HOG-CHOLERA. 417 



Linear cultures upon agar-agar present a translucent, 

 rather circumscribed, grayish, smeary layer. 



Upon potato a yellowish coating is formed, especially 

 when the culture is kept in the thermostat. 



Bouillon made with or without pepton is clouded in 

 twenty-four hours. When the culture is allowed to stand 

 for a couple of weeks without being disturbed a thin 

 surface-growth can be observed. 



Milk is an excellent culture-medium, but is not visibly 

 changed by the growth of these bacteria. Its reaction 

 remains alkaline. 



The hog-cholera bacillus is a copious gas-producer, 

 capable of breaking up sugars into CO 2 , H, and an acid, 

 which, formed late, eventually checks its further devel- 

 opment. No indol and no phenol are formed in the 

 culture-media. 



The bacillus is hardy. Smith found it vital after being 

 kept dry for four months. It ordinarily dies sooner, how- 

 ever. The thermal death-point is 54 C., maintained for 

 sixty minutes. 



The bacillus is markedly pathogenic for animals. 

 Small quantities introduced subcutaneously into rabbits 

 or mice kill them in from seven to twelve days. The 

 animal appears quite well for three or four days, then 

 begins to sit quietly in the cage and eat but little, or 

 refuses to eat at all, until death takes place. 



In Smith's experiments one-four-millionth of a cubic 

 centimeter of a bouillon culture injected subcutaneously 

 into a rabbit was sufficient to cause its death. Before 

 death the temperature abruptly rises 2-3 C., and re- 

 mains high until death. Larger quantities may kill in 

 five days. Injected intravenously in small doses the ba- 

 cillus may cause death in forty-eight hours. 



When the animal is subjected to a postmortem exam- 

 ination the spleen is found enlarged, firm, and dark red 

 in color. The liver is found to contain small yellowish- 

 white necrotic areas which sometimes occur in one, some- 

 times in several acini, and not infrequently surround the 



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