* 
2 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
— 
ing section, Figure 32, it is seen that with the formation of the spindles 
in dë? and d’? these cells have yielded to the well known tendency to 
take a more rounded form at the time of karyokinesis; the inner parts 
of the cells have been withdrawn toward the surface and used in in- 
creasing the dorso-ventral dimensions of the cells. The animal pole 
has been thereby pushed still farther in the direction in which it has 
been steadily migrating, so that it is actually past the micromere end of 
the egg. The cells of the quadrants A, B, and C, being in a “resting ” 
condition, give way to the compression, and become much deeper and 
flatter than before. The cell . retains its position at the macromere 
end of the egg, but lying in a concavity, partly surrounded by the 
other cells. The spindle lies in the deeper (more dorsal) parts of the 
cell, with its right end (Fig. 33) deepest, and close to the wall of 
the cell A view from the ventral end of the egg (Plate 5, Fig. 35) 
shows that this “right” end is really anterior, and that the spindle lies 
in an antero-posterior plane, coincident with the plane separating the 
quadrants A and B. The anterior (inner) end of the spindle lies close 
against the boundary between a’! and 054, 
The division which now ensues is of an extraordinary character. The 
anterior end of the spindle is pressed against the periphery of the cell 
at the place above mentioned, and a minute vesicle is given off, which 
lies embedded between the cells / and 053, This, after the division 
is finished, is shown in Figure 38 (Plate 5), the vesicle being 
labelled de.. 
During division, the granular cloud which was described as occupying 
the anterior half of the periphery of the cell moves still farther toward 
the anterior margin, and shows a tendency to concentrate into a more 
definite group; the individual granules become larger also (Fig. 38). 
In d*? and d*? the spindles are parallel to the spindle in d*', the 
right ends being nearer the boundary of the cells, and deeper within 
the egg. The latter fact is shown in the transverse section, Figure 36, 
passing through the cells of the third layer. The divisions are un- 
equal, as foreshadowed by the position of the spindles, but tho inequality 
is much less than in the case of d*'. The completed division is shown 
in Figure 37. The cleavage takes place first in d“. 
At about the same time as the division of d*? occurs that of the dor- 
sal coll, d*-^, Here the spindle is in the short axis of the cell; the 
cleavage is equatorial and unequal, the dorsal cell being much the 
smaller (Fig. 37). 
During the occurrence of the cleavage of these cells other changes, 
