230 N. M. STEVENS, 
same stage as Fig. 1b. It was just outside of the region of smallest 
oocytes, and was attached to one of the epithelial cells bordering on 
that region. In this stage, the cytoplasm stains more deeply, and the 
chromosomes, which have become much more irregular in outline, 
have begun to send out fine branches of less stainable material than 
the body of the chromosomes. Figs. 4—9 were all drawn with the 
same magnification, BAncH & Long, ob. 1/,,, oc. C. 
As the oocyte increases in size, the nucleus becomes larger, and 
the chromosomes more widely separated; the fine side branches grow 
longer, and the body of the chromosome appears to be composed of 
irregular granules, variously arranged (Figs. lc and d). It will be 
noticed that these oocytes are connected with the wall of the sperm- 
duct by two cells derived from the epithelial layer of the ovary. Up 
to this point, the cytoplasm of the oocyte stains rather deeply and 
shows no special structure. The four largest oocytes shown in Fig. 1 
are of about the same age as the four smallest in Fig. 2. 
Fig. 10 shows an older oocyte, drawn to the same scale as 
Fig. 2: here the cytoplasm has begun to assume the reticular character 
so conspicuous in the larger oocytes of Fig. 2, and globules of yolk 
material are seen at the periphery. The side branching of the chromo- 
somes is somewhat coarser and more irregular than in the preceding 
stage, and the branches stain more deeply. In Fig. 2a, a slight 
thickening in the hitherto very thin membrane is perceptible on the 
side farthest from the spermduct; the yolk globules are much more 
numerous at the periphery, and a few are scattered in the cytoplasm, 
which is now plainly reticular; the chromosomes are somewhat shorter, 
very irregular in outline, and the finer less stainable side branchings 
have disappeared, perhaps withdrawn into the body of the chromosome. 
In Fig. 2b, is shown a nearly ripe oocyte with thick membrane, 
evenly distributed yolk globules, and chromosomes reduced to very 
short and rather thick rods which are also shown in Fig. 11. In 
all oocytes at this stage, a large number of black granules appear 
near the nuclear membrane, which is much thinner than on the op- 
posite side; this group of granules is always found between the 
nucleus and the spermduct. The cytoplasm at this point is of a 
different character and stains more deeply. There is every appear- 
ance here of an outward movement of material from the nucleus 
into the cytoplasm. In the stages where the greatest reduction in 
the size of the chromosomes occurs, the nuclear plasm} stains more 
deeply as though filled with fine granules of chromatin, and large 
