ELIMINATION OF SEX CHROMOSOMES ° 487 
I have tried to find again all the polar body stages figured in 
my former paper in order to reéxamine them, but it has not been 
possible to discover several of them owing to the fading of the 
stain. I wished especially to reéxamine figs. XY; NV, P, Q, which 
show the lagging chromosomes passing into the polar bodies, 
but have not succeeded in finding them again. All three rep- 
resent the same spindle under different conditions. While these 
figures were drawn with as much care as possible I now realize 
that some of them might receive a clearer interpretation in the 
light of the information that I have gained from a new study 
of the polar spindle. One point is especially clear that in most 
cases the circle enclosing the chromosomes of the polar bodies 
of the male-producing egg was drawn so as to include the lagging 
chromosome, while in reality the ordinary chromosomes lie in 
one vesicle and the accessory in another clear area at the side 
othe latters, hus ini tigs, xX: C,.G, dee, Sel UW, the 
sixth chromosome generally shown as bifid represents the lagging 
chromosome. 
In the new preparations I have found only one anaphase of 
a female-producing egg, fig. 22. Fortunately this is a very clear 
case. Six chromosomes lie at each pole, and there is no lagging 
chromosome present. Three of the outer chromosomes are 
dumb-bell shaped. The only other cases of this kind of egg are 
the doubtful case, here refigured, fig.21, and the outer pole shown 
in my former paper in fig. X; K. 
Summary 
The evidence shows that four of the five chromosomes of 
the male-producing egg divide equally when the polar body is 
formed. One chromosome lies in the middle of the spindle and 
becomes divided into equal parts. It finally passes out into 
the polar body, just before the latter cuts off, and fails in con- 
sequence to become incorporated in the nucleus of the polar body. 
In all these respects its behavior is closely similar to that of the 
lagging chromosome described by McClung for this chromosome 
in the spermatocytes of orthoptera. 
