156 MISS ANNIE L. SMITH ON THE ANATOMY 
maceration. The veins are interlaced by strands of sclerenchyma 
(fig. 2), and curve in at the base of the leaf, entering the stem 
together as one bundle. 
The whole plant appears to be adapted to desert growth and 
even to the occurrence of desert fires. The natives are in the 
habit of burning down the grass every year, and this specimen 
bore distinct traces of scorching ; the soft tissue of the broad 
leaves is burned, except the part protected by the leaf below (fig. 
2), the sclerenchyma is laid bare, but the leaf as a whole remains ; 
the secondary branches and leaves, which are unharmed, are of 
more recent and evidently very rapid growth. The plant was 
gathered after the first two or three tornados of the rainy season, 
but before the rainy season proper, i. ¢. just when everything is 
starting growth. The larger internodes and smaller leaves of 
the crowded branches indicate very clearly a change in the con- 
ditions of life. 
The stipular sheath of the stem is strongly sclerotic ; the same 
arrangement of cells extends up the back of the leaf over the 
midrib (Pl. VIII. fig. 4), affording additional protection against 
external influences. The cortex is crushed, and as a rule the 
normal phloem is very much reduced. The part of the stem I 
have chosen for figure 5 showed the phloem more distinctly than 
atany other point. The outer xylem consists of wood fibres and 
vessels with bordered pits; the vessels of the inner xylem are 
spiral. Just inside these, round the periphery of the pith, are 
groups of phloem (fig. 5) belonging to the leaf-trace bundles. 
This tissue passes out to form the bi-collateral bundle of the leaf, 
and remains active in the inner protected portion of the leaf, the 
normal phloem being much crushed (fig. 4). The smaller bundles, 
as is often the case, do not seem to be bi-collateral. Scattered 
irregularly through the xylem is a series of phloem islands 
developed centrifugally from the cambium (figs. 5 & 6). This 
is plainly seen from the radial position of the cells of the phloem 
islands, which consist of sieve-tubes and companion cells with 
parenchyma. There are also some islands in process of formation 
which show no trace of internal cambium. The medullary 
phloem groups show no cambium; the central pith is composed 
of large pitted cells densely filled with needle crystals of calcium 
oxalate. 
I have not drawn any longitudinal sections owing to the state 
of the material ; callus had in each case formed over the sieve- 
