. Fresh-water biology. Freshwater biology. BLUE-GREEN ALGAE in Fro. 55. Aphanizomenon Jlos-aquae Ralfs. X 465. (Original.) 50 (49, si) Filaments short, straight, densely aggregated in parallel bundles to form small, feathery, plate-liie masses. Aphanizomenon Morren. Filaments witliout sheath, straight or somewhat taper- ing at the end; united in small, spindle - shaped or plate-like, free-floating bun- dles; spores much elongated, cylindrical, soUtary, not bor- dering on the intercalary heterocyst. A. fios-aquae Ralfs is sometimes found floating in great abundance in the still waters of ponds
. Fresh-water biology. Freshwater biology. BLUE-GREEN ALGAE in Fro. 55. Aphanizomenon Jlos-aquae Ralfs. X 465. (Original.) 50 (49, si) Filaments short, straight, densely aggregated in parallel bundles to form small, feathery, plate-liie masses. Aphanizomenon Morren. Filaments witliout sheath, straight or somewhat taper- ing at the end; united in small, spindle - shaped or plate-like, free-floating bun- dles; spores much elongated, cylindrical, soUtary, not bor- dering on the intercalary heterocyst. A. fios-aquae Ralfs is sometimes found floating in great abundance in the still waters of ponds and lakes. 51 (49, So) Filaments free; cells shorter than their diameter. Nodularia Mertens. Filaments enclosed in a thin, often evanescent sheath; free-floating as single filaments or united into colonies of indefinite form; heterocysts Intercalary, depressed; spores almost spherical, in rows, not bordering on the hetero- cysts. Fig. s5. Nodularia sp. X 465. (Original.) 52 (48) Heterocysts terminal and the spores always contiguous to them. Cylindrospermum Kiitzing. Filaments without sheath relatively short, aggregated to form an expanded film or colony of indefinite shape; vegetative cells cylindrical, longer than the diameter; het- erocyst terminal; spores gen- erally solitary, borne next to the heterocyst. Common on damp earth and stones. 53 (27) Filaments with true or false branches S4 54 (60) Filaments bearing false branches; sheaths firm, of more or less equal thickness; filaments consisting of a single row of cells, with heterocysts (except Plectonema). Family Scytonemaceae . 55 55 (56) 59) Without heterocysts or spores Plectonema Thuret. Filaments consisting only of vegetative cells, without heterocysts; false- ly branched, branches single or in pairs; borne singly in a firm, colorless or yellowish sheath. P. wollei Farl. occurs in some abundance in ponds, attached to stones, etc. Fig. 58. Plectonema wollei Farlow. X 260. (After Kirchner.) 56 (sSi 59) With intercalary h
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
