1 70 Gibson . — Contributions towards a Knowledge 
scalariform tracheids. The dorsal cords remain for a con- 
siderable distance distinct, but sooner or later fuse with the 
marginal protoxylems on the same side as that on which they 
were originally formed, after undergoing fusion amongst 
themselves (PI. IX, Fig. 26). 
The stem is covered by a cuticle and well-marked epidermis, 
the cells of which are narrow, elongated, and have thick 
external walls. These cells contain chlorophyll, and give rise 
to unicellular strongly cuticularized hairs whose almost occluded 
lumina are continuous with those of the epidermal cells. The 
hairs are longer and more numerous on young than on old 
stems, and the rhizome has none. The cortex consists of 
elongated parenchymatous cells without intercellular spaces, 
the cells being of greater diameter in the middle than in the 
inner layers. The cell-contents are scanty save in the layers 
next the lacuna. The chloroplastids are ovoid or rod-shaped 
and are accompanied by red granules. The lacuna is distinct 
but partially filled by a reticulum of chlorophyll-bearing cells 
which arise singly or in pairs from the cortex and are connected 
with the endodermal cells internally (PI. IX, Fig. 27). The 
endodermal cells are not unfrequently branched and show 
the usual cuticular ring. These cells are very long at the 
origin of branches. 
The stele is covered externally by a pericycle, usually two 
layers thick. A few protophloem-elements occur just within 
and are followed by one to two layers of sieve-tubes. The 
sieve-tubes almost surround the xylem, being interrupted 
opposite the marginal protoxylems by one or two parenchyma- 
cells only. The phloem-parenchyma occurs in one to three 
layers, the cells being long and narrow. Reticulate tracheids 
occur in the metaxylem. 
Wojinowid ( 23 ) remarks that this species has no trichomata, 
contrasting it in that respect with S. lepidophylla. I have 
already pointed out under that species that trichomata appear 
to me to be wanting in X. lepidophylla , whilst they are most 
undoubtedly present in X Braunii. 
Dangeard ( 22 ) describes the structure of the stem of 
