Stem of Angiopteris evecta. 511 
section on the left side, which corresponds to the under 
surface of the stem. The circular outline of the roots at 
any point indicates their perpendicular descent through the 
tissues of the stem at this particular part of their course. 
In Fig. 14 partly decayed steles are shown making their 
appearance at the periphery of the root ; these assume 
positions further removed from the surface of the stem as 
the diameter of the sections increases, and are obviously the 
remaining parts of an outer meshed cylinder of vascular 
tissue. 
The steles shaded in the diagrams are those arising from 
the branching of the single large stele (s) shown in Fig. 13. 
The denudation of the stem has apparently taken place 
to a greater extent on the upper surface, since it is there 
that these decayed steles make their appearance in the 
greatest numbers. Moreover, on the under part of the stem 
there are traces of an original surface. 
Towards the apex of the stem the vascular system maintains 
the same general characters as in the fully mature parts, and, 
though on a much smaller scale, a transverse section of the 
stem at a distance of about 1 cm. below the apex is closely 
analogous to those taken at levels of complete development. 
The closing up towards the apex of the meshes in the vascular 
tissue, and the change of the outer network into a closed 
cylinder, which are described by Mettenius 1 in his paper on 
A. evecta , are probably to be correlated with the decay in 
the upper parts of the stem. 
By carefully removing the young leaves from the apex of 
the stem, and noting the position of the leaf-trace bundles, 
the manner in which these steles make up the roughly con¬ 
centric circles shown in a transverse section of the stem 
can be clearly seen. 
With regard to the development of the roots from the 
stem-bundles, there appears to be no regularity of arrange¬ 
ment ; some leaf-bases contain no roots at all, while others 
are so much penetrated by roots making their way to the 
1 Mettenius (’64), p. 506 . 
