164 



THE AMERICAN NATURALIST 



[Vol. XLVII 



from experiments in cross breeding, that the body pattern 

 of the Brown Leghorn is not a unit, but is composed of 

 several parts. 



These departures from the ideal and the probable vari- 

 ability in the gametic constitution of supposedly pure- 

 bred stock may be expected to influence the behavior of 

 the birds under castration. They indicate also that a 

 character which at one time may behave as a secondary 

 sexual character, at others forms a normal character of 

 both races. 



Experimental. — Without taking time to describe the 

 details of the experiments, except to note that the gonads 

 were removed from the chicks when they were 21-28 days 

 old, that is, they were much younger than is the case in 

 commercial caponization, we may proceed directly to a 

 consideration of the results, taking up first the effects of 

 castration on the male. 



Seven of the castrated males reached four months of 

 age, then three were accidentally killed. The autopsies 

 on these three showed an entire absence of testicular 

 material in two cases. The third had a tiny nodule, pos- 

 sibly testicular, on the mesentary near the former site of 

 the testis. 4 All four survivors were kept until they were 

 16 months of age. Two were then killed for study. They 

 developed the normal plumage of the male and were it 

 not for the small comb and wattles they would have had 

 nearly the same appearance as a normal cock (Fig. 1). 

 They are, however, somewhat fuller plumaged and rather 

 heavier looking birds than a normal cock. The spurs are 

 well developed but on the other hand these capons are 

 less active in their movements, are non-combatants and 

 show no sexual instincts. They have never been heard 

 crowing, though they may be made to squawk or even 

 cluck like a cock. 



One of these capons was somewhat anomalous in that 

 he had much the same appearance as a normal cock. He 

 had a large comb but did not crow. At one time he 



* Unfortunately this material was not sectioned. 



