ELIMINATION OF SEX CHROMOSOMES 485 
the nucleus has begun to form. It contains five distinet chro- 
mosomes. Midway between the poles is the lagging chromosome 
completely divided into equal or nearly equal parts. A few 
traces of the spindle fibers are discernible. This is the clearest 
ease that I have found and shows very distinctly the conditions 
at this stage. 
The next case, fig. 8, is not so instructive, since the chromo- 
somes in the inner nucleus have in one place seemingly stuck 
together so that only four bodies are seen. The lagging chro- 
mosome could not be found but the five outer chromosomes are 
distinct. 
Fig. 9 shows the polar body nearly constricted off. The five 
inner chromosomes are clearly seen. The lagging chromosomes 
were not found and may have been fused with the lump of chro- 
matin in the polar body that represents the massed chromosomes. 
In fig. 10 (and in figs. 9, 11, 12 and 138) the egg nucleus is 
represented nearer the surface than in the actual section. The 
nucleus of the polar body contains a fused mass of chromatin. 
What appears to be the lagging chromosome lies on its outer 
wall, and is partially constricted into halves. The inner nucleus 
shows five equal or nearly equal chromosomes. As this is the 
only case observed where the lagging chromosome lies on the 
outer wall of the nucleus of the polar body, and as it is difficult 
to see how the chromosome could have reached this position; and 
moreover’ since the double body is smaller than the lagging chro- 
mosome in the other cases; it may be that this deeply staining 
body is not the lagging chromosome at all but a pair of displaced 
yolk granules. This interpretation is supported by the next case. 
In this instance fig. 11 the inner nucleus is well formed and 
its chromosomes diffused or at least not stained: In the polar 
body there is a nucleus in which four chromosomes can be made 
out with the double lagging chromosome lying on the inner side 
of the nucleus. <A yolk granule lies on the outer wall of the 
nucleus. 
A similar stage is shown in the next figure, fig. 12. The inner 
or egg nucleus shows its contained chromosomes in process of 
