No. 2.] THE OOGENESIS OF BUFO LENTIGINOSUS. 423 
The vitelline bodies begin to increase in number before the 
resolution of the large compound-nucleoli and’at a time when 
the nucleus contains but a very few plasmosomes: they are 
scattered throughout the cytoplasm, chiefly in the zone midway 
between the periphery of the egg and the nuclear membrane; 
and very few of them ever lie close to the nucleus. These 
facts would seem to preclude the possibility that the vitelline 
bodies are extruded nucleoli, although in their staining reac- 
tions and in their general appearance they are strikingly like 
these structures. 
One of the reasons given by Will forconsidering the rounded 
bodies which he finds in the cytoplasm of the egg of Rana as 
extruded nucleoli is that he first finds these bodies in a light 
area close to the nucleus. Preparations of young ovarian 
eggs of Bufo that have been badly preserved frequently give 
the impression that nucleoli lie outside of the nucleus in a 
fluid space marked off from the cytoplasm. If such prepara- 
tions are examined under an immersion lens, one finds that 
the light area which apparently surrounds the nucleus is, in 
reality, a portion of the nucleus itself, since the nuclear mem- 
brane is readily found where the clear area comes in contact 
with the cytoplasm. In such eggs, owing doubtless to the 
imperfect penetration of the fixing fluid, all of the more fluid 
portions of the nuclear substance seem to be collected at one 
side or around the periphery of the nucleus, while the granu- 
lar achromatin and most of the nucleoli are massed together 
either in the middle of the nucleus or at one side of it. Pro- 
jections from this mass sometimes extend across the fluid 
substance to the nuclear membrane and thus give the appear- 
ance of an ameeboid nucleus without a nuclear wall. In 
nuclei of this character nucleoli are sometimes found stranded 
in the fluid substance and, under low magnification, they appear 
to lie in the cytoplasm. The clear area which separates the 
nucleus from the cytoplasm in many eggs is doubtless an arte- 
fact produced through the action of reagents: I do not think 
that it is present in the living egg. 
The vitelline bodies are rarely found close to the periphery 
of the egg at the stages of Figs. 36-39, and I have seen noth- 
