Pathogenesis, Anatomical Changes. 



395 



through the body ; this is substantiated by the experience that 

 in sucking calves inflammations of the joints develop sometimes 

 by way of metastasis, and that in some cases changes charac- 

 teristic of contagious pleuro-pneumonia are found in the lungs 

 of fetuses of diseased pregnant animals. 



The virus evidently exerts its pathogenic action through toxins. 

 This conception is supp6rted by the character of the inflammatory proc- 

 esses and the fever, 

 also by the fact that 

 rabbits, in the abdomi- 

 nal cavity of which the 

 virus propagates for a 

 time inside of collo- 

 dion sacks, die months 

 afterwards from ca- 

 chexia, although the 

 virus proper has ap- 

 parently not passed 

 into the circulation of 

 the body. According 

 to Arloing the exudate 

 contains a. toxic sub- 

 stance, which may be 

 precipitated by alco- 

 hol, does not lose its 

 activity when heated 

 to 80°, but produces a 

 very severe intoxica- 

 tion if inoculated even 

 in very small quanti- 

 ties into the blood of 

 cattle and goats. 



Anatomical 

 Changes. In acute 

 cases a smaller or 

 larger part of the 

 lungs is found hep- 

 atized, free from air 

 and not elastic; on 

 incision a clear 

 serous, yellow fluid 

 oozes from the out 

 surface in great 

 quantities and later 

 coagulates to a gela- 

 tinous mass. The 



a pale yellow network, formed by an increase of the interlobular 

 connective tissue, which separates the hepatized lung into 

 various sized islands, and according to the stage of hepatization 



Fig. 63. Cut surface of the lung in contagious pleura- 

 pneumonia: ( a ) normal lung tissue ; (b) red hepati- 

 zation; (c) gray hepatization ; (d) incipient necrosis ; 



(e) interalveolar septum with dilated lymph spaces; 



(f) blood vessels with thrombus; (g) bronchi. (After 

 a preparation of the pathologic anatomical collection.) 



