DIVISIONS IN OVAKIES. 217 



state, seem to be connected with perpendicular lines forming the pla- 

 centa. Brongniart mentions a case where the marginal placenta was 

 entire, while the axis was prolonged separately, and totally uncon- 

 nected with the placenta; he also notices peculiar monstrosities, which 

 seem to prove that, in some cases at least, marginal placentation must 

 take place. 



446. Upon the whole, then, it appears that marginal, or, as it is 

 often called, carpellary placentation generally prevails; that axile 

 placentation explains easily cases such as Primulaceae, while such in- 

 stances as Caryophyllacese are explicable on either view. 



447. Occasionally, divisions take place in ovaries which are not 

 formed by the edges of contiguous carpels. These are called spurious 

 dissepiments. They are often horizontal, and are then 



called phragmata (<pj Hypo,, a separation), as in Catharto- 

 carpus Fistula (fig. 395), where they consist of transverse 

 cellular prolongations from the walls of the ovary, only 

 developed after fertilization, and therefore more properly 

 noticed under fruit. At other times they are vertical, as 

 in Datura, where the ovary, in place of being two-celled, 

 is thus rendered four-celled; in Crucifera?, where the pro- 

 longation of the placentas forms a replum (replum, leaf of a 

 door) or partition; in Astragalus and Thespesia, where the 

 dorsal suture is folded inwards ; and in Diplophractum, 

 where the inner margin of the carpels is reflexed (fig. 388). 

 In Cucurbitaceae, divisions are formed in the ovary, appa- 

 rently by peculiar projections sent inwards from curved parietal pla- 

 centas. In some cases, horizontal dissepiments are supposed to be formed 

 by the union of carpels situated at different heights, so that the base 

 of one becomes united to the apex of another. In such cases, the 

 divisions are true dissepiments formed by carpellary leaves. The 

 anomalous divisions in the ovary of the Pomegranate have been thus 

 explained. 



448. The ovary is usually of a more or less spherical or curved form, 

 sometimes smooth and uniform on its surface, at other times hairy and 

 grooved. The grooves, especially when deep, indicate the divisions 

 between the carpels, and correspond to the dissepiments. The dorsal 

 suture may be marked by a slight projection, or by a superficial groove. 



449. The ovary is either free in the centre of the flower, or it is 

 united to the surrounding parts, more especially to the calyx. The 

 union may take place completely, so that the calyx is adherent through- 

 out, and becomes superior while the ovary is inferior, as in the Melon 

 (fig. 396, o being the ovary, I the upper part of the adherent calyx); 

 or it may take place partially, as in Saxifragaceae (figs. 397, 398), where 



Fig. 395. Pistil of Cassia, or Cathartocarpus Fistula, in an advanced state, cut longitudinally 

 to show the spurious transverse dissepiments, or phragmata. 



