CONTAGIOUS PLEUROPNEUMONIA. 



DESCRIPTION OF PLATES. 



Plate XXIX. Upper or dorsal surface of the lungs of the ox, reduced to one- 

 twelfth of the natural size: a, a', the ri^ht and left principal lobes. 

 Tlicse are the har'est and are situated posteriorly, resting u]>on the 

 diaphragm ; h, h', the ventral lobes, situated Ijetween the principal 

 lobes; and c, c', c" the most anterior, or cephalic, lobes. The right 

 anterior is divided into two lobes (c, c'), the left is single (c"); 

 (1, trachea, or A^indpipe. 



In the majority of the lungs examined in the laboratory of the 

 bureau which were affected with contagious pleuropneumonia the prin- 

 cipal lobes (a, «') were primarily affected. 



Plate XXX. Bronchopnumonia. The ventral or middle lobe of the right lung 

 affected with collapse and beginning bronchopneumonia. The liglit 

 yellowish portions represent healthy lung tissue; the red represmts 

 the disease. It will be noticed that the lines between the loljules are 

 quite faint, indicating little or no inflammation <<t the connective tissue 

 between the lobules. The healthy lung tissue is seen to be raised aliove 

 the level of the diseased portion. In contaginus pleuropneumonia the 

 exact reverse is the case, the diseased portions being very much larger 

 than the healthy. 



Plate XXXI. Contagious pleurc.ipneumonia. Appearance of a cow's lung af- 

 fected with contagious pleuropneumonia when sections or slices are 

 made of it and cut surfaces examined. 

 Fig. 1. Transverse section through the right principal lobe in a case of 

 acute pleuropneumonia. The area drawn includes the air tubes, veins, 

 and arteries, and illustrates the great thicki>ning of the interlobular 

 connective tissue into liroad whitish liands and of the walls of the air 

 tube.s, veins, and arteries: a, air tul>e cut oliliquely ; a', air tube cut 

 directly across ; b, arteries cut across ; c, large vein completely <iccluded 

 by a thrombus or plug formed during life. The great thickening of 

 the walls of the artery and vein in tins disease is especially brought 

 out by stating that in the healthy lung they are so thin as to be easily 

 overlooked. 

 Fig. 2. Transverse section of tlie principal lobe in a case of acute pleuro- 

 pneumonia, illustrating the different kinds of hepatization or consolida- 

 tion of the lung. Tliese are indicated liy the different colors from 

 dark' red to reddish yellow. This variation of cc^lor is regarded by 

 some as the real marltling characteristic of pleuropneumonia, while the 

 whitish bands penetrating the lung tissue in all directions constitute 

 the true marliling according to other observers. 



Plate XXXII. ('ontagious pleuropneumonia. This illustrates what are called 

 infarctions. The right half of the figure shows nearly normal lung 

 tissue. The left represents a blackish mass, in whicli the lung tissue 

 is filled with blood and solidified. This is caiised liy the plugging of 

 the vein carrying away the blooil from this portion. The heart f.irees 

 the blood through the artery into the tissue at considerable pressure, 

 but owing to the fact that its return is prevented, the minute blood 

 vessels rupture and the air vesicles become distended with blood, which 

 coagulates and causes the firmness of the tissue. 

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