LOBAR PNEUMONIA. 339 



HEMORRHAGIC INFARCT. 



Infarctions are usually multiple, and occur in the centre of 

 the lower lobe, or near the root of the lung ; when superficial 

 they form a slight elevation beneath the pleura. They are 

 wedge-shaped, firm, brown in color, and are separated by a 

 distinct line of demarcation from the surrounding lung-tissue. 



FIG. 149. 



r 



Hemorrhagic infarct of the lung (Kaufmann). The section contains a portion of 

 the plugged vessel beyond the site of the embolus. It and the pulmonary 

 alveoli are filled with blood, which, in the latter, has passed through the capil- 

 lary walls, rendered pervious by malnutrition. This blood may be derived 

 from the pulmonary vein and also from the bronchial artery, which communi- 

 cates with the capillaries of the alveolar walls. 



Microscopically the air-spaces are found to be crowded with 

 red blood-corpuscles (see Fig. 149). 



Pneumonia is the term employed to designate inflammation 

 of the lung, in contradistinction to inflammation of the bronchi 

 or pleura. Histologically and clinically there are several 

 well-defined varieties of pneumonia : 



LOBAR PNEUMONIA. 



Lofcar pneumonia is an acute, infectious, self-limited disease, 

 with a definite clinical course, and characterized pathologic- 

 ally by an extensive inflammation of the lung, involving an 

 entire lobe. 



