HISTOCHEMICAL AND BACTERIOLOGICAL STUDIES ON DIGESTION IN NINE SPECIES OF LEECHES (ANNELIDA: HIRUDINEA)

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Abstract
The leech gastrodermis is not differentiated morphologically into secretory and absorptive structures and there is little structural difference between crop and intestine. Endopeptidases, lipases and amylases are not produced in any part of the digestive system, but exopeptidases are consistently present in the intestinal gastrodermis. It is suggested that these act intra- and extracellularly, and achieve proteolysis in the absence of endopeptidases by slowly degrading protein chains by progressive removal of terminal units. A bacteriological survey shows that in 2 species the gut flora can play an important if not dominant part in digestion of fats, carbohydrates and protein; in other species there is evidence that it participates to a lesser but still significant extent in all digestive processes.