KINDS OF PLACENTATION. 283 
is called a free central placenta, as in the Caryophyllaceze (figs. 
633, pl, and 634, p), and the Primulacez (jig. 635, pl). 
Besides the regular kinds of placentation just described, it 
sometimes happens that the ovules are placed more or less 
RIG. 630. Fic. 634. 
Fie. 632. 
7p 
vpl, ; 
ye 
SS 
Fig. 632. Transverse section of the young ovary of Campion (Zychnis), show- 
ing five partitions proceeding from the walls of the ovary to the placentas 
in the centre ; these partitions are destroyed by the growth of the ovary, 
so that the placentation is ultimately free-——Fig. 633. Vertical section of 
Cerastium hirsutum (Caryophyllacee). o. Ovary. p. Free central pla- 
centa. g.Ovules. s. Styles and stigmas. Fig. 634, Transverse section 
of the same with the two portions or sections separated. o. Ovary. p. 
Placenta, g. Ovules. s. Styles and stigmas. From Jussieu. 
irregularly in the cavity of the ovary. Thus, in the Flowering 
Rush (fig. 636), they cover the whole inner surface of the ovary 
Fig. 635. Fic. 636. 
stig , 
Fig. 635. Vertical section of the pistil of Cyclamen (Primulacece). s. Sepals. 
pl. Free central placenta. sf. Style. stig. Stigma.-Fig. 636. Vertical 
section of the flower of the Flowering Rush ( Butomus umbellatus ), Showing 
the inner surface of the ovaries covered all over with ovules. 
except the midrib ; in which case the placentation is sometimes 
described as superficial. Other irregularities also occur: thus, in 
the Nymphxa, they are attached all over the dissepiments ; in 
