582 F. O. BOWER. 
rather that a process of change goes on in the cell walls of the 
tissues already formed, and extends gradually inwards, accom- 
panied by loss of the cell contents. 
From the bases of the leaves bundles are seen to enter the 
stem (‘‘ blatt-spurschicht,” De Bary, ‘ Vergl. Anat.,’ p. 632. 
** Vascular stratum,’’ Hooker). These pursue for a certain dis- 
tance a nearly parallel course; later they break up into irregular 
branches. ‘This is best seen in fig. vii1, B. This fact is easily 
reconciled with what we have already seen in transverse sections. 
In comparing the several figures it must be remembered that the 
dotted line in fig. vii1, B, indicates the point to which the trans- 
verse section, fig. v1, 6, corresponds: while the section, fig. v1, 
5, is taken at a point some distance below the branching of the 
bundles of the leaf trace (Blatt Spurbiindel). From these 
bundles of the leaf trace branches are given off in different direc- 
tions; for clearness sake these, and others which intertwine with 
them, may be ranged into several categories according to the 
direction of their course ; these categories merge, however, into 
one another. ; 
(a) Branches which run horizontally. These take a course 
along the inner margin of the bundles of the leaf trace (fig. v1, 6) 
and send out branches between these bundles towards the 
periphery ; or they take a direct course between the bundles of 
the leaf trace, and run out into the peripheral part of the stock ; 
this is most common at the centre of the stock, fig. v1, B. 
(2) Branches which ascend either (i) into the central lobes, or 
(ii) into the upper peripheral parts of the stock (fig. vimt, a). 
Lastly (c), there is a third series of bundles which are appa- 
rently not in direct connection with the bundles of the leaf trace : 
these run up the stem, and passing between the bundles of the leaf 
trace (apparently without any anastomosis) continue their course 
into the lobes of the crown. We have thus a direct vascular con- 
nection kept up between the following several parts of the plant 
(1), between the leaf and the peripheral part of the stock (2), 
between the leaf and the lobes of the crown, and (3) between the 
lower part of the stock and the crown. It will be seen later 
that these connections are similarly kept up in the older plant. 
The mutual vascular connection of different parts of the peri- 
phery of the stock is also very complete. In fig. viii it is shown 
that amastomosis of bundles in this part of the plant is frequent. 
This is more evident in tangential sections at the periphery, and 
more especially in old plants, where the bundles are seen to form 
a most complicated and irregular network. In the special plant 
under consideration (fig. 111) these ramifying branches collect as 
they pass from the summit of the stock, so that they appear in 
transverse section (fig. vi, 6) as a regular peripheral series. It 
