674 
J. P. Munson 
the central nucleus or vesicle in the yolk nucleus of the spider, pl. XXX, 
fig. 20. 
I do not see how such a perfectly shaped thing coidd be an artefact. 
I take it as an indication of the location of the eentrosome, indeed pro- 
bably the eentrosome itself, which need not necessarilv be a single granide, 
but in the relaxed uncontracted state, assumes the appearance of a nucleus. 
In the later or advanced stages of the egg, this body assumes various 
shapes and appearances, owing to the variable distribution of the amorphous 
granides. It is apt to have the appearance represented in fig. 3. 
There is never more than one of these, though, as in fig. 3, there 
may be several large, spherical or irregulär masses of deeply staining 
substance in various parts of the cytoplasm. These, however, never assume 
the form of an aster like the cytocenter. Instead of forming large deeply 
staining masses, this substance may be scattered all through the cyto- 
plasm as is shown in figs. 8 and 9. 
In many of the larger eggs, the cytocenter has all the charaeteristics 
of a typical ceiitrosome and aster, fig. 10. The most delicate' preservation 
is required to see this. If good fixing has been secured, most of the differen- 
tial stains make these bodies prominent. 
Interpretation and Summary. There is in the cytoplasm of 
the oogonia of Clemmys, a large eentrosome, which is greatly reduced 
when the division to form the follicle takes place. In the cell which be- 
comes the oocyte, (the one usually which is centrally located) this c-entro- 
some persists as a typical eentrosome and aster at one pole of the genninal 
vesicle. 
It consists of a central granule, with a circle of microsomes surround- 
ing it, and astral rays extending to a second and a third circle of microsomes. 
The latter circle intersects the genninal vesicle, and fonns a body about 
the size of the genninal vesicle. It seems to be a receptade into which 
fluids from the germinal vesicle, possibly karyolymph, is poured. This 
fluid acting on substances in the cytoplasm, either in the neighborhood 
of the germinal vesicle or around the astral body, causes Chemical changes 
which result in a new deeply staining substance, figs. 2, 4, 5, 6. This 
new substance, metaplasm perhaps, is then diffused apparently by cur- 
rents in the interfillar substance or cytolymph, forming larger or 
smaller aggregations. 
On application of reagents, the karyolymph filling the cavity of the 
aster and central vesicle or eentrosome, is coagulated. It then seems 
slightly granulär and resembles in appearance and staining reaction, the 
matrix of the germinal vesicle. It has none of the charaeteristics staining 
