The encyclopdia britannica; a dictionary of arts, sciences, literature and general information . central regionextending between the apo-physis and the operculum iscomposed of sterile tissue andforms the columella (c). Im-mediately around this is the young sporogonium enclosedin the calyptra (c). B, Similar plant with an almost mature sporogonium; i,seta;/, capsule; c, calyptra. C, Median longitudinal section of a capsule, with the setagradually widening into theapophysis at its base; d,operculum; p, peristome;o, annulus; c, columella;s, archesporium; h, air-space between the spore-sacand the
The encyclopdia britannica; a dictionary of arts, sciences, literature and general information . central regionextending between the apo-physis and the operculum iscomposed of sterile tissue andforms the columella (c). Im-mediately around this is the young sporogonium enclosedin the calyptra (c). B, Similar plant with an almost mature sporogonium; i,seta;/, capsule; c, calyptra. C, Median longitudinal section of a capsule, with the setagradually widening into theapophysis at its base; d,operculum; p, peristome;o, annulus; c, columella;s, archesporium; h, air-space between the spore-sacand the wall of the capsule. layer of cells from which thespores wiU be developed {s), and the layers of cells on eitherside of this form the walls of the spore-sac, which will containthe spores. Between the wall of the capsule, which is composedof several layers of cells, and the spore-sac is a wide intercellularspace (Jt) bridged across by trabeculae consisting of rows ofchlorophyll-containing cells. At the junction of the operculum{d) with the rest of the capsule is a circle of cells forming the. Fig. 12.—Funaria hygrometrica. (After Goebel.)A, Germinating spores. (X550.) filament with brown walls from which the filaments ofchlorophyll-containing cells(6) arise; fe, young moss-plant ; TO, its first rhizoid. s, Wall of spore; v, vacuole;TO, , Part of a developed proto-nema. (X90.) ^, Creeping annulus (a), by help of which the operculum is detached atmaturity as a small lid. Its removal does not, however, leavethe mouth of the capsule wide open, for around the margin aretwo circles of pointed teeth forming the peristome. These arethe thickened cell-walls of a definite layer of cells (/>), and appear 7o6 BRYOPHYTA as separate teeth owing to the breaking down of the unthickenedcell-walls. The numerous spores which have been developed inthe spore sac can thus only escape from the pendulous capsulethrough narrow slits between the teeth, and these are closed indamp air. The u
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectencyclo, bookyear1910
