CELL SIZE AND NUCLEAR SIZE Oe 
meres in question without making the macromeres smaller than 
the micromeres, thus reversing the usual inequality of this divi- 
sion; in short the division of these cells represents the nearest 
possible approach to normal conditions. 
Figs. 27 and 28 show eggs of the same type as the preceding, 
but at a stage after the formation of the second set of micro- 
meres (2a—2d) and during the division of the first set (la—1d). 
Here also these micromeres are normal in size, although the size 
relations, and the cytoplasmic or yolk content of the macromeres 
from which they came, are very abnormal. In the cleavages which 
follow after the centrifuging, complete regulation has occurred, 
so far as this is possible. It is not possible for regulation to take 
place by the redistribution of cytoplasm and yolk by passage 
through a cell membrane. 
Fig. 26 represents an egg which was centrifuged for thirty 
minutes during the second cleavage, and then fixed twelve hours 
later. At the time of centrifuging the nuclear division in the 
second cleavage was complete, but the division of the cell body was 
suppressed. Consequently each of the blastomeres, AB and CD, 
contained two nuclei, which by subsequent division in the manner 
indicated in fig. 22 have given rise to two sets of micromeres, 
la-1d, and 2a-2d. Both sets of micromeres have divided, as 
indicated by the connecting bonds, thus forming a somewhat ab- 
normal cap of sixteen micromeres. The nuclei of the macromeres 
are indicated by the reference lines from the letters 24—2D. 
Other cases similar to this one will be shown and described in 
another paper, but this one egg shows that it is possible for both 
the nuclei of a binucleate cell to divide at the same time and to 
give rise to separate cells, each with a single nucleus, and that such 
cells may approximate in form and position normal blastomeres. 
Fig. 29 represents an egg which was centrifuged for four hours 
at the close of the second cleavage, and fixed at once after centri- 
fuging. The yolk has been forced out into lobes, which are still 
connected with the protoplasmic portions of the cells except in 
the case of one cell, where the lobe has been completely separated. 
It is a significant fact that the point at which the lobe forms, and 
consequently the point where the cell membrane is weakest lies 
