446 OBSERVATIONS ON THE STRUCTURE 



own substance; the coats and albumen of the seed being 

 formed of that portion which remains.'^ 



In the same year, M. Auguste de Saint liihare' shows 

 that the micropyle is not always approximated to the um- 

 bilicus ; that in some plants it is situated at the opposite 

 extremity of the ovulum, and that in all cases it corresponds 

 with the radicle 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 connection with the parietes of the ovarium ; 

 mistaking, as I believe, contact, which in some plants un- 

 questionably takes place, and in one family, namely, Plum- 

 baginese, in a very remarkable manner, but only after a 

 certain peried, for original cohesion, or organic connection, 

 which I have not met with in any case. 



In 1815 also appeared the masterly dissertation of Pro- 

 fessor Ludolf Christian Treviranus, on the development of 

 64.7] the vegetable Embryo,^ in which he describes the ovu- 

 lum 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. 



In 1822, Mons. Dutrochet, unacquainted, as it would 

 seem, with the dissertation of Professor Treviranus, pub- 

 lished his observations on the same subject.* In what re- 

 gards 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 pre- 

 sumed that they were not disposed to adopt the statements 

 of these authors respecting it. 



Professor Link, in his P/dlosophia Botanica, published 

 in 1824, adopts the account given by Treviranus, of the 



' Id. loo. oit. 



" Mm. du Mtis. d'Hist. Nat. ii, p. 270, et seq. 



' Entwick. des Embryo im Pflanzen-Ey . 



^ Mem. du Mus. d'Hist. Nat. torn, viii, p. 2il, et seq. 



