460 DR. ERIC DRABELE ON THE 
spaces formed in the usual manner. In the centre of the pith runs a vessel surrounded 
by a sheath of prosenchymatous elements, some of which are lignified. 
(9) CoRYPHA UMBRACULIFERA, Linn. 
Some of these roots show the contractile nature very clearly. The surface is 
transversely wrinkled and the whole root is very parenchymatous. 
(a) Large contractile Root.—The limiting-layer is much disorganized and is followed 
by a parenchymatous cortex with extremely irregular air-spaces, the cells bounding 
which often show signs of extensive mucilaginization of their walls. No fibres or 
lignified cells are present. The endodermis is cuticularized and consists of square cells 
with no trace of lignification. The pericycle is ill-defined, but appears to consist of one 
layer of parenchyma with rather dense contents. 
The whole of the ground-tissue of the central cylinder is parenchymatous, the xylem- 
plates and the phloem-groups being widely spaced in its periphery. There is no 
medulla, the whole central portion being occupied by polygonal strands of small thin- 
walled parenchyma, each enclosing a single lignified vessel. These strands are separated 
from one another by compressed and disorganized bands of cells. These strands 
correspond to the sclerenchymatous medullary strands which occur in so many palm-roots. 
(b) Non-contractile Roots.—The cortex is composed of parenchyma, some of the cells of 
which contain starch-grains staining bright red with saffranin. 
The grains show the leucoplasts very admirably, they are of the normal small conical 
form. Through the cortex run bundles of fibres, bounded by cells containing crystals 
of calcium oxalate. Very irregular air-spaces are present. 
The endodermis is composed of cells about three times as long as broad, many of which 
are lignified, the rest being cuticularized. The pericycle is made up of two layers of 
lignified cells with large pits in their walls. 
The ground-tissue of the cylinder is very greatly reduced. 
The protoxylem- and phloem-groups occupy the periphery of the cylinder, while the 
whole interior is occupied by enormous vessels embedded in sclerenchymatous sheaths, 
partially separated from one another by the ground-parenchyma. 
(10) LicvALA GRACILIS, Blume. 
Limiting-layer of thin-walled lignified non-cuticularized cells. 
The outer cortex is composed of small-celled slightly lignified parenchyma. In some 
roots the lignification proceeding both centripetally and centrifugally has not met, 
so leaving a narrow zone of non-lignified elements. This is best seen in young roots 
and appears to have undergone lignification in older roots. This is followed by a 
parenchymatous inner cortex with large radially extensive air-spaces and provided with 
elongated, square-ended, deeply pitted, lignified cells. There are no fibres. The inner- 
most layers of the cortex are without air-spaces. The endodermic cells are much 
thickened and lignified in the “ fibrous” manner, 
The pericycle consists of two layers of lignified pitted cells. Internally to this comes 
a zone of sclerenchyma in which are embedded the protoxylem- and phloem-groups. This 
