264 BOTANICAL GAZETTE [APRIL 
the middle cell, which divides transversely, making a chain of 
four cells (figs. 46,48). The succeeding division is in the ter- 
minal cell, which divides longitudinally, giving rise to the first 
two cells of the cotyledon (figs. g9, 50). The cell 6 (jig. 49) 
gives rise to the stem tip, while the cell d (fig. 49) divides 
transversely, forming the six-celled pro-embryo with five tiers of 
cells (figs. 5z, 53). The next division is in the cell 4, which 
divides longitudinally (figs. 54, 55), and gives rise to the seven- 
celled pro-embryo (fig. 56). During this time the remaining 
synergid is a very active cell, and appears to assist the vesicular 
cell in its function (figs. 46, 48, 54, 55). There now occur sev- 
eral divisions in rapid succession, but not always in the same 
order: Usually the two terminal cells divide longitudinally ; the 
celld (fig. 59) also divides longitudinally; while in the cell 
above this transverse division occurs, giving rise to an eleven- 
celled pro-embryo with six tiers of cells (figs. 57, 58, 59, 60, 
6z). Each one of the four terminal cells now divides trans- 
versely (fig. 62), so that the young cotyledon becomes an 
octant. That the process is not always so typical will be seen 
from fig. 63, where one of the four cells has divided longitudi- 
nally, and another one is dividing transversely, while there are 
only five tiers of cells. 
After the formation of the octant of the cotyledon, the next 
thing which usually occurs is the cutting off of the dermatogen 
by periclinal divisions in these eight cells, and the same process 
usually goes on in the tier above at the same time (fig. 64). 
The cell in tier e (fig. 6¢) now divides longitudinally, while the 
cell f ( Jig. 64) still remains single (fig. 65). In one case, how- 
ever, I observed that this cell f ( fig. 66) also had divided longi- 
tudinally. This is a very interesting variation, since it would 
change the entire course of the development of the root tip and 
_ suspensor. It is another illustration showing that no hard and 
fast lines can be drawn for the development of an embryo. The 
suai lena. of the embr 
Be ie 
o ae ee apt to show variations _ 
ge acter must change the whole | 
_ course of development. ‘The ———— of cells for 
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