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ON THE SEXUAL ORGANS OF THE CYCADACE^. 71
the exostome, and lience it often happens in ripe fruits that the sum-
mit of the woody part is prolonged into a tubular point.*
The vascular bundles, which are direct prolongations of one of the
vascular bundles of the carpophyll, pass through the cellular layer
nearly to the summit, and in ripe fruits are closely applied to the
woody portion. Thev do not anastomose, and their number varies in
different genera and species, but usually they are grouped, as has
already been stated, on opposite sides. Frequently they leave impres-
sions on the woody layer.
It seems, however, that in the formation of the coat all the tissues of
the carpophyll are not equally developed. In Cycas revoluta, for ex-
ample, and in the genera Zam'ia and EncepJialartos, the epidermis is
evidently continuous from one part to the other (Plate XCI. fig. 1) ;
in C. Rumpliii the epidermis of the ovules is not densely hairy, like that
of the carpophyll, and the ovules are surrounded at the base by a
hairy ring, or cup- shaped dilatation of the carpophyll.f Up to what
point the external layer of the coat is composed, on one side of a por-
tion of the parenchyma of the carpellary leaf, and on the other of the
whole, could only be determined when the development has been
completely studied. From a superficial examination it might be sur-
mised that the hairy cup of the ovule in the species belonging to the
second division of the genus Cycas is of the same nature as the hairy
surface of the o\aiIes in C. revoluta. I have akeady (Analecta Bot.
Indica, ii. p. 31) pointed out this distinction, which is not an unim-
portant one. But in using the terras integumentum externum and in-
tertmm, I had no intention, in opposition to the opinion which I my-
self have expressed as to the simple structure of the coat, of distin-
guishing morphologically two distinct integuments. These expres-
sions, possibly badly chosen, only apply to the external and internal
layers.
I have already pointed out that the nucleus in Cycads is not deve-
loped before its coat, but contemporaneously with it. J I have never
observed its first appearance. In the course of its development both
it and the embryo-sac pass through very different stages, and I was
* (Plate XCI. fig. 4, 5.) This has also been stated by Karsten to be the case
with Zamia muricata.
t See, amongst others, the figure of C. Rumpliii, in Linnsea, xxv. tab. 2.
X Karsten has confirmed this point in Zamia muricata. The nucleus and
its coat appear simultaneously. (Monatsb. Berlin. Akad., Dec. 18th, 1856. )f
but