Usually smaller than in Rhizobium legumi- nosarum and R. trifolii. Gram-negative. Growth on mannitol agar is rapid with tendency to spread. Streak inoculation is raised, glistening, semi-translucent, white, slimy. Occasionally mucilaginous, but this character is not so marked as in Rhizobinni trifolii. Very slight acid formation from glucose, galactose, mannose, sucro.'^e and lactose. Aerobic. Optimum temperature, 25° C. Source: Isolated from root nodules of Phaseolus vulgaris (kidney bean), P. angusti- folius (bean) and P. multiflorus (scarlet runner) (Burrill and Hansen, 111. Agr. Exp. Sta. Bui. 202, 1917, 137). Habitat: Widely distributed in the soils In which beans are grown. 3. Rhizobium trifolii Dangeard, 1926. (Le Botaniste, Ser. 16, 1926, 191.) tri.fo'li.i. L. noun trifoliuni clover, tre- foil; M.L. neut.n. Trifolium generic name of clover; M.L. gen. noun trifolii of clover. Rods. Motile by means of peritrichous flagella. Bacteroids from nodules are pear- shaped, swollen and vacuolated, rarely x- or y-shaped. Gram-negative. Growth on mannitol agar is rapid. The colonies are white becoming turbid with age. Frequently mucilaginous. Streak cul- tures transparent at first. Growth mucilagi- nous, later flowing down the agar slant and accumulating as a slimy mass at the bottom. Produces large amounts of gum. Slight acid production from glucose, ga- lactose, mannose, lactose and maltose. Aerobic. Optimum temperature, 25° C. Source: Isolated from root nodules of species of Trifolium (clover). Habitat: Widely distributed in the soils where clover grows. 4. Rhizobium lupini (Schroeter, 1886) Eckhardt et al., 1931. {Phytomyxa lupini Schroeter, in Cohn, Kryptogamen-Flora von Schlesien, 3, I, 1886, 135; Eckhardt, Baldwin and Fred, Jour. Bact., 21, 1931, 273.) lu.pi'ni. L. noun lupinus the lupine; M.L. mas.n. Lupinus generic name of lupine; M.L. gen. noun lupini of Lupinus. Rods. Motile by means of 1 to 4 flagella, usually 2 or 3. Bacteroids are vacuolate rods, seldom if ever branched. Gram-nega- tive. Growth on j-east water, mannitol agar is scant to moderate with alkaline reaction. Beef -peptone gelatin: Little growth with extremely slow liquefaction. On galactose an alkaline reaction serves to differentiate Rhizobium lupini from all fast-growing rhizobia (R. phaseoli, R. rneli- loti, R. trifolii and R. leguminosarum) . An initial alkaline reaction followed more quickly by an acid reaction on rhamnose and xylose separates R. lupini from slow- growing R. japonicum and the Rhizobium sp. from cowpea. In general Rhizobium lupini produces slight to moderate acidity on pentose sugars and no change or alkaline reaction on hex- oses, disaccharides or trisaccharides. Litmus milk: No serum zone; no reduc- tion; slight alkaline reaction. Meager growth on potato and parsnip slants and on carrot agar. Aerobic. Optimum temperature, 25° C. Source: Isolated from root nodules on Lupinus (lupine), Serradella and Orniihopus. Habitat: Widely distributed in soils in which these legumes grow. 5. Rhizobium japonicum (Kirchner, 1895) Buchanan, 1926. (Rhizobacterium ja- ponicum Kirchner, Beitrage z. Biol. d. Pflan- zen, 7, 1895, 213; Buchanan, Proc. Iowa Acad. Sci., 83, 1926, 81.) ja.po'ni.cum. M.L. adj. japonicus of Japan. Rods. Motile by means of monotrichous flagella. Bacteroids of nodules are long and slender with only occasional branched and swollen forms. Gram-negative. Growth on mannitol agar is slow and scant. The streak is slightly raised, glisten- ing, opaque, white, butyrous, with little gum formation. Pentose sugars give better growth than the he.xoses. Little if any acid formed from carbohy-
