PLEUROPNEUMONIA. 
831 
and diarrhoea is often present. Percussion of the affected 
side elicits a dull sound quite unlike the drum-like re- 
sonant tone which is given out when the healthy chest 
is struck. 
If the animal is allowed to live it becomes extremely ema- 
ciated, and the breathing day by day is more laboured as the 
respiratory surface is decreased by continuous deposits, until 
at length the breathing is carried on through the mouth, 
which is opened in a gasp at every inspiration, and the animal 
soon dies from exhaustion. 
Post-mortem appearance . — According to the duration of the 
disease the lungs will be more or less affected. The right 
lung is believed to be more frequently affected than the left, 
and the diseased surface will vary from a patch of a few 
inches square to the great part or whole of one lung ; 
sometimes portions in both lungs are affected, and occasion- 
ally a mass of lung tissue in the centre of one lung is impli- 
cated, all other parts being healthy, and instances where 
animals have recovered from this form of the disease, the 
effected portion of the lung has been found, when the ox was 
slaughtered, quite separated from the surrounding healthy 
tissue and enclosed in a fibrinous covering. Effusion of 
serous fluid into the cavity of the chest is an invariable con- 
comitant of the last stage of the disease, and coincident with 
this there are usually observed large accumulations of fibrin 
on the surface of the lungs or rather of the membrane which 
is reflected over them. 
In old cases of the disease it often happens that the lungs 
become affected with abscess ; but suppuration or the forma- 
tion of matter is not one of the ordinary results of pleuro- 
pneumonia, the affection not being of an actively inflammatory 
character, but rather belonging to the class of infectious 
fevers, the local disease in the lungs being always congestive, 
and therefore passive rather than active. Lesions of other 
parts, such as congestion of the leaves of the third stomach 
(many plus), spots of extravasated blood in the ventricles of 
the heart, and other complications which are interesting to 
the pathologist, are met with, but they are not of much im- 
portance to the agriculturist who is principally concerned 
with those post-mortem appearances which will enable him 
to distinguish the disease. 
Microscopic appearances of the morbid parts . — Numerous 
examinations of the tissues of animals affected with pleuro- 
pneumonia have established the fact, that there is nothing in 
the products of the disease which can be properly termed 
characteristic. The material which is deposited in the con- 
