. The algae. Algae. EUPHYCOPHYTA 47 CoELASTRACEAE: Scenedesmus {scene, rope; desmus, fetter). Fig. 21 The planktonic colonies are composed of four, eight, or more rarely, sixteen cells attached to each other at one point by mucilage pads. This type of colony has probably originated from that in which cells are attached at one point indiscriminately, as in An- kistrodesmus. The two end cells of the chain may differ in shape from the others and often have processes which are elaborations of the. Fig. 21 Scenedesmus. A, 5". acuminatus. B, 5. acuminatus with mucilage bristles, C, 5. quadricau
. The algae. Algae. EUPHYCOPHYTA 47 CoELASTRACEAE: Scenedesmus {scene, rope; desmus, fetter). Fig. 21 The planktonic colonies are composed of four, eight, or more rarely, sixteen cells attached to each other at one point by mucilage pads. This type of colony has probably originated from that in which cells are attached at one point indiscriminately, as in An- kistrodesmus. The two end cells of the chain may differ in shape from the others and often have processes which are elaborations of the. Fig. 21 Scenedesmus. A, 5". acuminatus. B, 5. acuminatus with mucilage bristles, C, 5. quadricauda. D, 5". quadricauda reproduc- ing. E-I, stages in the formation of daughter coenobia in S. quadricauda. (After Fritsch.) mucilaginous cell envelope: these processes are probably to be correlated with the planktonic mode of life, whilst tufts of bristles performing the same function and similar to those of Pediastrum are also recorded. Protosiphonaceae: Protosiphon (proto, first; siphon, tube). This family has in the past been placed in the Siphonales (see p. 96) but in respect of that order it possesses several anomalous features, method of reproduction, haploid condition, type of environment, plastid, pigments, etc. and it has now been trans- ferred to the Chlorococcales. There is probably but a single species, P. botryoides, but it exists in a number of different strains, one from the deserts of Egypt tolerating temperatures up to 91° C and salt concentrations up to I per cent. It commonly grows associated with a very similar 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
