or filamentous; may reach 100 to 150 microns in length; homogeneous in young cultures but become granulated, beaded and swollen in old cultures and tend to frag- ment into rods and cocci; large spherical swellings packed with granules common; cholesterol globules appear among the growth; only rods and short filaments appear in pathological material; non-branching; non-acid fast; colonies on ascitic agar 1 to 2.5 mm in 3 days, circular, low convex, colorless; L-phase variants are common; highly virulent for mice causing polyarthritis. Causes rat-bite or Haverhill fever in man Streptobacillus p. 451 {S. moniliformis) Not as above: grow well on media without blood or .serum 66 66. Colonies colorless 67 Colonies yellow 70 67. Organisms grow in 0.5 per cent peptone containing filter paper, causing the latter to disintegrate; gelatin liquefied; nitrite produced from nitrate; starch hydrolyzed Cellulomonas p. 601 Not as above 68 68. Lactose fermented in two days ' 69 Lactose fermentation delayed; enteric pathogens Shigella p. 384 (Shigella Group, Rome, 1953, slow lactose-fermenters) 69. Encapsulated cells; pathogenic Klebsiella p. 344 Not as above Achromobacter p. 300 70. Curved rods which transform completely into coccoid forms during growth of the colony. Rods elongate and divide. At the point of division the rods grow out at an angle to the original axis and divide again at the angle when the cell has doubled its length. This process continues until a colony is formed. Ultimately the rods trans- form completely into cocci Arthrobacter p. 605 Note: The emphasis lies on the final transformation into cocci. Some authori- ties may consider that limited true branching may occur. If this is admitted the dividing line between Arthrobacter and Nocardia becomes very slim. The author's observations of Arthrobacter globiforme fit the above statement, and it is suggested that these criteria be adopted, true branching forms which later disintegrate being assigned to Nocardia. Not as above; starch hydrolyzed Flavobacterium p. 309 In addition to the above, the following species, two of them plant pathogens, ter- minate at this point: Pseudomonas iridescens, Corynebacterium agropyri and Bacte- rium stewartii. 71. Non-motile 72 Motile 103 72. Acid and gas from glucose 73 Acid but no gas from glucose 77 No acid or gas from glucose 85 73. Only a small amount of gas from glucose; causes dysentery in man; agglutinated by polyvalent antiserum to Shigella jlexneri Shigella p. 384 (Newcastle strain) Organisms which cause bacillary white diarrhoea of chickens; agglutinated with Salmonella group D "O" antiserum Salmonella p. 368 (S. puUorum) Not as above 74 74. Bioluminescent on 3 per cent salt agar, especially with a fish base; pleomorphic and branching rods on asparagine-sugar media; 2-3-butylene-glj-col produced Photobacterium p. 193 Not bioluminescent 75 75. Gelatin liquefied; nitrites produced from nitrates; methyl-red negative; Voges-Pros-
