8o 
THE OVULE 
(basal). In the unilocular ovary of Caryophyllaceae, Primu- 
laceae (Figs, in Pt II), &c. a peculiar free-central placenta 
runs up through the middle, the ovary looking like a multi- 
locular ovary that has lost its partitions or septa . 
6 
Fig. 8. 
Fig. 7* 
Fig. 7. Cross section of flower of Myrtus communis , showing 
tricarpellary, trilocular ovary, with axile placentae. 
Fig. 8. Cross section of flower of Corydalis cava , showing 
bicarpellary, unilocular ovary, with parietal placentae. 
The concrescence of carpels may also include the styles, 
or the styles and stigmas. Branching or multiplication 
(p. 70), the formation of false septa (below), epigyny (p. 72), 
and other phenomena, often further complicate the morpho- 
lo gy- 
Details of the internal structure of the ovule must be 
sought elsewhere ; a few notes must suffice here. The ovule 
(Fig. 9) is borne by a stalk or fwiicle (f) upon a more or 
less swollen placenta (pi.), and consists of a mass of tissue, 
the nucellus (nu), enclosed in one or two coats (integument, 
ii, oi) which spring from the base (chalaza, cJi) of the ovule 
and leave a narrow opening (micropyle, m) at the apex. 
The nucellus contains one (or sometimes more than one) 
large cell, the megaspore or embryo-sac (e). This germinates 
in situ and in most Gymnospermae produces a mass of 
tissue (endosperm) filling up the interior of the sac and 
bearing archegonia near the micropyle. In Angiospermae 
there are usually only a few nuclei or cells produced, as in 
Fig. 9. The original spore nucleus divides to form eight, of 
which two unite to form a new central nucleus (n) } while 
