ed that,
"from the structure of the Ovulum, even in the unimpregnated state, I
entertain no doubt that the radicle of the Embryo points to the
umbilicus."*

(*Footnote. Flinders Voyage loc. cit.)

My attention had been first directed to this subject in 1809, in
consequence of the opinion I had then formed of the function of the
Chalaza in seeds;* and sometime before the publication of the observation
now quoted, I had ascertained that in Phaenogamous plants the
unimpregnated Ovulum very generally consisted of two concentric
membranes, or coats, enclosing a Nucleus of a pulpy cellular texture. I
had observed also, that the inner coat had no connexion either with the
outer or with the nucleus, except at its origin; and that with relation
to the outer coat it was generally inverted, while it always agreed in
direction with the nucleus. And, lastly, that at the apex of the nucleus
the radicle of the future Embryo would constantly be found.

(*Footnote. Linnean Society Transactions 10 page 35.)

On these grounds my opinion respecting the Embryo of Cephalotus was
formed. In describing the Ovulum in this genus, I employed, indeed, the
less correct term sacculus, which, however, sufficiently expressed the
appearance of the included body in the specimens examined, and served to
denote my uncertainty in this case as to the presence of the inner
membrane.

I was at that time also aware of the existence, in several plants, of a
foramen in the coats of the Ovulum, always distinct from, and in some
cases diametrically opposite to the external umbilicus, and which I had
in no instance found cohering either directly with the parietes of the
Ovarium, or with any process derived from them. But, as I was then unable
to detect this foramen in many of the plants which I had examined, I did
not attach sufficient importance to it; and in judging of the direction
of the Embryo, entirely depended on ascertaining the apex of the nucleus,
either directly by dissection, or indirectly from the vascular cord of
the outer membrane: the termination of this cord affording a sure
indication of the origin of the inner membrane, and consequently of the
base of the nucleus, the position of whose apex is therefore readily
determined.

In this state of my knowledge the subject was taken up in 1818, by my
lamented friend the late Mr. Thomas Smith, who, eminently qualified for
an investigation where minute accuracy and great experience in
microscopical