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28 DR. J. D. HOOKER ON WELWITSCHIA. 
perianth is developed; and I have stated that its solitary integument appears, as a 
tumid ring, round the base of the nucleus within the perianth, immediately after its first 
appearance. 
Up to the stage figured at Plate VIII. fig. 6, the perianth is seen by transmitted light 
to have grown much more rapidly than the ovule, the nucleus of which is now wholly 
immersed in its integument, and the embryo-sac has made its appearance. At fig. 7 
the ovular coat has risen far above the nucleus, and forms a conical body with a tubular 
mouth, as is also shown in the section of another ovule (Plate IX. fig. 9), which is about 
35th of an inch long. At this period the embryo-sac (Plate VIII. fig. 18) may easily be 
removed entire from the nucleus, and is a circular or transversely oblong, compressed, 
hyaline sae, containing a pale yellow transparent mass of endosperm-cells. In the next 
stages (Plate VILI. figs. 8, 9, 10), the apex of the ovular integument is more produced 
into a tube (better seen at figs. 15 and 16), which is contracted above the middle, and 
browned at the lacerated apex: the browning indicates that the parts so coloured have 
ceased to grow, having become almost horny in consistence. "The nucleus, which varies 
a good deal in form, is now either conical or subhemispherical, with a terminal mamilla, 
depressed at its apex. 
The ovule of the female flower has now attained about the same stage of development 
and dimensions as that of the hermaphrodite flowers figured at Plate VI. figs. 11 & 14; 
but there are the following essential differences between them :—in the female flower the 
styliform apex of the integument of the ovule is straight, rigid, browned, and lacerated at 
its apex; whilst that of the hermaphrodite flower is shorter, stouter, with more fleshy 
walls, is never sphacelated, is bent in a sinuous manner, and terminates in a broad, 
papillar, expanded dise, with a funnel-shaped orifice. 
The tissues of the ovule present nothing different from those of other plants; the 
nucleus consists of a dense, soft, cellular tissue. The integument is a very delicate 
cellular membrane (Plate VI. fig. 15), becoming rigid towards the tubular portion, which 
consists of three to six layers of delicate cells, of which those of the inner layer have their 
inner walls much thickened and rendered horny by secondary deposits (Plate VII. fig. 17). 
There is no vascular tissue in the ovule itself; but, as in the hermaphrodite flower, two 
vaseular bundles ascend the axis below, and terminate abruptly exactly at the insertion 
of the integument round the base of the nucleus (Plate IX. figs. 11, 12). 
The general resemblance of the ovule here described to that of other Gymnosperms is 
very obvious, whether as regards the structure and position of the integument and its 
tubular prolongation, or the large embryo-sae, so easily removed, in which cell-formation 
has commenced previous to impregnation. In all these plants, too, the ovular integu- 
ment (or the innermost, when there are two of these) is more or less carried up by the 
growing ovule, and often forms a small calyptriform pileus at the apex of the seed,—a 
faet which will call for attention when considering the relations of the seed, after the 
deseription of that body and its contents. 
The ovule of Welwitschia entirely accords with that of Ephedra, except in the discoid 
apex of the integument of the latter, which is oblong and obliquely truncate. The ovule 
