Encysted Masses. 51 



If at a later stage we open an animal which has passed 

 through the above condition, the following may be met 

 with : A hard, resistant mass is felt at some portion of 

 the lung, usually the lower and back portion, and on 

 laying it open it is found to consist of dead lung tissue 

 in which the hepatized lobules and interlobular tissue, 

 the air tubes and blood vessels are still clear and dis- 

 tinct, but the whole is separated from the still living lung 

 by a layer of a white pus-like liquid, outside which is a 

 dense, fibrous sac or envelope, formed by the develop- 

 ment of the surrounding interlobular exudation. From 

 the inner surface of this dense cyst, the firm, thick bron- 

 chial tubes and attending vascular systems project in a 

 branching manner like dirty white stalactites, and these 

 with the interlobular tissue thickened by its now firmly 

 organized exudation, may form bands extending from 

 side to side of the cavity. (See engraving.) 



At a still more advanced stage the dead and encysted 

 lung tissue is found to have been entirely softened and 

 the sac contains but a mass of white liquid debris, or, 

 still later, a caseous mass of its dried, solid matters, 

 upon which the fibrous covering has steadily contracted, 

 so as to inclose but a mere fraction of its original area. 

 In hundreds of post mortems we have only once seen 

 the dead and encysted lung the seat of putrid decompo- 

 sition, and never found the cavity opening into a pervious 

 air tube. 



There remains to be noticed the condition of the air 

 tubes and accompanying vessels in the diseased lungs. 

 In all cases where we see the starting point of the dis- 

 ease we find in the small tubes leading to the affected 

 lobules, a loss of the natural brilliancy of the mucous 

 membrane which has become clouded and opaque, and 

 the tissue beneath it infiltrated and thickened. In more 

 advanced cases and above all, in those showing the drop- 

 sical condition of the interlobular tissue, we find a simi- 



