. The algae. Algae. EUPHYCOPHYTA 203 becomes club-shaped. The lowest cell at the narrow end elongates to form the first rhizoid whilst the cell at the other end divides twice by two longitudinal walls at right angles to give a quadrant. Further divisions result in the development of a central group of cells, the primary medulla, with the cortex outside. Additional rhizoids are produced and the apex of the embryo becomes flat- tened and one cell produces a hair with a basal intercalary meristem. Excessive growth of neighbouring cells results in the formation of a terminal depression and additio
. The algae. Algae. EUPHYCOPHYTA 203 becomes club-shaped. The lowest cell at the narrow end elongates to form the first rhizoid whilst the cell at the other end divides twice by two longitudinal walls at right angles to give a quadrant. Further divisions result in the development of a central group of cells, the primary medulla, with the cortex outside. Additional rhizoids are produced and the apex of the embryo becomes flat- tened and one cell produces a hair with a basal intercalary meristem. Excessive growth of neighbouring cells results in the formation of a terminal depression and additional hairs are produced. Next all the cells of the first hair, except the basal one, disappear and the basal cell becomes the three-sided apical cell. In those Fucales, Fucus, where the adult condition of the apical cell is four-sided, this change in the apical cell takes place quite early, the new four- sided cell being cut off from the original three-sided one. The pecuhar salt marsh fucoids (see p. 349) are interesting in that the juvenile three-sided apical cell persists throughout life. Yvcaceae: Pelvetia (after the French botanist. Dr. Pelvet). Fig. 114 The fronds in this genus have no mid-rib and are linear, com- pressed or cyHndrical with irregular dichotomous branching. Air. ^ S Fig. 114 Pelvetia canaliculata. A, plant ( x f). B, megasporangium (x6o). C, mature fertilized sporangitim ( x 72). ne= rejected nuclei. D, germinating oospores ( x 72). E, microsporangia ( x 156). (Aj original; B-E, after Scott.). 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
