486 DR. ERIC DRABBLE ON THE 
(62) Cocos NUCIFERA, Linn. 
The tegumentary layers are of the usual type, but greatly indurated. In the outer 
zone of the parenchymatous cortex are abundant mucilage reservoirs, containing mucilage 
of a brown colour and raphides. More internally are regular small air-spaces. 
The lignified elements of the cortex, consisting of small, square stone-cells, are almost 
confined to a zone immediately external to the endodermis. 
The endodermis is lignified ; the pericycle is two cells in thickness, but frequently 
interrupted. There is a broad, greatly indurated, fibrous zone in which the xylem and 
phloem are embedded peripherally. 
There is only one ring of large internal vessels. A medullary strand of fibrous tissue, 
with a single internal vessel, is present in the small pith. 
In a larger root air-spaces are well developed in the inner cortical layers, but are very 
irregular, and lignified elements are more generally distributed. Internally is an 
extensive pith, with large and very regular air-spaces. 
(63) DIPLOTHEMIUM MARITIMUM, Mart. 
The limiting-layer is normal, and is succeeded by elongated elements with pitted walls, 
which give place internally to longer and less lignified fibrous elements. 
These become more parenchymatous internally, and finally pass into the parenchy- 
matous inner cortex, with its small, irregular air-spaces. Throughout this region occur 
small lignified parenchymatous elements, particularly richly distributed just outside the 
endodermis, where they form a more or less definite zone. In this zone the elements are 
true stone-cells. The endodermis is lignified, and the pericycle consists of two layers of 
lignified and pitted cells. The fibrous zone is fairly broad, and contains the considerably 
extended xylem-groups and the large internal vessels arranged in one irregular ring, 
with a few vessels still more internally placed. The phloem-groups are also greatly 
extended radially, generally as far as the internal limits of the xylem-groups. The central 
medulla contains many fibrous strands, each with one central vessel. Sometimes two of 
these strands run in contact with one another, and occasionally they are connected 
externally with the fibrous zone. 
(64) MARTINEZIA CARYOT#FOLIA, H. B. & K. 
The limiting-layer and tegumentary layers are normal. The parenchymatous cortex 
possesses a system of irregular air-spaces and bundles of fibres, each bundle being pro- 
vided externally with longitudinal rows of stegmata. Individual lignified parenchymatous 
elements are also found in these regions and form a specially developed layer around the 
. endodermis. The endodermis is lignified and the pericycle is one-layered. A broad 
zone of fibrous tissue contains the xylem and phloem. V-formation occurs occasionally, 
but usually there is a large internal vessel to each protoxylem-group. 
In a larger root the arrangement of internal vessels is more irregular, and xylem V’s 
and Y’s are of frequent occurrence. 
