130 BACTERIOLOGY 



Gelatin colonies. Deep : round oval, often a bright ring between centre and 

 border. Surface; in 48 hours colony the size of a pin's head; white, 

 glistening, convex ; microscopically, grayish brown, opaque. 



Gelatin stab. In depth, a good growth, white; often gas produced; surface 

 growth convex. 



Agar colonies. Deep: fusiform. Surface: slimy glistening drops. 



Agar slant. Growth thick, slimy, spreading; condensation water, slimy 

 turbid. 



In glycerine agar, gas production. 



Bouillon. Turbid; a delicate membrane, which adheres to walls of tube, be- 

 coming thicker, and sinking; later a slimy flocculent sediment, and 

 clear medium above. Culture has the odor of walnuts. 



Blood serum. Growth not so abundant as on agar; no liquefaction. 



Potato. A thick, creamy layer, color of potato, with raised border; odor of 

 trimethylamine and ammonia. 



Agar stab. Gas production at 37 C. 



Milk. Coagulated slowly ; after 6 days at 37 C. acid, with a cheesy odor. 



Do not grow on acid media, but best on one weakly alkaline. Maltose, glucose, 

 and lactose fermented. Cane sugar not fermented. Litmus reddened. 



Pathogenesis. Subcutaneous inoculation of mice causes death by general 

 septicaemia in 24 hours. Guinea pigs, intraperitoneal^, death in 36-48 

 hours, with peritonitis. 



Habitat. Isolated from India ink. 



23. Bact. pallescens Henrici 



Bakterienflora des Kases, Baseler, Philos. Diss., 1894. 



Indistinguishable from Bact. aerogenes, except that bouillon is not rendered 



turbid. 

 Habitat. Isolated from cheese. 



24. Bact. fermentationis Chester 



Report Del. College Ag. Expt. Sta., 1899. 



Morphology. Bacilli 0.8 : 1.25-3.0 fx. 



Gelatin colonies. Deep : round, entire, homogeneous, yellowish brown, 

 0.1-0.3 mm. Surface: macroscopically, moist, glistening, punctiform, 

 0.5-1.0 mm., later convex flat, dull white, 1. 0-1.5 mm. Colonies re- 

 main small after several weeks. Microscopically, round, entire, brownish 

 in the centre, becoming gradually lighter toward the edge, or grayish 

 yellow throughout, strongly refracting and amorphous. 



