. The microscope and its revelations. stomates, but that the structure of these organs is far lesscomplex in them than in this humble liverwort. The frond of Marchantia usually bears upon its surface, as shownin fig. 503, a number of little open basket-shaped yemmiparous antceptacles (fig. 505), which may often be found in all stages of develop-ment, and are structures of singular beauty. They contain whenmature a number of little green round or oblong discoidal (/emmce,each composed of two or more layers of cells ; and their wall is sur-mounted by a glistening fringe of • teeth. whose edges a
. The microscope and its revelations. stomates, but that the structure of these organs is far lesscomplex in them than in this humble liverwort. The frond of Marchantia usually bears upon its surface, as shownin fig. 503, a number of little open basket-shaped yemmiparous antceptacles (fig. 505), which may often be found in all stages of develop-ment, and are structures of singular beauty. They contain whenmature a number of little green round or oblong discoidal (/emmce,each composed of two or more layers of cells ; and their wall is sur-mounted by a glistening fringe of • teeth. whose edges are themselvesregularly fringed with minute outgrowths. This fringe is at firstformed by the splitting up of the epiderm. as seen at I!, at thetime when the conceptaele and its contents are first making theirwav above the surface. The little genuine are at first evolved assingle globular cells, supported upon other cells which formfootstalks; these sinyle cells, undergoing binary subdivision. theirevolve STRUCTURE OF 3IAKCHANTIA 667. themselves into the gemma? ; and these gemma, when mature,spontaneously detach themselves from their footstalks, and lie freewithin the cavity of the commonly they are at lastwashed out by rain, and are thuscarried to different parts of theneighbouring soil, on which theygrow very rapidly when well sup-plied with moisture; sometimes,however, they may be found --row-ing whilst still contained withinthe conceptacles. forming naturalgrafts (so to speak) upon the stockfrom which they have been de-veloped or detached : and many ofthe irregular lobes which the frondof Marchantin puts forth seemto have this origin. The verycurious observation was long agomade by Mirbel, who c-irefullywatched the development of ;liiiiin<t\ that stomates are formedon the side which happens to beexposed to the light, and thatrhi/oids are put forth from thelower side, it being apparently amatter of indifference which side ofthe little gemma is at
Size: 1751px × 1427px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
