The distribution of chitin in an insect

Abstract

AbstractBy treating the clean skeletal tissue of an insect with concentrated KOH at 160° C., the contained chitin is converted to chitosan, and all pigmentation and admixtures are removed. The per cent distribution of chitin, expressed as chitosan, in the exoskeleton of the cockroach, Periplaneta fuliginosa, ranges from 37.65 in the dorsal abdomen to 18.22 in the hindwings. Other regions contain the following per cents: ventral abdomen, 37.11; metathoracic legs, 35.55; mesothoracic legs, 33.28; prothoracic legs, 32.24; pronotum, 31.55; head, 31.07; genitalia, 29.28; dorsal thorax, 29.07; ventral thorax, 28.33; antennae, 27.77; cerci, 25.65; and forewings, 19.99. Regional variations are constant in different individuals of the same species. The crop and gizzard contain 18.69 per cent; the hindgut, 18.15 per cent. The remainder of the alimentary tract contains no chitin. Traces of chitin are found in the trachea. No chitin is found in the egg‐cases of this species. No correlation between chitin content and pigmentation or hardness is shown. Based on results from three trials, using thirty insects, the per cent of chitosan in the clean, dry chitinous material from the entire animal is 29.60; the per cent of chitosan based on the weight of the live animal averages 2.01.