336 BACTERIOLOGY 



Gelatin colonies. Small, yellowish white, becoming sunken in the liquefied 

 gelatin ; zone of liquefied gelatin turbid — flocculent, later becoming con- 

 centric. Microscopically, in 16-18 hours small, round, yellowish, coarsely 

 granular ; the central colony becomes irregular — brecciated. 



Gelatin stab. A napiform liquefaction, with an air-bubble depression at the 

 top, becoming saccate ; gelatin turbid — granulated or shows yellowish 

 white masses. 



Agar colonies. Deep : round — irregular — naviculate, entire, knobbed or 

 granular, becoming darker, or a brownish nucleus, with a grayish zone. 

 Surface: round, whitish-brownish, moist, glistening, entire, translucent, 

 slightly raised. Microscopically round, light yellowish, translucent, 

 punctate — granulated. 



Agar slant. Growth brownish gray, moist, glistening, or yellowish brown. 



Blood serum. Slowly liquefied. 



Bouillon. Slightly turbid ; a wrinkled fragile membrane ; alkaline ; becoming 

 clear. 



Milk. Coagulated in 2 days at 37°, acid. 



Potato (acid). No growth; on alkaline potato growth dirty white — yellow- 

 ish, scarcely raised, moist, glistening, becoming brownish red, spreading. 

 H2S positive. Indol positive. No gas in glucose, lactose, or saccharose 

 bouillons. In glucose bouillon the production of left-handed lactic acid. 



Litmus milk. On the surface, a blue pellicle, below this a red discoloration. 



Pathogenesis. Inoculations per os and by ingestion gave positive results with 

 young cats and rabbits (see text-books). Intraperitoneal inoculations of 

 guinea pigs cause distention of the abdomen, subnormal temperatures, 

 and general collapse. Bacilli in the peritoneal cavity, or, with large doses, 

 in the blood and small intestines. Intravenous injections of rabbits cause 

 toxaemia and death in 18 hours ; with smaller doses a true cholera picture 

 may follow. 



Habitat. Isolated from the alvine discharges and intestinal contents of chol- 

 era patients, and in water supplies during epidemics. 



Probable Varieties of Msp. comma. 



{A") Pseudo-cholera-spirillum Rdnan : Annales Pasteur Institut, VI, 1892, 621. 



Bacilli much larger than Msp. comma ; commas and S forms. 



Gelatin colonies. Small, lenticular, with outgrowths ; centres darker and yef- 



lowish, becoming in 4 days surrounded by a liquefied zone. 

 Gelatin stab. Like Msp. comma., but grows more rapidly. 

 Agar slant. Growth thick, creamy white, limited. 



