INDKX. 



(JOT) 



mixing witli llic oviila, 50S ; 

 opinion of Professor Ainici lliat 

 they come into contact with tlic 

 ovulum, 508-9 ; traced into the 

 aperture of tlie ovulum, 510; the 

 autlior not so far advanced, 509 ; 

 origin of tlie pollen tubes, 509; 

 their growth, 509, 510; a vital 

 action, which may be excited by 

 the stigma of another species, 509- 

 510 ; their nutriment, whence de- 

 rived, 510; effect of action of pol- 

 len on stigma, 510; subsequent 

 changes in the ovulum, ibid. ; for- 

 mation of the embryo, ibid. ; cel- 

 lular thread })assing from its apex 

 to the apex of the original nucleus, 

 510, 511; changes in the embryo, 

 511 ; seed and its funiculus en- 

 tirely without vessels,511; areola, or 

 nucleus of the cell, its position, &c. 

 511- 514; spirally striated cells 

 in, 51i, 515, 5-lS ; raphides in, 

 515 ; mucous tubes in various 

 species, ibid.; structure of fibrillae, 

 constituting the pubescence of the 

 aerial roots in, 548 



Orchideae and Asciepiadeae, analogy 

 between the two orders, 530; in 

 the presence of an additional part, 

 consisting of a modification or ))ro- 

 duction of the stigma, 530-1 ; in 

 the frequency and necessity of the 

 agency of insects in fecundation, 

 531 ; penetration of pollen tubes 

 into the cavity of the ovarium, 

 531-2 ; function of the granules 

 within the pollen tubes in reference 

 to impregnation, 532 



Orchideaj and Asciepiadeae, supple- 

 mentary observations on the fecun- 

 dation of, 545 — 551 



Orchis fusca, cellular thread of ovu- 

 lum in, 547 



Orchis Morio, mucous tubes entering 

 the aperture of ovulum in, 540 ; 

 cellular thread of ovulum in, 547 



Orchis ustulata, cellular thread of 

 ovulum in, 547 



Orobanchete, Mr. Lindley's idea of 

 the placentation of, controverted, 

 562 



Oudncy, Dr. Walter, plants collected 

 by in Central Africa, 257, 259, 200, 

 272 



Oudnrya, characters of the genus, and 



obs( rvations on its structure, 272 

 Ovarium, vascularity of, compared 

 with that of the leaf, 379 note; 

 theoretical view of the origin or 

 formation of, 555 ; excej)tions to 

 the ordinary condition of, 555-0 ; 

 origin of various forms of compound, 

 457 — 503 ; supposed excej)lions iu 

 Orehidece and Orobancheaj con- 

 sidered, 557 — 502 

 Ovulum, structure of the unimpregna- 

 ted, in Ccphalotus, indicates the 

 position of the radicle of (he future 

 embryo, 77, 410; structure and de- 

 velopment of in llalllcsia, and in 

 riiaiuogamous plants generally, 

 40f)-7; in llydnora and Cytinus, 

 407; structure of the uninipregna- 

 ted, 439—452; in Kingia, 439; iu 

 Ccphalotus, n, 440 ; generally con- 

 sists of two coats enclosing a nu- 

 cleus, 440 ; origin and relation of 

 the coats, and of the future embryo, 

 440-1 ; structure of ovulum, as de- 

 scribed by Grew, Malpi;,'hi, Came- 

 rarius, Morland, Etienne Francois 

 GeotiVoy, Claude Joseph Geoffroy, 

 Vaillant, Keedham, Adaujou, 

 Spallanzani, Gtrrtner, Turpiii, 

 Kichard, Mirbel, Auguste de Saint- 

 Hilaire, Ludolf Christian Trevira- 

 nus, Dulrochet, and Link, 442-7; 

 in what respects the account given 

 differs from all those observers, 

 447; exceptions to the general 

 structure in Compositic and Lcuma, 

 448 ; importance of distinguishing 

 between the coats of the ovulum 

 and those of the ri|)e seed, 449 ; 

 how determinable, 449 — 152; struc- 

 I ture and development of unimprcg- 

 I nated, in Orcludere, 504-5 ; iu As- 

 i clepias, 549-550; the ovulum 

 j naked in Cvcadere, Conifera;, Kphc- 

 i dra, and Gnetum, 453 ; arguments 

 in favour of this view. 454; objec- 

 tions to it, 454-5; origin of the 

 ovulum in Cycadcie and Coniferac, 

 458-9 

 Ovules, their marginal insertion in 

 the simjile j)istilla, and in the com- 

 ponent parts of the compound 

 ovarium, sliown in various instances. 

 379 note; cases of a|)|)arcnl ex- 



