366 BACTERIOLOGY 



gonidia. Stain by Gram's method. Grow at 20 , but best at 37 C. 



Aerobic. 

 Gelatin colonics. Round, slightly raised, brownish, but with a whitish dry 



chalky appearance in the centre, becoming concentric. Gelatin around 



the colony dark brown and slowly liquefied, leaving a chalky crust on the 



surface of the liquefied gelatin. Microscopically, filamentous, tan 



becoming opaque in centre with a filamentous border. 

 Gelatin stab. In depth, short radiate bundle-like outgrowths after some 



time; on the surface like gelatin colonies, gelatin slowly liquefied 



beneath. 

 Agar stab. In depth, bristly outgrowths; on the surface, growth moist, 



yellowish, glistening, raised,. becoming dry, warty; agar stained a deep 



brown. 

 Agar slant. Growth brownish, slightly spreading, becoming whitish, chalky. 

 Bouillon. On the surface, a delicate and later a tough membrane. 

 Glucose bouillon. Radiate masses at the bottom ; medium brownish. 

 Milk. A tough yellowish brown growth on the surface ; medium rendered 



alkaline and peptonized. 

 Potato. Growth yellowish yellowish brown, becoming chalky. The 



medium is stained a deep brown or black. The culture has an intense 



mouldy odor. 

 Habitat. Air, water, and stomach contents. 



12. Streptothrix violacea Rossi-Doria 



I.e., 1891. 



Morphology. Typical Streptothrix, with branched mycelium and spore for- 

 mation and aerial hyphae. Stain by Gram's method. No anaerobic 

 growth. 



Gelatin colonies. Violet, isolated, becoming united and forming a rugose 

 membrane ; also the medium stained violet. 



Bouillon. Scanty growth ; compact nodules at the bottom and isolated 

 colonies on the surface ; medium colored a faint wine-red. 



Potato. Red violet colonies, with a whitish bloom and a brownish discolora- 

 tion of the medium. 



Milk. Violet points of growth ; medium slowly peptonized. 



Pathogenesis. Negative, or injection of 2 cc. intraperitoneal^ into test animals 

 may cause a pseudotuberculosis of the mesentery, spleen, liver, and lungs. 



Habitat. Air and water. 



