DISEASES OP THE BLOOD. 137 



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 peri-bronchial 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 these embolic plugs. 



'^ 6. Thus numerous arteries of varying size may be 

 stopped up. 



" 7. The most varied forms of hsemorrhagic 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." 



Thus we are advanced a stage in our knowledge of the 

 pathology of this disorder. We see that in it, as in other 

 specific affections, the poison localises itself in a special 

 tissue, and there originates specific lesions. Sometimes 

 the disorder rapidly runs its course, leading to death from 

 congestion of the lungs ; more frequently it progresses 

 as above described, lasts for six weeks or two months, 

 and causes death by anaemia. In other cases, making an 

 average which varies much (from 20 per cent, to 70 per 

 cent.)' in different outbreaks, recovery takes place. The 

 animal passes through a prolonged convalescence, during 

 which, it is said, he is capable of communicating the disease, 

 and ultimately may be fattened for the butcher. Animals 



