No. 2.] THE OOGENESIS OF BUFO LENTIGINOSUS. 403 
new generation of nucleoli from chromatin granules, there is 
a constant formation of new nucleoli and a gradual dissolu- 
tion of the old ones during the growth stages of the ova. The 
disintegration of small nucleoli composed of a ring of chro- 
matin enclosing a plasmosome body (Figs. 39-43) has already 
been described. The beginning of a dissolution of some of the 
larger nucleoli is shown in Fig. 42. In this nucleus many of 
the nucleoli are stained black with iron hematoxylin; others 
appear grayish, since they seem to have lost their capacity for 
staining intensely. The latter nucleoli are gradually dissolved 
in the karyoplasm; they are never resolved into chromatin 
threads. Although the process of dissolution usually involves 
the whole nucleolus, sometimes only a portion of it disappears 
leaving one or several small, rounded bodies (Figs 4or 8) Tt 
is possible that the small groups of nucleoli shown in Figs. 40 
and 43 may have been formed in this manner. 
As a rule the majority of the nucleolar masses which lie 
in the meshes of the chromatin spireme or against the nuclear 
membrane at the stage of Figs. 26-34, resolve into plasmo- 
somes and oxychromatin filaments at about the time that the 
larger compound-nucleoli undergo their resolution (Figs.-35; 
39, Y). These masses differ from the larger ones in that they 
contain a relatively greater quantity of plasmosome material 
and a much smaller amount of chromatin. One or two of these 
nucleolar bodies, rarely more, escape dissolution at the stage 
of Figs. 35-38 and appear in later stages as slightly irregular, 
round or oval structures which stain as uniformly, thougn in 
many cases not as intensely, as in an earlier period (Fig. 30, 
X). These bodies increase rapidly in size after the stage of 
Fig. 39, and they usually undergo a somewhat different mode 
of resolution from that of the other compound-nucleoli. At 
an early period in the resolution of these bodies the Oxy- 
chromatin, which has been attached to the outer surface of 
the plasmosome substance (Fig. 40), breaks away and be- 
comes scattered throughout the nucleus, being indistinguish- 
able from the oxychromatin produced by the earlier resolu- 
tions of nucleolar masses. Sometimes all of the plasmosome 
