The silk is structureless secration in the form of cocoon consisting of continuous filament. There are two varieties of silk i.e. domesticated silk and wild silk. Domesticated silk can be cultivated and manufactured for textile purpose. On the other hand, wild silk can be produced from uncultivated caterpillar. Caterpillar through its gland secrates colorless fluid. This color-less fluids, on contact with air hardens and forms composite threads. Mostly each caterpillar has two aqueduct glands and also two spinning glands. These four glands are symmetrically located on each side of the silk worm near the head and secrete two kinds of fluid. Depending of the type of silk that is to be made the spider mixes the fluid from the different glands and regulates the speed and volume of release. The liquid from two larger glands converges at one opening in the head to produce 'Fibroin'. These opening are generally known as worm's spinnerette. The flow i.e. fibroin joined by the secretion of two other symmetrically located glands, which produces silk glue or 'sericin'. The fluid solidifies in contact with air and forms a double filament, known as 'Bave'. Each single filament is called a 'Brin'. So each brin consists of a central portion i.e. fibroin covered with sericin. This concept of secretion leads to the discovery of man-made fibers. This paper throws light on such kind of silk fiber.
Spider silk is protein fiber spun by spiders. It is also known as "Gossamer". Spider silk is an extremely strong material and is on weight basis stronger than steel. It has been suggested that a pencil thick strand of silk could stop a Boeing 747 in flight. Spiders use their silk to make webs or other structures, which function as nets to catch other animals, or as nests or cocoons for protection for their offspring. They can also suspend themselves using their silk, normally for the same reasons.
The author is associated wisth the Department of Textile Chemistry at D.K.T.E. Societys Textile & Engineering Institute, Ichalkaranji, Dist-Kolhapur (M.S.)