STUDIES IN THE REGULATION OF BLOOD-SUGAR CONCENTRATION IN CRUSTACEANS. I. NORMAL VALUES AND EXPERIMENTAL HYPERGLYCEMIA IN LIBINIA EMARGINATA

¹ Marine Biological Laboratory, Woods Hole, Mass., and Reed College, Portland, Oregon

1. Removal of the sinus glands by eyestalk ablation in unfed Libinia emarginata has no significant effect on the blood-sugar concentration when compared with similarly unfed controls.

2. Values for true blood sugar, as distinguished from total reducing substances, were determined after yeast fermentation of blood samples. In starved animals the concentration of total reducing substances is between 8-9 mg. per cent; that of non-fermentable reducing substances, 6-7 mg. per cent; that for true blood sugar is therefore about 2 mg. per cent.

3. Injection of eyestalk extract increases the concentration of total reducing substances in the blood. This increase is in the fermentable component, amounting to over 400 per cent of that in the uninjected animal, and therefore probably represents a true hyperglycemia.

4. Asphyxia also causes hyperglycemia, the total reducing substances in blood samples being two to three times the concentration preceding asphyxia.

5. Removal of the sinus gland by eyestalk ablation prevents the appearance of the hyperglycemia of asphyxia. The sinus gland may be a mediator in certain hyperglycemic responses of crustaceans, but does not seem to be concerned in alimentary hyperglycemia.