614 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



congested, and extensive liemorrliages into tlie submucous tissue, often 

 into the lumen of the digestive tube, take place. These lesions have 

 been described somewhat in detail in the last report. The si)leen and 

 blood are found to contain a large number of the hog-cholera bac- 

 teria. 



Both typos of the disease produced by feeding lead to a speedy termi- 

 nation by death in from six days to two weeks. The difference above 

 given may perhaps be referred to a difference in the virulence of the 

 bacteria. In the type first described the bacteria may be loss adai)ted 

 to a parasitic life. Their poisonous effects are exerted hjcally in de- 

 stroying the mucous membrane. In the second type the bacteria are 

 capable of entering the blood, to be distributed to all the organs where 

 the hemorrhagic lesions are caused by their growth. 



(b) Feeding pure culhires of the bacterium of hog-cholera. — In 

 the preceding report (p. 207) two very severe cases of hog-cholera 

 are reported as having been produced by the feeding of pure liquid 

 cultures. These positive results are not always obtained, as some of 

 the following experiments indicate: 



Pigs Nos. 155 and 156 were fed February 8, 188G. with 200« of a beef-infusion 

 peptone culture derived from a mouse wliich had succumbed to inoculation. The 

 animals remained well. Pig No. 155 was fed February 1 with lOO"""^ of liqiiid cult 

 ures of the bacterium of hog-cholera without manifesting any symptoms of disease 



The rapidly fatal effect from the ingestion of the viscera of swine 

 containing the specific bacterium may be harmonized with the nega- 

 tive results above recorded when we consider the different condition 

 of the bacterium in the liquid cultures and in the infectious viscera. 

 In the latter case the bacteria are enveloped by connective and cel- 

 lular tissue, which protect them from the destructive effect of gastric 

 digestion, so that they are carried into the intestine wdiere the path- 

 ological lesions are first manifested. In culture fluids the bacteria 

 are in the most vulnerable state, and are easily accessible to the ac- 

 tion of the gastric juice, which very probably does not permit any to 

 pass alive into the duodenum. 



That the condition of the stomach is a very important factor in the 

 production of the disease when the virus has entered it seems a very- 

 reasonable assumption. If the virus reaches the empty stomach 

 coated with an alkaline mucus it is more likely to multiply and reach 

 the duodenum than when the stomach is filled with food which is 

 being actively digested. In order to test this assumption the follow- 

 ing experiment was tried: 



December 13. — Three pigs were fed each with 300'^'= of beef infusion in wliich the 

 bacterium of hog-cholera had been multiplying for three days at a temperature of 

 90° to 95° F. The beef infusion had been neutralized, and sterilized in two Hasks, 

 and the cultures, when examined before the experiments, were found to contain the 

 motile bacterium only. 



The pigs were prepared for the feeding as follows: No. 348 received no food for 

 over twenty-four hours. A 3 per cent, solution of sodium carbonate in beef in- 

 fusion was "then given to increase the alkalinity of the stomach. Of this about 1 

 liter was consumed. It was then fed with 300'^^'= of culture Uquid mixed with beef- 

 broth to make 1 liter. No. 350 was starved in the same way, but received no alkali 

 before consuming the culture. No. 342Hvas not deprived of food before eating the 

 culture. 



The result confirmed our anticipations. No. 348 showed signs of disease in two 

 days. On the third it was unable to rise, and died on the same day. The jwfit 

 mortem examination showed a considerable congestion of the mucous membrane of 

 the duodenum and jejunum, as well as of the large intestine. The fundus of stomach 

 affected in the same way. The Uver was gorged \\'ith blood, as well as the portal 

 system. There were no marked lesions of the other viscera. That the hog-cholera 



