Tii'port. on the Pathological Anatomy of Phitro-pncnmonia, 193 
like tunnels punched out of a resisting substance, such as a piece 
of turnip (see Fig. 2). The tissue about the blood-vessels is 
changed in exactly the same way as that around the bronchus, 
the elements becoming altered in a similar manner. 
After a time the walls of the blood-vessels become engaged, 
the external coat being first attacked, and the other coats in 
turn becoming thickened and rigid. Often the vessel wall may 
be increased to several times its normal thickness, and yet the 
intima looks healthy on the surface. Here and there the intima 
seems to be also affectiHl. Small red roughened patches are seen 
on the inner surface of the vessel. The colour seems to depend 
on staining with the blood contained within the vessel itself. 
When these rough patches are as large as two or three millimetres 
across, they are always coated over with a thin pale coagulum. 
These clots increase in thickness with the increase in size of the 
damaged patch. Often the intima seems destroyed around the 
entire calibre of the vessel, or for a considerable extent along one 
side. In these cases, where the roughness of the intima is exten- 
sive, the altered surface cannot be so well seen, as the clot which 
Fig. 4. — Showing Tliromhus of Artery, 
A. Artery. V. Bronchus. T. Thronibns, tapering off to a fine point of fresh coagiilura. 
1. Interlobular tissue. 
covers it is very thick (Fig. 4). The vessel is thus partially 
occluded by a thrombus, which, in the case of small vessels, soon 
VOL. XIV. — S. S. O 
