14 BOTANICAL GAZETTE [JULY 
packed together, but farther up many small intercellular spaces 
occur. These spaces open into the larger spaces between the 
rounded parenchyma cells surrounding the vascular bundle under 
the base of the sori, and these in turn connect with the still 
larger canals in the mesophyll which surrounds the capsule just 
within the hypodermis (fig. 33). 
In the region near the basal pit the inner hypodermis seems 
to be pretty sharply separated from the cells of the inner por- 
tion of the basal wall (jig. 33), running down from the dorsal 
side of the capsule as a very thin layer which abuts against the 
overlapping edge of the outer layer of the basal wall. The cells 
of the inner portion of the basal wall in this region are thin- 
walled and have small intercellular spaces between them, sug- 
gesting thus the tissue that was described by Russow as filling 
the “lens-shaped space” in this part of the capsule of Marsilia. 
There is, however, no indication of a duplication of the hypo- 
dermis to shut off these cells from the rest of the capsule (see 
Russow "72 or Johnson ’98), nor is there any trace of the rod of 
brown cells described by Russow as occupying the anterior end 
of this lens cavity. 
THE VASCULAR BUNDLE SYSTEM. 
This system has been carefully studied by Meunier, and since 
my own work confirms his in all essential points, I have, with 
his consent, reproduced several of his figures (figs. 36-38) of its 
mature anatomy. 
In the development of the vascular system we have already 
seen that the axial bundle of the stalk comes from section I 
entirely, and this is true also of the simple continuation of this 
bundle into the capsule (a4, fig. 24). The rapid modification in 
shape and position of the various parts of the capsule, however, 
makes it practically impossible to trace out the origin of the 
many branches in the capsule with reference to segments and 
meristem layers, as it was possible to do in Marsilia. 
After penetrating unbranched nearly to the base of the sori 
(fig. 33), the axial bundle divides, sending one branch to the 
