RELATING TO SECONDARY SEXUAL CHARACTERS. 79 



on occasion. They will fight each other, if two strangers meet, but the 

 attacks are not violent or prolonged. A normal male beats them 

 easily, and afterwards they run away from such birds. The combs and 

 wattles are very small and pale. If a piece of the testis is left in, the 

 comb is a fair index of its size. In the birds that changed back toward 

 a Sebright the comb slowly enlarged. After the second operation it 

 decreased again as the plumage once more changed to that of the cock. 



Goodale's results with ovariotomized females are especially note- 

 worthy, since here for the first time we have definite information as to 

 the effects of the operation. By using a well-established breed, the 

 brown Leghorn, in which the dimorphism of the sexes is very striking, 

 the results are made all the more convincing. Goodale found that it was 

 possible to completely remove the ovary of young birds, for at an early 

 age the ovary is sufficiently compact to make its entire removal pos- 

 sible. Later the ovary becomes more diffuse, and complete removal 

 is almost impossible. In a few successful cases, in which the ovary 

 had been completely removed, the bird assumed the full plumage of 

 the Leghorn cock, with red back, black breast, and long, pointed hackle 

 and saddle feathers. Spurs developed in all the operated females, even 

 when the ovary was not entirely removed. There can be little doubt 

 that the ovary holds back the development of the spurs, but as some 

 hens sometimes develop spurs, especially in certain breeds, it is not 

 entirely certain that in these cases the loss of the ovary is the cause of 

 the appearance. The comb (and wattles) developed to different 

 degrees; in some birds it was as large as in the cocks, in others no 

 larger than in the normal hen, but in all cases it was larger than in the 

 capon. What to conclude is doubtful. Tentatively it may be suggested 

 that the genetic complex that gives the female (ZW) produces a comb 

 as large as that shown by the female independently of the ovary, but 

 beyond this point the ovary inhibits the further development of the 

 comb, presumably by means of the same internal secretion that holds 

 down the cock plumage in the hen. In the male, on the other hand, 

 the genetic complex (ZZ) produces a comb much smaller than that of 

 the female (no more than that of the capon), and the testes produce a 

 substance that causes this comb to grow to the size of that of the cock. 

 Possibly, however, other internal secretions are involved. 



The operated hens are quiet and nearly voiceless. None of Goodale's 

 birds were heard to crow, yet this seems to be a well-known peculiarity 

 of old hens that have become cock-feathered. The operated hens are 

 not larger than the normal hens of the same breed. Their legs remain 

 short, as in the normal hen; and in this respect and in size the ovarioto- 

 mized bird is externally a female. The poullards "never visit the 

 nests, never sing or cackle, show none of the normal female reactions, 

 and few or none of the male." 



