Abstract
The precocious development of sexual characters following homeoplastic hypophyseal implants in juvenile Leghorn females was previously discussed by Domm. 1 In a second series the effects of daily subcutaneous injections of hebin on these characters were studied. 2
Light brown Leghorn females ranging from 21 to 47 days at the beginning of the experiment received daily injections of hebin over a period ranging from 14 to 36 days. The daily dosages administered per bird varied from 4 to 32 rat units. Head furnishings were measured and birds weighed at regular intervals as in experiments on cockerels. All treated females remained active and in good condition. In none of the experiments did there seem to be a significant difference in weight between treated and control, both groups showing consistent gains throughout.
Here, as in the male, the first effect to be noticed was a phenomenal growth of head furnishings. This was definitely noticeable within 48 hours in individuals receiving higher concentrations. In such experiments the head furnishings revealed a continuous high rate of growth throughout, becoming large and masculine in character. Bird No. 249, 28 days old when the experiment began, received 20 rat units daily for 21 days and was killed on the day following the last injection. Its comb measured 1.7 cm. in length and 0.5 cm. in height when experiment began and 4.5 cm. by 2.3 cm. on the day the bird was killed. The best control increased from 1.3 cm. length and 0.4 cm. height to 2.1 cm. by 0.7 cm. during this period. The growth of head furnishings in treated females frequently approximates that of similarly treated males. The comb in such individuals is stout of blade and erect whereas that of similar size in normals, only found in much older individuals, shows a thin lobby blade. Plumage, spurs, and behavior were apparently unaffected.
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