396 Contagious Pleuro-pneumonia. 



they appear gray, pale red, or dark brownish-red in color 

 (variegated, marble-like cut surface; Fig. 63). In the broader 

 beams of the network the dilated lymph spaces are found as 

 round, oval or fissured depressions, filled with yellow lymph or 

 more fibrinous exudate, while the imnaediately adjoining con- 

 nective tissue appears uniformly gelatinously infiltrated. The 

 enclosed airless foci are pale red and fi,rm especially at the 

 border of the hepatized lung portion, sometimes on the periph- 

 ery, while the center is still dark red and elastic. The walls 

 of the bronchi in the affected parts of the lungs also show 

 serous infiltration and are dilated, while their lumen contains 

 much fibrinous exudate. The peribronchial and mediastinal 

 lymph glands are swollen and filled with fluid. 



The pleura over the affected parts of the lungs is sometimes 

 lusterless, injected and covered with a very fine, veil-like fibrin- 

 ous membrane. Usually however friable deposits 1-2 cm. thick, 

 pale yellow, are found on its surface, under which the pleura 

 appears thickened, and the underlying connective tissue is fre- 

 quently serously infiltrated. In the majority of cases the 

 pleural cavity contains at the same time more or less (some- 

 times up to 15 to 20 liters) clear yellow, or turbid, yellowish- 

 gray exudate mixed with fibrin-flakes, and in rare cases, the 

 mediastinal connective tissue is also saturated by a similar 

 exudate. 



In more chronic cases the connective tissue streaks on 

 the cut surface of the lungs consist of white, firm connective 

 tissue, while the lobules lying between them are uniformly hepa- 

 tized and necrotic, sometimes even calcified. In such cases 

 so called sequesters are found frequently in one or both lungs, 

 that is one or rarely several necrotic lung portions which are 

 from nut to fist size or even larger. Their surface is knobbed, 

 the outside layers mushy and softened, while the inside is still 

 firm, and the cut surface is diffusely mottled. The necrotic por-. 

 tions are enclosed in thick connective tissue capsules, to which 

 they are sometimes still partly adherent, and their inner sur- 

 face is covered with a gray, smeary mass. The capsule may be 

 closed or may communicate with the neighboring bronchus 

 (Arloing found a sequester enclosed in a connective tissue cap- 

 sule as early as the fiftieth day). Exceptionally even in the 

 lung tissue proper, dull yellow areas may be found, which are 

 only partly separated from the surrounding parts and show 

 evidences of acute inflammation, while in other cases evidences 

 of fresh pneumonia may be observed in the vicinity of an old, 

 encapsulated sequester. In the chronic cases the pleura is usu- 

 ally much thickened, but the surface may still be covered with 

 loose pseudo-membranes, or the pleural membranes may adhere. 



In some cases the autopsy may further reveal serous or 

 fibrinous pericarditis, similar inflammation on the peritoneum, 

 on the diaphragm, and in the portal portion of the liver; in 

 young calves sero-fibrinous inflammation may exist in different 



