. Fresh-water biology. Freshwater biology. no FRESH-WATER BIOLOGY 43 (28) Filaments simple, unbranched; with heterocysts; living singly or in gelatinous masses, often of definite form. Sheaths very delicate, mostly confluent. Cells generally torulose, in a single row . Fanuly Nostoceae . 44 44 (47) Filaments enclosed within a gelatinous mass of definite form. 45 45 (46) Forming delicate, hollow, cylindrical colonies. Wollea Bornet and Flahault. Delicate colonies; filaments straight or slightly bent, arranged in tolerably parallel rows, with a common gelatinous envelope; heterocysts intercalary
. Fresh-water biology. Freshwater biology. no FRESH-WATER BIOLOGY 43 (28) Filaments simple, unbranched; with heterocysts; living singly or in gelatinous masses, often of definite form. Sheaths very delicate, mostly confluent. Cells generally torulose, in a single row . Fanuly Nostoceae . 44 44 (47) Filaments enclosed within a gelatinous mass of definite form. 45 45 (46) Forming delicate, hollow, cylindrical colonies. Wollea Bornet and Flahault. Delicate colonies; filaments straight or slightly bent, arranged in tolerably parallel rows, with a common gelatinous envelope; heterocysts intercalary; spores in chains, bordering on one or both sides of the heterocysts. W. saccala Bor. and Flah. occurs in stagnant water. Fig. 52. Wollea saccata Bornet and Flahault. a, X 250: b, natural size. (After WoUe.) 46 (45) Colonies spherical, or of varied form; with the enclosed filament irregularly interwoven and contorted. , , Nostoc Forming leathery or slimy gelatinous masses, at first spher- ical or oblong, later of varied form, solid or hollow, and attached or unattached; filaments contorted and curved in all directions; the gelatinous sheath sometimes sharply delimited, more often fused with the enveloping jelly. Cells globular, barrel-shaped, or cyUndrical; heterocysts intercalary, or (when yoimg) sometimes terminal; spores globular or oblong, formed in rows in varying number be- tween the heterocysts. Forming free-floating or attached masses, on damp ground, wet rocks, etc. Fig. 53- Nostoc commune Vaucher. (Original.) <i, natural size; b, X 465. 47 (44) Filaments more or less straight, free-floating or forming a thin mucous stratum 48 48 (52) Heterocysts and spores intercalary 4g 49 (5°! 51) Filaments naked, or with a thin sheath; single, or aggregated into formless, flocculent masses; cells equal to or longer than their diameter Anabaena Bory. Filaments straight or drcinate, naked or enclosed in a thin sheath, free floating as single filaments or united to form
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
