20 Campbell . — The Development of the Flower and 
immediately below (Fig. 33), and this is later followed by 
a quadrant-wall in the same cell. The cell next above the 
suspensor divides by a varying number of transverse walls 
into a short row of cells, the uppermost of which undergo 
quadrant-divisions by vertical walls, much like those described 
in the cell next the terminal quadrants. The lowermost of 
the series of cells above the suspensor remains for some time, 
at least, undivided, but may finally undergo division by 
vertical walls. 
The suspensor-cell may finally become much enlarged, but 
this takes place at a later period than is usual in Naias or 
Zannichellia ; as in them, the nucleus finally reaches a very 
large size (Fig. 39). 
The later divisions in the terminal cells vary a good deal, 
and the first division in each quadrant-cell may be either 
approximately vertical or longitudinal (Figs. 35, 37, 38). The 
second divisions are also more or less variable, but the result 
of the early divisions is usually the formation of a central 
group of four cells surrounded by a single layer of peripheral 
ones. The four inner cells form the primary group of 
plerome-cells for the cotyledon ; while the outer ones, by 
subsequent periclinal divisions, develop the dermatogen and 
periblem. 
While these divisions have been taking place in the terminal 
group of cells, a similar separation of a central group of 
plerome-cells also occurs in the segments lying just below the 
terminal group (Figs. 35, 37) ; and later, similar but less 
regular divisions occur in some or all of the basal segments. 
The number of these basal segments is usually three, and, as 
a rule, all of them sooner or later show vertical divisions ; but 
transverse divisions are only found at a later period of develop- 
ment, and then only sparingly, so that the limits of the 
original segments may be made out for a long time (Fig. 39). 
Finally the limits become indistinguishable, and it is difficult 
to tell exactly how far the primary segments contribute to 
the different members of the older embryo. In this respect 
Lilaea differs from Naias and Zannichellia , where the relation 
