190 Report on the Pathohgieal Anatomy of Pleuro-pneumonia. 
here and there some of the branches breaking off and remaining 
impacted in the tube. 
After the removal of the plug, the mucous membrane lining 
the bronchi is found to be rough and discoloured, and stripped 
of its epithelial lining. In the neighbouring tubes there is gene- 
rally intense congestion of the membrane, with patches and 
streaks of ecchjmosis scattered here and there over the surface. 
The longitudinal folds of the membrane are always greatly 
exaggerated, showing firm contraction of the wall of the tube. 
Throughout the opaque part which shows the actual focus of 
disease the mucous membrane is of a dull-grey, or muddy-yellow 
colour, uneven and rugged on the surface. 
Wherever the lining membrane of the bronchi is congested, 
they are found to have suffered more deeply. Their proper 
walls are thickened, their coats being separated one from the 
other by a kind of tough exudation. The walls of those air-tubes 
which contain the firm plugs are always enormously thick and 
dense. Even the small tubes, which are normally very thin, 
transparent, and yielding, become tough, opaque, and rigid 
canals, the wall often exceeding in diameter the lumen of the 
tube. Besides the thickening of the walls of the bronchi, their 
delicate connective sheath is implicated throughout the diseased 
part. This fine elastic substance becomes the seat of dense 
exudation, which changes the thin, yielding, cobweb-like sheath 
into a tough and rigid case (Fig. 2, A). This exudation 
Fig. 2. — Transverse Section of Broncho-vascular System, contrasting 
the Healthy with the Diseased State. 
A. In a state of advanced disease. A. Artery, partially excluded by a thrombus. B. Bronchus, 
contracted and plugeed. V. Vein. C. Common broncho-vascular sheath, thickened by exuda- 
tion. I. Interlobular tissue. P. Lobular parencliyma. 
B. A corresponding broncho-vascular system in health. 
appears to be very similar in character to that which fills the 
interlobular spaces, and it presents the same varieties and occupies 
the same relation to the tissue in both these situations. By means 
of the exudation, the peribronchial lymph-passages are rendered 
strikingly obvious, as if they had been filled with some pale opaque 
