BLOOD SUGAR AND ACTIVITY IN FISHES WITH NOTES ON THE ACTION OF INSULIN

¹ From the Zoölogical Laboratory, Duke University

1. Correlations between the blood sugar, hemoglobin, body-form, activity and habits of fifteen species of marine teleosts are pointed out.

2. The fishes that show the greatest activity, those that feed at the surface or are aggressively predaceous, have the highest blood sugar concentration. The sluggish bottom feeders have low sugar content in the blood.

3. Insulin shock may be easily produced in active species of fishes. In sluggish forms no external evidence of the action of insulin could be detected.

4. The blood sugar of fishes is reduced by the action of insulin. Less time is required for reduction of sugar content to take place in the active fishes than in the sluggish forms, due probably to differences in the metabolic rate of the different species. In the sluggish forms the sugar content may be reduced without convulsions or shock being apparent.

5. The normal sugar of some of the sluggish fishes is often lower than the insulin-reduced sugar of the more active fishes.