Horse-blood agar: Slight hemolysis. Rabbit-serum agar: Poor growth. Semi-solid media: Growth throughout the medium is neither definitely smooth nor definitely granular. Carbohydrates not attacked. Methylene blue is slowly reduced. Aerobic, facultatively anaerobic. Serologicall}^ distinct from the other mem- bers of this genus. Pathogenicity: Unknown. Comments: Shoetensack (Kitasato Arch. Exp. Med., 11, 1934, 277; also see ibid., 13, 1936, 175 and 269) isolated organisms of this genus from the tissues and nasal secretions of dogs suffering from distemper and re- garded these organisms as comprising two distinct types, differing from each other in their cultural characteristics: Asterococcus canis, type I, Shoetensack (Shoetensack, op. cit., 1936, 175; Canomyces 'pulmonis I, Sabin, Bact. Rev., 5, 1941, 57; Canomyces canis I, Sabin, ibid., 334) and Asterococcus canis, type II, Shoetensack (Shoetensack, op. cit., 1936, 175; Canomyces pulmonis II, Sabin, op. cit., 1941, 57; Canomyces canis II, Sabin, ibid., 334). Klieneberger (Jour. Hyg., 38, 1938, 458), furthermore, noted that type I differed serologically from type II. Type I apparently produced distemper in dogs on subcutaneous inoculation and was regarded by Shoetensack as the etiological agent of the disease; this organism is not now re- garded as the cause of canine distemper. Shoetensack's organisms were lost and can- not, with certainty, be identified wuth any of the recently established species from dogs. Source: Isolated from the vaginae and throats of dogs. 7. Mycoplasma hyorhinis Switzer, 1955. (Filterable agent of infectious, atrophic rhinitis of swine, Switzer, Jour. Amer. Vet. Med. Assoc, 123, 1953, 45; also see Vet. Med., 48, 1953, 392; Amer. Jour. Vet. Res., 16, 1955, 540.) hy.o.rhi'nis. Gr. noun hys, hyos a swine; Gr. noun rhis, rhinis nose; M.L. gen. noun hyorhinis of a hog's nose. Elementary bodies appear as minute, coccoid rods 0.3 to 0.6 micron in size. Stain distinctly blue with Machiavello's stain. Gram-negative. Serum agar colonies: 0.01 to 0.1 mm in diameter, smooth, glistening, entire; some of the colonies have a small central eleva- tion; the central portions become granular as the colonies age. Carbohydrates not attacked. Withstands 56°C. for 30 but not for 60 minutes. Remains viable for 2 to 3 weeks at 4°C. and for more than 10 months at -40°C. Pathogenicity: Produces an irregular mortality pattern when inoculated into chicken embryos. Heart and liver lesions are produced in the embryos, the outstand- ing lesion being a severe pericarditis which is usually present in those dead after the seventh day postinoculation. When inocu- lated intraperitoneally into pigs 6 weeks or less of age, the organism produces severe fibrinous pericarditis, moderate fibrinous pleuritis and mild peritonitis; from 5 to 20 per cent of the inoculated pigs usually de- velop arthritis. Similar lesions produced by this organism occur in swine under field conditions. Not pathogenic for mice or guinea pigs when inoculated intraperi- toneally or for mice on intranasal instilla- tion. Inoculation into the trachea, nasal cavity, infraorbital sinus or conjunctival sac of 10-day-old chickens fails to produce any symptoms. Comment: Further studies are needed in order to determine the cultural and physio- logical characteristics of this species. Source: Isolated from the nasal cavity of swine with infectious atrophic rhinitis; also found in apparently healthy pigs. Pleuropneumonia-like organisms were also isolated by Carter and McKay (Canad. Jour. Comp. Med., 17, 1953, 413) and by Carter (Canad. Jour. Comp. Med., 18, 1954, 246) from the nasal cavities of swine wuth atrophic rhinitis and from the tissues of pigs suffering from an infectious condition (Glas- ser's disease) similar to that reported by Switzer; young pigs inoculated intraperi- toneally with secondarj^ cultures developed typical lesions. Habitat: Found in the nasal cavity of swine. The etiological agent of a generalized
