74 EDWIN G. CONKLIN 
at the outer pole of the axis which passes through the centrosome 
and nucleus and these axes mark the position of the spindles 
of the third cleavage. Here, as in every other instance, the 
smallest nucleus is found in the cell which has the smallest amount 
of cytoplasm. 
Fig. 30 is a drawing of an egg which was centrifuged ten min- 
utes in gum arabic, during the first cleavage, and fixed four 
hours later during the third cleavage. Macromeres A and B 
are richer in cytoplasm and poorer in yolk than C and D, and 
correspondingly the spindles and asters are larger in the former 
than in the latter. 
Figs. 31 and 32 represent eggs which were centrifuged four 
hours during the first cleavage, and were fixed six hours later. 
In both eggs the macromeres A and B are richer in cytoplasm and 
poorer in yolk than C and D. In fig. 31 the cells A and B con- 
tained more cytoplasm and divided earlier than C and D; at least 
one-half of the cytoplasm in the latter cells has gone into the 
formation of the micromeres, which are still, however, smaller 
than normal. ‘The first cleavage in this egg did not pass through 
the animal pole, marked by the polar bodies, but was displaced 
to one side, and the spiral form of the cleavage is not clearly 
preserved in the cells C and D. While the regulation in the size 
of these micromeres is not complete, the tendency to approach 
the normal condition is evident. Fig. 32 is similar to fig. 31, 
though .the macromeres C' and D of this egg contained a larger 
amount of cytoplasm than in fig. 31, and the regulation in the 
size of the micromeres is complete. 
Fig. 33 shows an egg, from the same slide as fig. 30, which was 
centrifuged ten minutes in gum arabic and fixed four hours later. 
The macromeres /A and /B contain more cytoplasm and are 
dividing earlier than /C and 1D, but the micromeres from the 
former are no larger than those from the latter. 
Fig. 34 represents an egg which was centrifuged for two and 
one-half hours during the first cleavage, and was fixed twenty-one 
hours later. The macromeres 2A and 2B contain much cyto- 
plasm, while 2C and 2D contain little and yet the micromeres 
formed from the latter are almost as large as those from the former. 
