. The essentials of botany. Botany. 208 PHYLUM VI. RHODOPHYCEAE taining the oogones becoming the fruit after fertihzation. Tetraspores occur in similar cup-shaped structures. 325. Polysiphonia contains plants in which the branch- ing, filamentous plant body is composed of more than one row of cells, usually of a central row surrounded by an outer layer, completely covering it. These shallow- water plants are often of marked beauty both in struc- ture and coloring. The tetraspores are produced in unmodified or slightly swollen branches, and originate within the tissues, but with the increase in
. The essentials of botany. Botany. 208 PHYLUM VI. RHODOPHYCEAE taining the oogones becoming the fruit after fertihzation. Tetraspores occur in similar cup-shaped structures. 325. Polysiphonia contains plants in which the branch- ing, filamentous plant body is composed of more than one row of cells, usually of a central row surrounded by an outer layer, completely covering it. These shallow- water plants are often of marked beauty both in struc- ture and coloring. The tetraspores are produced in unmodified or slightly swollen branches, and originate within the tissues, but with the increase in size of the tetra- sporangia they eventually reach the surface and slip out as large, deeply colored naked cells. The special antheridial branches consist of a central axis with numerous short, crowded, radiating branchlets whose extremi- ties (antherids) abstrict the naked, colorless sperms. The oogone possesses a trichogyne, and is surrounded by a few protective cells. The sperms carried by currents of water come in contact with the trichogyne, and attach themselves to it and form cell walls. The nucleus of one passes into the trichogyne, and unites with that of the oogone. The oogone now fuses (for nutritive pur- poses, as there are no nuclear fusions) with a large nearby cell (the auxiliary cell) into which the zygote nucleus passes, and from which arise the filaments which produce the carpospores. In the meantime the surrounding cells produce an urn-shaped structure (pericarp) with an opening at the top from which the naked carpospores escape at maturity. 326. Irish Moss (Chondrus) is so easily obtained at the apothecaries that it may well be cited as one with a parenchymatous, much branched plant body. The oogones and afterward the spore fruits are immersed in. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original
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