ANATOMY OF THE ROOTS OF PALMS. 467 
cylinder is sclerenchymatous, no pith being present. Two rings of large vessels succeed 
the protoxylem-groups internally, and Vis are formed. Not infrequently the phloem- 
groups also form V's, and thus we find a xylem V enclosing a phloem V and this again 
enclosing a small xylem-group. 
(27) Mrerroxyton Rumputt, Mart. 
This root resembles that of M. Sagu in all respects, except that no complete phloem 
V's were found. One incomplete phloem V occurred, one limb being separated from the 
rest of the structure by a portion of sclerenchyma, the apical group being continuous 
with the other limb. 
(28) PLECTOCOMIA ELONGATA, Blume et Mart. 
The limiting-layer is exfoliated, the periphery being occupied by fibrous lignified 
elements. More internally these elements become extremely densely lignified and 
sclerozed, the lumina being almost occluded. The inner cortex is mainly parenchymatous 
with small air-spaces, and through this portion run strands of long narrow fibres 
surrounded by stegmata. Of the parenchymatous elements many individual cells are 
lignified and deeply pitted. These may occur in long strings, cell after cell being lignified 
in the same manner, and some of the elements are usually much elongated. In some 
cases large elongated elements are also present with very thick walls, and containing 
mucilage and raphides. The endodermis is thin-walled and only slightly lignified. The 
pericycle is also thin-walled. The sclerenchymatous zone is composed of elements 
extremely densely lignified, thickened and sclerozed, very dark-coloured, and with their 
lumina nearly occluded. ! 
The vascular elements are normal in structure and arrangement. There is a central 
parenchymatous pith, in which are a few lignified elements. 
IV. CEROXYLINZ. 
(29) CaRYoTA OCHLANDRA, Hance. 
The limiting-layer is well marked and of the usual type. It is succeeded by a narrow 
zone of small elongated lignified elements with reduced lumina. | 
These are followed by the parenchymatous inner cortex, the outer layers of which are 
dense, while the broad inner zone is provided with large air-spaces very irregularly 
developed. Amongst these are scattered bundles of fibres. The endodermis is of the 
usual lignified type; the pericycle is two cells in thickness; the sclerenchymatous zone 
extends to the centre of the root (7. e., there is no pith), and in this are arranged peripherally 
the protoxylem- and phloem-groups. The large internal vessels are exceptionally well 
developed and extend to the centre of the root, the structure recalling that of the 
non-contractile root of Corypha wmbraculifera, Linn., but here on a much smaller scale 
V-formation occurs with the outer members of these internal vessels. 
SECOND SERIES.—BOTANY, VOL, VI. ox 
