Amino-Acids in the Hæmolymph of the Dragon-fly Nymph, Aeschna cyanea

Abstract

ALTHOUGH it is well known that the non-protein nitrogen content of insect hæmolymph is high and that a large proportion of it is present as amino-acids, few investigations have been made as to their nature. Florkin and Duchateau¹ showed that the hæmolymph of Dytiscus marginalis contained small quantities of histidine and tyrosine, and reported the absence of arginine, tryptophane, phenylalanine and cystine. A more thorough analysis by Ussing² revealed the presence in the blood of Melolontha vulgaris of lysine, arginine, histidine, tyrosine, leucine, valine, tryptophane and almost certainly hydroxyproline. The latter is also present in the blood of Oryctes nasicornis.