Silk

A number of recent reviews and books on silkworm and spider silks have been published and the historical aspects of the field are reviewed therein (Livengood, 1990; Robson, 1985; Asakura and Kaplan, 1995; Kaplan et al., 1991, 1992b, 1994). Silks can be defined as externally spun fibrous protein secretions. Of the natural fibers, silks represent the only ones that are spun by the producing organism. These fibers are remarkable materials when considering their biosynthesis, processing, and functional properties. These proteins are produced within specialized glands by a variety of organisms including silkworms (and most other lepidoptera larvae), spiders, scorpions, mites, and flies. Silks differ in properties, composition, and morphology depending on the source, and in many spiders different silks are synthesized for different functions.