DR. J. D. HOOKER ON WELWITSCHIA. 9 
10, and these are only distinguishable towards the periphery ; the others are so indistinct 
and confused towards the centre that they cannot be accurately estimated. The pits are 
usually in one series on each ridge; but sometimes, probably from the ridges being con- 
fluent, two are seen here and there; and they amount to upwards of, one hundred on 
the circumference of a large specimen, diminishing in numbers on the ridges towards 
the centre. In old crowns these pits become raised on mammillary eminences. Radiating 
and concentric fissures of various depths intersect these ridges as the plant grows older. 
The crown, according to Dr. Welwitsch, sometimes attains 12-14 feet in circumference 
(Bibl. Univ. Genéve, July 1861), and, if Mr. Monteiro’s informant be correct, even 6 feet 
in diameter. It is very possible that the concentric ridges rudely represent annual incre- 
ments to the plant; for the soft texture of the cones and peduncles is opposed to the view 
that these are more than annual, as is the fact that the cones sent by Dr. Welwitsch, 
Mr. Baines, and Mr. Monteiro, respectively, have all advanced to the same state of deve- 
lopment. On the other hand, though, as is seen by Mr. Baines’s drawing (Plate I. fig. 2), 
the cones are produced in great abundance, it is very improbable that in old specimens 
every pit indicates the presence of a fully developed peduncle with cones; for in this 
case each of the large plants must have borne at one time many hundreds of cones. 
The surface of the crown is sometimes hoary, and presents under the microscope 
scattered, minute, hair-like bodies. These are peculiar spicular cells, hereafter to be 
described, which are developed within the tissue of the plant, but become exposed 
through its superficial disintegration. 
The Stock presents several remarkable features, especially the deep horizontal groove 
between it and the crown, the transverse ridging of its surface below the leaf, and the 
occasional presence of flower-buds, and even of the scars of fallen peduncles, on its cir- 
cumference. It often presents an upper lighter and a lower darker portion, the junction 
of which probably indicates the depth to which the specimen was sunk in the soil: this is 
well shown in Dr. Welwitsch’s specimen, figured at Plate I. fig. 1., and agrees with his 
description of the stem being only partially buried; whereas those of Mr. Monteiro, 
which he states were immersed in the soil up to the origin of the leaves, do not show it. 
The stock either terminates more or less abruptly downwards—most conspicuously 
so in all Dr. Welwitsch’s specimens (Plates I., II., III. & IV.),—or tapers into the root, 
as in Mr. Monteiro’s (Plate V. figs. 1-4, & Plate XI. figs. 1, 5, 7). The deep transverse slit 
dividing the stock from the crown, and at the base of which the leaves originate, is a 
most curious feature: it is nearly an inch deep in the largest specimen which I cut 
open; it clasps the leaf-base throughout its extent when the plant is fresh; but as the 
latter dies, its walls separate, leaving half-an-inch space between the upper and lower 
surfaces at the widest part (Plate XI. fig.1). Whether fresh or dry, its orifice is so con- 
tracted that there is very little external trace of its existence, and its lips clasp the leaf 
so tightly that the latter, even when detached at the base, cannot be withdrawn entire. 
The object of this arrangement is, no doubt, to protect the young growing part of the 
leaf from the dry atmosphere. 
The compression of the stock varies much in amount, and is no doubt proximately due 
to the dilatation of the base of the leaf, and consequent bilateral character of the trunk. 
C 
