15. Mycoplasma laidlawii (Sabin, 1941) Freundt, 1955. (Types A and B, Laidlaw and Elford, Proc. Roy. Soc. London, B, 120, 1936, 292; Sapromyces laidlawi AB, Sabin, Bact. Rev., 5, 1941, 59; Freundt, Internat. Bull, of Bact. Nomen. and Taxon., 5, 1955, 73; also see Edward, Internat. Bull, of Bact. Nomen. and Taxon., 5, 1955, 91.) laid.law'i.i. M.L. gen. noun laidlawii of Laidlaw; named for P. Laidlaw, one of the bacteriologists who first isolated this spe- cies. Relatively stable mycelioid structure with filaments of moderate length (10 to 30 mi- crons) (0rskov, Zent. f. Bakt., I Abt., Orig., IJtl, 1938, 229; also see Acta Path, et Micro- biol. Scand., 19, 1942, 586; Freundt, un- published observation) . Elementary bodies, but no filaments, have been demonstrated in electron micrographs by Ruska and Poppe (Ztschr. f. Hyg., 127, 1947, 201) and by Kandler and Kandler (Arch. f. Mikro- ho., 21, 1954, 178 and 202). Gram-negative. Serum is not required for growth. Horse-serum agar: Neither film nor spots are produced. Horse-blood agar: Alpha hemolysis. Semi-solid media: Fluffy growth near the surface. Broth: Strong opalescence. Hydrogen sulfide is not produced. Acid from glucose, fructose, maltose, starch, glycogen and dextrin; acid may or may not be produced from galactose. No acid from mannose, lactose, sucrose, xylose, salicin, glycerol, mannitol or dulcitol. Nitrites not produced from nitrates. Ammonia is not produced. Methylene blue is rapidly reduced. Sodium tellurite is slowly reduced. Aerobic; poor growth under anaerobic conditions. Optimum temperature, about 30°C. Growth between 22° and 37°C. Laidlaw and Elford {op. cit., 1936, 292) recognized three serological types by agglu- tination tests: A, B and C. A and C are quite distinct antigenically, and B is more closely related to A than to C. Comments: Various strains, which are similar to the A and B strains of Laidlaw and Elford culturally, phj-siologically, sero- logically and with respect to their habitats, have been described in the literature, viz. Seiffert's Strains (Seiffert, Zent. f. Bakt., I Abt., Orig., 139, 1937, 337; also see ibid., 140, 1937, 168; Klieneberger, Jour. Hyg., 40, 1940, 204; and Kandler and Kandler, Zent. f. Bakt., II Abt., 108, 1955, 383) and S Strains (Edward, Jour. Gen. Microbiol., 4, 1950, 4). The C strains of Laidlaw and Elford are regarded by Sabin {op. cit., 1941, 59) as belonging to a separate species, Sapromyces laidlawi C. The C strain has been lost and has not been compared culturally or physiologically by appropriate methods with the A and B strains for which reason it has not been included in Mycoplasma laidlawii Freundt. Source: Isolated from sewage (Laidlaw and Elford). Seiffert obtained his strains from manure, humus and soil, and Edward secured his as a contaminant of cultures from the genital tract of cattle. Habitat: Apparently frequently found as saprophytes in sewage, manure, humus and soil. ADDENDUM TO CLASS II. SCHIZOMYCETES VON NAEGELI. BACTERIA SITVIBIOTIC OR PARASITIC IN PROTOZOA. In studying various species of Protozoa, protozoologists have occasionally found them to be infected with organisms living either on the surface of the protozoan cells or more fre- quently intracellularly. Many of the intracellular microorganisms cause diseases that may destroy the host organisms. These intracellular parasites of Protozoa are of the size of ordinary bacteria. Some have the morphology of cocci, and these have sometimes been placed in a special genus, Carijo- cocciis Dangeard, near the genus Micrococcus Cohn, while one species has been placed in Micrococcus. In a similar way other species have been placed in Cladothrix Cohn {Sphaero- tilis Ktitzing) or in Myxococcus Thaxter. Some spirally shaped cells have been assigned to a special genus placed near Vibrio and Spirillum. Still others of these bacteria form spores
