Abstract

1. When the suprarenal glands are removed from drakes they die after a mean interval of about 8 hours. They can be kept alive by the hourly injection of cortical extract. The amount of extract which must be injected varies at different times in the year, becoming much larger during the breeding season.

2. The testes of the drake out of the breeding season weigh 1 to 4 grams. From January to May they increase in size to about 80 grams. During June they rapidly decline to the former small size. The curve of change in weight is closely parallel to the curve for the amount of cortical extract required after adrenalectomy, but the changes in the latter curve precede those in the former.

3. After adrenalectomy castrated drakes require one third to one half of the amount of cortical extract necessary to keep normal birds alive during the breeding season. The increase in requirement of cortical extract during the breeding season is not due to the large amount of male hormone in the circulation, since injections of testosterone propionate do not increase the requirement. The increased requirement seems to be due to the need for cortical hormone while the testes are growing.

4. Injection of cortical extract in solution in olive oil instead of in water enables injections to be made at 4-hour intervals instead of 1-hour intervals. The addition of 10 per cent palmitic acid to olive oil prolongs the action of the injected hormone presumably by delaying the rate of its absorption. Benzoylation of cortical extract prolongs the action of the extract.

5. Drakes can be kept alive in vigorous health for long periods after adrenalectomy by daily injection of 5 mgm. desoxycorticosterone acetate.