244 DIVISIONS IN OVARIES. 



the dissepiments, as in Nymphsea and in Butomus mnbellatus (figs. 

 427, 428) ; also, though very rarely, along the dorsal suture, as in 

 Cabomba, or on lines within the margin, as in Orohanche, has been 

 supposed to confirm this view. Schleiden argues in favour of it, from 

 the case of Armeria, where there are five carpels and a single ovule 

 attached to a cord, which arises from the axis, and becomes curved 

 at the apex, so as to suspend the ovule ; also, from cases, such as 

 Taxus, where the ovule appears to be naked and terminates a branch. 

 This theory of placentation, however, cannot be easily applied to all 

 cases ; and Gray says that it is disproved in cases of monstrosity, 

 iu which the anther is changed into a carpel, or where one part of the 

 anther is thus transformed and bears ovules, while the other, as well 

 as the filament, remain unchanged. In the case of Lufia foetida, the 

 entangled fibres of the carpellary leaves, even in the young state, 

 seem to be connected with perpendicular lines forming the placenta. 

 Brongniart mentions a case where the marginal placenta was entire, 

 while the axis was prolonged separately, and totally unconnected 

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

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

 place. 



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

 called, carpellary placentation, generally prevails ; that axile placenta- 

 tion explains easily cases such as Primulaceae; while such instances as 

 CaryophyllacesB are explicable on either view. 



Occasionally, divisions take place in ovaries which are not formed 

 by the edges of contiguous carpels. These are called spurious dissepi- 

 ments. They are often horizontal, and are then called 

 pliragmata ((pgdy/j^a, a separation), as in Cathartocarpus 

 Fistula (fig. 429), where they consist of transverse 

 cellular prolongations from the walls of the ovary, only 

 developed after fertilisation, and therefore more pro- 

 perly noticed under fruit. At other times they are 

 vertical, as in Datura, where the ovary, in place of 

 being two-celled, is rendered four-celled ; in Cruciferee, 

 where the prolongation of the placentas forms a re- 

 plum (replum, leaf of a door) or partition ; in Astragalus 

 and Thespesia, where the dorsal suture is folded in- 

 ^"^^"^ wards ; in Oxytropis where the ventral suture is 

 folded inwards ; and in Diplophractum, where the 

 inner margin of the carpels is inflexed (fig. 422). In Cucurbitacese, 

 divisions are formed in the ovary, apparently by peculiar projections 

 inwards from curved parietal placentas. In some cases horizontal 

 dissepiments are supposed to be formed by the union of carpels 



Fig. 429. Pistil of Cassia or Catliartocarpus Fistula, in an adranced state, cut longi- 

 tudinally, to show the spurious transverse dissepiments, or phragmata. 



