The bacillus is anærobic, liquefying, tardily motile, and sporogenous. When spores form the bacillus loses its motility. It grows at room temperatures, in ordinary culture media which have a feebly alkaline reaction, and in an atmosphere of hydrogen, but more actively at a temperature of 36° to 38° C. Below 14° C. growth ceases and the bacillus is killed at 60° to 65° C. The spores, however, can resist a temperature of 80° C., in water for an hour, and 100° C. for four minutes. It was this unusual resistance of the spore to heat that enabled Kitasato to kill off the contaminating organisms and obtain pure cultures from the surviving spores. The spores will survive desiccation for years, retaining their virulence, and may live 2½ months in putrefying material. The addition to the culture medium of 1½ to 2 per cent. of glucose makes the growth much more rapid and abundant, and causes opacity in the medium. The upper portion clears up in 6 or 7 days by the precipitation of the bacilli as a grayish mass. In a glucose culture medium growth is not prevented by the presence of oxygen at the surface. The colonies formed in gelatine plate cultures show an opaque centre with fine divergent rays, and a similar radiating growth is shown in deep stick cultures. At the end of the second week the gelatine begins to liquefy and form a little gas, and finally the whole mass becomes soft and sticky. The bacillus does not liquefy blood serum. Cultures have a disagreeable aromatic odor. The bacilli stain readily in aniline colors and by Gram’s method. The spores may be stained by Ziehl’s method. To 10 parts of a 10 per cent. alcoholic solution of basic fuchsin, add 100 parts of a watery solution of carbolic acid. Float the cover glass upon this, heating gently for three to five minutes until steam begins to rise, wash well in water, and decolorize in nitric or sulphuric acid, 25 per cent. solution, then in 60 per cent. alcohol to remove color from albuminous background. Wash in water and mount. By placing the specimen for two minutes in a watery solution of methylene blue a contrast is obtained, the bacillus blue and the spore red.