phus serum is of very great importance. These are the so-called X-strains from ty- phus patients found by Weil and Felix. They first cultivated strains X and X2 from the urine of typhus patients and later the fa- mous Xi9 . The two former were aggluti- nated weakly, the latter strongly (up to 1 :50,000). The diagnosis of typhus by agglu- tination with strain X19 proved to be ex- cellent and the reaction took place in the serum of almost 100 per cent of those suffer- ing from the disease. . . . The typhus strains of proteus have recently been divided into the two types of Felix and Weil, the H forms and the O forms. The former grows as a thin opaque film, the latter lacks this char- acter and grows as non-spreading slimy colonies; frequently without distinct fia- ella. . . " (For further description of H and O forms, see Moltke, op. cit., 1927, 156.) The X2 and X19 strains mostly ferment maltose . A Relationship to "ther species : Hauser described Proteus vulgaris as a rapid gela- tin-liquefier and Proteus mirabilis as a slow liquefier. Wenner and Rettger (Jour. Bact., 4, 1919, 332) found the property of gelatin liquefaction too variable to serve as a basis for separation of species. They suggested that this differentiating character be set aside and that the two species be differenti- ated on the basis of maltose fermentation, the species fermenting the sugar receiving the name Proteus vulgaris, and the species failing to attack it, Proteus mirabilis. This suggestion was accepted by Bergey et al., (Manual, 1st ed., 1923) and by Weldin (Iowa Jour. Sci., 1, 1927, 147) ; their work was con- firmed by Rustigian and Stuart (Jour. Bact., 45, 1943, 198) and by Thornton (Jour. Bact., 48, 1944, 123). Also see Moltke (op. cit., 1927, 156). Source: Isolated from putrid meat, in- fusions and abscesses. Habitat: Found on putrefying materials. 2. Proteus mirabilis Hauser, 1885. (Hauser, Sitzungsber. d. phys.-med. So- zietat zu Erlangen, 1885, 156; Bacterium mirabilis (sic) Chester, Ann. Rept. Del. Col. Agr. Exp. Sta., 9, 1897, 101.) mi.ra'bi.lis. L. adj. mira6z7is wonderful, surprising. Short rods, 0.5 to 0.6 by 1.0 to 3.0 microns, occurring singl}^, in pairs and frequently in long chains. Motile by means of perit- richous flagella. Gram-negative. Gelatin colonies: Irregular, swarming. Gelatin stab: Slow, stratiform liquefac- tion. Agar colonies: Gray, irregular, swarming. Agar slant: Thin, bluish gray growth, spreading over the surface. Broth: Turbid; thin, gray pellicle; sedi- ment. Litmus milk: Slightly acid, becoming alkaline; peptonized. Potato: Dirtj^ gray, spreading growth. Putrefactive odor produced. Indole not produced. Hydrogen sulfide is produced. Acid and gas from glucose, fructose, ga- lactose, xylose and trehalose. Acid and gas usually produced slowly from sucrose. No acid or gas from lactose, maltose, dex- trin or mannitol. Most of the XK strains do not attack maltose. Sodium citrate is usually utilized as a sole source of carbon. Acetylmethylcarbinol frequently pro- duced weakly. Nitrites produced from nitrates. Phenylpyruvic acid is produced from phenjdalanine, and leucine is rendered al- kaline. Aerobic, facultatively anaerobic. Optimum temperature, 37° C. Source: Isolated from putrid meat, in- fusions and abscesses. Also reported as a cause of gastroenteritis (Cherry and Barnes, Amer. Jour. Pub. Health, 36, 1946, 484). Habitat: Found on putrefying materials. 3. Proteus morganii (Winslow et al., 1919) Rauss, 1936. (Organism No. 1, Mor- gan, Brit. Med. Jour., 1, 1906, 908; Bacillus morgani Winslow, Kligler and Rothberg, Jour. Bact., 4, 1919, 4&; Salmonella morgani Castellani and Chalmers, Man. Trop. Med., 3rd ed., 1919, 939; Bacterium morgani Hol- land, Jour. Bact., 5, 1920, 215; Rauss, Jour. Path, and Bact., 42, 1936, 183.) mor.ga'ni.i. M.L. gen. noun morganii of Morgan; named for H. de R. Morgan, the
