318 BOTANICAL GAZETTE [ NOVEMBER 
each of the quadrants. /zg. 27 represents a peculiar variation 
or abnormality in the development of the i es of the basal | 
embryo cell. 
To the inner cells of the tier d, fig. 20, one can refer the 
origin of plerome and periblem, the central cells forming the 
plerome and the single layer between this and the dermatogen 
giving rise to the periblem. 
The transverse division begun in the dermatogen has extended 
throughout this tier d (fig. 27), and is followed by another radial 
division in the dermatogen, while a longitudinal division occurs 
in the innermost cells of tier c (fig. 2g). Aseries of longitudinal 
walls also begins to appear in tier d, followed by irregular 
transverse divisions (fig. 25). The entire embryo is now develop- 
ing rapidly. The basal embryo cell has undergone the third 
and transverse division, forming two tiers of four cells each 
next the suspensor (fig. 25, fand g).. In the region where the 
cotyledons arise, diagonal division has occurred, while in the 
region of the stem tip it has been longitudinal. The plerome 
is quite distinct and is shaded in the figure. 
A more adyanced stage is shown in fig. 28. The cotyledons 
develop more rapidly and the embryo becomes obcordate (figs. 
29-31). The plate of cells nearest the suspensor undergoes a 
series of transverse divisions as well as longitudinal ones. This 
division extends to some of the adjoining dermatogen cells (jig. 
30), and gives rise to’the calyptrogen, which becomes continuous 
with the dermatogen and by successive transverse divisions cuts 
off the root cap. The inner plate, by longitudinal divisions, 
contributes to that part of the root tip from which the periblem 
of the radicle is developed (fig. 33, f, g). Beyond this stage i 
is impossible to get central sections through the entire embryo. 
The cotyledons fold together and curve upward toward the antip- 
odal region ( fig. 34), and in the mature state the embryo fills 
the entire cavity of the embryo sac. 
THE SUSPENSOR. 
The basal suspensor cell never divides after the first trans- 
verse division of the oospore. The intermediate cell contributes 
