132 Swine Plague. 



pericardium. The peribronchial lymph glands are acutely 

 swollen, and not infrequently studded with small hemorrhages. 



The mucous membrane of the stomach and intestines shows 

 a catarrhal swelling and frequently also numerous hemorrhagic 

 spots. In some cases the surface is covered with fine croupous 

 pseudo-membranes, or it may appear as though sprinkled with 

 bran as a result of the necrosis of the epithelium. These 

 changes are especially marked in the posterior part of the small 

 intestines or in the large intestine. The solitary follicles and 

 the Peyer's patches are swollen or contain shallow ulcers. 

 The spleen usually shows no changes or only a slight swelling. 

 Sometimes it contains several pale-red firm areas. ■ The kidneys 

 are hyperemia, and some wedge-shaped portions are sometimes 

 grayish in color. 



In the chronic cases the lungs of the greatly emaciated 

 carcass show extensive necrotic foci without any signs of acute 

 inflammation. Exceptionally there may be sequestra inclosed 

 in thickwalled cavities or cavities which communicate with 

 the bronchi. In other cases fairly large hepatized areas of the 

 lungs are studded with numerous small yellow or gray necrotic 

 foci. 



Caseous foci may also be found in the peribronchial and 

 mesenteric glands, in the tonsils, in some joints, in bones and 

 in the subcutaneous connective tissue. Possibly also so-called 

 caseous inflammation of the intestines, in which the mucous 

 membrane of the large intestines is broken down forming a dry 

 mushy mass, belongs to the anatomical lesions of swine plague 

 (Schiitz, Peters). 



In the peracute cases the bipolar bacteria are present 

 usually in great numbers in the blood and in all organs. In 

 subacute cases they may be' found in the affected parts of the 

 lungs, the bronchial secretion and in the exudate of the serous 

 membranes, sometimes also in the blood and likewise in great 

 numbers. On the other hand, in the chronic cases they may be 

 demonstrated only in the necrotic regions, mostly in association 

 with other bacteria and even in such cases they may be detected 

 only with great difficulty. 



According to the histological examinations of Marek the hemor- 

 rhages develop either as a result of bacterial emboli or as a result of 

 a toxic affection of the walls of the blood vessels (the latter especially 

 in the kidneys). The infarcts of the lungs and kidneys may also 

 result from thrombosis of blood vessels. The pneumonia is rarely 

 catarrhal but more frequently croupous, developing in its later course 

 a coagulation necrosis. Coagulation necrosis may also be observed 

 in small foci in the liver and in the adrenals. The nephritis, which 

 is present in all acute cases, leads to parenchymatous degeneration of 

 the epithelial cells, serous infiltration of the interstitial tissue, hemor- 

 rhages and necrotic foci. 



Symptoms. After artificial infections by subcutaneous or 

 intratracheal injections or by inhalation of virulent material, 

 the time of incubation is usually only a few hours or one to 



