Fost-Mqrtem Appearances. 47 



On the surface of the diseased lung and to a less ex- 

 tent on the inner side of the ribs is a fibrinous deposit 

 (false membrane), varying from the merest rough pellicle 

 to a mass of half an inch in thickness, and in the worst 

 cases firmly binding the entire lung to the inner side of 

 the chest and to the diaphragm. These false membranes 

 are usually of an opaque white, though sometimes tinged 

 with yellow, and in the deeper layers even blood-stained, 

 especially over an infarcted lung. A noticeable feature 

 of these false membranes and one that serves to distin- 

 guish them from those of ordinary pleurisy is that they 

 are commonly limited to the surface of the diseased por- 

 tion of lung, or if more extensive that portion which cov- 

 ers sound lung tissue is much more recent, and has prob- 

 ably been determined by infection from the liquid thrown 

 out into the chest. 



In the lung itself the most varied conditions are seen 

 in different cases and at different stages of the disease. 

 The diseased lung is solid, firm and resistant, seems to 

 be greatly enlarged because it fails to collapse like the 

 nealthy portion when the chest is opened, is greatly in- 

 creased in weight and sinks in water. When cut across 

 it shows a peculiar linear marking (marbling) due to the 

 excessive exudation into the loose and abundant connect- 

 ive tissue which separates the different lobules of the ox's 

 lung from each other. This exudation is either clear, and 

 therefore dark as seen by reflected light, or it is of a yel- 

 lowish-white, and when filled with it the interlobular tis- 

 sue appears as a net-work, the meshes of which vary from 

 i. line to an inch across, and hold in its interspaces 

 the pinkish-gray, brownish-red, or black lung tissue. 



When only recently attacked the lung may present two 

 essentially different appearances : 



1. Most frequently the changes are most marked in 

 the interlobular connective tissue, which is the seat of an 

 abundant infiltration of clear liquid, a sort of dropsy. 



