed two Nestorian monks to bring some silkworm eggs from China. They accomplished this by concealing the eggs in the hollows of their bamboo staffs. Silk culture in the Levant dates from about this time. Through the Moors sericulture was brought into Spain about the ninth century, and by the twelfth, century it had reached Italy, where it gradually developed until it became a national industry. France began sericulture during the thirteenth century, and in the sixteenth century some Flemish weavers brought the industry to Spital-fields in London. It was encouraged by royalty in both England and France, but the culture in England has never been very successful. Thus it was more than four thousand years from the time silk reeling was first discovered until it had spread over Europe. Silk fabrics, however, were an important article of commerce as early as in the days of the Roman Empire.
In 1838 Mr. Samuel Whitmarsh introduced sericulture to America, and repeated efforts have been made by individuals and by the government to encourage the industry in various parts of this country, but none of these have met with any marked success. Beginnings were made in Connecticut and Pennsylvania, but both these enterprises were cut short by the untimely freezing of the mulberry trees upon which the silkworm feeds. A recent attempt in Utah is proving unsuccessful because of a lack of skilled labor to reel the cocoons. The hope that communities where the women and children have no employment might take up this industry to increase their incomes seems to be vain. The greatest difficulty, apparently, is in the reeling of the cocoons. That this is not the only difficulty is shown by the fact that even when the government set up a filature to carry on this work, the returns from the silkgrowers were very small. The cheapness of labor in silk-producing countries makes it apparently impossible for the United States to compete in this part of the industry. Better organization and more skilled labor might lessen the difficulty, but since the silk is of rather inferior quality, and has been produced at a cost of four or five dollars a pound, while imported raw silk can be bought for from four to eleven dollars a pound, the outlook is not encouraging. It should be noted, however, that at the present time one-third of all the silk cloth manufactured in the world is made in this country from raw silk imported from southern Europe and Asia.
The countries in which silkworm cultivation is most successful are Italy, France, Spain, Austria, China, Japan, and India. The French and Italian silks are better reeled than much of the Chinese and Japanese, as these countries do not always use the most improved machines.
There are two distinct types of silk produced, that from the cultivated silkworm, or Bombyx Mori, carefully reared and fed on the leaves of the white mulberry tree, and that from several varieties of wild silkworms which are not carefully reared and which feed on other kinds of trees. The cultivated silk is as a rule finer and more even than the wild, and may be much more readily spun from the cocoon. The wild silks, however, furnish an attractive variety of fabric, commonly known as pongee or tussur. Japan, China, and India all produce these wild silks.
The silk industry, although not nearly so large as the cotton or woolen industries, is important, in that it provides us with a beautiful fiber which has been unequaled in fineness, luster, and strength. As has been said, this industry is most successful where labor is very cheap, because of the large amount of hand work required in the culture of the worms and in the reeling of the silk from the cocoons. Necessarily, the cultivation is restricted to countries where the mulberry tree will flourish.