22 BOTANICAL GAZETTE [SEPTEMBER 
Discussion 
APICAL CELL.—STRASBURGER (38) was the first to cast doubt 
upon the existence of an apical cell in the embryo of the Abietineae. 
He felt doubtful of it because it did not appear to be a constant 
feature. The instances in Pinus described and figured by him in 
which he considered the apical cell absent are practically the same 
as some of the more unusual ones described in this paper. He 
regards embryos like figs. 13, 14, and 21a as having no apical cell; 
and while he recognized that in embryos like figs. 16 and 18 an 
apical cell seems to be present, he considered this apical cell growth 
not constant and that it has no phylogenetic significance. 
CouLTeR (8) expresses the opinion that an apical cell is only 
simulated in Pinus and does not in reality exist. He is probably 
misled by the appearance of nearly vertical oblique walls in the 
terminal cell and by embryos like figs. 13 and 21a. COULTER and 
CHAMBERLAIN (9, 10) do not mention an apical cell, and thus imply 
that such a stage does not exist, but point out that the problem of 
the development of the pine embryo after the first few divisions is 
an open one. 
Saxton (33) overlooked STRASBURGER’s work (38, 39), and 
although Coutrer had expressed the opinion that an apical cell 
is only simulated, he is inclined to regard the terminal cell of the 
P. pinaster embryo as an apical cell. When he failed to find an 
oblique spindle he seemed not fully convinced about the existence 
of a true apical cell, which he figured only in young embryos up 
to 30 cells. For these reasons the writer considered it necessary 
to give considerable study and attention to the proof of the exist- 
ence of an apical cell in the early embryo. 
A series of embryos (figs. 9, 7, 8, 10, 13, and 14) may be selected 
showing the first oblique wall in all positions, from nearly transverse 
to vertical. This variation in the first oblique wall has made an 
occasional embryo hard to explain as having an apical cell. Fig. 15 
shows how the next wall comes in, and after this stage the apical 
cell may easily be found, except that it is frequently very much to 
one side. The apical cell cuts the first oblique segment at no 
fixed stage, but probably at the time when the embryo is well 
separated from its neighbors in the embryo system. This same 
