. A manual of botany. Botany. 136 MANUAL OP BOTANY no differentiation into members. It is known as the pro- thallium, and is usually a green flattened expansion of small size. Its cells contain chloroplastids. From the under side a number of root hairs are developed which attach it to the soil. Sometimes the prothallium has a central somewhat thickened portion known as the cusldon. Sometimes it is almost fila- mentous, recalling the protonema of a moss. It always becomes quite free from the spore. On the under side of the prothalliimi the sexual organs are developed, the antheridia lying to th
. A manual of botany. Botany. 136 MANUAL OP BOTANY no differentiation into members. It is known as the pro- thallium, and is usually a green flattened expansion of small size. Its cells contain chloroplastids. From the under side a number of root hairs are developed which attach it to the soil. Sometimes the prothallium has a central somewhat thickened portion known as the cusldon. Sometimes it is almost fila- mentous, recalling the protonema of a moss. It always becomes quite free from the spore. On the under side of the prothalliimi the sexual organs are developed, the antheridia lying to the basal end and the Fig. Fig. 894. Protballus (gametophyte) of Fern. After Kny. archegonia, which are formed later, towards the anterior or apical region. In a few cases a prothallium develops only one or other of the sexual organs, but generally both are to be found in the relative positions described. When the spore germinates, the outer coat ruptures and the inner one grows out into a green filament consisting of a single row of cells [fig. 895,1-4). The end cell of the row soon divides longitudinally, and the plate-like prothallium becomes recog- nisable. The growth is soon continued by the formation of an apical cell (fig. 895, 5), which after a while is found to lie in a sort of notch or depression in the anterior 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 Green, J. Reynolds (Joseph Reynolds), 1848-1914. London, J. & A. Churchill
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbotany, bookyear1895
