78 THE GENETIC AND THE OPERATIVE EVIDENCE 



bemerkt J. Geoffrey St. Hilaire (p. 511), dass Fasanen haufiger selbst als die 

 Hiihner hahnenfedrig werden, wahrend fiir den Pfau, den man doch stets eines 

 natiirlichen Todes sterben lasst, ihm nur ein einziger Fall (der von Hunter) 

 bekannt geworden. Wahrend Lorenz (vide Tichomirow) auf dem Moskauer 

 Markt haufiger hahnenfedrige Weibchen von Phasianus colchicus und mongol- 

 icus aufgefunden, ist ihm dieses fur Ph. chrysomelas bisher kein einziges Mai 

 gelungen, obgleich die Zahl der jahrlich in Moskau feilgebotenen Exemplare 

 dieser Art sich auf 8000 Stuck belaufen mochte." 



The preceding cases relate to exceptional changes in the plumage as 

 observed in nature, or in birds kept under domestication. We may next 

 examine the cases where the ovary or the testis has been removed. 



The earlier observations of Berthold, Wagner, Hanau, Samuel, 

 Sellheim, Pirsche, Foges, Shattock, and Seligman are sufficiently 

 covered by later work quoted below. Sellheim's work, however, is 

 especially to be noted, since he gives some measurements covering the 

 weight of the brain, heart, and body of the cock and capon, as well 

 as observations on the skull and skeleton. The weight of the brain 

 is slightly less in the capon, but the body-weight is greater. He ques- 

 tions whether the ovary has ever been successfully removed, and he 

 shows that the operation of resecting the oviduct does not, as was 

 supposed, lead to the degeneration of the ovary. On the contrary, he 

 found that after the effects of the operation had been removed the 

 ovary began again its functions. 



From Goodale's careful summing up of the effects of castration only 

 the following points need be recalled: The feathers are little changed; 

 some of them, the hackles especially, become longer. The lowermost 

 tier of wing coverts are elongated as compared with those of the cock. 

 The spurs are practically the same in the capon and cock. The capon 

 is disinclined to give voice, but at times he crows. The molting is not 

 affected. The size of the capon is larger. He pays little attention to 

 the hens. He is not pugnacious, and if attacked will not often fight. 

 As a rule he does not pursue the hens, but if a hen squats down as the 

 capon approaches he will mount and go through the characteristic 

 mating reaction. The comb is extremely small, much smaller than 

 that of the female of the same race; it is infantile rather than feminine. 



Comparing these results with those that I have observed in the 

 castrated Sebright, we find that aside from the assumption of the full 

 plumage of the cock-feathered bird the Sebright shows all of the 

 characteristic features of the capon. The spurs develop, perhaps even 

 more fully than in the normal Sebright cock. He seldom crows, and 

 then weakly. The birds appear large, but the excessive development 

 of the feathers produces the effect. I have not weighed them to show 

 whether an actual increase in size takes place. Two of my birds are 

 notably large for Sebrights, but the others are smaller. Both large and 

 small cocks occur in the strain that I have used. My Sebright and 

 other capons neglect the hens, but I have seen them tread the hens 



