. The algae. Algae. Fig. 130 Gelidium corneum: a, plant ( x|); b, apex; c, section of thallus; d, carpogonial branch; e, carpospores (ca) and nutritive cells (nu). (a, after Oltmanns; b-e, after Kylin.) primary pericentral cells, with a peripheral zone of small cells with interspersed hyphae. There is no true auxihary cell, but the presence of nutrient cells in the vicinity of the carpogonial branch results in the production of a complex structure composed of several carpo- gonia with small nutrient cells in short branches, and only one of these carpogonia needs to be fertiUzed. After fertihza
. The algae. Algae. Fig. 130 Gelidium corneum: a, plant ( x|); b, apex; c, section of thallus; d, carpogonial branch; e, carpospores (ca) and nutritive cells (nu). (a, after Oltmanns; b-e, after Kylin.) primary pericentral cells, with a peripheral zone of small cells with interspersed hyphae. There is no true auxihary cell, but the presence of nutrient cells in the vicinity of the carpogonial branch results in the production of a complex structure composed of several carpo- gonia with small nutrient cells in short branches, and only one of these carpogonia needs to be fertiUzed. After fertihzation a single gonimoblast filament initially grows out into the mass of nutritive cells, but it later branches so that a number of terminal carpo- sporangia are finally formed. In the Japanese G. amansit, the principal source of agar (cf. p. 448), the tetraspores are shed when the water temperature rises to 20° C. and the carpospores when it rises to 24° C, shedding occurring each afternoon. The spores be- come fixed to the rock surface after being in contact for about ten minutes. The maximum temperature for germination is about 25°- 26° C. The sporelings can grow in brackish water and this markedly affects the length of the primary rhizoids. Growth is slow at first but later becomes very rapid. More than one erect shoot may arise from each basal pad or the lateral buds may grow horizontally giving rise to stolons from which more buds may arise. Cryptonemiales The members of this order are very diverse in habit. A number are unixiial and similar in structure to the Gelidiales, whilst others 235. 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 Chapman, V. J. (Valentine Jackson), 1910-. London, Macmillan; New York, St. Martin's Press
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Keywords: ., bo, bookcentury1900, bookcollectionbiodiversity, booksubjectalgae
