94: THE SECOND BOOK OF BOTANY. 



FIG. 188. FIG. 189. FIG. 190. 



V. 



Fig. 188 is a section across the middle of an 

 ovary, and Fig. 189 is a section across the upper part 

 of the same ovary. The partitions that appear in one 

 and are not seen in the other, must be false they 

 cannot be formed by the sides of adjacent carpels. 



In Fig. 190 the placentae are parietal, but a mem- 

 brane is formed, reaching across the ovary, and form- 

 ing a false dissepiment. These false dissepiments, 

 you see, are developed, in some cases, from the dorsal 

 suture ; in others, from the placentae. 



It may sometimes be difficult to decide between 

 true and false dissepiments ; but, as your knowledge 

 of plants increases, the different members of the same 

 group will often be found to afford transitional char- 

 acters that make evident what otherwise would be 

 uncertain. 



EXERCISE XXXH. 

 Modes of Dehiscence. 



To understand the modes of dehiscence, pictured 

 in this exercise, you have only to prepare a three- 

 celled compound ovary, as directed in Ex. XXX., 



