70 EDWIN G. CONKLIN 
pole. The first cleavage plane is nearly equatorial in position, 
and one of the cells contains most of the cytoplasm. The 
spindles for the second cleavage have formed and the spindle 
in the cell containing the larger amount of cytoplasm is distinctly 
larger than the one in the other cell; each is proportional in size 
to the resting nucleus from which it came and to the volume of 
cytoplasm in the cell. The fact that the polarity of the cells has 
not been changed by the abnormal position of the first cleavage 
plane is indicated by the fact that the spindles are parallel to 
each other, but not to the plane of cleavage, as in normal eggs. 
In short there is evidence that the spindles here attempt to take 
up the positions which they would have occupied in a normal 
egg, with meridional cleavage. 
Fig. 18 represents an egg from a lot which was centrifuged fifteen 
minutes in gum arabic, as reeommended by Lyon (’04), and which 
was fixed three hours after removal from the centrifuge. Fig. 
19 shows an egg which was centrifuged thirty minutes, and was 
fixed six hours later. In both cases the centrifuging took place 
during the first cleavage, as is shown by the unequal distribution 
of cytoplasm and yolk on both sides of the first cleavage plane. 
In the second cleavage, which evidently occurred after the eggs 
were removed from the centrifuge, the cytoplasm was distributed 
equally to the daughter cells. In fig. 18 the second cleavage took 
place a little earlier in the cell rich in cytoplasm (AB) than 
in the other (CD), but the smaller size of the nuclei in the latter 
is probably due in part to the fact that these cells are poor in 
cytoplasm. In fig. 19 the inequality.in the distribution of cyto- 
plasm at the first cleavage is much greater than in fig. 18; never- 
theless the second cleavage occurred in the cell poor in cytoplasm 
(CD) at nearly the same time as in the other cell (AB). Although 
the nuclei in the cells C and D are much smaller than those in A 
and B, their structure shows that they are in nearly the same 
stage of the cell cycle. Their smaller size is due to the smaller 
quantity of cytoplasm in which they lie. Figs. 17-19 indicate 
that the absolute size of the nucleus has little to do with the time 
of its division; small nuclei in yolk-rich cells divide almost as 
rapidly as large nuclei in cells rich in cytoplasm. 
