glycerol; experimentally produces general- ized tuberculosis in voles but not in guinea pigs or rabbits. Source : Isolated from naturally occurring tuberculosis in the field vole, Microtus agres- tis, and the bank vole, Clethrionomys glareo- lus. Habitat: The cause of generalized tuber- culosis in voles; transmissible to guinea pigs, rabbits and calves, causing localized infections. 11. Mycobacterium avium Chester, 1901. (Tuberculose des oiseaux, Strauss and Gamaleia, Arch. Med. exp. et Anat. path., 1891; Bacillus der Hiihnertuberculose, Maf- fucci, Ztschr. f. Hyg., 11, 1892, 449; Bacillus tuberculosis gallinarum Sternberg, Man. of Bact., 1893, 392; Mycobacterium tuberculosis aviiim Lehmann and Neumann, Bakt. Diag., 1 Aufl., 1, 1896, 370; Chester, Man. Determ. Bact., 1901, 357; Mycobacterium tuberculosis typus gallinaceus Lehmann and Neumann, Bakt. Diag., 4 Aufl., 3, 1907, 553.) a'vi.um. L. noun avis a bird; L. gen.pl. noun avium of birds. Common name: Avian tubercle bacillus. Original description supplemented by material from Topley and Wilson (Princip. of Bact. and Immun., London, 2nd ed., 1936, 315). Rods resembling those of the bovine type of tubercle organism. Agar: After 4 weeks, slight, effuse, trans- lucent growth with fine, granular surface. Glycerol agar colonies : After 3 to 4 weeks, raised, regular, hemispherical, creamy or white colonies. Dorset's egg slants: After 4 weeks, con- fluent, slightljr raised growth with smooth, regular surface. Glycerol egg slants : After 4 weeks, luxuri- ant, raised, confluent, creamy to yellow growth with perfectly smooth surface. Winn and Petroff (Jour. Exp. Med., 57, 1933, 239), Kahn and Schwartzkopf (Jour. Bact., £5, 1933, 157), Birkhaug (Ann. Inst. Past., 54, 1935, 19), Reed and Rice (Canad. Jour. Res., 5, 1931, HI) and others have shown variation to follow the course de- scribed for many species. Winn and Petroff have separated four colonial types: smooth, flat smooth, rough, deep j^ellow smooth. These also differ in chemical and physical properties. The smooth form exhibited the greatest degree of virulence, the flat smooth a lower virulence, while the chromogenic smooth and the rough were relatively be- nign. Some authors have failed to demon- strate this difference in virulence. The above description applies primarily to the smooth form. Broth: After 4 weeks, very slight viscous to granular bottom growth; no pellicle, no turbidity. Glycerol broth : After 4 weeks, diffuse, tur- bid growth with a viscous to granular de- posit. Coagulated beef serum: After 4 weeks, thin, effuse, grayish yellow growth with smooth surface. Glycerol beef serum: After 4 weeks, lux- uriant, raised, confluent, yellow to orange- yellow or occasionally pale pink growth with a smooth glistening surface. Glycerol potato: After 4 weeks, luxu- riant, raised, confluent growth with smooth to nodular surface. Litmus milk: Growth, but no change in the milk. Fructose, arabinose and sucrose are uti- lized; glucose is slightly utilized; galactose and lactose are not utilized (Merrill, Jour. Bact., £0, 1930, 235, based on the examina- tion of one strain). Optimum temperature, 40° C; range 30° to 44° C. (Bynoe, Thesis, McGill Univer- sity, Montreal, 1931). Optimum pH, between 6.8 and 7.3 (By- noe, loc. cit.). Pathogenicity: Produces tuberculosis in domestic fowls and other birds. In pigs it produces localized and sometimes dissemi- nated disease. Experimentally in the rabbit, guinea pig, rat and mouse it may proliferate without producing macroscopic tubercles — tuberculosis of the Yersin type. Man, ox, goat, cat, horse, dog and monkey are not in- fected. Antigenic structure: By agglutination, absorption of agglutinins and complement fixation, Mycobacterium avium maj' be dis- tinguished from other members of the genus (Tullock et al.. Tubercle, 6, 1924, 18, 57 and 105; Wilson, Jour. Path, and Bact., ^8, 1925, 69; Mudd, Proc. Soc. E.xp. Biol, and
