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TII

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Originally appearing in Volume V10, Page 633 of the 1911 Encyclopedia Britannica.
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TII . See also:

AST RORHIZIDIACEAE.—See also:Simple forms, rarely polythalamous (some Rhabdamminidae), but often branching or radiate; test arenaceous, loosely compacted and traversed by chinks for pseudopodia (Astrorhizidae), or dense, and opening by one or more terminal pylomes at ends of branches. Marine, Fam. The test of some Asirorhizidae is so loose that it falls to pieces when taken out of See also:water. Haliphysenia is remarkable for its See also:history in relation to the " gastraea theory." Pilulina has a neat globular See also:shell of spongespicules and ' See also:fine See also:sand. Genera, Astrorhiza (Sandahl) in every See also:case gives off granules and irregular masses. -(" chromidia ") of similar reactions, which See also:play an important See also:part in See also:reproduction. During the maturation of the microsphere the nuelei.disappear; and the cytoplasm breaks up into, a large number of zoospores, each of which is soon provided with a single inns leua, whether. entirely derived from the See also:parent-See also:nucleus or front the coalescence 6fehromidia, or from both these See also:sources is still uncertain... These zoospores are amoeboid ; they soon secrete a shell and reveal themselves as megalospheres, the See also:original See also:state of the megalospheric forms. In the adult megalosphere the solitary nucleus disappears and is re-placed by hosts of See also:minute vesicular nuclei, formed by the.concentration of chromidia. Each nucleus aggregates around it a proper See also:zone of dense See also:protoplasm; by two successive mitotic divisions each See also:mass becomes quadri-nucleate, and splits up into four biflagellate, uninucleate zoospores. These are pairing-cells of gametes, though they will not pair with members of the same brood.

In the zygote resulting from pairing two nuclei soon fuse into one; but this again divides into two; an embryonic shell is secreted, and this Is the microspheric type, which is multinuclear from the first. F. Schaudinn compares the nuclei of the adult See also:

Foraminifera with the (vegetative) See also:meganucleus of Infusora (q.v.) and the chromidial mass with the See also:micronucleus, whose See also:chief See also:function is reproductive. Since megalospheric forms are by far the most abundant, it seems probable that under most conditions they also give rise to megalospheric See also:young like themselves; and that the See also:production of zoospores, (fig. 22), Pilulina (Carptr.) (fig. 19), Saccammin4 (Sars) (fig. 19), Rhabdammina (Sars), Botellina (Carptr.), Hallphysema (See also:Bowerbank) (fig. 22). IV. LITUOLIDACEAE.—Shell arenaceous, usually fine-grained, definite and often polythalamic, recalling in structure calcareous forms. Lituola (Lamk.) (fig. 19), Endothyra (Phil.), Ammodiscus (See also:Reuss), Loftusia (See also:Brady), Hapl iphragmium (Reuss) (5g.

22), Thurammina (Brady) (fig. 22). V. MILIoLIDACEAB.—Shells porcellanous imperforate, almost invariably with a camptostyle leading from the embryonic (fig. 23, 3). IX. GLOBIGERINIDACEAE.—Shells vitreous, coarser perforated; See also:

chambers few spheroidal rapidly increasing in See also:size; arranged in a trochoid or nautiloid See also:spiral. See also:Globigerina (I,amk.) (23, 6; 4, 12); Hastigerina (Wyville See also:Thompson) (fig. 23, a); Orbulina (d'See also:Orb,) (fig. 23, 8).

End of Article: TII

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TIIE SKULL FROM THE SIDE (norma lateralis)

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