unimpregnated Ovulum in Phenogamous Plants. 361 
sels*, and as consisting of a uniform parenchyma, in which 
the embryo appears at first a minute point, gradually con- 
verting more or less of the surrounding tissue into its own 
substance; the coats and albumen of the seed being formed of 
that portion which remains+. 
In the same year, M. Auguste de Saint Hilaire} shows that 
. the micropyle is not always approximated to the umbilicus; 
that in some plants it is situated at the opposite extremity of 
the ovulum, and that in all cases it corresponds with the ra- 
dicle of the embryo. This excellent botanist, at the same time, 
adopts M. Turpin’s opinion, that 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, con- 
tact, which in some plants unquestionably takes place, and in 
one family, namely, Plumbagineze, in a very remarkable man- 
ner, but only after a certain period, for original cohesion, or 
organic connexion, which I have not met with in any case. 
In 1815 also appeared the masterly dissertation of Professor 
Ludolf Christian Treviranus, on the developement of the vege- 
table Embryo §, in which he describes the ovulum before fecun- 
dation as having two coats; but of these, his inner coat is evi- 
dently the middle membrane of Grew, the chorion of Mal- 
pighi, or what I have termed nucleus. 
In 1822, Mons. Dutrochet, unacquainted, as it would seem, 
with the dissertation of Professor Treviranus, published his ob- 
servations 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. 
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 re- 
specting 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 
yascular cord. Yet he seems not to admit the function ascribed 
to it, and asserts that it is in many cases wanting**. 
|To be continued.] 
* Elém. de Physiol. Vég. et de Bot. tom. i. p. 314. + Id. loc. cit. 
t Mém. du Mus. d Hist. Nat. ii. p. 270, et seq. 
§ Entwick. des Embryo im Pflanzen-Ey. 
|| Mém. du Mus, d’ Hist. Nat. tom. vit. p. 241, et seq. 
q Elém. Philos, Bot. p. 338. *® Td. p. 340. 
Vol. 67. No. 337. May 1826. 2Z LY. Report 
