78 SIR DIETRICH BRANDIS ON THE 
As might be expected, the nerves are further apart in broader leaves, but besides the 
width of leaf the individuality of each species is also well marked. 
A Bamboo without a midrib is Chusquea pinifolia, Nees (Pl. 14. fig. 39), which 
inhabits the mountains of South-east Brazil between 3000 and 6000 feet. The leaves 
are narrow and have, as a rule, three stouter and, alternating with them, four thinner 
nerves. As already mentioned, this species is anomalous, as it has no apparent cavities, 
The bands of bulliform cells in the upper epidermis, however, in this as in all other 
Bamboos, alternate with the longitudinal nerves; each vascular bundle is supported by 
two girders of sclerenchymatous fibres, but the intervening chlorophyll parenchyma is 
continuous, not interrupted by apparent cavities. 
The midrib always contains several vascular bundles, arranged in two horizontal lines, 
one below the upper, the other above the lower epidermis, each bundle adjoining or 
enclosed in the girders of sclerenchymatous fibres, which are immediately under the 
epidermis. The two lines of vascular bundles are, with rare exceptions, separated by a 
broad, rarely narrow, band of large cells. These, like the cells of the parenchyma- 
sheath, which enclose the longitudinal nerves, frequently contain starch. This tissue, as 
a rule, has intercellular spaces and the walls are often lignified. When this band is 
narrow it widens out to the right and left (Pl. 12. fig. 19, Dendrocalamus strictus). In 
most cases there are 2 to 6 vascular bundles below the upper and 1 to 4 above the lower 
epidermis. There are, however, exceptions: thus Dendrocalamus strictus has only one - 
vascular bundle above and one below, and Dendrocalamus Hamiltonii (P1. 12. fig. 20) has — 
6 in the upper and 18 to 20 in the lower line. These figures relate to the middle of the — : 
leaf halfway between base and apex. As may be expected, the midrib has not the same — 
structure throughout the length of the leaf. This is illustrated by Pl. 14. figs. 32-94, — | 
representing transverse sections of the midrib of Melocanna bambusoides at the base, in 1 
the middle, and below the apex of the leaf. It will be noticed that the number of d 
vascular bundles above the lower epidermis diminishes from 4 to 1, while below the — 
upper epidermis there are 4 at the base and in the middle, and 3 near the apex. In this 4 
species some of the upper vascular bundles show an inverted orientation, the phloem — 
being lateral and in some cases situated on the upperside of the xylem. The vascular — 
bundles scattered in the pith of the rhachis of Simaba glandulifera (C. De Candolle, y. 
‘Anatomie comparée des feuilles, t. 1. fig. 15) seem to show a similar irregularity in 
orientation. | 
In some cases the vascular bundles of the midrib are enclosed in the belts of — 
sclerenchymatous fibres mentioned above. Instances are Arundinaria Falconeri amd 
Melocanna bambusoides, in the middle of the leaf (Pl 14. fig. 33). In these cases the 
two belts of sclerenchymatous fibres have united and the vascular bundles of the midrib 
are imbedded in a mass of sclerenchymatous fibres. The vascular bundles of the midrib 
have not, as a rule, a separate parenchyma-sheath, and it may, I suppose, be assumed that 
the tissue of large cells in the midrib, previously adverted to, has the function of à 
parenchyma-sheath. 
It has long been known that all Bamboos, like other Grasses, have transverse veins 
