Precocious Development of Sexual Characters in the Fowl by Homeoplastic Hypophyseal Implants. I. The Male. 20

Abstract

A series of light brown Leghorn cockerels ranging from 22 to 86 days in age were given daily subcutaneous homeoplastic hypophyseal implants. In the first experiment the entire hypophysis was utilized while in subsequent tests only the anterior lobe was employed. The number of daily implants per bird varied from 19 to 28. The treated birds, as well as controls, were weighed and the head furnishings measured at regular intervals, at first daily, later on alternate days. All treated individuals remained active and in excellent condition throughout the experiments so that they could not be distinguished from controls in this respect. In fact treated males were consistently somewhat heavier than their respective controls when treatments were discontinued.

One of the effects, quite apparent after 4 to 5 days' treatment, was a stimulation of head furnishings. These became turgid and reddish in color and revealed noticeable growth. In the longer treatments there was a noticeable slackening in growth toward the close of the experiment while in some of these there was a cessation followed by a slight regression in size. Bird No. 167, 59 days old when the experiment began, received 23 daily implants. On the day the experiment started its comb measured 4.7 cm. in length and 2.6 cm. in height, while 15 days later it measured 7.5 cm. in length and 4.5 cm. in height, the maximum size attained. On the day following the last implantation, 24th day of the experiment, when the bird was killed, measurements of comb were 6.8 cm. in length and 4.0 cm. in height. The best control comb showed a gradual increase during this period from 4.5 cm. in length by 2.6 cm. in height to 5.8 cm. in length by 3.5 cm. in height.