Nor 24) MICRODECTOP OS GRYELOTALPA COSTA. 311 
so that in the next stage I was not able to decide from their posi- 
tion whether g?, 4* had divided again or whether certain of the 
other cells had divided. I did find, however, one egg with about 
sixty-four cells, in which the two cells next to 4°-0%, d*—d* were as 
large as g and / are before dividing. The arrangement of the 
other cells is diagrammatically sketched in the cut. It was neces- 
sary to make a diagram, because all the 
cells could not be seen in the same field of 
view. In this one egg I did not find the 
two cells in the center. I cut sections 
to see if I could find spindles going in, 
but the critical section was completely 
broken. I know there were no cells in 
the interior for the reason that when 
they are present they can always be 
distinguished in optical section in the 
whole cleared egg. 
After this time the two cells in the interior are found in 
various stages of disintegration. As late as the 112-cell stage, 
after the blastoderm has appeared on the surface of the egg, 
two deeply stained patches can still be seen in the interior. 
Shortly after this stage they disappear altogether, and no other 
cells are seen in the yolk until the egg is about forty-eight 
hours old (Fig. 39). Weismann and Ischikawa (87) have 
described three secondary polar bodies in Bythotrephes longi- 
manus, which are carried into the interior of the egg during the 
early segmentation stages. These polar bodies subsequently 
disintegrate, though as late as the 32-cell stage remnants of 
them could still be detected in the axial space between the 
blastomeres. Dr. Mead (95) also has found that the polar 
bodies of Amphitrite are taken into the axial cells, where they 
are absorbed. These results of Weismann and Ischikawa and 
of Mead led me to suppose that the two cells found in the 
interior of the Microdeutopus egg were polar bodies. I there- 
fore made a careful study of the eggs before the 32-cell stage. 
Since I found no cells which had not been derived from one of 
the two blastomeres of the 2-cell stage, I conclude that the cells 
in the interior cannot be polar bodies. In the literature which 
