568 
EXPLANATION OF THE PLATES. 
Fig. 6. A vertical section of the same : a, the central free placenta ; &, ovula ; 
c, point where the placenta is connected, before fertilisation, with the stig- 
matic tissue. 
Fig. 7. A perpendicular section of the pistillum of Vaccinium amcenum : a, 
inferior ovarium combined with the tube of the calyx ; 6, limb of the calyx ; 
c, epigynous disk ; d, placenta ; e, ovula ; f, style ; g, stigma. 
Fig. 8. A transverse section of the ovarium of Hydrophyllum canadense, showing 
its remarkable placentation ; a, wall of the ovarium ; 6, left placenta ; c, right 
placenta ; e, one of their points of union, the other is seen on the opposite 
side ; d, a fleshy secreting annular disk. In this case, two placentae grow up 
face to face from the base of the ovarium, and gradually unite at their edges (e), 
enclosing the ovula within the cavity they thus form ; this is proved by Ne- 
mophila, in which the placentation is the same, except that the placentae are 
always distinct from each other ; one of these placentae, the ovuliferous face 
turned towards the eye, is represented at fig. 8. 
Fig. 9. A perpendicular section of the inferior ovarium of Thamnea uniflora ; 
after A. Brongniart : a, tube of the calyx ; 6, wall of the ovarium ; c, epigynous 
disk ; d, ovula collected round a columnar placenta. 
Fig. 10. Transverse section of the ovarium of Viola tricolor, showing its parietal 
placentation : a, one of the three placentas. 
Fig. 11. Stigma of the same plant, which is inflated and hollow, with an orifice 
obliquely situated at its apex. 
Fig. 1 2. Bifid stigma of Chloanthes Stcechadis ; after Ferdinand Bauer. 
Fig. 13. Hairy apex of the style and stigma, with its indusium, of Brunonia 
australis ; after Ferdinand Bauer : a, stigma ; 6, indusium. 
Fig. 14. The same, divided perpendicularly ; a, stigma; 6, indusium. 
Fig. 15. Stigma of Banksia coccinea, with a part of the style; after Ferdinand 
Bauer. 
Fig. 16. The earliest state of the ovula of Cucumis Anguria ; this, and the 
succeeding figures, to 25 inclusive, are after Mirbel. 
Fig. 17. Three of these ovules in a more advanced state. 
Fig. 18. An ovulum at the period when the apex of the nucleus (a) is just ap- 
pearing through the primine. The foramen has already become oblique with 
respect to the apex of the ovulum. 
Fig. 19. An ovulum of the same, at the period when the secundine is appearing 
through the foramen : a, nucleus ; 6, border of secundine ; the nucleus is now 
more oblique than before. 
Fig. 20. An ovulum of the same, at a subsequent period, but still long before the 
expansion of the flower ; the several parts are more developed ; the nucleus, 
which at first was terminal, has now become lateral, and is evidently turning 
towards the base of the ovulum : a, nucleus ; 5, border of secundine. 
Fig. 21. An ovulum of the same, after fertilisation. In the interval between this 
state and the last, the primine has grown over the secundine and nucleus ; the 
apex of the latter has turned completely to the base of the ovulum ; and the 
foramen is contracted into the little perforation at a. 
Fig. 22. Ovulum of Euphorbia Lathyris, in a very young state, long before the 
expansion of the flower: a, kind of cap projecting from the wall of the ovarium, 
and into which the apex of the nucleus (6) is inserted ; this hood finally closes 
over the foramen, into which it protrudes as the nucleus retreats ; c, the 
primine ; the secundine is a similar cap included within the primine. 
