THE PISTIL, : 115 
ing what is called the placenta or trophosperm. It is this 
body that bears the ovules. 
442. The carpels, like leaves on a branch, are developed 
round a central axis, towards which all their margins are 
turned; and the placents, being formed at the margins of 
the leaves, are almost always next this imaginary centre line 
or axis, running down interiorly on the edges of the carpels. 
And hence the dissepiments appear to run backwards or out- 
wards from the placente. 
443. The margins of each carpel may be united—or the 
_ margins of adjoining carpels; and the placenta may be on 
the united margins of one carpel—or on the united margins 
of two adjoining carpels. 
444. The placente are central, when in the situation de- 
scribed in paragraph 442, the dissepiments being entire. 
445. A free central placenta is formed when the dissepi- 
ments in a many-celled ovary shrink backwards, or become 
obliterated, and the placenta remain united in the centre of 
the ovary, as in Lychnis and many of the Caryophyllee. 
This class of plants illustrates well the formation here al- 
luded to ; for in the early stage, the dissepiments may be seen 
running in a line from the centre to the circumference, but 
gradually disappear as the ovary advances to maturity. 
446. The placente are parietal, when, owing to the con- 
traction of the dissepiments, which do not divide the ovary 
into several distinct cells, but merely project from its inner 
surface, they are placed. near its walls, on the free edges of 
the Stpivtignts: as in Poppy. = 
447. When the ovary is free inthe flower, that is, forms _ 
no adhesion to the sides of the calyx, its base and that of the 
stamens being inserted into the top of the receptacle, it is 
called superior ; and they are inferior, or hypogynous ; as in 
Tulip, Poppy, Crowfoot (Ranunculus.) See Frontispiece, 
Fig. 5, the Poppy, in which the stamens and corolla are seen _ 
inserted into the receptacle, below the pistil. _ sg 
448, When the ovary adheres to the sides of the alyx, a 
th verest an eats ee ina etg RES : 
