18 GONADECTOMY IN RELATION TO THE SECONDARY 



No. 140. The first operation was made June 15, 1913. The exact 

 age of the bird was unknown, as the original band had been lost, but 

 she was approximately 3 months old. The ovary was apparently 

 completely removed without hemorrhage. The apparently complete 

 removal was demonstrated to members of the staff of the Station for 

 Experimental Evolution at Cold Spring Harbor. Several weeks after 

 the operation the bird had not developed any trace of male plumage. 

 Accordingly, August 9, she was operated upon again. Lying over the 

 suprarenal was a considerable mass of ovarian tissue, in addition to a 

 minute piece farther back. Both pieces were removed. By September 

 7 new feathers had replaced those that were pulled at the time of the 

 operation. The distal portions of the new feathers were female, the more 

 proximal giving evidence of the absence of the influence of the ovary 

 by transverse vermiculations, which, however, were brownish. By 

 October 16 male feathers were present in various portions of the body. 

 However, the younger feathers that were growing at this time were 

 entirely female in character, indicating that some change had taken 

 place. This led to a re-examination of the site of the ovary. This was 

 empty, but attached to the mesenteries was a bit of ovary, the size of 

 a small pea, while attached to the oblique septum on the left side was 

 a bit of ovary containing one macroscopic ovum. Both were removed. 

 However, no further progress was made in assuming male characters. 

 The bird was kept until June 21,1913, when she was killed and exam- 

 ined. The oviduct was infantile, except that the walls of the vaginal 

 region were somewhat thickened and corrugated. On the site of the 

 ovary was a single small object like an immature ovum, about 1 mm. in 

 diameter. On the right side was a body 5 or 6 mm. in diameter bearing 

 (partially embedded) two small vesicles filled with a deep-yellow serous 

 fluid. This body has not yet been examined histologically. Evidently, 

 then, from the history of this bird we may conclude that a very small 

 amount of ovarian tissue is sufficient to produce normal female char- 

 acters. There is a point, however, at which, either because the amount 

 of tissue is so small or possibly because of injury received during the 

 operation, the fragment of ovary no longer suffices to produce female 

 secondary sex characters. Similar results have been obtained in other 

 cases, as, for example, Nos. 20 and 137. 



MALE DUCKS COMPLETELY ORCHIDOTOMIZED. 



The results of castration of drakes, as far as investigated, appear to 

 be independent of age. Much, however, clearly depends on the com- 

 pleteness of the removal and, less clearly, on the nature of the material 

 left behind. The testicles are not always readily removed, because 

 in early stages they are cylindrical objects, pointed at each end and 

 attached along one side to the iliac. In ducks, the elongated condi- 

 tion is maintained much longer than in fowl. In either case, if the 

 correct procedure is followed, it is possible to remove the testicles com- 



