ns
loose, fibrinous plugs, or it may be greatly distended with air, especially
in the still normal portions of the lung. The pleura is seldom seriously
diseased. If we contrast with these features the firm dark-red
hepatizations, the plugging of the veins, the extensive interlobular
deposits, and the well-marked pleuritis in pleuropneumonia, there is little
chance for confusion between well-developed cases of these two lung
diseases.

It should not be forgotten, however, that the lesions of the disease known
as contagious pleuropneumonia may be confined to the serous membranes of
the thorax, or they may be confined to the parenchyma of the lungs; they
may affect a whole lobe, or only a small portion of it; they may or may not
cause the so-called marbled appearance. In the same way bronchopneumonia
may vary as to the parts of the lung affected, the extent of the lesions,
the degree and kind of pathological changes in the interlobular tissue, the
color of the lung on cross section and the amount of hepatization. In
individual cases, therefore, it is often necessary to take into account the
history of the animal, the course of the disease, and the communicability
of the affection before a diagnosis can be made between the two diseases.

_Prevention and treatment._--The prevention of pleuropneumonia, as of other
contagious diseases, consists in keeping animals so that they will not be
exposed to the contagion. As the disease arises only by contagion, there is
no possibility of an animal becoming affected with it unless it has been
exposed. If, therefore, pleuropneumonia exists in a locality the owner of
healthy cattle should make every effort to keep his animals from coming
near affected ones or which have been exposed. He should be equally
particular not to allow persons who have been on the infected premises to
visit his own pastures, stables, or cattle.

If pleuropneumonia breaks out in a herd, every animal in it should be
slaughtered, the stables thoroughly cleaned and disinfected, and no other
cattle allowed on the premises until a period of 90 days has elapsed.

Medical treatment of affected animals is unavailing and should not be
attempted. No matter how valuable the diseased animals may have been before
they contracted the disease, they should at once be destroyed and the
contagion eradicated. This is the best policy for the individual as well as
for the community.

The eradication of this disease by local or Na