CHAr. II- OVARY. 175 



edges [Jig. 133.) : in that case the placentae do not project 

 at all into the cavity of the ovary, but are still more strictly 

 parietal than the last. 



132 133 134 



Another class of anomalies of a still mo're remarkable cha- 

 racter, is that in which the dissepiments are obliterated, while 

 the placentEe remain a distinct mass in the centre of the 

 ovary, as in Lychnis ; forming what is called a free central 

 placenta {fig. 132.). But, if we examine these plants at a very 

 early period of their formation, long before the flowers expand, 

 the explanation of the anomaly will be obvious. Such plants 

 are, at that time, constructed upon the ordinary plan, with 

 their dissepiments meeting in the centre and forming there a 

 fungous placenta ; but subsequently the shell of the ovary 

 grows more rapidly than the dissepiments, and breaks away 

 from them ; while the excessive growth of the placenta after- 

 wards destroys almost all trace of them : their previous pre- 

 sence is only to be detected by lines upon the shell of the 

 ovary, or by a separation of the mass of ovules into distinct 

 parcels upon the placenta. 



All partitions whose position is at variance with the fore- 

 going laws are spurious. Such spurious dissepiments are 

 caused by many circumstances, the chief of which are the 

 following : — they are caused by expansions of the placenta, 

 as in Cruciferae, when they form a partition stretching from 

 one side to the other of the fruit ; or they are mere dilatations 

 of the lining of the pericarp, as in Cathartocarpus Fistula, in 

 which they are horizontal ; or they are internal expansions of 

 the dorsal or ventral suture, as in Amelanchier, Astragalus, 

 and Thespesia, in which they are distinguishable from their 

 dissepiments by not bearing the placentae, and by being op- 

 posite the stigma, or by projecting beyond the placentae ; or, 

 finally, they are caused by the sides of the ovary projecting 



