SEX STUDIES. XI 17; 
ductive organs, and the large coiled oviduct of a laying bird 
(fig. 14). At the posterior end, to the right of the cloaca is a 
crumpled mass, which is apparently a partly developed right 
oviduct. No Wolffian duct was found on the left side, but the 
immense size of the oviduct made it difficult to dissect on that 
side. The organs of the two sides are very different in external 
appearance, as can easily be seen in the photograph. The right 
one is an active testis and the left one an inactive ovary. Fig- 
ure 23 is a photograph of a section of the testis, a large mass of 
tubules with very little connective tissue between them. Part 
of this same section is shown at greater magnification in figure 
24. This resembles a section of a normal active testis. The 
black threads are fully formed spermatozoa, and they are 
bunched into groups for each Sertoli cell in normal manner. The 
vas, strange to say, is no larger than in the birds with no organ 
on this side, and not as much coiled as the one in 1429. The 
left reproductive organ closely resembles the ones in 1428, 1425 
and 1427 in external appearance. On the surface are a couple 
of depressions which might be degenerate oocytes or discharged 
follicles. One place shows an orange mass like a corpus luteum. 
Histologically the main substance is like that of 1427, and re- 
sembles the stroma of an ovary with solid cords of cells in it, 
but no oocytes (fig. 25). The peripheral tissue, however, looks 
like a thickened germinal epithelium and contains several large 
spaces which may have been oocytes. In the place with the 
orange spot on the surface there is a mass of tissue containing 
groups of cells with yellow pigment material, as described for 
discharged or atretie follicles in study X. The entire stroma 
shows great streaklike masses of secretion taking acid stains, as 
in the organs of 1425 and 1428. In one limited area of the ovary, 
there are a few interstitial cells filled with granules. In bothovary 
and testis there are a few nests of lutear cells near the surface. 
This condition in the testis is shown in figure E, as it is unusual 
to find them in a testis, and probably indicates the generally 
unbalanced sex condition of the animal which looks as though 
it might be changing from female to male. This is the most 
interesting of the Holland birds, absolutely indifferent as to 
THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 25, No. 1 
