Goodale’s results with ovariotomized females are especially noteworthy, 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 possible. 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 ovariotomized 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.”