18 ALICE M. BORING AND RAYMOND PEARL 
sex behavior and yet with sperm in the testis, and at least one 
corpus luteum remnant on the ovary, and the oviduct of a 
laying hen. In external appearance, it is more like a male than 
the others, which fact correlates well with the active condition 
of the testis and inactive diseased ovary with only one corpus 
luteum scar. The interstitial cells can scarcely be held account- 
able for the male secondary sex characters, as the only ones in 
Fig. E Portion of testis from 1426, showing some lutear cells between the 
seminal tubules at the periphery (X 570). 
an active secreting condition are a few in the ovary. This 
bird is the most balanced hermaphrodite of the series, and close- 
ly resembles bird 16, described by Pearl and Curtis, as to its 
internal structure, except for the active condition of the testis. 
A comparison of these five Holland birds shows a general 
correspondence between the degree of femaleness of their ex- 
ternal characters and their internal structure. They are all 
fundamentally females in which the ovary for some reason has 
failed to reach complete development. In all but 1429 and 1426 
the lutear cells are immature. In 1426, a testis has developed 
