49 
Saprophytic Monocotyledon. 
(8) The larger central cells, with lignified, simply pitted 
walls, have nuclei and are elongated longitudinally and repre- 
sent the conjunctive tissue. 
II. The Stem — A. The Rhizome. 
(1) The epidermis consists of elongated cells with fairly 
thin walls and a distinct cuticle. No stomata occur. 
(2) It is succeeded by about four layers of cortical paren- 
chyma, the cells of which have thin pitted cellulose-walls. 
Within lies— 
(3) A general sclerenchyma -sheath about four cells in thick- 
ness. The cells composing it are sclerenchymatous fibres. 
The outermost layer is tolerably regular and simulates the 
endodermis of the root. The remaining three layers of cells 
have evenly thickened pitted walls, and possess only small 
lumina. 
(4) The vascular bundles are arranged close within the 
general sheath and are numerous. 
Each full-sized vascular bundle is still small but possesses 
well-marked phloem- and xylem-portions (Fig. 6). 
The phloem is constituted of narrow sieve-tubes with trans- 
verse plates, and elongated parenchyma-cells in which no 
differentiation of companion-cells was visible. 
The xylem has long tracheides with transverse pits, fibres, 
and a protoxylem of a few narrow loose spiral vessels about 
which lie elongated narrow parenchyma having thin walls, 
with wide shallow pits. The intercellular spaces around the 
spiral vessels are very small. 
(5) The pith consists of broad parenchymatous cells with 
thin pitted lignified walls. The cells are elongated in the 
direction of the axis. The conjunctive tissue connecting the 
pith with the general sheath is constituted of cells which 
gradually change from the typical pith-cells to sclerenchyma- 
fibres as they approach the sheath. 
E 
