176 Hormones and the Behavior o£ Fowl 



effects almost invariably appear soon after the operation and may bring 

 about a more or less complete masculinization of sexual characters. The estro- 

 genic effects usually become evident some time later and are chiefly mani- 

 fested by the plumage (Domm^). 



Following daily injections of testosterone, sinistrally ovariectomized pou- 

 lards became noticeably more aggressive. They were observed to crow more 

 frequently than uninjected controls and likewise displayed more interest in 

 the female, notably evidenced by the greater frequency of "waltzing." How- 

 ever, like their uninjected control mates, they were never observed to copulate, 

 but merely "waltzed" and stopped or "waltzed" and pecked. These individuals 

 definitely became more masculine in their general reactions under the influ- 

 ence of testosterone but apparently they were unable to copulate, at least under 

 the stimulus conditions prevailing in these experiments. 



6. The Effect oj Estrogen in Bilaterally Ovariectomized Poulards. These in- 

 dividuals, normally lacking aggressiveness, seemed to become more timid and 

 even lethargic following daily injections of estrogen; they completely ignored 

 the dummy and normal females in all tests. Bird 132WUR, eighteen days after 

 the beginning of injections, squatted for a normal rooster and received copula- 

 tion. These experiments at this date were handicapped by the lack of a vigor- 

 ous rooster, since all the males were in molt. It is possible that the injected 

 poulards would have squatted regularly at this time for an aggressive, vigorous 

 rooster in sexual prime. Hence, a rooster was brought into full sexual ag- 

 giessiveness by daily injection of 2.0 mg. of testosterone. In the presence of this 

 rooster, bird 132WUR squatted regularly and 118PU squatted on the forty- 

 second day of injection. Bird 128RU did not squat until November 10, after 

 it had been severely beaten by its cage mate. Although she received copulation 

 subsequently when exposed to the rooster it is not known whether she was 

 receptive or merely too weak to resist. 



On several occasions an estrogen injected bilaterally ovariectomized pou- 

 lard squatted for an estrogen-injected capon and received copulation. These 

 birds were all identical in plumage, lacked any vestige of gonads, and had 

 received the same injections. 



It seems apparent from these observations that androgen induced crowing 

 and "waltzing" but did not induce copulation in the bilaterally ovariecto- 

 mized poulard. These individuals became definitely more active and aggres- 

 sive in the presence of the introduced female or dummy as a result of the 

 injections. It is also evident that androgen increased the frequency of crowing 

 and "waltzing" in sinistrally ovariectomized poulards but, as was the case in 

 the bilaterals, it did not induce them to copulate, at least under the various 

 stimulus situations provided. 



Estrogen, on the other hand, apparently induces only the squatting pattern 

 in the bilaterally ovariectomized poulard. It will be noted that this is in strik- 

 ing contrast to the effect of estrogen in the capon. One point deserves particu- 

 lar mention, bilaterals receiving estrogen completely ignored the dummy or 



