BUKEAU OF ANIMAL INDUSTRY. ■ Q21 



On examination the skin of No. 3 was found discolored at the place of inocula- 

 tion. The surface of the muscular tissue at tliis point was dotted with ecchymoses, 

 interspersed with whitish areas which corresponded to altered muscular tissue! 

 Tliis was wliitish, friable, evideutly dead. Such masses could be found to a depth 

 of 1"^'" in the muscles of the thighs. This alteration seemed to follow along the 

 planes of the intermuscular septa. A patch about 1<^™ in diameter on the muscular 

 wall of the abdomen contiguous with the place of inoculation was similarly affected. 

 In the a,bdomen the vessels of the intestine were injected, spleen full of blood, mottled 

 dark red and grayish, friable. Lungs somewhat congested. The stomach con- 

 tained a small mass of food embedded in considerable viscid translucent mucus; the 

 caecum and large intestme were filled -with a yellowish soft food mass. 



The bacteria of hog-cholera were present in largo numbers in the liver and 

 spleen. There were fewer in the kidneys and lungs ; very few in blood from the heart. 

 A tube culture m gelatine from the spleen developed nimaberless colonies in each of 

 three needle tracks, gi-owing precisely like cultures from the spleen of swine. A 

 liquid culture from the blood showed the motile bacterium on the following day, 

 and line cultures made therefrom revealed the same grovsrth on plates as that* from 

 swine. 



Guinea-pig No. 4 presented the same local as well as general lesions. The spleen 

 was dark in spots and very friable. Vessels of the mesentery injected. The bac- 

 teria were as abundant in the organs as in No. 3. Cultures made as described for 

 No. 3 proved identical with the latter. 



These animals are as a rule more refractory than rabbits with reference to the 

 virus of rouget, rabbit-septicaema, and a new pathogenic microbe described in a 

 subsequent section of this report. 



Microscopic examination of tissues of infected ariimals. — In sec- 

 tions of 4:issues from cases of hog-cholera, cnt after being imbedded 

 in pure paraflBne,_ the bacteria stain very well in aniline water methyl- 

 violet. The sections may be treated afterward with a i per cent, solu- 

 tion acetic acid without removing the stain. Treated in this way and 

 examined with a ^V or -iV homogeneous immersion the bacteria ap- 

 pear in plugs or clumps, never isolated. In the spleen such colonies 

 are seen in thespleen pulp near the trabeculse; in the kidney the plugs 

 are rare even in the most hemorrhagic cases. In sections of the wall 

 of the large intestine of a recent case in which there was much extrav- 

 asation, the submucous tissue was infiltrated with red blood corpus- 

 cles, which had forced their way between the bundles of areolar tissue 

 and among the fat cells. Occasionally masses of corpuscles were seen 

 beneath the serosa. In a number of sections carefully examined no 

 bacteria could be detected. 



When we take into consideration the coagulation necrosis produced 

 by this bacterium when injected beneath the skin in mice, pigeons, 

 rabbits, and guinea-pigs, and its tendency to grow in plugs or colo- 

 nies, the hemorrhagic effect is easily explained. The growth in the 

 smaller blood vessels coming in contact with the walls destroys them 

 and gives rise to extravasation. In the intestinal mucosa the extrav- 

 asation may lead to a cutting off of the food supply and consequent 

 necrosis and ulceration. 



The liver of a mouse which had succumbed to hog-cholera, inter- 

 spersed with whitish specks and patches of necrosed tissue, was ex- 

 amined in the same way. The section contained unstained areas 

 corresponding to the patches of coagulation necrosis seen with the 

 naked eye. These unstained areas are dotted with stained, shriveled 

 nuclei and surrounded by a zone of leucocytes. The bacteria are 

 found m small clumps both within and on the periphery of the un- 

 stained areas. They are also present in the capillaries of the sur- 

 rounding tissues. In the larger vessels they are present, but scattered. 



In the muscular wall of the abdomen of a guinea-pig invaded from 

 the seat of inoculation on the thigh the bacteria had penetrated in 



