Nuphar by Tittmann.*

(*Footnote. Keimung der Pflanzen page 19 et 27 table 3 et 4.)

In support of this explanation, which differs from all those yet given, I
may here advert to an observation published many years ago, though it
seems to have escaped every author who has since written on the subject,
namely, that before the maturity of the seed in Nymphaeaceae, the
sacculus contains along with the embryo a (pulpy or semi-fluid)
substance, which I then called Vitellus, applying at that time this name
to every body interposed between the albumen and embryo.* The opinion
receives some confirmation also from the existence of an extremely fine
filament, hitherto overlooked, which, originating from the centre of the
lower surface of the sacculus, and passing through the hollow axis of the
Albumen, probably connects this coat of the Embryo in an early stage with
the base of the nucleus.

(*Footnote. Prodr. Flor. Nov. Holl. 1 page 306.)

The same explanation of structure applies to the seeds of Piperaceae and
Saururus; and other instances occur of the persistence either of the
membrane or of the substance of the amnios in the ripe seed.

It may be concluded from the whole account which I have given of the
structure of the ovulum, that the more important changes consequent to
real, or even to spurious fecundation, must take place within the
nucleus: and that the albumen, properly so called, may be formed either
by a deposition or secretion of granular matter in the utriculi of the
amnios, or in those of the nucleus itself, or lastly, that two substances
having these distinct origins, and very different textures, may co-exist
in the ripe seed, as is probably the case in Scitamineae.

On the subject of the ovulum, as contained in an ovarium, I shall at
present make but one other remark, which forms a necessary introduction
to the observations that follow.

ON THE STRUCTURE OF THE FEMALE FLOWER IN CYCADEAE AND CONIFERAE.

That the apex of the nucleus is the point of the ovulum where
impregnation takes place, is at least highly probable, both from the
constancy in the appearance of the embryo at that point, and from the
very general inversion of the nucleus; for by this inversion its apex is
brought nearly, or absolutely, into contact with that part of the
parietes of the ovarium, by which the influence of the pollen may be
supposed to be communicated. In several of those families of plants,
however, in which the nucleus is