274 THE THEORY OF THE GENE 



having efferent ciliated canals and "rete testis." He con- 

 cluded that the right gonad of birds is not a rudimentary 

 ovary, but a right rudimentary testis that enlarges when 

 the left ovarv is removed to become a testis. The evidence 

 does not, I think, necessitate this conclusion, for it is 

 known that in the early stage of development of the 

 reproductive organs in vertebrates, the essential acces- 

 sory organs of the male and the female are present in 

 both sexes. It is possible, therefore, that upon interfer- 

 ence with the normal process of development (removal 

 of the left ovary) these rudimentary organs may begin 

 to develop and produce a testis-like structure, which, in 

 most cases so far reported, does not contain sperm-cells. 

 The occurrence of globular organs (reported by Goodale 

 and Domm) on the left side also would seem to support 

 this view, rather than that advanced by Benoit. 



A preliminary report of the results of ovariotomy in 

 young birds has recently been given by L. V. Domm 

 (1924). The birds when they become adult not only show 

 secondary male characters in their plumage, comb, wat- 

 tles, and spurs, but fight with normal cocks, crow, and 

 attempt to tread hens. One bird had a "white testis-like 

 organ" in the position of the normal ovary (removed). 

 Associated with the organ was also a small ovarian fol- 

 licle. On the right side there was also a testis-like organ. 

 A second bird was similar as to its gonads. In a third 

 bird a testis-like organ was present only on the right side. 

 In none of these cases are germ-cells or spermatozoa 

 reported as present. 



Whether these cases are strictly sex reversals cannot 

 be definitely stated, unless Benoit 's observation on the 

 presence of sperm is confirmed. Aside from this unique 

 statement, the other results appear to show definitely 

 that, after removal of the ovary, a structure develops re- 

 sembling in its appearance a testis (except for the pres- 



