Precocious Development of Sexual Characters in the Fowl by Homeoplastic Hypophyseal Implants. II. The Female. 20

Abstract

In a series of experiments daily subcutaneous homeoplastic hypophyseal implants were made on juvenile light brown Leghorn females. 1 These ranged in age from 28 to 59 days respectively when experiments began. In only one experiment was the entire hypophysis employed, while in all others only the anterior lobe was utilized. The number of implants received in any one experiment varied from 19 to 28. Weights were taken and measurements of head furnishings made at regular intervals as in experiments on cockerels. Treated females remained in excellent condition and were not adversely affected throughout any of the experiments. In none of the experiments was there a significant difference in weight between treated and control. In some the treated individuals were a trifle heavier than their respective controls, in others the reverse was true. This was not the case with treated males which were usually significantly heavier than their controls.

The first and most obvious effect to be noted was the phenomenal growth of head furnishings. These, pale and small when experiments began, became reddish and turgid after 5 to 6 days' treatment and revealed steady growth. Bird No. 178 was 22 days old when experiment started. It received 28 daily implants and was killed on the day following the last treatment. Its comb measured 1.3 cm. in length and 0.4 cm. in height when the experiment began, while on the day following the final implant it measured 4.0 cm. in length and 2.1 cm. in height, a creditable size for a pullet 4 months of age. The comb was quite stout, firm, and erect, resembling much more a male comb of similar size than the flabby, loppy comb of similar dimensions on an older female.