Ig18| BUCHHOLZ—PINUS 201 
chemical nature in Pinus was not determined. The word “basal” 
seems fitting because it is, in a real sense, basal to the embryos in its 
position. Doubtless careful search will reveal this in many other 
gymnosperms. Whether the rosette is present as in fig. 41, 
elongated as in fig. 54, or absent as in Podocarpus, the basal plate 
is always formed in the egg cavity on the walls toward the 
embryos. 
APICAL CELL.—A distinct apical cell stage exists from the time 
the embryo cells first have walls. In fig. 1 the suspensor cells (s) 
are the first segments of their respective apical cells (a). Here 
the 4 primary embryos are apparently still united; but if they may 
be looked upon as organizing distinct from each other, the 4 cells 
which gave rise to the lower 8 cells of the 16-celled embryo are 
embryo initial cells. The work of CouLTER and CHAMBERLAIN (9), 
FERGUSON (13), and KILDAHL (19) has shown that these which we 
call embryo initial cells were formed in the mitosis between the 
4-nucleate and 8-nucleate proembryo, the place where KILDAHL (19) 
found that the first walls appeared. FERGUSON (13) and KILDAHL 
(19) found that the rosette and upper open tier organize next, 
from the upper 4 nuclei (although Ki~pant found exceptions to 
this), and therefore this lowest tier of the 12-celled stage is a hold- 
over since the first appearance of walls. 
The second segment of the apical cell is the initial cell of the 
first embryonal tube. This segment, as well as the third and 
fourth, are formed by an apical cell of 1 cutting face. Figs. 1-6 
all show apical cells of a single cutting face, while in figs. 7, 8, 9, 11, 
and 12 the first oblique wall of the apical cell has appeared. This 
wall is sometimes only slightly tilted, as in fig. 9, or it may be nearly 
vertical, as in figs. 10 and 14. 
The stage at which this oblique wall first appears is not always 
the same. A large number of embryos .of P. Banksiana were 
examined in order to determine the average condition in this respect. 
This study showed that these variations are somewhat similar to 
those found in the number of tubes in the early suspensor divisions. 
In nearly two-thirds of the cases the first oblique wall appeared after 
the primary suspensor and 2 embryonal tube initial cells (3 sus- 
pensor divisions) had been formed by the apical cell of one cutting 
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