No. 2.] DEVELOPMENT OF BIDDER’S ORGAN. 449 
this cell, and also in a few others lying near it, the cytoplasm 
contains a number of yolk spherules of various sizes. These 
spherules were not formed at the periphery of the egg, as is 
the case with the yolk spherules that first appear in the ovarian 
ova, but they were formed in, and from the substance of the 
yolk-nuclei scattered throughout the cytoplasm of the cell. 
The cytoplasm appears much vacuolated and the nucleus is 
in an advanced state of degeneration, while many of the large 
yolk spherules are disintegrating. The process of dissolution 
at first affects only a part of the yolk spherule, leaving a 
crescent shaped structure (Fig. 26, Y) which remains for a 
time and then disappears. This egg seems to me to furnish 
convincing evidence that yolk-spherules are formed from the 
substance of yolk-nuclei, and it also shows that the failure of 
the cells of Bidder’s organ to develop into functional eggs can- 
not be due entirely to their inability to form yolk, as Knappe 
claims. 
The compound-nucleoli which are found in some eggs dur- 
ing early post-synizesis stages (Figs. 9, 10) begin their reso- 
lution, as a rule, soon after the spireme divides into seg- 
ments. These bodies first become very irregular in outline 
(Fig. 21), and subsequently several light areas appear in them 
(Fig. 22). In later stages a differential stain, such as safranin 
and gentian violet, shows that these structures are composed 
of a mass of rounded plasmosomes embedded in chromatin 
granules (Fig. 23). The component parts of these masses 
are soon separated (Figs. 24-25), and the plasmosomes be- 
come distributed throughout the nucleus. Very little chro- 
matin is found in the compound-nucleoli in the cells of Bid- 
der’s organ compared with the amount that goes into the 
formation of the large nucleolar masses in the ovarian ova. 
Usually, after the resolution of the compound-nucleoli, the 
chromatin granules become scattered through the karyoplasm, 
only in exceptional cases (Fig. 20) is enough of the chromatin 
-separated from the spireme after synizesis to form oxychro- 
matin filaments. Nucleolar masses similar to those shown in 
Figs. 23-24 are evidently present in the cells of Bidder’s 
organ in Bufo vulgaris since Ognew states that he sometimes 
