Lesions 603 



conferred upon hogs by treatment with the desiccated blood 

 and serum of such animals. This seems to make it certain 

 that hog cholera is caused by some unseen and unknown 

 virus and that the bacillus of Salmon and Smith is an in- 

 cidental and probably accidental factor, not responsible for 

 the disease itself, but only for certain of its clinical pecu- 

 liarities. The form of hog-cholera resulting from successful 

 inoculation with the bacillus is unlike the real disease in 

 not being contagious, but that caused by the filtered blood- 

 serum of sick hogs corresponds perfectly with the sponta- 

 neous disease, and is quite as contagious. The hog-cholera 

 bacillus is markedly pathogenic for laboratory animals. Small 

 quantities introduced subcutaneously into rabbits or mice 

 kill them in from seven to twelve days. Guinea-pigs are 

 less susceptible, o.i c.c. of a virulent culture often being 

 required to kill them. 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. 



Pigeons are still more refractory, and Smith found that 

 0.75 c.c. of a bouillon culture injected into the breast- 

 muscles was required to kill them. 



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. The tem- 

 perature abruptly rises 2-3 C., and remains high until 

 death. Subcutaneous injection of larger quantities may 

 kill in five days. Injected intravenously in small doses the 

 bacillus may kill rabbits in forty-eight hours. 



Lesions. When the rabbit is examined post-mortem, 

 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, 



