326 SEED OR MATURE OVULE. 



ovule also is transformed, and, when fully developed, constitutes the 

 seed. After fertilisation, the foramen of the ovule contracts, the 

 young plant gradually increases in its interior, by the absorption of 

 the fluid matter contained in the sac of the amnios (embryo-sac), 

 solid nutritive matter is deposited, and a greater or less degree of 

 hardness is acquired. The seed then is the fecundated mature ovule 

 containing the embryo, with certain nutritive and protective append- 

 ages. When ripe, the seed contains usually a quantity of starchy 

 and ligneous matter, azotised compounds, as caseine and vegetable 

 albumen, oily and saline matters. It sometimes acquires a stony 

 hardness, as in the case of the seed of Phytelephas macrocarpa, which 

 yields vegetable ivory. Oare'must be taken not to confound seeds 

 with single-seeded pericarps, such as the Achsenium and Caryopsis, in 

 which a style and stigma are present ; nor with bulbils or bulblets, 

 as in Lilium bulbiferum and Dentaria bulbifera, which are germs or 

 separable buds developed without fecundation. 



Seeds are usually enclosed in a seed-vessel or pericarp, and hence 

 the great mass of flowering plants are called angiospermous (ayyoz, or 

 ayyitov, a vessel, and dncigiho,, a seed). In Ooniferae and Oycadacese, 

 however, the seeds are generally looked upon as having 

 no true pericarpial covering, and fertilisation therefore 

 takes place by the direct application of the poUen to the 

 seed, without the intervention of stigma or style. Hence 

 the seeds, although sometimes protected by scales, are 

 truly naked, and the plants are called gymnospermous 

 Hg. 676. (yu/ii/oj, naked, and g<?rig/ia, a seed). Occasionally, by 

 the early rupture of the pericarp, seeds originally covered become 

 exposed. This is seen in Leontiee and Cuphea. In Mignonette, the 

 seed-vessel (fig. 575) opens early, so as to expose the seeds, which 

 are called seminude. 



Besides being contained in a pericarp, the seed has its own 

 peculiar coverings. Like the ovule, it consists of a nucleus or kernel, 

 and integuments. In some instances, although rarely, all the parts of 

 the ovule are visible in the seed — viz., the embryo-sac or quintine, 

 the quartine, the tercine or covering of the nucleus, the secundine, 

 and the primine. In fig. 576 there is a representation of the seed of 

 Nymphsea alba, in which se indicates the embryo-sac, containing the 

 embryo, e; n, the cellular farinaceous covering (quartine), formed 

 round the embryo-sac ; mt, membrane formed round the nucleus 

 (tercine) ; mi, the secundine ; t, the primine. In general, however, 

 great changes take place by the development of the embryo ; the 

 embryo-sac is often absorbed, or becomes incorporated with the 

 cellular tissue of the nucleus ; the same thing occasionally takes place 



s ; Kg. 675. Fruit or capaule of Mignonette (SeseiZa odarata), opening early, so that the 

 ovules become seminude. 



