Glucose Absorption in the Cockroach

The physiology of absorption from the gut in insects has been little studied. In particular there is a paucity of information on the absorption of nutrient substances from the gut. Much of what is known on this subject is qualitative in nature, and has usually been indirectly derived from specialized investigations on digestion or storage of nutrient materials. The majority of these studies have been adequately summarized in the review by Waterhouse & Day (1953). In the present investigation the absorption of C-labelled glucose from the gut of the adult cockroach {Periplaneta americand) has been studied, using a dye, Amaranth, as a marker. The dye is not absorbed from the lumen of the cockroach gut and thus the percentage absorption of glucose can be calculated from the glucose/dye ratio in the various parts of the gut. This technique has been recently used by Reynell & Spray (1956a) using phenol red as a marker to study intestinal absorption in the rat. Phenol red is, however, unsuitable for the study of poorly absorbed substances, since these authors were only able to get a 90 % recovery of the dye from the intestine. Amaranth, at least in the cockroach, is not limited in this way, for it was possible to recover this dye quantitatively.