I. Effect of Swingle extract on maturity in rats. In view of the known effect of certain adrenal tumors, and possibly hyperplasias, in producing sexual precocity in children, and because of the general impression that mature rats were less susceptible to sarcoma than younger animals, an attempt was made to produce precocious maturity in rats, with the intention of then testing their relative susceptibility to tumors. One of the methods used was to inject young rats with adrenal cortical extract, prepared after the manner of Swingle and Pfiffner.
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Four litters of rats were used, half of which were injected daily with extract in doses amounting to 20 gm. of adrenal cortex to 200 gm. of rat weight. The extract was freshly prepared every 10 to 12 days, and was tested on adrenalectomized rats to insure its potency.
Corey and Britton
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have reported changes in the ovaries and testes of rats following similar treatment, which they interpreted as a stimulation to sexual maturity. The present groups were watched carefully for signs of maturity (the opening of the vagina and vaginal smears in the females; the behavior of the males in the presence of females in oestrus), and it was found that the controls matured as early, and in some cases earlier, than the injected animals. (Table I.)
II. Effect of Swingle extract on egg-laying in chickens. In May, 1930, I reported a degeneration of the ovaries of chickens following the injection of a watery extract of adrenal cortex.
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It was desirable to know whether Swingle and Pfiffner's lipoid extract acted in the same way. Five laying hens were injected every other day with 1 cc. of Swingle extract. These chickens were followed for 49 days, receiving 25 injections.
