Abstract
Prednisone, prednisolone and hydrocortisone, administered in doses of 1 mg. daily for thirty days, depressed the growth rate of rats. Prednisolone and hydrocortisone caused atrophy of the adrenal glands and increased the relative weights of the thyroid glands and testes. The apparently similar effects produced by prednisone were not significant. The seminal vesicles were not affected significantly by prolonged administration of prednisone, prednisolone or hydrocortisone. Pretreatment of rats with these steroids prevented the adrenal ascorbic acid depletion normally caused by laparotomy under ether anaesthesia. Prednisolone was slightly more potent and prednisone was considerably less potent than hydrocortisone in producing these effects.