12 EDWIN G. CONKLIN 
poses that when the spindle, lying at right angles to the egg axis, 
is pushed far toward the animal or vegetal pole, a ‘ball’ is formed 
at the opposite pole. Whether this ‘ball’ is homologous with 
the yolk lobe I shall discuss in another paper in which the arti- 
ficial production of such ‘balls’ will be considered, but I wish to 
point out here that although the first and second cleavage spindles 
in the large eggs of Crepidula and Fulgur le near the animal 
pole, and far from the vegetal, the yolk lobe in these forms is 
very small, whereas in the minute eggs of the oyster and the clam, 
where the spindles are much nearer the vegetal pole, the yolk lobe 
is relatively very large. If, as I believe, this lobe is the result of 
an unsymmetrical distribution of yolk and egg substance with 
reference to the egg axis, or in the case of Ascaris with reference 
to the normal division plane, the great size of the lobe in some 
cases and its minute size in others, in which the area lying outside 
the ‘‘ Wirkungskreise”’ of the spheres is much greater than in the 
former, would find a ready explanation. 
II. Cell size and nuclear size in eggs and blastomeres 
Strasburger (93) was the first to show by detailed measure- 
ments that a fairly definite ratio exists between the nuclear size 
and the cell size in the embryonic cells of any given species of 
plant. He gives tables of measurements of the sizes of nuclei 
and cells in some forty different species, the nuclei ranging in 
diameter from 16 to 3y, and the cells from 24y to 5u. In gen- 
eral he found that the ratio of nuclear diameter to cell diameter 
is approximately as 2 to 3; and the ratio which exists in any case, 
is held to be due in general to the ‘working sphere of the nucleus,’ 
1e., to the extent to which the metabolic interchange between 
nucleus and cytoplasm can reach. 
Gerassimoff (’01, ’02) found, in the cell division of Spirogyra, 
that when both daughter nuclei were caused to remain in one of 
the daughter cells, that cell grew to a larger size than normal, and 
he therefore concluded that the nuclear size determines the cell 
size. 
