OBGAJfS OF EEPRODUCTION. 277 



Fig. 618. Fig. 619. Fig. 620. 



Fig. 618. Transverse section of the 

 young ovary of Campion {Lych- 

 nis), showing five partitions 

 proceeding from the walls of 

 the ovary to the placentas in the 

 centre ; these partitions are de- 

 stroyed by the growth of the 

 ovary, so that the placentation 



is ultimately free. Fig. 619. Vertical section of Cerastium Idrsutum 



(Caryophyllacece). o. Ovary, p. Free central placenta, g. Ovules s 



Styles. Fig. 620. Transverse section of the same with the two portions 



separated, o. Ovary, p. Placenta, gr. Ovules, s. Styles. From Jussieu. 



Besides the regular kinds of placentation just described, it 

 sometimes happens that the ovules are placed more or less ir- 

 regularly in the cavity of the ovary. Thus, in the ^lowering 

 Eush {Butomus) {fig. 622) they cover the whole inner surface of 

 the ovaries ; in the Nymphcea, they are attached all over the dis- 

 sepiments ; in Cahomba, they arise from the dorsal suture ; and in 

 Broomrape (Orobancke), from placentas placed within the mar- 

 gins of the ventral suture. 



Fig. 622. 



Fig. 621. Vertical section of the pistil of Cyclamen (Primulacecn). s. Sepals 



pi. Free central pi icenta. st Style, stig. Stigma. J'fg'. 622. Vertical 



section of the flower of the Flowering Rush, showing the inner surface 

 of the ovaries covered all over with ovules. 



2. Origin of the Placenta. — Having now described the dif 



