hat the micropyle is the
cicatrix of a vascular cord, and even gives instances of its connexion
with the parietes of the ovarium; mistaking, as I believe, contact, which
in some plants unquestionably takes place, and in one family, namely,
Plumbagineae, in a very remarkable manner, but only after a certain
period, for original cohesion, or organic connexion, which I have not met
with in any case.

(*Footnote. Mem. du Mus. d'Hist. Nat. 2 page 270 et seq.)

In 1815 also appeared the masterly dissertation of Professor Ludolf
Christian Treviranus, on the development of the vegetable embryo,* in
which he describes the ovulum before fecundation as having two coats: but
of these, his inner coat is evidently the middle membrane of Grew, the
chorion of Malpighi, or what I have termed nucleus.

(*Footnote. Entwick. des Embryo im Pflanzen-Ey.)

In 1822, Mons. Dutrochet, unacquainted, as it would seem, with the
dissertation of Professor Treviranus, published his observations on the
same subject.* In what regards the structure of the ovulum, he
essentially agrees with that author, and has equally overlooked the inner
membrane.

(*Footnote. Mem. du Mus. d'Hist. Nat. tome 8 page 241 et seq.)

It is remarkable that neither of these observers should have noticed the
foramen in the testa. And as they do not even mention the well-known
essays of MM. Turpin and Auguste de St. Hilaire on the micropyle, it may
be presumed that they were not disposed to adopt the statements of these
authors respecting it.

Professor Link, in his Philosophia Botanica, published in 1824, adopts
the account given by Treviranus, of the coats of the ovulum before
impregnation:* and of M. Turpin, as to the situation of the micropyle,
and its being the cicatrix of a vascular cord. Yet he seems not to admit
the function ascribed to it, and asserts that it is in many cases
wanting.**

(*Footnote. Elem. Philos. Bot. page 338.)

(**Footnote. Id. page 340.)

The account which I have given of the structure of the vegetable ovulum,
differs essentially from all those now quoted, and I am not acquainted
with any other observations of importance respecting it.

Of the authors referred to, it may be remarked, that those who have most
particularly attended to the ovulum externally, have not always examined
it at a sufficiently early period, and have confined themselves to its
surface: that those who have most minutely examined its internal
structure, have trusted