It is usually stated that the carbon dioxide molecule is here split by means of energy derived from the oxidation of nitrogen, but apart from the fact that none of these processes can proceed until the temperature rises to the minimum cardinal point, Engelmann's experiment shows that in the purple bacteria rays are used other than those employed by green plants, and especially ultra-red rays not seen in the spectrum, and we may probably conclude that "dark rays" - i.e. rays not appearing in the visible spectrum - are absorbed and employed by these and other colourless bacteria. The purple bacteria have thus two sources of energy, one by the oxidation of sulphur and another by the absorption of "dark rays." Stoney (Scient. Proc. R. Dub. Soc., 1893, p. 154) has suggested yet another source of energy, in the bombardment of these minute masses by the molecules of the environment, the velocity of which is sufficient to drive them well into the organism, and carry energy in of which they can avail themselves.

Fig. 22.  Portions of colony of Bacillus   Proteus.

Fig. 22. - Portions of a colony such as that in fig. 21, highly magnified, showing the kinds of changes brought about in a few minutes, from A to B, and B to C, by the growth and ciliary movements of the filaments. The arrows show the direction of motion. (H. M. W.)

Authorities

General: Fischer, The Structure and Functions of Bacteria (Oxford, 1900, 2nd ed.), German (Jena, 1903); Migula, System der Bakterien (Jena, 1897); and in Engler and Prantl, Die natürlichen Pflanzenfamilien, I. Th. 1 Abt. a; Lafar, Technical Mycology (vol. i. London, 1898); Mace, Traité pratique de bakteriologie (5th ed. 1904). Fossil bacteria: Renault, "Recherches sur les Bactériacées fossiles," Ann. des Sc. Nat., 1896, p. 275. Bacteria in Water: Frankland and Marshall Ward. "Reports on the Bacteriology of Water," Proc. R. Soc., vol. li. p. 183, vol. liii. p. 245, vol. lvi. p. 1; Marshall Ward, "On the Biology of B. ramosus," Proc. R. Soc., vol. lviii. p. 1; and papers on Bacteria of the river Thames in Ann. of Bot. vol. xii. pp. 59 and 287, and vol. xiii. p. 197. Cell-membrane, etc.: Butschli, Weitere Ausfuhrungen über den Bau der Cyanophyceen und Bakterien (Leipzig, 1896); Fischer, Unters. über den Bau der Cyanophyceen und Bakterien (Jena, 1897); Rowland, "Observations upon the Structure of Bacteria," Trans. Jenner Institute, 2nd ser. 1899, p. 143, with literature. Cilia: Fischer, "Unters. über Bakterien," Pringsh. Jahrb. vol. xxvii.; also the works of Migula and Fischer already cited.

Nucleus: Wager in Ann. Bot. vol. ix. p. 659; also Migula and Fischer, l.c.; Vejdovsky, "über den Kern der Bakterien und seine Teilung," Cent. f. Bakt. Abt. II. Bd. xi. (1904) p. 481; ibid. "Cytologisches über die Bakterien der Prager Wasserleitung," Cent. f. Bakt. Abt. II. Bd. xv. (1905); Mencl, "Nachträge zu den Strukturverhältnissen von Bakterium gammari" in Archiv f. Protistenkunde, Bd. viii. (1907), p. 257. Spores, etc.: Marshall Ward, "On the Biology of B. ramosus," Proc. R. Soc., 1895, vol. lviii. p. 1; Sturgis, "A Soil Bacillus of the type of de Bary's B. megatherium," Phil. Trans. vol. cxci. p. 147; Klein, L., Ber. d. deutschen bot. Gesellsch. (1889), Bd. vii.; and Cent. f. Bakt. und Par. (1889), Bd. vi. Classification: Marshall Ward, "On the Characters or Marks employed for classifying the Schizomycetes," Ann. of Bot., 1892, vol. vi.; Lehmann and Neumann, Atlas and Essentials of Bacteriology; also the works of Migula and Fischer already cited. Myxobacteriaceae: Berkeley, Introd. to Cryptogamic Botany (1857), p. 313; Thaxter, "A New Order of Schizomycetes," Bot. Gaz. vol. xvii. (1892), p. 389; and "Further Observations on the Myxobacteriaceae," ibid. vol. xxiii. (1897), p. 395, and "Notes on the Myxobacteriaceae," ibid. vol. xxxvii. (1904), p. 405; Baur, "Myxobakterienstudien," Arch. f.

Protistenkunde, Bd. v. (1904), p. 92; Smith, "Myxobacteria," Jour. of Botany, 1901, p. 69; Quehl, Cent. f. Bakt. xvi. (1896), p. 9. Growth: Marshall Ward, "On the Biology of B. ramosus," Proc. R. Soc. vol. lviii. p. 1 (1895). Fermentation, etc.: Warington, The Chemical Action of some Micro-organisms (London, 1888); Winogradsky, "Recherches sur les organismes de la nitrification," Ann. de l'Inst. Past., 1890, pp. 213, 257, 760, 1891, pp. 92 and 577; "Sur l'assimilation de l'azote gazeux, etc.," Compt. Rend., 12 Feb. 1894; "Zur Microbiologie des Nitrifikationsprozesses," Cent. f. Bakt. Abt. II. Bd. ii. (1896), p. 415; "Ueber Schwefel-Bakterien," Bot. Zeitg., 1887, Nos. 31-37; Beitr. zur Morph. u. Phys. der Bakterien, H. 1 (1888); "Ueber Eisenbakterien," Bot. Zeitg., 1888, p. 261; and Omeliansky, "Ueber den Einfluss der organischen Substanzen auf die Arbeit der nitrifizierenden Organismen," Cent. f. Bakt. Abt. II. Bd. v. (1896); Schorler, "Beitr. zur Kenntniss der Eisenbakterien," Cent. f. Bakt. Abt. II. Bd. xii. (1904), p. 681; Marshall Ward, "On the Tubercular Swellings on the Roots of Vicia Faba," Phil. Trans., 1877, p. 539; Hellriegel and Wilfarth, "Unters. über die Stickstoffnahrung der Gramineen u. Leguminosen," Beit. Zeit. d.

Vereins für die Rübenzuckerindustrie (Berlin, 1888); Nobbe and Hiltner, Landw. Versuchsstationen (1899), Bd. 51, p. 241, and Bd. 52, p. 455; Mazé, Annales de l'Institut Pasteur, t. II, p. 44, and t. 12, p. 1 (1897); Prazmowski, Land. Versuchsstationen, Bd. 37 (1890), p. 161, Bd. 38 (1891), p. 5; Frank, Landw. Jahrb. Bd. 17 (1888), p. 441; Omelianski, "Sur la fermentation de la cellulose," Compt. Rend., 4 Nov. 1895; van Senus, Beitr. zur Kenntn. der Cellulosegährung (Leiden, 1890); van Tieghem, "Sur la fermentation de la cellulose," Bull. de la soc. bot. de Fr. t. xxvi. (1879), p. 28; Beyerinck "Ueber Spirillum desulphuricans, etc.," Cent. f. Bakt. Abt. II. Bd. i. (1895), p. 1; Molisch, Die Pflanze in ihren Beziehungen zum Eisen (Jena, 1892). Pigment Bacteria: Ewart, "On the Evolution of Oxygen from Coloured Bacteria," Linn. Journ., 1897, vol. xxxiii. p. 123; Molisch, Die Purpurbakterien (Jena, 1907). Oxydases and Enzymes: Green, The Soluble Ferments and Fermentation (Cambridge, 1899). Action of Light, etc.: Marshall Ward, "The Action of Light on Bacteria," Phil. Trans., 1893, p. 961, and literature.

Resistance to Cold, etc.: Ravenel, Med. News, 1899, vol. lxxiv.; Macfadyen and Rowland, Proc. R. Soc. vol. lxvi. pp. 180, 339, and 488; Farmer, "Observations on the Effect of Desiccation of Albumin upon its Coagulability," ibid. p. 329. Pathogenic Bacteria: Baumgarten, Pathologische Mykologie (1890); Kolle and Wassermann, Handbuch der pathogenen Mikroorganismen (1902-1904); and numerous special works in medical literature. Immunity: Ehrlich, "On Immunity with Special Reference to Cell-life," Proc. R. Soc. vol. lxvi. p. 424; Calcar, "Die Fortschritte der Immunitäts- und Spezifizetätslehre seit 1870," Progressus Rei Botanicae, Bd. I. Heft 3 (1907). Bacteriosis: Migula, l.c. p. 322, has collected the literature; see also Sorauer, Handbuch der Pflanzenkrankheiten, I. (1905), pp. 18-93, for later literature. Symbiosis: Marshall Ward, "Symbiosis," Ann. of Bot. vol. xiii. p. 549, and literature.

(H. M. W.; V. H. B.)