cal with those of Salmonella poona and Sal- monella worthington. There is no correhition between the sero- tj^pes and the biochemical characters except for Shigella flexneri 3, which acidifies rham- nose, and Shigella flexneri 6, which has par- ticular biochemical characters. Serotype Shigella flexneri 6 contains strains each of which possesses biochemical properties at variance with those of the other strains as well as with those of the other serotypes of this species : strain Boyd 88 produces acid from mannitol and glucose and sometimes late acid from dulcitol; strain Shigella (Type Manchester) produces acid and gas from mannitol and glucose and late acid and gas from dulcitol; Shigella (Type Newcastle) does not ferment manni- tol but produces acid and gas from glucose and late acid and gas from dulcitol. Other varieties of Shigella flexneri have been reported as not fermenting mannitol: Nelson (1948) isolated non-mannitol-fer- menting strains whose type antigens were similar to those of Shigella flexneri 4 (Boyd 103) . Shigella rabaulensis Munford and Mohr (1944) and Shigella rio de Assis and Stafkow- sky (1948) also belong to this group: S. rabaulensis has an R antigen which, al- though belonging to the group antigen, is specific for S. rabaulensis; S. rio is a degen- erate variant of S. rabaulensis. Denier and Huet (Bull. Soc. Path. Exot., 5, 1912, 263) isolated a strain, which they called Saigon Bacillus, in Indo China which does not ferment mannitol; it produces acid without gas from glucose, maltose and occasionally from rhamnose and xylose in 12 to 24 days; it does not ferment mannitol, lactose, su- crose, dulcitol or sorbitol and it produces indole; it has a type 4 major antigen and minor antigens similar to those of several other serotypes oi Shigella flexneri. Pacheco, Rubinsten, Piechaud and Kirch suggest that the name Shigella saigonensis be used to include all strains of S. flexneri which do not ferment mannitol. Source: Isolated from feces in cases of dysentery. Habitat: The most common cause of dys- entery epidemics and sometimes of infantile gastroenteritis. Found in the feces of the sick and in the feces of convalescents or of carriers of dysentery bacilli. 6. Shigella alkalescens (Andrewes, 1918) Weldin, 1927. (Bacillus alkalescens An- drewes, Lancet, 194, 1918, 560; Weldin, Iowa State Coll. Jour. Sci., 1, 1927, 179; Proshi- gella alkalescens Borman, Stuart and Wheeler, Jour. Bact., 48, 1944, 363.) al.ka.les'cens. Arabic al the; Arabic noun gaily the ashes of saltwort, etc.; M.L. part. adj. alkalescens alkaline-making. Rods, 0.5 by 1.0 to 1.5 microns, occurring singly and in pairs. Non-motile. Gram-nega- tive. Cultures in gelatin, on agar, in broth and on potato are similar to those of Shigella flexneri Castellani and Chalmers. Litmus milk: Turns blue in 4 to 10 days; whey produced in 3 to 5 days. Indole is produced. Hydrogen sulfide not produced. Acid but no gas from glucose, mannitol, xylose, rhamnose, maltose, dulcitol, sorbitol and occasionally from sucrose. Lactose, dextrin and salicin are not attacked. Nitrites produced from nitrates. Trimethylamine produced from tri- methylamine oxide; trimethylamine also produced from choline. Aerobic, facultatively anaerobic. Optimum temperature, 37° C. Growth at 45.5° C. Not generally accepted as pathogenic. Distinctive characters: Produces tri- methylamine from choline. Certain strains (serotypes 1 and 2) have the property of agglutinating the erythrocytes of man, monkeys, dogs or sheep (Griffith, 1948). Source: Isolated from the feces of con- valescents from dysentery and from healthy individuals; also isolated from a blood cul- ture by Starkey (Jour. Canad. Med. Assn., 31, 1934, 41) and from cases of bacilluria by Snyder and Hanner (Jour. Inf. Dis., 60, 1937, 51). Habitat: Found in the intestinal canal. Suspected as a cause of diarrhoea. 7. Shigella sonnei (Levine, 1920) Wel- din, 1927. (Group III of Sonne, Sonne, Cent, f. Bakt., I Abt., Orig., 75, 1915, 408; Bacillvs
