PRECOCIOUS COPULATORY ACTIVITY INDUCED IN MALE RATS BY SUBCUTANEOUS INJECTIONS OF TESTOSTERONE PROPIONATE1

GONADOTROPIC and gonadal hormones induce many of the somatic and physiological signs of pubertas praecox in immature rats if administered repeatedly in appropriate doses (1, 2). Whether these somatic changes are accompanied by psychosexual changes, however, cannot be definitely concluded from the published studies available to the author. Reports on the masculinisation of young chicks suggest that the somatic and psychosexual changes may, to a marked extent, go hand in hand. Domm and v. Dyke (3) reported that male chicks cro.wed at the age of 9 days, following 6 daily injections of a gonadotropic hormone (hebin), and that treading appeared when the chicks were 13 days old, following 10 daily injections of hebin. Hamilton (4) caused male chicks to crow at the age of 10 days, by injections of testOsterone propionate from the second day after hatching.