8 INTRODUCTORY ESSAY. 
ridge on the side of the insertion of the spadices, As the spadices are onm 
on the leaf-sheaths, and as the leaves, though really gis PIN A pim d 
i i t has it on the side opp . 
i i de has the ridge on one side, the nex 
ThE ha pe d course of the fibro-vascular bundles which pass into the 
ai dio into its homologue the leaf-sheath flagellum. The fibro-vascular bundles 
^ a internode of the stem pass into the sheath next above, which dea M 
MR i i slight longitudinal swelling 
i gth; their course is marked by a g g j 
Ni ge pe the side which corresponds with the analogous swelling on 
o 
the internode; this ridge usually ends near the mouth of the sheath where th 
e spadix 
is inserted. 
The stems of Calami are usually rather spongy in the centre, and are always 
very hard externally, though they are at the same time flexible and elastic, | The 
stems of Culami divested of their sheaths have almost always a polished surface, 
and look as if covered with a thin layer of vitreous varnish; sometimes, however, 
the surface is opaque, but almost always is of a straw-yellow colour, especially 
when dry. This vitreous appearance of the naked canes of many Calami is due to 
the presence of a very thin layer of a silieious substance which entirely covers 
them. 
When the stem of a Calamus,” more particularly of one that has a very” 
polished and shining | surface, is bent, small thin lamellæ may be seen to crack off 
as the result of the fracture of the thin eoating of silicious material with which the 
cuticle of the stem is laden. In these lamelle no cellular structure whateve 
be made out. The cells which constitute the 
immediately underlie this cuticle, 
r can 
epidermal layer of the Stem, and 
are also more or less laden with silica, frequently: 
to such an extent that even after incineration they retain their form and preserve 
their minutest details, so that even the characteristic structure of the stomatic cells. 
continues unaltered. The histological elements of the inner part of the stem are, 
however, only very partially silicised. 
This abundant silicious secretion in the tissues of Palms 
h which the wood of Pal 
in a fossil state may not depend entirel 
y on a molecular substitution of siliea for 
cellulose in the wall of their cells, but may also be due to the 
impregnation of that substance which probably already existed during life in the 
tissues of the Palms of past ages. 
suggests to my mind. 
ms is found silicised 
The more polished and vitreous the surface of a stem is, the more it iş 
impregnated with silica and the more it is valued for economic purposes, In the 
category of species whose stems are thus valuable are included €, cæsius, Q, 
optimus, C. tenuis, C. Rotang, ete, 
IV.—The Leaves. 
The leaves or fronds of scandent Calami often appear at first sig 
owing to their being separated from each other by considerable interval 
the elongated character of the internodes, When, however, 
together, as is the case near th 
e apex of the stem where 
less dense crown, a spiral tristichous a 
ht alternate, 
s because of 
the leaves are closer 
they form a more or 
‘rangement is quite obvious, 
