182 DYSENTERY, HOG AND CHICKEN CHOLERA. 



the fact that by heating cultures to a temperature above 

 60 C., which kills the bacilli, does not seem to have any 

 effect on the activity of the poison. 



Protective inoculations in animals have been performed with 

 positive results, and the serum of immunized animals has 

 been found to possess the power of agglutination, and to be 

 both protective and curative. 



HOG CHOLERA. 

 Bacillus Sui Pestifer. 



History. In the dejecta of hogs affected with cholera 

 Salmon and Smith have succeeded in isolating a bacillus 

 which they found to be the specific cause of this disease. 



Morphology. It is a short, thick rod, 1.20 to 1.50 mikrons 

 in length, and 0.6 to 0.7 mikron in breadth, actively motile, 

 containing flagella, stains by all the anilin dyes, but not by 

 Gram's method. 



Biologic Characters. It is aerobic and grows in all the cult- 

 ure-media. Its growth on gelatin is visible in from twenty- 

 four to forty-eight hours; the colonies appear irregularly 

 round and the gelatin is not liquefied. On agar-agar the 

 colonies are translucent and rather circumscribed. Upon 

 potato the colonies are yellow. Bouillon is clouded and a 

 thin surface growth may be observed. In milk it does not 

 generate acids and does not coagulate it. 



It produces gas copiously, but no indol. 



Vitality. It withstands drying for a long time. Its ther- 

 mal death-point is 54 C. 



Pathogenesis. It is intensely pathogenic for every labor- 

 atory animal, death being preceded always by a rise of 

 temperature, and postmortem lesions affecting chiefly the liver 

 and kidneys are seen. Sometimes the lesions are found in 

 the intestines and Peyer's glands also. The bacillus is found 

 in all the organs. Artificially swine are inoculated with dif- 

 ficulty. 



Immunity in animals has been produced by Salmon and 

 Smith by injections of gradually increasing doses of cultures 



