DR. J. D. HOOKER ON WELWITSCHIA. 27 
flat towards the axis, and tumid opposite the scale. The walls of the cavity are thin, 
coriaceous or chartaceous, and slightly thickened at the edges; they consist of four 
layers of tissue: 1, a cellular epidermis; 2, a thick layer of felted filiform liber-cells 
(Plate VII. figs. 11 & 12), which are cylindrical, transparent, tortuous, and blunt at either 
end; 3, a very delicate layer of thin-walled, spirally-marked, fusiform cells, the markings 
very close and delicate (fig. 10); 4, an inner epidermis, often broken up at the edges. 
A few spicular cells (fig. 8) are scattered here and there in the substance of the walls 
of the cavity. The hyaline wings have an undulated appearance, owing chiefly to the 
arrangement of their tissues: these consist of two layers of epidermis, enclosing thread- 
like liber-cells: the latter, towards the cavity, form a loose cottony mass that is very 
conspicuous when the pericarp is torn open, but in the wings they are reduced to a very 
thin stratum, and run in so tortuous a manner towards the periphery as to give the wings 
the undulated appearance mentioned above; they terminate close to the margin, in blunt 
apices. The vascular bundles that traverse the wings, run in arches from the main 
bundles along the edge of the cavity, and are lost before reaching the periphery. 
The perianth of the female flower corresponds to the outer (lateral) leaflets of that of the 
hermaphrodite; for not only is their position the same (right and left of the axis), but the 
winged keel of the hermaphrodite leaflets answers to the beautiful wing of the female ; 
and the greater distance apart of the bases of the hermaphrodite leaflets on the side to- 
wards the scale, corresponds with the mouth of the female perianth opening in the 
same direction. 
The female perianth corresponds to the outer coriaceous covering of the ovule in 
Ephedra and in Gnetum, differing only in form, and perhaps in being developed after 
the nucleus of the ovule makes its appearance. In anatomical structure it is almost 
identical with Ephedra, in which I find the same abundance of liber-cells (though 
running in straight lines) and a similar layer of delicate spirals. The perianth of Ephedra 
differs in being trigonous, unwinged, and having three vascular bundles: in Gnetum, 
again, it is, as in Welwitschia, often compressed and bifid when young, of a much denser 
texture, and traversed by many vascular bundles* ; it possesses comparatively little liber, 
and no spiral vessels t, but a profusion of rigid acicular cells; and the mouth of the 
perianth surrounds and tightly embraces the styliform process of the ovular integument. 
Ovule of the Female Flower previous to Fertilization. 
I have described the earliest observed condition of the ovule in the flowers contained 
in the uppermost scales of the half-ripe cones, as presenting a minute naked blunt 
papilla, about goth of an inch long (Plate IX. fig. 1), around the base of which the 
* In G. scandens there are seven or eight bundles in the short stipes of the immature fruit, which divide into two 
series of numerous parallel branches: one series traverses the pericarp, the other supplies the ovular coats. 
T These, however, probably occur in Gnetum ; for Griffith describes these rigid acicular cells in the outer or baccate 
coat of the fruit of that genus as sometimes being spirally marked (Linn. Trans. xxii. 303). 
E 2 
