INDKX. 



605 



mixing with the ovula, 508 ; 

 opinion of Professor Amici that 

 they come into contact with the 

 ovulum, 508-9 ; traced into the 

 aperture of the ovulum, 540 ; the 

 author not so far advanced, 509 ; 

 origin of the pollen tubes, 509; 

 their growth, 509, 510; a vital 

 action, which may be excited by 

 the stigma of another species, 609- 

 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 passing 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, 514, 515, 548 ; raphides in, 

 515 ; mucous tubes in various 

 species, ibid.; structure of fibrillse, 

 constituting the pubescence of the 

 aerial roots in, 548 

 Orchidese and Asclepiadeae, analogy 

 between the two orders, 530; in 

 the presence of an additional part, 

 consisting of a modification or pro- 

 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 

 Orchidese and Asclepiadeae, 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 

 Orobanchese, Mr. Lindley's idea of 

 the placentation of, controverted, 

 562 

 Oudney, Dr. Walter, plants collected 

 by in Central Africa, 257, 259, 260, 

 272 



Oudneya, characters of the genus, and 

 observations on its structure, 272 



Ovarium, vascularity of, compared 

 with that of the leaf, 379 note; 

 theoretical vievp of the origin or 

 formation of, 555 ; exceptions to 

 the ordinary condition of, 555-6 ; 

 origin of various forms of compound, 

 457 — 563; supposed exceptions in 

 Orchidese and Orobancheie con- 

 sidered, 557—562 



Ovulum, structure of the unimpregna- 

 ted, in Cephalotus, indicates the 

 position of the radicle of the future 

 embryo, 77, 440 ; structure and de- 

 velopment of in RafBesia, and in 

 Phajuogamous plants generally, 

 406-7; in Hydnora and Cytinus, 

 407 ; structure of the unimpregna- 

 ted, 439—452; in Kingia, 439; in 

 Cephalotus, 77, 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, Malpighi, Came- 

 rarius, Morland, Etienne Prancois 

 Geoffroy, Claude Joseph Geoffrey, 

 Vaillant, Needham, Adanson, 

 Spallanzani, Gaertner, Turpin, 

 Richard, Mirbel, Auguste de Saint- 

 Hilaire, Ludolf Christian Trevira- 

 nus, Dutrochet, and Link, 442-7; 

 in what respects the account given 

 differs from all those observers, 

 447 ; exceptions to the general 

 structure in Compositte and Lenina, 

 448; importance of distinguishing 

 between the coats of the ovulum 

 and those of the ripe seed, 449 ; 

 how determinable, 449 — 452 ; struc- 

 ture and development of unimpreg- 

 nated, in Orchidese, 504-5 ; in As- 

 elepias, 549-550; the ovulum 

 naked in Cycadese, Coniferse, Ephe- 

 dra, and Gnetum, 453 ; arguments 

 in favour of this view, 454 ; objec- 

 tions to it, 454-5; origin of the 

 ovulum in Cycadese and Coniferse, 

 458-9 

 Ovules, their marginal insertion in 

 the simple pistilla, and in the com- 

 ponent parts of the compound 

 ovarium, shown in various instances, 

 379 note; cases of apparent ex- 



