180 THE DISEASES AND DISOEDEES OF THE OX. 



rule the inflammation is more marked in the lung tissue itself 

 than in the pleurae, but in some cases the reverse is said to be 

 the case. 



The air-tubes, the veins, arteries, and lymphatics, are sur- 

 rounded externally by exuded lymph, and at the same time 

 tend to be obliterated internally by the clots which are formed 

 within them. Many of the air-tubes generally contain frothy 

 serum, and those of the diseased part are frequently occluded 

 by clots of fibrine, which may extend into the larger tubes as 

 hollow cylindrical masses. Thus we find in the interior of the 

 wind-pipe and of the bronchial tubes large quantities of coagu- 

 lated lymph, which sometimes blocks up the passages to such 

 an extent as to form hollow or solid counterparts of the 

 air-tubes. This has been also seen in cases of sporadic 

 pleuro-pneumonia. 



The lining membrane of the chest, the pleura, is in a healthy 

 animal smooth, glistening, and transparent ; but when it has 

 been inflamed, it has an opaque and rough appearance. 

 Butchers sometimes strip the ribs of their pleural covering in 

 order to disguise the marks of disease. The ribs will then be 

 seen to present an unnaturally clean, white appearance. The 

 flesh of animals which have died of the malady is dark, harsh, 

 unhealthy in appearance, moist, or even dropsical. The fat also 

 is yellowish, and there is a general absence of blood. 



Preventive Teeatment. — We now complete our present 

 subject, pleuro-pneumonia, and as we approach that part of 

 it which is at once most interesting and most deeply involved 

 in doubt, we cannot forbear looking forward in imagination to 

 the standpoint of men who will be writing on this all-important 

 topic of preveutive measures years hence. 



In view of what has already been done by means of vacci- 

 nation, and also by inoculation with attenuated virus, we may 

 well believe that by no means the last word has been said 

 regarding these most important operations. 



We have said above that the mortality in cases of epizootia 

 pneumonia is about 52 per cent. Oxen which recover, having 

 escaped the notice of those who would otherwise have ordered them 

 to be slaughtered, may be said to have been, as a rule, affected 

 only in one lung. If both are diseased, there is small chance 

 of the avoidance of death. With regard to treatment, the first 



