. A manual of botany. Botany. THALLOPHYTA—ALG^ 49 form a true tissue, but are bound together by a kind of inter- cellular substance, or are surrounded by a common gelatinous coating. Each row of cells grows by division of the terminal one, which is sometimes much larger than the others. There is no intercalary growth of the filament by division of any of the other cells, though lateral branches may arise from them. The successive cells of the row or rows constituting the thallus communicate with each other by a kind of rudimentary sieve- plate [fig. 798), though they can hardly be described as
. A manual of botany. Botany. THALLOPHYTA—ALG^ 49 form a true tissue, but are bound together by a kind of inter- cellular substance, or are surrounded by a common gelatinous coating. Each row of cells grows by division of the terminal one, which is sometimes much larger than the others. There is no intercalary growth of the filament by division of any of the other cells, though lateral branches may arise from them. The successive cells of the row or rows constituting the thallus communicate with each other by a kind of rudimentary sieve- plate [fig. 798), though they can hardly be described as sieve- tubes. Fig. Fitj. 798. Semi-diagrammatic longitudiual section of an old and stout portion of Ceramium rubrum, showing continuity between the protoplasmic contents of the axial or central cells, a, a, at their ends ; and laterally with the cortical cells, &, by protoplasmic threads, and also that of the cortical cells iiil^r ne by threads radiating from the central mass in each cell. After T. Hick. Fig. 799. Procarp of one of the Bed Seaweeds, tr. Trichogyne. sp. Spermatia. The branch to the left bears a cluster of autheridia. After Kny. The flattened forms usually grow at their margins, new cells arising from divisions in certain cells in definite positions there. The characteristic colouring matter is red, and is found in chromatophores in the cells. As in the last group, chloro- phyll is present in addition to the phycoerythrine. The group is characterised by great peculiarity in its methods of reproduction, which are both sexual and asexiial. The gametophyte bears sexual organs and gonidia, the latter. 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
