Davis and Domm i ^n 



the inhibition of behavior patterns. Many female birds show mascuHne be- 

 havior in the fall, such as territory holding (Michener and Michener;" Lack^) 

 or singing (Bullough and Carrick""), but cease these activities in the spring. 

 The obvious interpretation of this sequence of events is that estrogen, when 

 it appears in the spring, inhibits the expression of masculine behavior in the 

 same manner as it inhibits the expression of the masculine plumage in certain 

 species. The results of our experiments suggest the likelihood that these 

 masculine behavior patterns are produced in the fall by androgen and not by 

 estrogen. However, experiments consisting of the simultaneous injection of 

 androgen and estrogen are required to test the hypothesis of inhibition. 



Summary 



1. In order to analyze the relation of certain endocrines to sexual behavior 

 patterns in the domestic fowl, a series of injections was performed on capons, 

 sinistrally and bilaterally ovariectomized poulards, and normal roosters, 

 using testosterone propionate, a-estradiol (Progynon-B), and stilbestrol. The 

 behavior was tested by exposing the injected bird to a normal rooster, to a 

 normal hen, or to a stuffed female dummy mounted in the pose of invitation 

 to copulation (squatting). 



2. Two out of three capons receiving testosterone copulated, croAs'ed, 

 "waltzed," and "tidbitted." The six capons receiving a-estradiol and two of 

 the three receiving stilbestrol copulated in the masculine manner. None of 

 them were known to crow or "tidbit." Two normal roosters receiving stil- 

 bestrol stopped crowing but continued to copulate. 



3. Three bilaterally ovariectomized poulards receiving testosterone crowed, 

 "waltzed," and became aggressive, but never copulated throughout the sixty 

 days of injections. Three sinistrally ovariectomized poulards reacted similarly. 

 Two out of three bilaterally ovariectomized poulards receiving a-estradiol 

 squatted for the rooster. In the stimulus situations employed in these experi- 

 ments copulation was not induced in poulards by injections of testosterone. 



4. Only in the male can the behavior patterns of copulation be induced by 

 both androgen and estrogen, while the patterns of crowing, "waltzing," and 

 "tidbitting" are under the control of androgen in both sexes. 



Addendum 



Since this manuscript was submitted an important report has appeared 

 (Zitrin'") describing induction of male copulatory behavior in a hen follow- 

 ing administration of male hormone. This bird, one of two treated white 

 Leghorn pullets, received a pellet of testosterone propionate, weighing ap- 

 proximately 41 mg., when it was five months old. The bird was observed to 

 tread a hen one hundred thirty-eight days later. Thereafter it was tested fre- 

 quently with a squatting hen and observed to copulate in the typical masculine 

 manner. "Waltzing" was seen only occasionally and was never very vigorous, 

 while crowing was heard but once after the bird had been treaded by a male. 



