BUREAU OF ANIMAL INDUSTKY. 



653 



Tliese inoculations having failed to produce immunity from natural 

 infection, a second experiment was tried by augmenting the dose of 

 strong virus used for the second inoculation. Thus Nos. 239, 242, 244, 

 and 245 received each i"'^ for the first inoculation May 27, No. 243 be- 

 ing retained in the same pen as a check. Of these No. 239 died of 

 hog-cholera as the result of the inoculation. The remaining three, 

 received two weeks later, on June 10, 2"" each of strong virus. The 

 cultures were prepared in beef infusion with 1 per cent, peptone. 

 They were usually the third or fourth culture, not more than one day 

 old. A second lol (Nos. 240, 254, 255, and 256) were inoculated at the 

 same time and in the same way, with this exception, that the second 

 dose was increased to 3'=*'. On June 24 all were placed in the large 

 infected pen. 



No. 239 died June 2, v.-ithin six days after receiving |" of the culture and as a re- 

 sult of the inoculation. The lesions vrere those of a very acute case, engorged spleen 

 and lymphatics, intense congestion of the mucosa of tlae large intestine and of the 

 intestinal tract in general. The lungs were likewise engorged and dotted with ex- 

 travasations. This animal was eating and apparently well on the morning of death. 

 The spleen was crowded with the bacterium of hog-cholera, and pure cultures of the 

 microbe w^ere obtained from it. 



No. 242 died July 17. The characteristic lesions of hog-cholera were found in it; 

 extensive ulceration of the caecum and colon; engorgement of spleen and lymphatic 

 glands with blood. Encysted masses at the point of inoculation. No. 224 succumbed 

 July 9 with practically the same lesions, besides the presence of a considerable quan- 

 tity of sermn in the abdominal ca%'ity. 



The check to this lot died July 13. The depth of the ulcerations in the cfecum 

 and colon had impUcated the serous covering, so that adhesions had formed between 

 the caecum and abdominal walls. Punctiform ecchymoses on serosa of ileum; the 

 mucosa not affected. The mucosa of ca?cum was found completely ulcerated, the 

 necrosis stopping abruptly at the edge of the valve; in the colon the necrosis re- 

 solved itself into large isolated ulcers. 



Of the second lot No. 240 died July 10. At the place of inoculation a firm pale 

 yellowish mass about one inch long was found. The lower portion of ileum, the 

 CEecum, the upper portion of colon, contained ulcers of different sizes. The duode- 

 num was occluded by a clot of blood. No. 254 died the same day with lesions of a 

 similar character. No. 255 died July 20. The spleen in this case was greatly aug- 

 mented in size and goi'ged with blood. The right lung was congested and adherent 

 to wall of thorax; considerable effusion in this pleural sac. The caecum and upper 

 portion of colon covered with deep blackish ulcers. A few small ulcers in ileum. 



* Check. 



tFrom inoculation. 



The foregoing experiments demonstrate the important fact that pigs 

 cannot be made insusceptible to hog-cholera by subcutaneous injec- 

 tions of pure cultures of hog-cholera bacteria. This method, which 

 was originally suggested and applied by Pasteur to anthrax and 

 rouget, therefore fails in this disease. , The experiments have been 

 sufficiently varied and extended to leave no doubt as to this point. 

 The subcutaneous injection of large as well as small quantities of cult- 



