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No. 2.] THE OOGENESIS OF BUFO LENTIGINOSUS. 401 
it stains deep blue, surrounding a central portion which either 
stains very faintly or appears colorless; similar bodies are 
shown in Figs. 40, 41, 43, etc. Ata later period the central 
portion of such nucleoli disappears, leaving only the chromatin 
ring. Subsequently the ring breaks at some point, thus becom- 
ing a crescent (Fig. 41), and it then disintegrates into small 
granules. Nucleoli of this character are probably derived from 
the oxychromatin of the larger compound-nucleoli, since they 
seem to be found most abundantly at the stages of Figs. 39-43. 
Similar nucleoli are figured by Carnoy and Lebrun and also by 
Lubosch. 
The oxychromatin threads produced by the resolution of the 
large compound nucleoli are massed together at the stage of 
Fig. 39; but they soon become scattered throughout the nucleus 
and are bent and twisted in a great variety of ways (Figs. 
40-43). Occasionally, as shown in Figs. 40 and 43, two of 
these filaments lie parallel or cross each other in the form of 
an X. Such an arrangement is purely accidental, since the 
filaments never have any definite arrangement in the nucleus. 
In some cases oxychromatin threads seem to be united with 
nucleoli (Fig. 43); but as the nucleoli stain differently from 
the filaments, it is readily seen that there is no true connection 
between them. 
Many of the figures given by Carnoy and Lebrun show 
granular chromatin filaments strikingly like those shown in 
my Figs. 40-43. These investigators consider that such fila- 
ments are derived from the substance of the nucleoli, and the 
contact of a nucleolus with a chromatin thread, as shown in 
my Fig. 43, is considered to be proof that the chromatin 
thread is being formed at the expense of the nucleolus. The 
feathery chromosomes are considered by Carnoy and Lebrun 
to be merely a special form of the filaments and in no way 
different from the others in origin or in fate. My observa- 
tions do not admit of such an interpretation, since in Bufo 
the feathery chromosomes can be traced back to the contin- 
uous filament formed after synizesis (Fig. 26), while the Oxy- 
chromatin threads are undoubtedly derived from the chromatin 
