1898 | THE LEAF AND SPOROCARP OF PILULARIA 15 
right side of the capsule and one to the left, forming a short 
transverse bundle perpendicular to the main trunk (7d, figs. 36, 
37). Each end of the transverse bundle soon divides again, 
sending one branch upward and dorsally in each case, and the 
other downward and ventrally (figs. 32, 33). Then each of 
these four branches, which correspond to what I have called the 
‘lateral branches of the dorsal bundle”’ in Marsilia, divides to 
form the three peripheral bundles of its respective valve (/d/, 
figs. 30, 36, 37). Of these bundles, the middle one of each valve 
gives rise, a short distance above its base, to a short branch 
(p abr, fig. 36) that turns abruptly into the capsule to join the 
placental bundle which runs through the length of the placenta 
just back of the sporangia (paJ, figs. 30, 36). Of the other two 
main branches in each valve, one runs along close to each edge 
of the latter (14 /, figs. 27-30), and all three fuse again at the 
tip of the valve (figs. 36, 38). There is never a fusion of bun- 
dles from upper and lower sori on the same side of the capsule 
as occurs in Marsilia, and the absence of this allows the separa- 
tion of upper and lower valves on each side, just as the absence 
of fusion across the median plain in Marsilia allows the separa- 
tion of the wall of the capsule into right and left valves. 
THE SORI. 
In the young soral segments the growth in a tangential direc- 
tion of sections II and V is comparatively slight, while the sec- 
tions dorsal to the marginal cell grow vigorously and thus push 
this cell around into a nearly ventral position (m c’, fig. 19), 
After increasing considerably in size, the marginal cell divides 
into halves by an anticline parallel to the median wall (sp ¢, fig. 
22), and then these halves are divided further by walls parallel 
to the first (figs. 23-26) and by others perpendicular to these 
(figs. 27-29), giving rise thus to the large number of sporan- 
gium mother cells of the sorus. During the growth and division 
of these derivatives of the marginal cell they are turned over, 
by the continued growth of the dorsal sections, so that the origi- 
nally outer surface finally faces toward the cells of section V, which 
