476 Boodle.—Anatomy of the Hymenophyllaceae. 
leaf. A small, early leaf of a plant had a comparatively small 
bundle, in which there appeared to be only two protoxylems. 
The leaf-trace in the stem has a continuous ring of meta- 
xylem, enclosing a central mass of sclerenchyma, and sur¬ 
rounded by phloem except on the adaxial side. There 
appear to be three protoxylem-groups lying between the 
metaxylem and sclerenchyma; one median and anterior, and 
two lateral. The nodal structure is illustrated by diagrams 
(Figs. 33-36). In Fig. 33 the stele of the stem is shown at x\ 
it contains two masses of sclerenchyma (which are shaded), 
derived from the next two leaves above. The leaf-trace (x) 
is seen on its way in through the cortex ; the shaded region 
inside the leaf-trace is the sclerenchyma ; and a is the axillary 
branch. In Fig. 34 one of the sclerenchyma-masses has dis¬ 
appeared from the stele of the stem, and the stele of the 
axillary branch has fused with the leaf-trace. In Fig. 35 
the second sclerenchyma-group has disappeared from the 
stele, and in Fig. 36 the leaf-trace is uniting with the stele 
of the stem, while a new leaf-trace (x") with its axillary 
branch (a) is coming in through the cortex. The xylem-mass 
of the leaf-trace with the sclerenchyma inside it fuses with 
the stele of the stem without any great change in arrange¬ 
ment of elements at first, consequently the protoxylem 
becomes immersed in the xylem of the stele, which is there¬ 
fore mesarch. Fig. 37 is an enlarged diagram of the stele (x) 
in Fig. 33. The sclerenchyma is shaded, and such proto¬ 
xylems as could be determined are represented by dots. 
Connected with the right-hand mass of sclerenchyma are 
seen the two lateral protoxylems of the petiole, the median 
one being absent or unrecognizable. On the left only one 
protoxylem is seen, probably produced by fusion of two 
lateral groups corresponding to those on the right. T\ Prieurii 
is exceptional in containing fibres in its petiole, and it has 
a two-fifth phyllotaxy, but allowing for the difference this 
causes in the stele, it does not diverge much from the type 
of T. radicans. There is less parenchyma accompanying the 
protoxylems, and two or three protoxylems pass in from 
