53 6 PATHOGENIC BACTERIA. 



interlobular veins. The kidneys are acutely inflamed 

 and the urine is albuminous. The heart-muscle is 

 spotted, gray, and fatty. In the intestinal tract the pic- 

 ture of the disease will be found to vary according to its 

 duration. 



The contents of the small intestine are yellowish, 

 watery, and mucous; Peyer's glands are enlarged. In 

 the neighborhood of the pylorus, ecchymoses and exten- 

 sive extravasations of blood are common. The bacilli 

 are found in all of the organs. 



The house mouse is very susceptible to the disease; 

 guinea-pigs much less so, -^ c.cm. of a virulent cul- 

 ture often being required to kill them. Pigeons are still 

 more refractory, and Smith found that Y A c.cm. of a 

 bouillon culture injected into the breast-muscles was 

 required to kill them. 



In spite of the fact that hog-cholera is a disease of 

 swine, and that it is from dead swine that the bacilli are 

 obtained, these animals are not very easily affected arti- 

 ficially. They show no symptoms when injected subcu- 

 taneously, but almost invariably die after intravenous 

 injection of 1-2 c.cm. of a virulent culture. 



Smith found that feeding with 200-300 c.cm. of a 

 bouillon culture after a day's fasting, or with small quan- 

 tities administered daily, would also cause death, with a 

 widespread diphtheritic inflammation of the stomach and 

 colon. Feeding with the organs of dead, hogs produces 

 the same lesions as the administration of the culture. 



As early as 1886 Salmon and Smith found it possible 

 to produce, in both very and partly susceptible animals, 

 immunity to hog-cholera by gradually accustoming them 

 to increasing doses of the bacteria. DeSchweinitz iso- 

 lated from cultures of the bacteria two toxic substances, 

 a ptomain (sucholo-toxin) and an albumose (sucholo-albu- 

 min), together with cadaverin and methylamin. With 

 these substances he seems to have been able to produce 

 immunity. Selander and Metschrrikoff found that im- 

 munity could be produced more quickly by the use of 



