AN OVARIAN HORMONE

The fact that double ovariectomy abolishes the cyclic changes which normally occur in the genital tract of female mammals demonstrates that these changes are due to some influence from the ovaries. That this influence is hormonal in nature is indicated by the maintenance of cyclic changes by autotransplantation of the ovaries to other sites in the body.¹Many attempts have been made to localize the seat of production of an internal secretion in definite ovarian structures. The follicles, the corpora lutea²developing in them after ovulation, and the interstitial tissue³have all been cited as possible sources, and many different ovarian preparations have been used clinically in the belief that therapeutic effects were being secured from accompanying hormones. But there appears to be no conclusive evidence of either a definite localization of the hypothetic hormone or of the specific effect claimed for the commercial ovarian extracts in