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 Cellulosegaehrung_ (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,
&c.," _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, &c.: Marshall Ward, "The Action of Light on Bacteria,"
_Phil. Trans._, 1893, p. 961, and literature. Resistance to Cold, &c.:
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 Immunitaets- und Spezifizetaetslehre
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.)

II. PATHOLOGICAL IMPORTANCE

The action of bacteria as pathogenic agents is in great part merely an
instance of their general action as producers of chemical change, yet
bacteriology as a whole has become so extensive, and has so important a
bearing on subjects widely different from one another, that division of it
has become essential. The science will accordingly be treated in this
section from the pathological standpoint only. It will be considered under
the three following heads, viz. (1) the methods employed in the study; (2)
the modes of action of bacteria and the effects produced by them; and (3)
the facts and theories with regard to