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cork, the cortex is found surrounding the central bundle, or stele. 
The stem consists of two distinct regions, a lower induviate, peren- 
nating, cork protected portion, and an upper green foliage portion. 
The cork in the lower portion is many layers thick, and when 
sections are cut and mounted in acetic acid as a preservative, the 
cork cells are found, after the lapse of a year, to have undergone a 
change. The walls are found covered with peculiar yellowish 
beads in chains. The appearance which the walls assume reminds 
one strongly of a suberized cell-wall, which has been acted upon 
by potash. The cause of this beaded appearance in Zahnum is 
not known. It is probably caused by the long action of the acetic 
acid. 
The cortex of the lower perennating portion consists of paren- 
chyma cells which are filled with starch, as a reserve material. If 
specimens of Zalinum teretifolum are gathered when the active 
storing of starch begins, beautiful leucoplasts in which are im- 
bedded compound, or aggregate starch grains are discovered. In 
the thicker stems, no chlorophyll is found, except in the region 
immediately beneath the corky envelope. The bundles of the 
tuberiform stem are collateral, the phloem is present as soft bast, 
which in the green foliage portion of the stems adds on the out- 
side some bast fibres for support and strength. In the green por- 
tion, the cork has disappeared. 
The bundles of the scape of Zalinum teretifolium illustrate 
that the development of the various cells of the mechanical tissue 
is dependent upon the strain imposed upon them. Consequently, 
the bast fibres here become clearly accentuated and are of a glist- 
ening white color, closely investing the wood by a continuous 
ring. Beneath the epidermis, collenchyma for strength is also 
found. fio 
The leaves are terete, 1-3 in. long, sessile with a flat base. 
In section, a leaf is somewhat crescentic at the base, the xylem 
portion of the vascular strand is toward the upper surface, and the 
bast toward the lower face. The bast fibres at the base of the leaf 
are conspicuous for strengthening purposes, and their cell-walls _ 
are of a yellowish tinge. A more distal section is the same as to” 
the position of the elements, but the thickened bast elements are 
wanting. Beneath the epidermis, a zone of chlorophyll tissue 
