Boodle . — Anatomy of the Gleicheniaceae. 7 29 
but with the remarkable difference, that here the more 
central part of the xylem is replaced by a mass of 
sclerenchyma surrounded by a ring of endodermis (Fig. 25, 
i.e.), pericycle, phloem [iph.) and conjunctive parenchyma. 
The upper part of the xylem has a rounded surface ; in the 
lower part the lobes correspond with the protoxylem-groups. 
One of the groups, however, appeared to have split into two, 
probably as a stage preliminary to the production of a root. 
A point to which we shall return is the occurrence of a few 
fibres in connexion with one or more of the protoxylems. 
The stele of G. pectinata is larger than that of any other 
species examined, the diameter of its xylem being if mm., 
while that of G. pubescens is 1^ mm. The larger forms of 
G. longissima could not be examined, but they would prob- 
ably have a stele at any rate as large as that of G. pectinata , 
and might possibly also show solenostelic structure. 
A section through the nodal region is seen in Fig. 26. The 
lower part of the stele remains as in the internode ; the central 
sclerotic tissue is in situ , and has a two-armed upward exten- 
sion, which fills the concavity of the band of tissue preparing 
to separate as a leaf-trace. At this point the whole mass 
of sclerenchyma has a form resembling a T, or perhaps still 
more like a longitudinal section of a mushroom. In Fig. 27 
the leaf-trace has become free, and is on its way out through 
the cortex. The stele is left open by a leaf-gap, so that 
both its central sclerenchyma and that of the leaf-trace are 
continuous with the cortical sclerenchyma. 
The petiolar bundle resembles the leaf-trace, but has a 
nearly circular external outline, broken of course at the point 
where the T-shaped promontory of cortical sclerenchyma 
passes into its interior. The xylem has the usual arched 
form, has one protoxylem in each of the two hooks of the 
xylem, and about ten other groups. Fibres are found in 
the slight bays of the hooks, and are scattered at intervals 
on the inner side of the xylem-arch. The fibres represent 
phloem-elements in the lower part, but may perhaps be 
pericyclic elsewhere. The petiolar bundle is thus like that 
