210 
ORGANOGRAPHY. 
BOOK I. 
There is undoubtedly a great deal of force in these argu- 
ments, and it is extremely probable that the ovule with its 
placenta is a developement of the axis, and not of the margin 
of a carpellary leaf, in numerous instances where its origin has 
been hitherto supposed to be of the latter kind; especially 
in Compositae, Graminaceac, Polygonaceac, Plumbaginaceae, 
Primulaceae, &c. But it does not follow that, because the 
placenta has sometimes, it must always have, such an origin. 
We know that leaves do produce buds, we also know that the 
axis produces them ; there is therefore no reason why the 
carpels, as well as the point of the axis which they enclose or 
surround, should not in like manner produce ovules. In fact 
we have numerous cases of monsters, especially in Crassulaceae, 
Amygdaleae, and Ranunculaceae, in which the ovules do most 
certainly grow on the margins of leaves only partially con- 
verted into carpels. Moreover Dr. Grisebach, in his excellent 
Genera et Species Gentianearum^ has shown that the placenta 
of that order cannot be an expansion of the axis, because the 
ovula are originally developed in two or three rows on the 
face of the carpels, forming a line of minute tumours from 
the base to half-way up the carpels ; “ quae quidem series, 
parenchymate magis inter ovula quam in dorso carpophylli 
crescente, demum ipsius superficiem fere integram subaequa- 
liter obtegunt,” 
Dr. Schleiden disregards the cases on record of leaves 
producing buds : but he will probably reconsider his opinions 
upon that point. 
12. Of the Receptacle. 
The part upon which the carpels are seated is the apex of 
the peduncle, or the summit of the floral branch, of which the 
carpels are the termination. Usually this part, which is called 
the receptacle, is flat, or merely a vanishing point; but in 
other cases it is very much dilated, and then assumes a variety 
of curious appearances. This receptacle is called torus, or 
thalamus as well as receptacvlum, and in Greek compounds 
has the name of clinium. 
In Anonacete and Magnoliaceae it elevates itself from the 
