176 RAYMOND BINFORD 
sion of the spermatozoon, we know forms the inner lining of the 
sperm-vesicle. The discarding of this capsular wall was not 
clearly made out, but figures 109 and 110 indicate that such a 
change takes place. In eggs taken soon after spawning the sperm- 
vesicle has increased considerably in size and the wall has taken 
on a vesicular appearance. This is shown in figures 110 and 111, 
which show the sperm-vesicle in two different aspects. The 
cavity of the vesicle gradually disappears, leaving only a notch 
on one side (figs. 108, 109, 110 and 112). Figure 112 was about 
an hour old. In eggs two hours old the vesicle has taken on the 
appearance of an ordinary nucleus containing granules of chro- 
matin (fig. 116). At this time it has gone about one-fourth of 
the distance from the circumference to the center of the egg 
ie STL: 
We will now turn our attention to the egg-nucleus. When the 
eggs are set free in the lumen of the ovary, just before spawning 
begins, the spindle for the first maturation division is already 
formed and its long axis is parallel with the surface of the egg 
(fig. 113). As the egg passes through the oviduct the spindle 
turns to a position perpendicular to the surface of the egg and 
the first polar body is cut off. This is shown in figure 114, which 
is from an egg that has just passed out of the oviduct. Efforts 
were made to count the chromosomes just after this division. 
Twenty-five to twenty-eight were counted. Thus the double 
number would be fifty to fifty-six. They are however so small 
and placed so closely together that it is difficult to distinguish 
them accurately. 
Between one and one-and-a-half hours after spawning the 
second maturation division takes place. The second polar body 
is apparently not cut off, but remains in the egg where it degen- 
erates and is absorbed by the cytoplasm. 
The female pronucleus is now formed and proceeds to the 
center of the egg, where it meets the male pronucleus. Figures 
115 and 116 are drawn from nuclei fixed at two hours and fifteen 
minutes after spawning. At this time it is not possible to tell 
which is the male and which the female pronucleus unless the 
