Report on the Patholor/ico! Anatomij of Fkuro-pneumoiia. 205 
3. From the inflamed pleura infective materials reach the 
lymphatics beneath it, and also those lying between the neigh- 
bouring superficial lobules. 
4. Extending along the interlobular lymphatics, the irritation 
and exudation may pass towards the deeper parts, so that an 
immense tract of lung is converted into a semi-translucent mass 
with swollen interlobular spaces. 
The consolidation formed in any of these ways may become 
intense induration, if the animal live long enough. 
With regard to the origin of the disease of the vessel wall 
we must also start from the peribronchial disease. 
1. The lymphatics of the bronchus readily allow the morbid 
products to pass to those immediately around the vessels. 
2. The wall of the vessel becomes greatly thickened by 
chronic inflammatory products. 
3. The inner coat — which resists the disease for some time — 
ultimately becomes diseased in small patches. 
4. The blood coagulates over the diseased inner coat, and may 
occlude a small branch at its origin, or even the entire vessel. 
5. Particles of the clot may break off, and, passing into the 
minute arteries, form there embolic plugs. 
G. Thus numerous arteries of varying size may be stopped 
up- 
7. The most varied forms of haemorrhagic infarction are thus 
produced. 
8. The infarction may become gangrenous, cheesy, or may dry 
up into a crumbling mass. 
9. A capsule may form around the most diseased part, and 
shut it off from the rest of the lung. 
If asked to give a pathological definition of pleuro-pneumonia, 
1 should say that it was : — A chronic, specific, local disease, 
starting in the bronchi, and insidiously implicating the paren- 
chyma of the lung, by occlusion of the bronchi and inflamma- 
tion extending along the lymphatics : the other organs and the 
blood possess a singular immunity from the specific contamina- 
tion. It is not accompanied by constitutional symptoms, and 
only gives obscure physical signs. At any time during the 
progress of the disease its existence may be manifested clinically, 
by the occurrence of complications — acute pleurisy or haemor- 
rhagic infarction with pleural inflammation — which excite high 
fever, with various functional derangements. 
