56 SWINE PLAGUE 



eased ventral lobe, and that the resting of a lobe against an in- 

 flamed serous surface, such as the pericardium, caused a pneu- 

 monic infiltration at the point of contact. 



The character and seat of the lung lesions are somewhat 

 variable. It is difficult to find two lungs exactly alike so far 

 as gross appearances go. This to be sure may be due largely 

 to the fact that animals die in different stages of the disease. 

 Yet there are differences evidently not dependent on this fact 

 which must be left for special pathological investigation. 



In general the cephalic (anterior) half of a swine-plague 

 lung is hepatized, of a dark-red or grayish-red color and firm 

 to the touch. The pleura is more or less thickened and 

 opaque, and possibly covered with easily removable, friable, 

 false membranes. In the more recently affected regions a 

 faint but quite regular delicate mottling with yellow is 

 observed to shine through the pleura when not thickened. 

 These minute hazy, yellowish dots usually occur in groups of 

 four. Occasionally whitish or yellowish patches varying 

 much in size are seen perhaps more frequently in the ventral 

 lobes. These correspond to homogeneous dead masses of lung 

 tissue. 



When such lungs are cut open, the section presents much 

 the same appearance, both as regards color, and mottling, as 

 when viewed from the surface, excepting that the details are 

 less distinct. In some cases in the most recently invaded ter- 

 ritories in the principal lobe and nearer the dorsum in the 

 other lobes, the dark or grayish-red cut surface shows grayish 

 lines usually arranged in curves and circles. These, so far as 

 determined, represent the cut outlines of the interlobular and 

 peribronchial tissue infiltrated with cells. It has already been 

 stated that these lines ma}^ represent the paths along which 

 the swine-plague bacteria invade the lungs from the pleural 

 surface. 



The cut ends of the bronchi of the ventral lobes are fre- 

 quently occluded with thick, whitish pus ; in the other lobes 

 a reddish froth is usually present. Rarely they also contain 

 thick glairy mucus in which particles of dry pus and lung 

 worms are imbedded. The contents of the air tubes in the 



