SEXUAL CHARACTERISTICS OF THELIA 595 
the freshly stained material. The body of the nymph was 
preserved in Gilson’s fluid and later sectioned, with the exception 
of the caudal end of the abdomen, which was prepared for whole 
mount (fig. 52). 
The structure of the gonads of this individual was compared 
with that of testes and ovaries of normal fourth instars. The 
normal testis is composed of tubules which are almost spherical 
and are bound together by their efferent ducts which unite 
eentrally to form the chief duct. This duct runs in the direction 
of the long axis of the testis, which is roughly an ellipsoid in 
form. The testis from surface view looks like a bunch of grapes. 
Each tubule is composed of a number of well-differentiated 
cysts, marked off by definite walls. Each cyst is filled with 
spermatogonia or spermatocytes, the cells in any one cyst being 
approximately in the same stage of growth or mitosis. The 
ovary presents a very different structure. The most conspic- 
uous portion consists of terminal chambers, elliptical in longi- 
tudinal section and placed side by side in a dorsoventral plane 
of the abdomen. From the anterior end of each terminal cham- 
ber runs a terminal filament, and from the posterior end, an 
ovarial tubule which later contains the large odcytes. The 
terminal filaments of each ovary converge and form a single 
support for the gonad, and the tubules likewise converge caudad 
to form an oviduct. <A section of the terminal chamber shows a 
wall of tall epithelial cells with clear cytoplasm. These cells are 
unlike the flattened epithelial cells covering the testicular tubules. 
In the region of the attachment of the terminal filament, one 
encounters oogonia in various phases of mitosis, and the rest of 
the chamber is filled with nurse cells and small odcytes pre- 
paratory to growth. ‘There are no subdivisions of the chamber 
into cysts. Thus, macroscopically and microscopically, the 
gonads of the two sexes are so distinctly different that they are 
not easily confused. That the gonads of the peculiar nymph 
under discussion were testes, there is not the least doubt. Cer- 
tain peculiarities of these testes will be noted later. 
We are, therefore, considering an individual with female soma 
and male germ glands. As already noted on page 586 (fig. 45), 
JOURNAL OF MORPHOLOGY, VOL. 32, NO. 3 
