202 BOTANICAL GAZETTE [SEPTEMBER 
face; one-fourth after 2 suspensor divisions; and one-tenth after 
4 suspensor divisions had been formed. 
It is often difficult to determine with certainty in an embryo like 
fig. 15, for example, at what stage the first oblique wall was formed. 
Here the last horizontal wall is tilted slightly, so one might think 
that this was modified by growth after the first oblique wall 
appeared; but it is also possible that this segment was first formed 
with a perfectly horizontal wall, and this later enlarged on one side 
to appear slightly oblique, so that the first real oblique wall is the 
one which appears nearly vertical. While these two interpretations 
could be given to fig. 15, in making the study referred to in the 
foregoing paragraph, the slightly oblique wall was looked upon as 
though it has been formed in an oblique position by the apical 
cell. 
A stage in which the apical cell has 2 cutting faces does not 
exist, or it is so shortened that it cannot easily be recognized. 
Figs. 15 and 16 have only 2 oblique segments cut off, but these 
are probably the first 2 segments of the apical cell stage with 3 
cutting faces. Apical cells with 3 cutting faces are found in 
embryos only slightly larger, such as figs. 17 and 18. Figs. 17-23 
are all from whole mounts in Venetian turpentine and. show 
pyramidal apical cells of 3 cutting faces. 
Many irregularities are found in regard to the position of the 
apical cell. It is frequently so far to one side of the tip of the 
embryo that it might be overlooked in some serial sections. A 
section of an embryo like figs. 17, 20, or 28, if cut in another plane, 
would not show the apical cell so favorably, and might be mistaken 
for an embryo without an apical cell. 
A very puzzling case is shown in fig. 21a, 6. Fig. 21a shows 
the embryo in a high.focus, with the shadows of nuclei of a lower 
focus shown by the dotted lines. Fig. 21b shows the nuclei and cell 
walls of the same as seen in low focus. This looks like an embryo 
which has no apical cell, and it is on the basis of very similar 
figures that STRASBURGER (38, 39), and other workers since, have 
denied the existence of an apical cell as a constant feature. In this 
particular instance the apical cell is at one corner of the lower tier of 
4 cells. It is either the cell to the right in high focus, or the lower 
