58 DR. J. D. HOOKER ON THE GENERA AND SPECIES 
between the wood-wedges, where they appear as medullary rays, lastly passing into the — 
loose hexagonal tissue of the circumference of the rhizome. 
Seven narrow, elliptical, pale white wedges succeed the woody axis that occupies 
the position of the pith, then radiate, are equal in length to about half the radius of the 
rhizome, and placed midway between the periphery and circumference; they are separated 
from one another by the broad medullary rays, which assume the character of cubical, 
hard, brittle wood-cells consolidated into one dense firm mass, protecting the softer tissue 
between them. The wedges themselves are formed of delicate, white, large tubes, placed 
end to end, and transversely marked with short lines, annular or spiral bands. 
A broadly semilunar or kidney-shaped mass of wood-cells (liber) is placed externally . : 
to each vascular wedge and curves round its outer extremity, and is either placed closely — 
in apposition to the vascular wedge, or is separated from it by a little cellular tissue. … 
These wood-cells are very large and thick-walled, are vertically elongated, and form long 
parallelograms placed end to end, and adhering firmly one with another, become of a 
dense yellow, almost crustaceous or osseous consistence; their walls are everywhere per- 
forated by minute canals, giving them a punctate appearance. 
The cortical portion or cellular tissue of the periphery is formed of hexagonal thick- 
walled, almost woody cells, with perforated faces, and there are scattered irregularly 
through it very large sclerogen-cells and liber-bundles. "This cortical portion is spongy 
in consistence, and its hexagonal cells gradually pass into the cubical ones of the me- 
dullary rays. ; 
Such appears to be the arrangement in the first year; in the second, more woody liber- | 
bundles are formed outside the semilunar ones, and alternating with them. The wedges 
of vascular tissue do not appear to be added-to much, but there is an appearance of incom- 
pleteness towards their circumference, as if a cambium-layer existed there. Strictly 
speaking there are only two well-defined kinds of tissue in the rhizome :—1. the delicate 
vascular wedges, and 2. the coarse, hard, hexagonal cellular tissue of the periphery, which 
becomes indurated between the vaseular wedges and passes into the slender woody tubes 
of the pith: the other tissues that are so conspicuous on a transverse section are not so 
on a vertical one, the broad sclerogen-tubes of the semilunar bundles of liber differing 
little from the cubical cells surrounding them, and the liber-bundles of the periphery 
altogether resembling the long woody tubes of the pith. 
Many deviations may be found in different specimens from the above-described 
arrangements of the cellular and vascular systems of the rhizome; but all, I think, may 
be easily reduced to this type. 
Red sas sears ee en consists of scattered bundles that run free and 
a plexus within the danh ice — where they partially anastomose, i 
erence, from which bundles are given off with great regularity 
towards the base of each scale. I do not find the tissues of these bundles to be more 
than rudimentary ; but traces of their each consisting of a bundle of woody tubes towards 
the axis, followed by delicate transversely b 
tubes : arred vessels, an À n- 
» may, I think, be detected. å s, and these again by sclerogen- 
nn the styles as occasionally united at their bases, which I have never 
3 that he has never observed the plants to be truly parasitical, though 
