Leaf and Sporocarp in Marsilia quadrifolia , L, 129 
activity of the apical cell is ended, by the appearance in it 
of a periclinal wall, the capsule or upper part of the sporocarp 
lies with its ventral side nearly in contact with that of the 
stalk (Fig. 31 a). The capsule is at this time about 1 mm. 
long, and the sori at the base about as far developed as 
that shown in Fig. 36. There is never any curling in of the 
extreme tip of the capsule, suggesting the circinate coiling 
of the leaf, and the sharp bending mentioned above is partially 
straightened out later, as Russow has shown, by the more 
rapid growth of the capsule at the base. 
The shape and size of the segments of the apical cell are 
very nearly like those formed in the leaf, and their earlier 
divisions are exactly the same. Walls I and II (Fig. 27) are 
followed by the transverse anticline dividing the marginal 
cell (t. a. 1 , Fig. 34), and wall III is formed in the same position 
as in the leaf. This is followed, however, by another anticline 
parallel to III (IV, Fig. 27), and then the regular alternation 
is resumed, wall V being on the ventral side, and VI, the last 
wall, on the dorsal side of the marginal cell (Fig. 28). We 
thus have one more section dorsal to the marginal cell than 
in the leaf, and the ultimate marginal cell is of the seventh 
grade instead of the sixth. 
The position of the section-walls given above is in general 
that found in all of the segments of the sporocarp, but certain 
exceptions are worthy of note. Thus wall IV, instead of 
running through to wall II as usual, often bends down to 
meet wall III at some distance from II (dotted line, Fig. 27). 
This type of division, however, was never seen in the lower or 
basiscopic marginal cells of the soral segments of the capsule. 
Again, section V is usually narrower in the basiscopic marginal 
cells of the soral segments of the capsule ( V, Fig. 34), and 
hence the basiscopic ultimate marginal cells, which are 
evidently ‘ the sorus mother-cells ’ of Biisgen, are the largest 
ones of the ventral side of the capsule. Finally, any marginal 
cell of the sporocarp, except the basiscopic one of the soral 
segments, may form a pericline instead of wall VI, and thus 
make the ultimate marginal cell of the sixth grade. This 
