66 LETTER XXXI. 



developed, it combines in some cases, in the same 

 species, as we have seen, two different forms of placen- 

 tation : the central and the parietal. 



EXPLANATION OF PLATE XXXL 



I. The Begonia Tribe. — 1. The inflorescence of the stained 

 Begonia (B. discolor) ; a a fertile flower ; be sterile flowers. — 2. A 

 side view of an anther, with the cleft through which the pollen escapes. 

 — 3. A transverse section of the same. — 4. A fertile flower.- — 5. One 

 of the twisted two-lobed stigmas. — 6. A transverse section of an ovary, 

 shewing the three cells, in each of which there is a double placenta 

 covered with ovules. — 7. A ripe seed-vessel. — 8. A seed very much 

 magnified. — 9. The embryo. 



IL The Fig-M.arigoi,d Tribe. — A. 1. A flower of Villet's 

 Fig-Marigold (Mesembryanthemum Villeti of the Gardens). — 2. Its 

 calyx and stamens. — 3. A stamen. — 4. A longitudinal section of the 

 ovary ; a, the insertion of the stamens ; b. the parietal placentae ; c, the 

 stigma. — B. 5. A ripe fruit of Mesembryanthemum, after Goertner. 

 — 6. A longitudinal section of it, shewing the manner in which the 

 seeds are attached to the bottom of the inner angle of the cells. — 7. A 

 seed. — 8. A section of it with the embryo and albumen. 



