Wernham, The Systematic Anatomy of the genus Cane'phora. 
459 
The Xylem of the main bündle forms an almost unbroken 
hollow cylinder, interrupted only by a small ventral gap which 
is almost completely blocked by sclerenchymatons fibres. The wood 
consisr* for the most part of secondary vessels, four to five elements 
broad. ic regulär radial arrangement. As compared with the stem, 
the wood in the petiole is comparatively loose in texture, being 
intersected by several conspicnous parenchymatous medullary rays, 
in some cases three to four cells broad. At one or two points 
these rays “fan out“ (Fig. 3, a, 4, f.) into patches of parenchyma; 
this parenchyma has no crystal contents. There are few or no 
fibres in the xylem. 
The central tissue in the concavity of the xylem is composed 
of cells rather large in section, with rather thick walls which show 
signs of lignification. Tannin and calcium oxalate are fairly 
abundant, the latter in the form, principally, of cluster-crystals; 
crystal-sand, displaying a strong tendency to aggregation, also occurs. 
The phloem appears to be coextensive ivith the xylem, the 
periphery of which it follows as far as the edge of the gap. In 
some parts the phloem is four to six cells broad, consisting of 
sieve-tube tissue and parenchyma. Tannin and calcium oxalate of 
the nature already described are very abundant. 
The phloem is surrounded by an almost continuous sheath of 
large conspicuous fibres with very thick walls (Fig. 3, 4, sc.), 
many of them being radially elongated as seen in transverse sec¬ 
tion. This petiolar sheath, and the nature of its elements, seems 
to be characteristic for this species. 
The “concavity-tissue“ is continuous through the gap with 
the ground tissue in which the vascular system is imbedded. This 
consists of thick-walled cells of varying size and shape, but there 
is no definite sclerenchyma. Calcium oxalate is very abundant as 
crystal-sand aggregated into irregulär masses, with a few small 
true cluster-crystals. Tannin is plentiful, especially in the outer 
zone. 
The epidermis is similar to that of the stem; but no definite 
hypodermis appears to be differentiated. 
The lateral vascular bundles consist chiefly of xylem arranged 
in a fan of three or four rays of about three vessels in each ray, 
the narrow part of the fan being ventrally situated; one or two 
vessels, isolated from this main group, also appear. This xylem 
is associated with a small amount of parenchyma, and one or two 
elements which appear to be sieve-tubes, on the dorsal side. This 
parenchyma contains crystal-sand of calcium oxalate. 
The lateral bundles are associated also with a few fibres, 
much of the type found in the neighbourhood of the median bündle. 
These are situated for the most part dorsally, and in some cases 
are radially elongated as seen in section. 
b) Midrib (Fig. 5, d). A large projecting rib (y. r.) runs 
ventrally, the dorsal side being relatively flat and ungrooved. 
The vascular system consists of a main bündle from which 
branches emerge to serve the secondary veins. The bulk of the 
