170 Helen Dean King. 
sharply distinct from the cytoplasm, which stain very intensely with 
iron hematoxylin (Fig. 19, Y.N.). These are the so-called “yolk- 
nuclei” which are always present in the normal ova at certain stages 
in their development, and which sometimes appear in the young 
cells of Bidder’s organ. The arrangement of the yolk-nuclei in 
the cell shown in Fig. 19 is very similar to that of the yolk-nuclei 
in the cells of Bidder’s organ. I have not been able to find any 
cells in these rudimentary ovaries that might be considered as inter- 
mediate in structure between normal and rudimentary ova. 
The larger cells in the rudimentary ovaries border the central 
cavity, and, owing to pressure, they are usually greatly distorted in 
shape. The average diameter of these cells is 0.6 to 0.7 mm.; while 
the diameter of their nuclei ranges from 0.17 mm. to 0.25 mm. As 
a rule the nuclei of these cells resemble to a remarkable degree those 
of young ovarian ova of the same size: they are rounded in outline and 
contain a large number of scattered nucleoli; the karyoplasm appears 
uniformly finely granular; and the chromatin threads have the 
feathery structure characteristic of the chromosomes in the young 
ovarian odcytes (Fig. 25). 
The structure of the cell body in many of these larger cells differs 
considerably from that normally found in the ovarian odcytes of 
the same size. As a rule the cytoplasm is much vacuolated, as if 
degenerative processes had already begun in it. In some cases the 
vacuoles extend radially from the periphery of the cell to the nucleus, 
giving the eytoplasm a striated appearance when examined under a 
low magnification; in other cases the vacuolated area extends only 
around the periphery of the cell and the cytoplasm surrounding the 
nucleus appears uniformly reticular (Fig. 23). There is a possi- 
bility that the vacuolization of the cytoplasm in these cells is due, 
in part at least, to the way in which the material was preserved. 
Flemming’s fluid, although an excellent fixing agent for the testes 
at, all stages of their development, is but a very indifferent fixative 
for amphibian ova after they have passed the synizesis stage. The 
cytoplasm of these large cells would doubtless appear much less 
vacuolated had some other fluid with greater powers of penetration 
been used in fixing the ovo-testes. 
