Triglochin maritimum j L. 101 
extremely probable that the four-celled embryo is formed by 
a transverse division of the central cell of the previous three- 
celled stage. 
The terminal cell next divides by a longitudinal wall which 
is frequently somewhat oblique; thus there is formed a five- 
celled embryo (Fig. 37). 
Up to this point the divisions which have taken place in 
the oospore of Triglochin are identical with those which have 
been described as occurring in Alisma Plantago and Sagittaria 
variabilis by Schafiher (13 a and 13 b), and also with those of 
the oospore of Sparganium as described by Campbell (1 b). 
The embryology of Triglochin differs from that of Lilaea 
subulata , H.B.K., as investigated by Campbell (1 c ), inasmuch 
as in Lilaea the first longitudinal division occurs before the 
four superposed cells are formed. 
The divisions which next occur may vary somewhat, as 
two distinct types were seen. 
It sometimes happens that the two terminal cells of the 
embryo may again divide, before any other division takes 
place, by longitudinal walls, thus giving rise to a group of 
four terminal cells in the same plane. Such a case is illus¬ 
trated in Fig. 38. When this is the case, the next division 
occurs in the cell immediately below the terminal ones, by 
means of a longitudinal wall (Fig. 38). 
In the second type of division the cell directly below the 
terminal embryo-cell divides before any further divisions 
take place: this seems to be the commoner sequence, and 
when such is the case the next division is a longitudinal one 
occurring in one of the two terminal cells; this division is 
followed by a similar one in that cell which is diagonally 
opposite to the cell just divided in the tier above. Very 
frequently, however, and immediately before this takes place, 
it happens that the cell next above the basal cell divides 
by a transverse wall, so that a tier of five cells, including the 
basal cell, results (Fig. 39). Divisions now go on rapidly, 
resulting in the formation of an embryo such as that illus¬ 
trated in Fig. 41, PI. VII. Up to this stage it is possible to 
