302 THE FLOWER. 



from the dorsal suture, as in the Flax (Ord. Linacese), the Service- 

 Berry, and many species of Vaccinium ; or by its introflexion, as 

 in Astragalus (Fig. 444). 



549. A compound ovary of two cells, or loculi, is bilocular ; of 

 three, trilocular ; of four, quadrilocular ; of five, quinquelocular ; 

 and so on. If of several without reference to the number, it is 

 said to be plurilocular^ or multilocular ; the former name being 

 used when the cells are comparatively few, the latter when more 

 numerous. We may, however, have a 



550. Ullilocillar Compound Pistil, where the ovary, although com- 

 posed of two or more carpels, is yet one-celled, that is, has a single 

 cavity. The cases of the sort are of two principal kinds, namely, 

 first, 



551. With a free Placenta in the Axis, as in the Primrose Fam- 

 ily (Ord. Primulacese), and in a large part of the Chickweed and 

 Pink Family, as shown in Fig. 384. This is usually explained on 



the supposition that the dissepiments are obliterated 

 or torn away by the expansion during the growth 

 of the ovary, these alone being wanting to com- 

 plete the structure of the normal compound ovary 

 already described, as will be seen by comparing 

 the diagram, Fig. 387, with Fig. 383. This is 

 demonstrably the true explanation in the Chick- 

 weed and Pink Family ; for the dissepiments, or 

 384 vestiges of them, may be detected at an early 



stage, and sometimes at the base of the full-grown 

 ovary ; while certain plants of the same family, of otherwise iden- 

 tical structure, retain the partitions even in the ripe pod. Other 

 cases, however, especially where there are a few ovules, or even a 

 single one, as in Thrift (Ord. Plumbaginacese), arising from the 

 base of the cell, are more properly referred to the other kind of 

 unilocular compound pistil, namely, that 



552. With Parietal Placeiltation, If we suppose a circle of three 

 carpellary leaves, with their margins turned inwards, yet not so as 

 to reach the axis, to cohere merely by their contiguous inflexed 

 portions, a one-celled tricarpellary ovary would result, with three 

 imperfect dissepiments projecting into the cavity, but not dividing 

 it into distinct cells (as in the diagram, Fig. 385). The placentae 



FIG. 334. Vertical section through the compound tricarpellary ovary of a plant of the 

 Chickweed Family (Spergularia rubra), showing the free central placenta. 



