The Absorption of Glucose by Ostrea edulis

Abstract

SUMMARY: Normal healthy oysters with openings drilled in both inhalent and exhalent chambers, remove considerable amounts of glucose from solution. The average diminution in 5 experiments, each consisting of two such animals kept in 4 litres of sea-water containing about 0-2% of glucose, was 8-17% at the end of 36 hours.In similar experiments, using the same oysters after their mouths had been plugged with wax and plasticine, there was only an average diminution of 1-4:6% in the glucose at the end of 36 hours. In two of the experiments there was no diminution, and in the three others there was evidence that one of the two oysters in each had been incompletely plugged and glucose had passed into the alimentary canal.Oysters which had been plugged for 8 days so that they were bleeding profusely, the mantle cavity containing vast numbers of leucocytes, were used for a third set of experiments in which the average diminution was 7-4% at the end of 36 hours.There was no evidence of bacterial decomposition of glucose within the experimental period.These results, taken with those of previous investigations, show that the ciliated epithelia of Lamellibranchs cannot absorb (nor ingest phagocytically). Absorption takes place in the tubules of the digestive diverticula within the alimentary canal, and, in the mantle cavity, only through the agency of phagocytes which are extruded in great numbers when Lamellibranchs bleed as a result of bad conditions.The opinion of Ranson that Marennin and other soluble matter is absorbed directly by the ciliated epithelia in the mantle cavity cannot be upheld, this material being deposited in the cells by the phagocytes which either absorb it directly from the mantle cavity and gut, or transport it from the digestive diverticula.