272 THE THEORY OF THE GENE 



lay eggs. When killed the bird was found to have exten- 

 sive tumor growths in the situation of the ovary. ' ' Incor- 

 porated in the dorsal aspect of this mass, there was a 

 structure exactly resembling a testis, while another, simi- 

 lar in appearance, was situated in like position on the 

 other side of the body." Every stage of spermatogenesis 

 was present in the testes. On the left side "a thin straight 

 oviduct could be identified having a diameter of 3 mm. 

 in its widest part near the cloaca. ' ' 



A second case has been recorded by Riddle. A ring 

 dove functioned first as a female, laying a series of eggs. 

 She ceased later to lay eggs, and frequently acted as a 

 male in courtship and copulation. Many months later she 

 died with very advanced tuberculosis. She was opened 

 and under misapprehension that she was her mate (a 

 male that had died YIV^ months earlier) was recorded as 

 a male. Later, when her number and record were deter- 

 mined, it was found that she had been the female, but the 

 "testes" had been thrown away. There is here no record 

 that the bodies identified as testes contained sperm. 



The Effect of Ovariotomy in Birds. 



The complete removal of the single left ovary of young 

 chicks is a rather difficult operation. In 1916 Goodale car- 

 ried out several successful operations of this kind. The 

 birds developed the full plumage of the male. Goodale 

 also reported the presence on the right side of a rounded 

 body with tubules which he compared with early ne- 

 phrogenous tissue. Benoit has also recently described the 

 effect of ovariotomy on young birds. In general, the effect 

 on the plumage, comb, and spurs is the same as in Good- 

 ale's birds, but in addition he describes the development 

 of a testis or testis-like organ in the situs of the rudimen- 

 tary right "ovary," and sometimes a similar organ in 

 the place of the left ovary removed. In one case germ- 



