. Fresh-water biology. Freshwater biology. Filaments consisting of vegetative cells and heterocysts; borne singly in a sheath; sheath tough, lamellose, frequently yellowish or brownish in color; false branches borne generally in pairs between the heterocysts. Forming felt-like masses on wet rocks, etc. Fig. 59. Scytonema mirabile Thuret. X 465. (Original.) 58 (57) Branches arising as a rule singly Tolypothrix Kiitzing. Filaments resembling closely those of Scytonema, but false branches arising singly as a rule instead of in pairs, as outgrowths in the region of the heterocysts; the latter 1-5
. Fresh-water biology. Freshwater biology. Filaments consisting of vegetative cells and heterocysts; borne singly in a sheath; sheath tough, lamellose, frequently yellowish or brownish in color; false branches borne generally in pairs between the heterocysts. Forming felt-like masses on wet rocks, etc. Fig. 59. Scytonema mirabile Thuret. X 465. (Original.) 58 (57) Branches arising as a rule singly Tolypothrix Kiitzing. Filaments resembling closely those of Scytonema, but false branches arising singly as a rule instead of in pairs, as outgrowths in the region of the heterocysts; the latter 1-5 in a row; spores (in a few species) elliptical, borne singly or in rows. Occurring among various aquatic plants in ponds and lakes. Fig. 60. Tolypothrix lanata Wart- mann. X 465. (Original.). 59 iSSt 56) With basal heterocysts. each sheath. . Two to several filaments enclosed in Desmonema Berkeley and Thwaites. Filaments sometimes slightly branched; heterocysts always basal. On stones, in brooks, and waterfalls. Fig. 61. Desmonema wrangelii Borzi. X 200. (After Borzi.) 60 (54) Filaments usually stout, bearing true branches; cells rounded, dis- posed generally in more than one row; heterocysts present. Family Stigonemaceae . 61 5i (62,63) Sheaths thick; firm SHgonema Agardh. Filaments free-floating or aggregated on the substratum to form lelt-like masses; filaments composed partly of two to several cell-rows, sometimes of a single row, enclosed in a thick, lamellose, yellow- ish or brownish sheath, which is often of irregular thickness. Hormogonia formed at the ends of the vegetative branches or in special short branches. Heterocysts commonly lateral, or less often intercalary. Vegetative cells rounded, frequently showing protoplasmic continuity. Growing generally on damp ot. 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 o
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
