Cholera Stiis, Hog Cholera, etc. 25 



temperature, and most actively at 85 to ioo° F. It may grow 

 as low as 6o° to 70 F. and as high as 104 . (Swine plague 

 bacillus grows at 55.4 ). 



On peptonized gelatine the surface colonies are usually round 

 and flattened, those in its substance globular and smaller, and 

 those at the bottom expanded next the glass and rising in the 

 center into the gelatine like a knob. At 48 hours they appear as 

 opaque whitish points and slowly increase to ^ to 2 mm. They 

 may be brown by transmitted light, the depth of color increasing 

 with age. On agar the colonies are grayish, shining and trans- 

 lucent and may reach the size of 4 to 6 mm. On potato (alkaline) 

 a straw yellow film is formed, darkening with growth. In bouil- 

 lon a turbidity appears in 24 hours, and in 1 or 2 weeks a precipi- 

 tate and surface film. 



The bacillus is usually larger in the gelatine and smaller in the 

 bouillon than it is in the tissues. It seems to produce neither 

 phenol nor indol. 



Its behavior with sugars is significant. It ferments glucose 

 producing acid and gas ; does not ferment saccharose nor lactose, 

 but turns the saccharose solution alkaline (no gas). In bouillon 

 containing muscle glucose, it may without additional glucose 

 form a little gas. The swine plague bacillus ferments saccharose 

 producing acids but no gas : it ferments neither glucose nor lac- 

 tose but turns the former acid. 



Milk is neither coagulated nor soured by the hog cholera 

 bacillus, but in 3 to 4 weeks it undergoes a change, becoming 

 saponified. 



Cultures have no special nor offensive odor. Some varieties 

 in close tubes may cause a faint acid odor. 



Oxygen is not essential to the success of a culture. The colonies 

 form as promptly and as large in the depths of gelatine, or in a 

 vacuum, as if in free air. 



The following table will serve to show differences between the 

 hog cholera bacilli, and related pathogenic microbes : 



