458 WILLIAM M. GOLDSMITH 
the female count, but to extend the study of the cells of this sex 
as far as possible. Over 200 slides were made before a satis- 
factory count of the oogonial chromosomes was obtained. Even 
after the difficulty of poor fixation was partially overcome, the 
overlapping and irregular arrangement of the crowded meta- 
phase chromosomes rendered the count practically impossible. 
The chromosomes of a single plate were never found in the same 
plane. Figure 85 shows two large chromosomes lying across 
the central part of the plate, while other figures (83 to 86) show 
a number of chromosomes lying at various angles to the meta- 
phase plane. This suggests that they have passed the typical 
metaphase condition and are approaching early anaphase. If 
this be true, and there is a stage in which the chromosomes are 
arranged in a single plane, a sufficiently large number of divi- 
sions have been studied to justify the statement that the meta- 
phase condition is practically instantaneous. The smaller chro- 
mosomes often lie in such close contact with the end of the 
larger that an especially good differentiation is required to dis- 
tinguish the bivalent nature. A number of instances were also 
noted in which a small chromosome is above, below, or in con- 
tact with a larger one (fig. 84). A number of plates were also 
found which showed more than the normal number of chromo- 
somes. The explanation of such cases is obvious from figure 
83, in which the V’s are almost perpendicular to the plane of 
the plate, thus a number of the arms are cut, causing each V to 
appear as two spherical chromosomes. <A very careful study, 
however, of a large number of plates fully establishes the female 
number as twenty-four. 
10. GROWTH PERIOD OF THE PRIMARY OOCYTE 
A. Formation of leptotene threads 
The reconstructing nuclei at the close of the last oogonial 
division differ from those of the earlier divisions. The telophase 
chromosomes remain for some time as compact, irregular chro- 
matin masses, with woolly or fibrillar connections (fig. 95). As 
the cell begins to grow and the nuclear membrane becomes 
