302 KING. [Vov. XIX. 
exact conclusion regarding their number. I believe, however, 
that the nucleus at this stage contains only the somatic number 
of chromosomes (24) which are usually arranged in twelve 
pairs. The question at once arises as to the value of the sister 
segments which form a pair. Is the splitting of the spireme 
shown in Figs. 28-30 a longitudinal division of chromosomes 
united end to end in the spireme or is it a separation of uni- 
valent chromosomes which had conjugated side by side? This 
question is very difficult to answer since it is impossible to de- 
termine what changes the chromatin undergoes during syn- 
izesis. As the nucleus apparently contains but twenty-four 
chromatin segments which in later stages of development are 
scattered throughout the nucleus and only occasionally found 
in pairs, I am inclined to the opinion that each .of the sister 
segments represents an odgonial chromosome. The paired 
arrangement of the chromosomes at the stage of Figs. 33-34 
strongly suggests that in the odcytes of Bufo synapsis is co- 
incident with synizesis as it is apparently in the spermatocytes ; 
yet for various reasons, which will be given later, I am inclined 
to consider that synapsis does not occur until the beginning of 
the maturation period. 
At the stage of Figs. 20-21 all of the young oocytes in a 
cyst are approximately of the same size and in practically the 
same stage of development. As the synizesis period approaches 
the oocyte which lies nearest the cavity of the ovary grows 
very rapidly and soon becomes several times the size of its 
neighbors. <A section of a cyst with the odcytes in this con- 
dition is shown in Fig. 37. The large cell bordering the 
cavity of the ovary has a diameter of 0.043 mm., and its 
nucleus measures 0.023 mm. in diameter. This odcyte is sur- 
rounded by a number of follicle cells and its nucleus contains 
paired chromatin threads. The other cells in the cyst are very 
nearly of the same size; each measuring about 0.015 mm. in 
diameter and containing a nucleus measuring 0.01 mm. in 
diameter. These smaller odcytes are in early post-synizesis. 
stages of development, and they are not degenerating, as sev- 
eral investigators who have found a similar condition of the 
