19 
Embryo in Lilaea subulata, H. B. K. 
into the cavity. The embryo-cell, as in Naias and Zanni- 
chellia , alone divides, the suspensor-cell remaining permanently 
undivided. Schaffner’s recent observations on Sagittaria and 
Alisma 1 show this to be the case in these forms also, 
although Hanstein 2 supposed that the primary suspensor-cell 
underwent subsequent divisions. 
The two cells arising from the first division of the egg in 
Lilaea are almost equal in size (Fig. 29), and much alike 
in the character of their cell-contents. With the elongation 
of the embryo, the free end becomes somewhat enlarged, and 
a transverse wall is formed in the embryo-cell (Fig. 31, b). 
The next division, at least in the few cases where this was 
seen, is in the terminal cell and is nearly vertical (Fig. 32). 
Following this is a transverse division in the middle cell, and 
next a further division, by a vertical wall, of each of the two 
terminal cells. The young embryo at this stage (Fig. 33) 
consists of six cells exclusive of the suspensor — the four 
terminal quadrants, only two of which show in the longi- 
tudinal section figured, and two cells between these and the 
suspensor. The latter has undergone no division, but there 
is a noticeable increase in the size of the nucleus which later 
becomes still more marked. In these early divisions of the 
embryo Lilaea agrees closely with Zannichellia and Naias , 
from which it differs mainly in the embryo being relatively 
shorter and the suspensor decidedly smaller. As in other 
similar embryos, the cells contain large vacuoles, the granular 
cytoplasm being principally confined to the neighbourhood of 
the nucleus and the periphery of the cell. 
There is no absolute uniformity in the next divisions. It 
not infrequently happens that the first wall in the terminal 
cell is oblique, and it is possible that sometimes the second 
vertical walls may be suppressed. This seems to have been 
the case in the embryo shown in Fig. 36. Probably the next 
wall to form, following the quadrant-division in the terminal 
cell, is in ordinary cases a median vertical wall in the cell 
1 Schaffner, The Embryo-Sac of Alisma Plantago, Bot. Gazette, March, 1896. 
2 Sachs, Text-book of Botany, 1882, p. 589. 
C 2 
