duck;L. fem.n. pestis plague; L. v. fero to carry; L. adj. pestifer pestilence-carrying; M.L. adj. anatipestifer duck-plague-carry- ing. Description prepared by Prof. D. W. Bruner, New York State Veterinary College, Cornell University, Ithaca, New York. Short rods, 0.3 to 0.5 by 1.0 to 2.5 microns, occurring singly, in pairs and in short chains. Non-motile. Gram-negative. Gelatin stab: Liquefaction. Blood agar colonies: Small, circular, transparent, entire. No hemolysis. Plain broth (horse meat) : Slight, uniform turbidity that becomes more dense at 48 hours of incubation at 37° C. After several days a bluish ring forms at the surface where contact is made with the test tube. No pel- licle is formed. The organism remains viable in this medium for about two weeks. Loffler's blood serum: Liquefaction. Coagulated egg medium (Dorset) : Lique- faction. Huddleson's thionin medium: Growth. Huddleson's basic fuchsin medium: Growth. Glycerol phosphate agar: Xo growth. Bile (10 per cent) in serum agar: Growth. Bile (40 per cent) in serum agar: No growth. Litmus milk: No visible change. Indole not produced. Hydrogen sulfide produced in slight amounts. Potato: No growth. Sodium thioglycollate medium: Growth in a ring about 1 cm below the surface. No acid from glucose or other carbohy- drates. Nitrites not produced from nitrates. May require CO2 for isolation, but be- comes aerobic after several transfers. Optimum temperature, 37° C. Not pathogenic for laboratory animals; however, with ducks it may produce death following intravenous infection of a freshly isolated culture. Not established as the causative agent in so-called new duck dis- ease. Source: Isolated from cases of septicemia in ducklings on Long Island, New York, 1932. Reisolated from Long Island ducklings by Bruner and Fabricant (Cornell Veteri- narian, U, 1954, 461). Habitat: Associated with a disease of ducklings. 5. Pasteurella pestis (Lehmann and Neumann, 1896) Holland, 1920. (Bacille de la peste, Yersin, Ann. Inst. Past., 8, 1894, 666; Pest Bacillus, Aoyama, Ztschr. f. Hyg., 21, 1895, 165; Bacterium pestis Lehmann and Neumann, Bakt. Diag., 1 Aufl., 2, 1896, 194; Holland, Jour. Bact., 5, 1920, 219.) pes'tis. L. noun pestis plague, pestilence. Rods, 1.0 by 2.0 microns, occurring singly. Characteristic bladder, safety-pin and ring involution forms. Non-motile. Polar stain- ing. Gram-negative. Gelatin colonies : Flat, gray, with granular margin. Gelatin stab: Flat surface growth. Ar- borescent growth in stab. No liquefaction. Agar colonies: Grayish white, translu- cent, iridescent, undulate. Agar slant: Growth grayish, viscid, thin, moist, translucent. Growth slow, favored by the addition of blood or sodium sulfite. Broth: Turbid or clear with flocculi in the fluid. Old cultures show a pellicle with streamers into the fluid (stalactites). Be- comes alkaline more slowly than Pasteurella pseudotuberculosis. See Bessonowa and Lenskaja (Cent. f. Bakt., I Abt., Orig., 119, 1930, 430). Litmus milk: Slightly acid or unchanged. No coagulation. Potato: Scant, grayish growth. Indole not produced. Lactose and rhamnose not attacked. Variable action on glycerol. Nitrites produced from nitrates. Temperature relations: Optimum, be- tween 25° and 30° C. Minimum, 0° C. Maxi- mum, between 43° and 45° C. Aerobic, facultatively anaerobic. Comments: Pasteurella pestis and P. pseudotuberculosis are not definitely dis- tinguishable b.y serological methods (Schiitze, Med. Res. Council, Syst. of Bact., London, 4, 1929, 478, and Wu Lien-teh, in Chun, PoUitzer and Wu, "Plague", National Quarantine Service, Shanghai, 1936). How- ever Thai and Chen (Jour. Bact., 69, 1955,
