180 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
connect the nucleolus with the nuclear reticulum, the chromatin 
appearing in the reticulum in scattered masses, chiefly at the nodes or 
close to the nuclear membrane. In preparation for the last odgonial 
division, the chromatin collects into larger masses, which may become 
strand like, but do not seem to form a definite spireme. ‘The concen- 
tration continues and the chromosomes in the form of a closely packed 
mass constitute the equatorial plate (Plate 4, Fig..29, o’go’.). Mean- 
while, the nucleolus has disappeared. The last odgonial spindle has 
no asters, neither could centrosomes be demonstrated, though prob- 
ably they are present. During the division the chromosomes remain 
so closely massed that their individuality is entirely hidden. ‘The com- 
pact cytoplasm, even before division is complete, may become more 
distinctly granular and less deeply staining (Fig. 29, 0’go’.). Some of 
the odgonia do not undergo this final division with their sister cells, 
and probably serve to start the next generation of eggs, which develop 
when the first have formed embryos. 
2. Odcytes— 'The final odgonial division results in the primary 
oécytes. ‘The chromatin of each odcyte remains for some time in a 
compact mass (Fig. 29, o’cy’.); but after a time it becomes more 
open. Meanwhile a nucleolus, which selects the plasma stains, has 
made its appearance (Plate 5, Fig. 30), and the chromatin mass has 
opened out into small irregular masses, evidently pieces of the original 
chromosomes. At this time a differentiation of the odcytes occurs; 
some of them at once become young egg cells, while others do not 
develop further. The latter are present in larger numbers, most of 
them furnishing food for the growing eggs. In these the chromatin 
becomes arranged in irregular masses along a delicate linin reticulum, 
which is limited mostly to the outer part of the nucleus (Fig. 34a). 
While these odcytes are perhaps not destined to become egg cells, they 
do not show degenerative changes (unless they are being, or are about 
to be absorbed), and hence under favorable conditions they may 
retain the capacity to form egg cells. In the odcytes which begin to 
grow at once the chromatin forms a definite spireme, at first so closely 
massed as to show little sign of its thread-like character (Fig. 30). 
As it becomes more open the spireme is easily made out, though I have 
not been able to determine whether a single thread or several threads 
are present. Figure 29 shows two oécytes (o’cy®.) already of con- 
_ siderable size, which, from their relative position and from the presence 
of interzonal filaments, are clearly sister cells. In these the spireme 
is well shown and each contains a single large nucleolus, though the 
one belonging to the left-hand cell does not appear in this section. 
