CONTAGIOUS PLEUROPNEUMONIA. 



DESCBIPTIOX 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 right and left principal lobes. 

 These are the largest and are situated posteriorly, resting upon the 

 diaphragm; b, b', the ventral lobes, situated between 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") ; 

 (J, 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, a') were primarily affected. 



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

 affected with collapse and beginning bronchopneumonia. The light 

 yellowish portions represent healthy lung tissue ; the red represents 

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

 quite faint, indicating little or no inflammation of the connective tissue 

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

 the level of the diseased portion. In contagious pleuropneumonia the 

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

 than the healthy. 



Plate XXXI. Contagious pleuropneumonia. 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 thickening of the interlobular 

 connective tissue into broad whitish bands and of the walls of the air 

 tubes, veins, and arteries : «, air tube cut obliquely ; a', air tube cut 

 directly across ; h, arteries cut across ; c, large vein completely occluded 

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

 the walls of the artery and vein in this 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 the principal lobe in a case of acute pleuro- 

 pneumonia, illustrating the different kinds of hepatization or consolida- 

 tion of the lung. These are indicated by the different colors from 

 dark red to reddish yellow. This variation of color is regarded by 

 some as the real marbling characteristic of pleuropneumonia, w^hile the 

 whitish bands penetrating the lung tissue in all directions constitute 

 the true marbling according to other observers. 



Plate XXXII. Contagious pleuropneumonia. This illustrates what are called 

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

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

 is filled with blood and solidified. This is caused by the plugging of 

 the vein carrying away the blood from this portion. The heart forces 

 the blood through the artery into the ti.ssue 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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