Elementary text-book of zoology, general Elementary text-book of zoology, general part and special part: protozoa to insecta elementarytextbo00clau Year: 1892 199 one or more rings of large cilia round the edge of a raised lid- like flap which is capable of being shut down. There is also an in- ferior row of cilia upon this flap running to the mouth. The free-swamming Infusoria often possess in addition to these delicate cilia and zones of cilia, thicker hairs and stiff' bristles, and more or less bent hooks, which are em- ployed in locomotion and for attachment. Certain fixed Infusoria as
Elementary text-book of zoology, general Elementary text-book of zoology, general part and special part: protozoa to insecta elementarytextbo00clau Year: 1892 199 one or more rings of large cilia round the edge of a raised lid- like flap which is capable of being shut down. There is also an in- ferior row of cilia upon this flap running to the mouth. The free-swamming Infusoria often possess in addition to these delicate cilia and zones of cilia, thicker hairs and stiff' bristles, and more or less bent hooks, which are em- ployed in locomotion and for attachment. Certain fixed Infusoria as Stentor (fig. 138) and Cotlmrnia secrete external coverings or shells, into which they retract themselves. Nourishment is taken in in a few cases by endosmosis through the whole surface of the body, , the parasitic Ojmlina. The Acineta feed themselves by sucking the body of their prey. They are without a mouth, and are incapable of taking in solid food. But they possess a number of long, nai-row, contractile t^entacles, which radiate from the surface of their bodies, and have the form of delicate tubes, presenting a structureless *»xternal wall and a semi-fluid gi-anular axis. The Acineta applies one or more of these organs to the body of an extraneous organism, when the substance of the latter travels down the interior of the granular axis of the tentacle into the body of the Acineta (fig. 139). By far the greatest num- ber of Infusoria possess an oral aperture, usually near the anterior pole of the body, and a second aperture which acts as anus, and which can be seen in a definite part of the body as a slit during the exit of the excreta. The body parenchyma, which is bounded by the external membrane, is divided into a viscid exoplasm and Fig. 13S.—Stentor lirtcUi Ehrbg. (after Stein). O, oral aperture witk Kiillet; PV, pulsating' vacuole; iV, nucleus.
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