| 释义 |
diatom|ˈdaɪətəm|
[ad. mod.L. Diatoma, f. Gr. διάτοµ-ος cut through, cut in half, f. διατέµνειν to cut through.]
A member of the genus Diatoma, or, in a wider sense, of the Diatomaceæ, an order of microscopic unicellular Algæ, with silicified cell-walls, and the power of locomotion, on which account they were formerly placed by many naturalists in the Animal kingdom. They exist in immense numbers at the bottom of the sea, as well as in fresh water; and their siliceous remains form extensive fossil deposits in many localities.
The genus Diatoma is distinguished by having the frustules, or individual cells, connected by their alternate angles so as to form a kind of zig-zag chain: hence the name.
1845Gray Lett. (1893) 332 Then the low, minute forms and Confervæ come..ending with diatoms, transitions to corallines through sponge, etc. 1853W. Smith British Diatomaceæ 25 During the healthy life of the Diatom the process of self-division is being continually repeated. 1858C. P. Smyth Astron. Exper. Teneriffe 6 The countless millions of diatomes that go to make a feast for the medusæ. 1862Dana Man. Geol. §74 Microscopic siliceous shields of the infusoria called diatoms, which are now regarded as plants. [1865Gosse Land & Sea (1874) 158 The name Diatoma..has reference to the readiness with which the strings or chains in which most of the forms are aggregated may be separated.] 1882Vines Sachs' Bot. 260 The movements of Diatoms are not altogether dissimilar to those of Desmids, and even the silicification of the cell-wall..is found, though to a smaller extent, in Closterium and other Desmids.
attrib.1880Carpenter in 19th Cent. No. 38. 605 Their exquisitely sculptured cases, accumulating on the bottom, form a siliceous ‘Diatom-ooze’, which takes the place in higher latitudes of the white calcareous mud resulting from the distintegration of foraminiferal shells. 1893A. H. S. Landor Hairy Ainu 74 Beds of lignite, coal of inferior quality, and diatom earth. |