BACTERIA PATHOGENIC FOR ANIMALS. 139 



Growth. Occurs at ordinary temperature, requiring oxygen 

 for development. It grows very slowly. 



Gelatine Plates. In the course of three days little round, 

 white colonies, which seldom increase in size, having a rough 

 border and very finely granulated. 



Stab Culture. A very delicate gray line along the needle- 

 track, which does not become much larger. 



Agar Stroke Culture. A moist, grayish-colored skin, more 

 appreciable at brood heat. 



Potato. At brood heat after several days a very thin, trans- 

 parent growth. 



Staining. Methylin blue gives the best picture. Gram's 

 method is not applicable. As the bacillus is easily decolorized, 

 aniline oil is used for dehydrating tissue sections, instead of 

 alcohol. 



Method : 



Loffler's methylin blue . hour. 



Alcohol 5 seconds. 



Aniline oil 5 minutes. 



Turpentine 1 minute. 



Xylol and Canada balsam. 



Pathogenesis. Feeding the fowls or injecting under the skin 

 will cause their death in from 12 to 24 hours, the symptoms pre- 

 ceding death being those of a heavy septicaemia. 



The bacillus is then found in the blood and viscera, and the 

 intestinal discharges, the intestines presenting a hemorrhagic 

 inflammation. 



Guinea-pigs and sheep do not react. Mice and rabbits are 

 affected in the same manner as the fowls. 



Immunity. Pasteur, by injecting different-aged cultures into 

 fowls, produced in them only a local inflammation, and they 

 were then immune. But as the strength of these cultures could 

 not be estimated, many fowls died and the healthy ones were 

 endangered from the intestinal excretions, which is the chief 

 manner of infection naturally ; the faeces becoming mixed with 

 the food. 



