ANGIOSPERMS. 



375 



cohere along iheir whole length, or only below, in which case the upper portions have 

 rather the appearance of a whorl of monomerous ovaries (Figs. 303, 304, 305, 306). 

 If the inflexed margins of the carpels form placentas in the centre of the ovary, the 

 ovules make their appearance in the central angles of the loculi, as in Fig. 305 ; but 

 they .not unfrequently divide at the centre into two lamellae, which are recurved and 

 swell out into placentas in the middle of the loculi, as is shown in Fig. 304 ; it is 

 obvious, that the two placentas inside a loculus correspond to the margins of the 

 carpel which forms the outer wall of the loculus. 



Spurious dissepiments may be formed in polymerous as well as in mono- 

 merous ovaries ; if the polymerous ovary is bilocular, it may in this way become 

 quadrilocular, if it has properly five loculi, these may become ten. The former 

 case is common in the Labiatae and Boragineae ; Fig. 307 

 shows that the ovary is formed by the union of two 

 carpels, the margins of which projecting inwards (/ to IV) 

 form a right and left placenta (/>/), and on each placenta, 

 which corresponds to a margin of a carpel, is a posterior 

 and an anterior ovule ; but a growth inwards from the 

 median line of the carpel thrusts itself in between the two 

 ovules of a loculus (/Fand VI x] and divides it into two 

 one-seeded lobes. As the outer part of the wall of each 

 of the four lobes subsequently becomes strongly convex 

 outwards and upwards (Fig. 307 \ the separation of the 

 ovary, composed originally of two carpels, into four separate 

 parts becomes still more marked, and finally these parts 

 separate as one-seeded lobes (nutlets), as is seen most completely in the Boragineae. 

 In Limim on the other hand the division of the five compartments of the ovary 

 into ten by false dissepiments is incomplete, since the ridges which project from 

 the median line of the carpels do not reach as far as the centre of the ovary. 



Before going on to consider ovaries with axial placentas, it must be mentioned, 

 that there are cases, in which the present state of our knowledge does not allow 

 us to determine with certainty, whether the ovules proceed from the axis or from 

 the margins of the carpels which are united to it, and these doubtful cases are 

 perhaps more numerous than is supposed. In the Caryophylleae, according to 

 Payer's observations on Cerasthim and Malachium, the broad extremity of the floral 

 axis becomes considerably elevated even before the formation of the carpels, which 

 then make their appearance in a whorl with their margins united, and attached by 

 them to the axis which rises above them ; each, so to speak, forms a pocket which 

 hangs by the side of the axis ; as the axis lengthens, the margins of the carpels form 

 radial dissepiments along it and between the pockets which enlarge into loculi 

 of the ovary; ultimately the carpels outgrow the apex of the axis, the dissepiments 

 becoming raised above it in Cerasthim and other genera as free lamellae which do 

 not meet in the middle, so that the ovary has five loculi below but continues uni- 

 locular above. The ovules appear in two parallel rows on the axile side of each 

 compartment, and appear to be formed from the axis. There are genera in the 

 Caryophylleae in which it is more probable that the placenta is axial, others where it 

 seems to belong rather to the carpels. 



FIG. 306. Ripe fruit of Die- 

 tamnus Fraxinella, the anterior 

 carpel being removed, and the two 

 lateral opened ; g the style. Natural 

 size. 



