686 
J. P. Munson 
in the center of the ring. I take this to be the yolk nucleus a real centro- 
sphere. 
Unbke the eggs previously described, the cat’s egg develops no true 
yolk spheres, such as are found in the mature egg of the pigeon, kingcrab 
and tortoise. Neither is there in the early stages any of those irregulär 
masses in the cytoplasm which I have designated as metaplasm. The 
presence of metaplasm in eggs developing true yolk spheres later, points 
to some connection between that metaplasm and the true yolk bodies. 
In the cat’s egg, the cytoreticulum is not so distinct, the cytoplasm is 
more uniformly granulär. But as the yolk nucleus (sphere) is really part 
of the living substance, it has the same index of refraction. It confirms 
the Statement of Balbiani, that in eggs having little yolk, it remains 
inconspicuous, because, in the living egg, it like the rest of the cytoplasm, 
is transparent; and by the influence of reagents, it changes like the rest 
of the cytoplasm. Consequently it remains as indistinct as ever. This 
to me is only another proof that it is a structural part of the cytoplasm, 
rather than a foreign, amorphous mass of chromatin or other substance. 
The Yolk Nucleus in Egg of Fish. 
In the egg of the goosefish, a similar bodv is conspicuous, figs. 54, 
55, 57, 60. It has the appearance of a large lump of archoplasm, located 
at one pole of the germinal vesicle, where the latter is shghtly indented. 
The horns of the archoplasmic mass extend out on either side of the ger- 
minal vesicle, fig. 57, and may even form a ring around it, fig. 54. 
In the widest, central part of this archoplasm, is a denser, spherical 
body, which Stands out prominently even in hematoxylin stains, fig. 55. 
In the center there is a elear vacuole or vesicle, fig. 57. But this may 
contain a deeply staining body suggesting the centrosome, figs. 54, 60. 
There are indications of indistinct, concentric rings, surrounding the central 
body; but astral rays are not distinctly visible in my preparations. 
There is only one of these in each egg; and as it bears the same con- 
stant relation to the germinal vesicle as that seen in the other eggs de- 
scribed, I have no hesitation in identifying it as the vitelline body or 
centrosphere. 
As I have not studied the fully developed eggs, I can say nothing 
as to the ultimate fate of this body. I can find no excuse, whatever, for 
assuming that this body originates from follicle cells, from fragments of 
the germinal vesicle, or from migrating nueleoli. There is nothing about 
it to suggest that it owes its origin to chromatin entering the cytoplasm 
from the nucleus. Rather, as I have suggested in the case of other eggs, 
