Abstract
It is well known that homoplastic implants of the anterior lobe of the pituitary induce sexual precocity in many animals. The present investigation continues the work of Wolf, 1 on frogs. The same technique of injection is used. Since, by giving daily implants of anterior lobe of the pituitary to mature frogs that had ovulated normally in April, it was possible to induce a second ovulation as early as October, it seemed of interest to determine how soon a second ovulation could be secured by this method, following a previous artificially induced one. By thus beginning the experiments with an artificially induced ovulation, the season of the year is apparently negligible, and the exact time of the first ovulation is accurately recorded.
The frogs were heavily parasitized and many died of “red-leg”. Fifty mature female leopard frogs (Rana pipiens), were given implants of 2 anterior lobes of the pituitary daily. Only 5 survived the entire experiment. After about the fifth implant, 44 were still living and had ovulated. The number of eggs discharged in every case exceeded four thousand. The second day after ovulation, an observational operation was performed in many to see if any mature ova remained undischarged. In no case were there more than 18 mature ova in the body cavity, ovaries, oviducts or uteri. (Postmortem examinations made on those that died of red-leg after ovulation confirmed these findings.) After 2 months, only 5 frogs were still living. Daily implants of anterior lobe were again given. After the third implant, one of the frogs died of red-leg.
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