212 
ORGANOGRAPHY. 
BOOK I. 
planatory remarks, prove indeed that he knew something of 
the matter, but by no means entitle him to the credit of having, 
at that time, made the world acquainted with it. The late 
Mr. Thomas Smith seems to deserve the honour of having 
first made any general remarks upon the subject: of what 
extent they exactly were is not known, as his discoveries, in 
1818, were communicated, as it would seem, in conversation 
only ; but it is to be collected from Brown’s statement that 
they were of a highly important nature. Since that period 
the structure of the ovule has received much attention from 
Brown, in England; Turpin and Adolphe Brongniart, in 
France; and Treviranus, in Germany; by all of whom the 
subject has been greatly illustrated. It is, however, to Mir- 
bel, — who, by collecting the discoveries of others, examining 
their accuracy, and combining them with numerous observ- 
ations of his own, has given a full account of the gradual 
developement and the different modifications of the ovule — 
that we are indebted for by far the best description of that 
important organ. His two papers read before the Academy 
of Sciences at Paris, in 1828 and 1829, are a model of careful 
investigation. 
Ovules have been compared to buds, and may be shown to 
be analogous to them in structure. Of the truth of this there 
can now be little doubt : for, to say nothing of such plants as 
Bryophyllum, which habitually form buds on the margins of 
the leaves ; or of Malaxis paludosa, in which the edge of the 
leaf is frosted by little microscopical points, that are neither 
exactly ovules nor exactly buds ; or of the bracts of Marc- 
graavia, which Turpin, with much ingenuity, has endeavoured 
by mere argumentation to prove analogous to the primine of 
the ovule ; it has been shown by Henslow that in the Mignio- 
nette the ovules do actually become transformed into leaves, 
either solitary or rolled together round an axis, of which the 
nucleus is the termination. (Camhr. Phil. Trans, vol. v. 
part i.) Engelman, also, mentions and figures instances of 
similar changes ; but he does not say in what plants, nor are 
his figures satisfactory. He, however, concludes, from the 
observations of himself and Schimper, that “ the ovules are 
buds of a higher order, their integuments leaves, and their 
