| 释义 |
aster|ˈɑːstə(r), æ-|
[a. L. aster, a. Gr. ἀστήρ star.]
†1. A star. Obs. as Eng.
1603Florio Montaigne i. xxi. (1632) 47 The revolutions..and carrols of the asters and planets. 1706[see 2].
2. Bot. A large genus of the family Compositæ, with showy radiated flowers, of which the N. American species are especially numerous. The only indigenous British species is the Sea Starwort or Michaelmas Daisy (A. Tripolium).
1706Phillips, Aster, a Star; also the Herb Star-wort, Spare-wort, or Cod-wort. a1761Mrs. Delany Autobiog. (1861) III. 507 A little pale purple Aster with a yellow thrum. 1864Bryant Autumn Walk iii, And the purple aster waves In a breeze from the land of battles.
3. China aster: a flower (Callistephus chinensis) allied to and resembling the asters proper.
1794Martyn Rousseau's Bot. xxvi. 392 Chinese Aster is an annual plant, with ovate angular leaves. 1859Jephson Brittany xvi. 268 A fine show of China asters in full bloom.
4. Cytology.
a. A star-shaped achromatinic structure surrounding the centrosome of a cell during mitosis.
b. The star-shaped grouping of the chromosomes during mitosis.
1879E. Klein in Q. Jrnl. Microscop. Soc. XIX. 414 We pass..to large nuclei..in which the deeply-stained fibrils are arranged like a single aster (‘Monaster’), apparently terminating freely at the periphery, but connected into a central network... Next, we trace these [fibrils] into a nuclei without a membrane in which the fibrils are similar in appearance to the preceding ones, but arranged as a double aster (‘Dyaster’). 1888Rolleston & Jackson Anim. Life p. xxv, A star or aster with a pronucleus as a centre. 1909J. W. Jenkinson Exper. Embryol. 107 Each sperm forms its own aster, and these combine with one another to form various irregular mitotic figures (triasters, tetrasters, and so on). 1920L. Doncaster Introd. Study Cytology iii. 31 The centrosome with its system of rays is called an aster, and the two asters with the sheaf of fibres connecting them are the achromatic or mitotic spindle. 1963New Scientist 7 Feb. 305 When an egg is fertilised, two structures called asters appear in the cell and a spindle forms between them. |