of Schizaea nialaccana . 503 
continuous with the pericycle of the stele, those on the inner 
with the outer cells of the pith — and by an endodermis like 
that of the stem-stele. The characters of the xylem and 
phloem are also exactly like those of the stem-stele, spiral 
tracheids being quite absent. The meristele retains these 
characters for some millimetres up the leaf, but at a distance 
of 1 cm. from the leaf-insertion practically all the characters 
of the leaf-bundle have been acquired. 
The leaf-bundle (Fig. 6) is circular or rather oval in outline, 
situated rather nearer the lower than the upper leaf-surface, 
and surrounded by an endodermis and pericycle exactly like 
those of the stem. The xylem has the form of a crescentic 
strand enclosing three or four large parenchymatous cells 
(which have strikingly large, elongated nuclei) and the band- 
shaped strand of sieve-tubes between its horns. The body of 
the xylem crescent is occupied by two large scalariform 
tracheids, side by side. Between these and the peridesm is 
a little group of spiral protoxylem-elements (Fig. fpxi), which 
in the adult leaf are crushed and often nearly obliterated 
(Fig. 6, fix.) \ The sides of the crescent are occupied by 
a few narrow scalariform tracheids (tr.), and at each horn, 
between these lateral tracheids and the sieve-tubes, is a group 
of fibres (^. t.f.) such as Boodle has described in a similar 
position in »S. digit ata. As in that plant, they are, pretty 
clearly, thickened and lignified sieve-tubes, their end walls 
bearing sieve-plate-like structures (Fig. 7, j. t.f.). The whole 
bundle in fact, except for the existence of the two large 
central tracheids, is simply a smaller edition of that found in 
the other species. In the last few millimetres below the fertile 
pinnae the spiral elements are not formed, and the parenchyma- 
cells between the xylem and phloem are smaller. Just below 
the lowest fertile pinnae the bundle is considerably enlarged, 
the tracheids increasing to thirty or more in number. 
As has already been said there is no distinction between 
petiole and lamina. For the first few millimetres from the 
1 There is no trace of the two lateral groups of spiral tracheids described by 
Prantl in the larger species S. Pennula and S. elegans. 
