BACILLUS GANGR^ENjE PULPM. 329 



from those of Arkovy in some points, 1 the following are 

 the characteristics (compare Zierler, C. B. xxvi, 417): 



Microscopically. — Stout rods, 4, a long, about 0.8-1.0 fx 

 thick, often united in chains. Actively motile. Stain- 

 ing of flagella has not been successful. Upon all nutrient 

 media large, oval spores soon form, which are difficult to 

 stain. Germination of the spores is equatorial, often 

 oblique to the axis of the spore (Hirai). Grows luxu- 

 riantly on all nutrient media, best at 37°. Gelatin plate : 

 Similar to subtilis, rapid liquefaction. Gelatin stab : After 

 two or three days saucer-shaped liquefaction, which becomes 

 cylindric. Upon the surface a very tough, wrinkled 

 film, which usually remains connected by a fine string 

 with the stab canal in the solid gelatin. The liquefied 

 mass gradually becomes colored smoky brown. After two 

 to four days fine, horizontal branches are seen throughout 

 the entire length of the stab canal. Anaerobic gelatin stab : 

 Without liquefaction and pellicle formation, the surface 

 gradually becomes depressed. The branches in the stab 

 are longer and more delicate. Agar plates : Thick plates 

 exhibit superficial colonies something like subtilis (39, 

 vi and vn) ; thin plates present dense, scalloped, concen- 

 trically striped, white growths, which, when magnified fifty 

 times, appear opaque, and from the rather sharp border 

 bunches of threads project outward. Deep colonies are 

 compact and often whetstone-shaped. Agar stab: The 

 growth rapidly spreads over the surface of the agar and is 

 whitish, dense, with a dull luster; soon it becomes a little 

 rough from the formation of small depressions and eleva- 

 tions. Potato : On first day, a delicate, membranous, 

 moist, spreading growth; after three to four days the same 

 becomes finely wrinkled and dirty red, and the neighbor- 

 hood of the growth is stained dirty violet. Bouillon is 

 very cloudy, with a dense, wrinkled surface pellicle. In a 

 few days, with the formation of a rather crummy precipi- 

 tate and brownish discoloration, the culture becomes clear. 

 Neither H 2 S nor indol is formed. Milk is coagulated after 

 two or three days. In grape-sugar bouillon there is 



1 Nothing was seen of the pleomorphism of Arkovy, and the ' ' cocci 

 forms" represented by Arkovy are often spores (C. B. xxni; Plate 

 XVIII, 10). 



