DescriptionImage from page 99 of "Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ" (1916).jpg |
Identifier: algvolimyxophy00west
Title: Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ
Year: 1916 (1910s)
Authors: West, G. S. (George Stephen), 1876-1919
Subjects: Algae
Publisher: Cambridge [Eng.] The University press
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library
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evalves, connecting bands, and intercalary bands fit against one another bybevelled and generally curved edges (consult fig. 58 A—C), but the con-nection is in some cases much looser than in others. Some diatoms possess longitudinal septa, which are invariably ingrowthsfrom the intercalary bands. Such septa are always more or less considerably 86 Bacillarieae perforated and approximately parallel to the valve-faces. The number oflongitudinal septa depends upon the number of intercalary bands. InMastogloia each cell has two longitudinal septa, in Tabellaria there arefrom two to twelve or more, and in Tetracyclus and Rhabdonema theremay be as many as twenty. These septa are generally plane, although theymay be undulated, as in Grammatophora. Karsten has distinguished thoseintercalary bands which possess longitudinal septa as intercalary valves(fig. 58 C and D). The perforations are large but variable. Sometimesone large window-like foramen is situated in the median part of the septum,
Text Appearing After Image:
Fig. 59. A and B, Tetracyclus lacustris Kalfs ; B is a longitudinal section of cell showing oneof the partial septa. C, longitudinal section of cell of Licmophora Lyngbyei (Kiitz.) Grun,showing partial septum. I) and E, Tabellaria fenestrata (Lyngb.) Kiitz.; Eis a longitudinalsection of cell showing the extent of the septa. F, Climacosphenia moniligera Ehreiib.,section of upper portion of cell to show the perforated septum, s, septum. C and F areafter 0. Miiller. and at other times the septum is only partial, the foramen occupying mostof the median part and the whole of one end (fig. 59-4—E). In Clima-cosphenia each septum has a series of numerous perforations (fig. 59 F).In Denticula the partial longitudinal septa are fused with numerous im-perfect transverse septa which pass inwards from the valves. Thus the interior of the diatom-cell may become chambered in variousways, and as will be noted subsequently these chambers very largelyaccommodate lobes of the chromatophores. SYMMETRY
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