DR. J. D. HOOKER ON WELWITSCHIA. 29 
of Gnetum, again, differs from that both of Ephedra and Welwitschia, in having two 
integuments, of which the interior corresponds to the single one of the other genera, 
and, as in these, terminates in the styliform process. In G. scandens, however, this styli- 
form process is shorter, far more rigid, swollen below the middle, and again much con- 
tracted at the base; as the seed developes, it dilates, becomes almost woody, and its 
cavity is closed up by the pressure of the thickening lips of the outer integument of the 
ovule, which closely embraces its lower portion, as the orifice of the perianth does its 
upper portion. The outer integument of the ovule of Gnetum is developed after the inner 
or styliform; but, as nothing analogous to it exists in Welwitschia, Y need not further 
allude to it here *. 
Viewed in reference to its position on the rachis of the cone, and its terminating the 
axis of the flower, the ovule of Welwitschia presents many puzzling points for consi- 
deration. Though subtended by a scale, the female flower does not bear organically the 
same relation to the vascular cords in that scale that usually obtains between flowers 
and the cords of their subtending bracts ; for not only is each organ (scale, perianth, and 
ovule) bilateral, and each furnished with a double vascular system, but the insertion of 
the scale is, as shown in Plate XIII. figs. 1 & 2, at a considerable interval below that of 
the perianth ; and the scale is not supplied by vessels directly from the principal bundles 
on its own side of the rachis of the cone (as the perianth and ovule are), but from 
lateral branches, which leave the principal bundles almost at a right angle. 
The structure of the scale, and its relation to the rachis, would thus have favoured the 
à priori supposition that it was a compound body, and that still stronger traces of com- 
position would be found in the floral organs. Such, however, is only partially the case. 
The female perianth appears, indeed, at its earliest stage as a lobed or double organ (which 
the scale does not), and its form and obvious correspondence with the male perianth 
* The development of the coats of the ovule of Gnetum is the subject of a communication from Dr. Griffith to Dr. 
Lindley (Veg. King. p. 233); and his detailed memoir on the same subject were afterwards — by the late 
Prof. Henfrey in our Transactions, vol. xxii. p. 299. 
My observations on Griffith’s specimens of Gnetum scandens, G. Gnemon, G. Brunonianum, and others, differ much, 
however, from those of that skilful investigator, whose account of the development of the ovular coats is certainly 
erroneous. In none of these species do I find the appearance of the inner coat to be either sudden or subsequent to 
the formation of the outer; on the contrary, the inner coat is first gradually developed around the nucleus as a cup 
with a fimbriated mouth, and it often overtops the nucleus before the outer coat makes its appearance. The latter 
first appears as a ring round the base of the inner coat, with a lobed or irregularly crenate, often oblique mouth ; 
both integuments grow together, but the inner at all periods exceeds the outer. The tissues of both are similar, 
viz. elongated cells ; neither contains vascular tissue when young, nor does the inner at any time; but the outer be- 
comes full of parallel vascular cords. I have found female flowers of G. scandens in which there has been no trace of 
the outer coat, though the inner had already grown far beyond the nucleus. There is a common monstrous state of 
the flower of G. Brunonianum, in which the perianth is globose and fleshy, and the nucleus of the ovule is — 
naked, and seated on a fleshy disc. 
It should be borne in mind that, at the time Dr. Griffith’s paper was written (Aug. 4, 1835), he was unacquainted 
with the true nature of the gymnospermous ovule, and also with Brown's remarks on Gnetum. I cannot, however, but 
consider that his observations relating to the ovule, and to the discrimination of the species (of which all the original 
materials and drawings are preserved at Kew), were probably not intended for publication in extenso. Both his figures 
and descriptions are inferior in accuracy to the beautiful analyses of Decaisne, in Blume's * Rumphia,’ iv. t. 176, 
where the development of the ovular coats is represented (figs. 18 & 19) as I have found it to be. 
