208 DISEASES OF THE PARENCHYMA OF THE LUNG. 



debilitated by misery and deficient nourishment ; as is also its frequent 

 appearance in lunatics, even where no foreign body has entered their 

 air-passages, and its occurrence in the course of severe asthenic fever, 

 measles, small-pox, and typhus. It would seem, indeed, as if a part, 

 which already has suffered derangement of its nutrition, were espe- 

 cially liable to die when its tissues are exposed to further inflammatory 

 disturbance ( Virchow). 



ANATOMICAL APPEARANCES. According to the distinction of 

 Laennec, there are two forms of pulmonary gangrene, the circum- 

 scribed and the diffuse : 



1. Circumscribed gangrene is the more common form. At isolated 

 points varying in size, from that of a hazelnut to that of a walnut, we 

 find the parenchyma of the lung converted into a bluish-green, moist, 

 frightfully fetid slough, resembling the eschar of the skin produced by 

 caustic potash. It is abruptly limited, and surrounded by cedematous 

 tissue alone. This sphacelous spot, which is at first tolerably firm, and 

 adherent to the adjacent parts, soon decomposes into an ichorous liquid, 

 which merely contains in its interior a somewhat hard greenish-black 

 core, mixed up with rotten and ragged debris of the tissue. 



The seat of circumscribed pulmonary gangrene is generally the 

 periphery of the lung, and the lower lobes. Not unfrequently a bron- 

 chus opens into the gangrenous spot ; the ichor of the slough enters 

 the tube, and an intense bronchitis is the result. 



In a few cases, the pleura also mortifies ; the slough softens, the 

 ichor flows into the cavity of the sac, and thus a dangerous pleuritis is 

 set up ; and if the gangrenous centre at the same time communicates 

 with a bronchus, pyopneumothorax may occur. In other instances, 

 diffuse gangrene arises from circumscribed gangrene of the lungs. In 

 very rare cases indeed, interstitial pneumonia arises in the surrounding 

 parts, resulting in incapsulation of the gangrenous point ; the sloughs 

 are ejected and cicatrization follows, such as we see in pulmonary 

 abscess. 



2. Diffuse gangrene of the lung not unfrequently attacks an entire 

 lobe. We then find the parenchyma decomposed and converted into 

 a putrid, tinder-like, black, stinking substance, saturated with blackish- 

 gray ichor. Unlike the preceding form, the process is not abruptly 

 limited, but is gradually merged in the oadematous or hepatized paren- 

 chyma. If the mortification reach the pleura, it too is destroyed. 

 Recovery never takes place, the patient dying of general constitutional 

 disturbance. 



Either form of gangrene may lead to introduction of decomposed 

 tissue into the veins, to embolism, and to metastatic abscess in thf 

 carious organs of the greater circulation. 



