684 
J. P. Munson 
In this section of the pigeon’s ovary represented in fig. 50, several 
oocytes of different sizes appear. They are all siuTounded bv a folliele. 
Like the oogonium which has no folliele, the oocytes are oval; the nucleus, 
now the germinal vesiele, is excentric. 
In osmic aeid preparations, a dark erescent Stands out proniinently 
in the thieker part of the eytoplasm. The horns of the erescent, partly 
surround the germinal vesiele. Higher magnifying powers reveal in the 
thickest part of this erescent, a round, light area. In favorable prepara- 
tions, a round dot, the centrosome, fig. 58, is distinctly visible, in the > 
center of the light area. Closer examination shows the whole stained body 
to be an attraction sphere, xvith astral ravs and concentric circles of micro- 
somes, fig. 52. 
1 take this structure to be a continuation of the similar structure 
seen in fig. 51. Without some positive proof of spontaneous generation, 
I do not feel justified in giving it another interpretatiou. The aetual 
proof of this conelusion eould be had, if it were possible to see the oogonium 
in fig. 51 aetually grow into the ooeyte in fig. 52. 
The structure in all is certainly identical, with slight differences 
readily accounted for by different amounts and disposition of gramües; 
as well as by the variable condensations incident to hardening and stain- 
ing the preparations. 
Anybody who has examined a hardboiled hen’s egg will not find 
it difficult, perhaps, to concede the possible connection of this centrosome 
and sphere with the central area of concentric circles of white and yellow 
yolk, the concentric zones in the mature egg being probably foreshadowed 
by the concentric circles of large mierosomes of the aster, fig. 52. I find, 
in fact, in all eggs in which the yolk nucleus is prominent, distinct in- 
dications of regulär stratification of the eytoplasm, as in the bird's egg. 
I am not aware that the female centrosome has yet been demonstrated 
in the mature hen’s egg. But if my suggestions are true, it ouglit to be 
found in the center of the latebra. If we compare the ovarian egg of the 
pigeon with that of the tortoise, the eonviction that the latebra of the 
bird’s egg develops out of the yolk nucleus, is irresistable. My prepara- 
tions suggest that this is indeed the attraction sphere of the ooeyte. 
The connection between the germinal vesiele of the bird’s egg and 
the latebra is similar to that between the germinal vesiele and the yolk 
nucleus in the egg of the tortoise. This connection also serves to explain 
the development of metaplasm, — (a kind of yolk, possibly corresponding 
to the early stages of yellow yolk in the hen’s egg) — around the yolk 
nucleus in the tortoise. As I have already intimated, it fonns a path or 
