456 DR. ERIC DRABBLE ON THE 
air-spaces. The cells of the innermost portion of the cortex immediately surrounding 
the endodermis are more closely packed and tangentially compressed. Embedded in the 
inner cortex are bundles of strongly lignified fibres, with small lumina and simple small 
pits. The endodermis is generally well lignified and thickened on all its walls, except the 
outer tangential. The inner tangential walls may be so greatly thickened as to bring 
about almost total occlusion of the lumina. In the fully mature root not a single passage- 
cell was observed. "The pericycle, usually two cells in thiekness, is, in the mature root, 
lignified and pitted, tbe lignification being most strongly developed opposite the 
protophloem. 
A thick zone of schlerenchyma, in which lie the xylem- and phloem-groups, surrounds a 
central irregular medulla. The vessels of the protoxylem are lignified and surrounded 
by a mass of small-celled parenchyma. The lignification decreases as we follow the 
metaxlyem centripetally, and in the large inner vessels it may be wanting altogether, 
the original cellulose walls remaining unaltered. "The layer of cells abutting directly on 
these large vessels is frequently parenchymatous, the elements having cellulose walls. 
Often two protoxylem-groups are found in connection with one large inner vessel, 
resulting in the V arrangement, the arms embracing a phloem-group. 
The medulla is parenchymatous. Into it may project one or more masses of the 
lignified sclerenchyma which encloses it, each mass containing a large vessel, but no 
separate sclerenchyma-strands were observed in the medulla. 
(2) PH@NIX ZEYLANICA, Trimen. 
This root is very similar to the last in all essential characters ; the medulla is, however, 
much smaller, the sclerenchymatous zone of the central cylinder extending almost to 
the centre of the root. The vessels are confined to the periphery of this zone. 
(3) PH@NIX sYLvEstrRIs, Roxb. 
The limiting-layer is cuticularized and lignified. Then comes a cuticularized and 
slightly lignified zone of about four cells in depth. These elements are parenchymatous 
and about twice as long as broad. Then follow two or three layers of thin-walled 
cellulose parenchyma, followed internally by lignified fibres. The outer portion of the 
inner cortex is composed of parenchymatous cells only. This is succeeded by a broad 
zone, with large air-spaces and bundles of fibres enclosed in a sheath of stegmata as in 
Ph. reclinata, Jacq. The groups of fibres are here seen to become lignified from the 
exterior towards the interior. The innermost layers of cortex are as in Ph. veclinata. 
The endodermis consists pr incipally of thin-walled cells slightly lignified, but non- 
lignified cells may occur at any point, as frequently opposite the protophloem as opposite 
the protoxylem. In longitudinal section the endodermie cells are seen to be from two 
to three times as long as broad. The pericycle is entirely non-lignified, consisting of 
ordinary cellulose parenchyma. Opposite the protoxylem it may be wanting entirely, 
so o that. the external protoxylem-elements abut directly on the endodermis. Opposite 
the protophloem the pericycle expands and is here two or three elements in depth. 
The — E and protophloem are enclosed in parenchymatous tissue. The 
dig dL E cr or : E raus 
Eeer (EC 
