396 
CHIYOMATSU ISH1KAWA. 
oviducts, connecting the two ovarian tubes together, and it also 
covers over other organs — the heart, the alimentary canal, &c. — 
and therefore may not properly be said to belong to the ovary. 
A similar layer of the connective tissue is stated to be present 
in the ovaries of Isopods and Amphipods. 
Below the connective- tissue layer comes a layer of epithe- 
lium cells. This layer (fig. 5) consists of cells with irregular 
outlines, of about 0‘03 mm. in diameter, provided with an oval 
nucleus of about OOl mm. in length. It extends all over the 
ovary and oviducts. The cells on the latter are much smaller 
than those on the former, although the nuclei are nearly of the 
same dimensions (compare figs. 5 and 6). The nuclei are very 
difficult to make out, even in silver staining. In fine prepara- 
tions, however, they appear to be provided with one or more 
very small dots — the nucleoli. 
This epithelium is sometimes (perhaps always) followed by 
another sheet of a cellular layer, apparently similar to it in 
structure, differing, however, from it in its being turned in, 
sometimes, though rarely, between the egg follicles. This 
cellular layer I am inclined to consider as akin to the ovarian 
stroma of other animals. 
Between this and the inner set of layers a space (figs. 7 and 
8) occurs filled with finely granular fluid, in which clear 
nucleated cells ( b c) are to be discerned. This space is not 
continuous all around the ovary. It remains always uncoloured, 
or only very slightly coloured by various staining fluids, and 
appears of a dirty yellow hue. Of the cells floating in it the 
nuclei and the nucleoli colour very deeply, while the cell body 
always remains uncoloured. They have a very delicate but 
definite contour. By these and other peculiarities they are 
easily distinguished from all the other cells found in the ovary. 
They are sometimes found solitary, when they have a round 
or oval form, but often in groups, when they are polygonal. 
Sometimes in narrow spaces they arrange themselves in com- 
pact rows of square cells. This granular mass evidently 
represents blood plasma and the cells blood-corpuscles. 
I made many attempts to inject the ovary with some 
