| 释义 |
‖ gemma|ˈdʒɛmə|
Pl. gemmæ.
[L.: see gem.]
†1. (See quot.) Obs.—1
1691Ray Creation ii. (1701) 305 The Gemma or cicatricula of the egg contained in the Female ovary.
2. Bot.
a. A leaf-bud as distinguished from a flower-bud.
1770C. Milne Bot. Dict. s.v. Gemma, Mr. Ray was the first who gave the name of Gemma to the bud, which had formerly been denominated germen. 1826Kirby & Sp. Entomol. (1828) III. xxix. 60 A state analogous to that of the larva in the insect begins in the plant when it..is evolved from the gemma. 1872Carpenter Anim. Phys. xv. 552 The bodies of the first class are known as leaf-buds or gemmæ in the Flowering Plants. 1880Gray Struct. Bot. 413/1.
b. In mosses, liverworts, etc.: A small cellular body which becomes detached from the mother-plant and originates a new one.
1830Lindley Nat. Syst. Bot. 325 In Jungermannia there is a third kind of reproductive matter, consisting of heaped clusters of little amorphous bodies, growing from the surface of the leaves, and called gemmæ. 1857Henfrey Bot. §324 The Hepaticae produce cellular bulbels or gemmae. 1867J. Hogg Microsc. ii. i. 308 These plants are produced by spores and minute cellular nodules called gemmae or buds.
3. Zool. A bud-like growth upon animals of low organization, which becomes detached and develops into a new individual.
1841–71T. R. Jones Anim. Kingd. (ed. 4) 123 The Alcyons..are reproduced..by gemmæ, which are developed around the preexistent polyps. 1851Richardson Geol. viii. 213 Small gemmæ, covered with cilia, which are free organisms during the first period of their existence. |