BACTERIA PATHOGENIC FOR ANIMALS. 



137 



Properties. They are motile ; do not liquefy gelatine. 



Growth .in culture at ordinary temperature, very slowly, and 

 the less oxygen the better the growth. 



Gelatine Plate. On third day little silver-gray specks, seen 

 best with a dark background, coalescing after awhile, pro- 

 ducing a clouding of the entire plate. 



Stab Cultures. In a few days a -very light, silvery -like clouding, 

 which gradually involves the entire gelatine ; held up against 

 a dark object, it comes plainly into view. , 



Staining. All ordinary dyes and Gram's method also. 



Tissue sections stained by Gram's method show the bacilli in 

 the cells, capillaries, and arterioles in great numbers. 



Pathogenesis. Swine, mice, rabbits, and pigeons are sus- 

 ceptible ; guinea-pigs and chickens, immune. 



When swine are infected through food or by injection a tor- 

 pidity develops with diarrhoaa and fever, and on the belly and 

 breast red spots occur which coalesce, but do not give rise to 

 any pain or swelling. The animal dies from exhaustion in 24 to 

 48 hours. In mice the lids are glued together with pus. 



FIG. 74. 



Bacillus Murisepticus. 



At the autopsy the liver, spleen, and glands are enlarged and 

 congested, little hemorrhages occurring in the intestinal mucous 

 membrane and that of the stomach. 



