468 Wernham, The Systematic Anatomy of the genus Canephora . 
is similar to the external ground-tissue; the cells are more or less 
circular in section, with rather thickwalls. There is, however, no 
special thickening of the cell-walls in the neighbourhood of the 
median bündle, such as we have obseryed in C. angustifolia. Cal¬ 
cium oxalate is abundant throughout the parenchymatous tissue; 
its mode of occurrence is essentially similar to that in the last- 
named species. There is a marked tendency for the crystal-sand 
to become aggregated, and a few quite large cluster crystals occur. 
Tannin is not very plentiful; most of it appears in a sub-epidermal 
band of four or fiye cell-layers. 
The epidermis presents no special features, except that the 
cuticle is appreciably thinner than in the previous species. 
The lateral bundles consist each of some fifteen to twenty 
yessels, with but little associated parenchyma. This group, moreoyer, 
is surrounded by a discontinuous set of large fibres, disposed more 
or less regularly. 
b) Midrib (Fig. 5, c). The shape in transverse section is 
distinctiye; as compared with the other species the ventral side is 
flat, approximately flush with the lamina. Dorsally the section 
presents a very prominent rib, of furrowed and folded outline. 
The main yascular bündle occupies the greater part of the 
sectional area. The xylem forms a broad ring, the secondary 
elements presenting a regulär radial arrangement and extending 
over about one half of the breadth; the primary wood is a con- 
spicuous feature in the midrib of this species. The vessels are 
small and much more numerous than in either of the other two 
species, the xylem-band being from ten to twelve yessels broad. 
The fibrous System of the wood is similar to that of C. angustifolia , 
but there are more fibres towards the inner side of the ring than 
in that species, particularly in the ventral region. The medullary 
rays are very few in number, and impregnated with tannin. 
The phloem is represented by a narrow band, densely packed 
with tannin; calcium oxalate also abounds, in the form of aggregations 
of crystal sand. The intra-xylary ground parenchyma consists of a 
few very large cells with thin walls; neither tannin nor calcium 
oxalate is plentiful in this tissue — the latter occurring in small 
sand-masses. The same applies to the extra-stelar ground tissue, 
except that the cells are not so large; here the tannin is confined 
for the most part to one or two layers immediately subjacent to 
the epidermis. The main bündle, and the branch bundles also, are 
surrounded each by a well-marked sclerotic sheath of one layer 
of small fibres; these are rather loosely arranged. 
The upper and lower epidermal surfaces are similar, of small 
square cells, much as in C. madagascariensis; the cuticle is, however, 
relatively thin. 
c) Lamina (Fig. 6, c). The blade may be described as sub- 
membranous, being of a thinner type than in the other two species 
described. Palisade and spongy tissue are not clearly differentiated; 
the former comprises two or three layers of cells rather smaller 
and richer in tannin than the underlying layers. The cell-walls 
