830 
PLEUROPNEUMONIA. 
blance to any other lesion of the lung structure. A section 
of the diseased tissue is said to present ,f a marbled appear- 
ance/’ and there is probably no term which will better 
express the condition as it appears to the unscientific ob- 
server. The white lines of newly-deposited fibrin, varying 
from the eighth of an inch to an inch in breadth, intersecting 
the dark masses of the congested lobules, give to the morbid 
part an aspect which can never be mistaken after it has once 
been carefully examined; and it may be said of pleuro- 
pneumonia, that its lesions are so well defined, that the 
evidence which is afforded by a post-mortem examination is 
absolutely conclusive. 
Inspection of those organs of the animal body which are 
principally implicated in the disease, however minute and 
complete it may be, only puts us in possession of a know- 
ledge of effects. It is evident enough that the lungs have 
O ^ o o 
received an excess of blood, and that a large quantity of the 
circulating fluid had been exuded into the tissue of these 
organs ; but the really important question is. What circum- 
stances conduced to these results ? And the only answer 
which the pathologist can offer is contained in a somewhat 
vague reference to “ blood poisoning.” As in other con- 
tagious diseases the blood of the animal affected with pleuro- 
pneumonia becomes charged with some poisonous material, 
which is excreted by the vessels of the lungs; for example, 
in small-pox, the virus is excreted by the skin, and the poison 
of the cattle-plague by the mucous membrane. In each case 
it is impossible to define the determining causes. We can 
no more understand why some of the constituents of the 
diseased blood are poured out in large quantity in the fibrous 
tissues of the lungs in pleuropneumonia than we can com- 
prehend the ultimate cause of the distinctive eruptions in the 
various exanthematous diseases. 
Symptoms of Pleuropneumonia . — The early indications of the 
disease are not very definite in character : a dry husky 
cough, with slight derangement of the appetite, diminution 
of the quantity of milk, and dulness of aspect are the prin- 
cipal signs; in the event of the disease being in the neigh- 
bourhood, however, these symptoms are suggestive enough 
to induce the owner to apply preventive measures, or to con- 
sign the affected animal to the butcher without waiting for 
the development of the malady. As the affection advances 
the breathing is disturbed, and when it is fully established 
the respiration is carried on with a peculiar grunt, the animal 
stands with the back arched, the cough is frequent and pain- 
ful, the appetite is almost lost, the secretion of milk ceases. 
