552 Hog-cholera 



the spleen is found enlarged, firm, and dark red in color. 

 The liver contains small yellowish-white necrotic areas 

 which sometimes occur in one, sometimes in several acini, 

 and not infrequently surround the interlobular veins. The 

 kidneys are acutely inflamed and the urine is albuminous. 

 The heart-muscle is spotted, gray, and fatty. In the intes- 

 tinal tract the picture of the disease will be found to vary 

 according to its duration. The contents of the small intes- 

 tine are yellowish, watery, and mucous; Peyer's glands are 

 enlarged. In the neighborhood of the pylorus, ecchymoses 

 and extensive extravasations of blood are common. The 

 bacilli are found in all of the organs. 



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

 and that it is from diseased and dead swine that the bacilli 

 are obtained, these animals are not very easily infected 

 artificially. They show no symptoms when injected subcu- 

 taneously, but almost invariably die after intravenous in- 

 jection of 1-2 c.c. of a virulent culture. 



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

 culture after a day's fasting, or with small quantities admin- 

 istered daily, would cause death, with a widespread diph- 

 theritic inflammation of the stomach and colon. Feeding 

 with the organs of dead hogs produces the same lesions as 

 the administration of the culture. 



Immunity. As early as 1886 Salmon and Smith found 

 it possible to produce immunity against hog-cholera in sus- 

 ceptible animals, by gradually accustoming them to increas- 

 ing doses of the bacteria. De Schweinitz isolated from cul- 

 tures of the bacteria two toxic substances, a ptomain 

 (sucholotoxin) and an albumose (sucholoalbumin), to- 

 gether with cadaverin and methylamin. With these sub- 

 stances he seems to have been able to produce immunity. 

 Selander * and Metschnikoff found that immunity could be 

 produced more quickly by the use of blood of infected 

 rabbits exposed to 58 C. This blood was found to be 

 exceedingly toxic. 



De Schweinitz f found that the introduction into cows 

 of progressively increased quantities of hog-cholera cultures 

 caused the development of an antitoxic substance capable 

 of protecting guinea-pigs from the disease. 



After several years of treatment, some horses that I 



*See "Centralbl. f. Bakt.," etc., Bd. xi, p. 339. 

 f'Centralbl. f. Bakt. u. Parasitenk.," xx, p. 573. 



