468 DR. ERIC DRABBLE ON THE 
(80) CAnxorA RUMPHIANA, Mart. 
The cortical tissues are generally similar to those in C. ochlandra, but not so much 
broken down by air-space formation. The lignified tissue of the outer cortex is more 
strongly developed. The bundles of fibres of the inner cortex are present as in the 
last species, and in addition to these is a zone of stone-cells just external to the 
endodermis. There is a very dense sclerenchymatous zone in the central cylinder, but 
here there is usually a small irregular pith in the centre, which may contain an air-space 
and some mucilaginous elements. The phloem-bundles are considerably prolonged 
centrally, and the large internal vessels of the xylem are developed to within a short 
distance of the central pith. Xylem and phloem V's are very frequent, and we may 
even get a phloem-group embraced by a xylem V, this again by a phloem V, the whole 
complex being embraced by a xylem V just incomplete at the apex, as shown in the 
accompanying diagram (text-fig. 10). 
Fig. 10. 
Ó EE 8 
(e d 
aos 
(31) Caryora URENS, Linn. 
The cortex is here much less richly supplied with air-spaces than in the last two 
species. The fibrous bundles are well developed, as are also the stone-cells surrounding 
the endodermis. These elements have extremely thick walls, almost occluding the 
lumina. The endodermis is of the usual lignified type and the pericycle is one-layered. 
The sclerenchymatous zone is broad and encloses a central pith. The phloem-groups do 
not extend nearly so far centrally as in C. Rumphiana, Mart., and the large internal vessels 
are much more peripherally placed, and they can with greater certainty be relegated to 
their own one or two protoxylem-groups. In the central pith run three strands 
of sclerenchyma, each with its central vessel. One of these strands is laterally connected 
with the sclerenchymatous zone. 
In a smaller root the structure is much the same, but only one medullary 
sclerenchyma-strand is present. 
(32) Caryora sp. (Queensland). 
The limiting and underlying layers are normal, but the latter contain large mucilage- 
cells with thick walls. The inner cortex has small and very irregular air-spaces. It has 
some thick-walled parenchyma and a few stone-cells. There are relatively few fibrous 
bundles in the cortex. The most striking feature of the inner cortex in this species 
is the extraordinarily rich development of mucilage-reservoirs, generally formed by the 
lengthening and thickening of the walls of a single cell. These cells may form rows, 
and are full of dense dark-coloured mucilage, in which lie raphides. The endodermis is 
typical and the pericycle is one-layered. Inside this is a comparatively narrow 
EE E 
