om dark red to grayish or yellowish red are produced.

The complete plugging of the veins may lead to the death of circumscribed
masses of lung tissue. A line of separation forms between the living and
the dead tissue and a thick cyst wall of fibrous tissue forms around the
latter. The dead tissue for a time preserves the appearance of lung tissue,
then undergoes disintegration and liquefaction. The softened mass is
finally absorbed, and the walls of the cyst, or capsule around it,
gradually collapse and form a cicatrix. This favorable termination takes
place only when the dead mass is not too large. It may, however, involve
over half of one of the large lobes. Under such circumstances recovery is
improbable. A more favorable termination is the abundant growth of fibrous
tissue around and into the hepatized masses. The formation of fibrous
tissue may extend to the pleura, or lung covering, and cause firm adhesion
of the lungs to the chest wall and to the pericardium, or heart case.

The same peculiar, inflammatory changes which take place between the
lobules of the lung and around the bronchi and vessels may invade the
pleural cavity, cause extensive membranous and spongy deposits on the
pleura and firm deposits around the heart and large arteries, the gullet,
and windpipe.

These are the main features of the lung disease caused by contagious
pleuropneumonia. In the typical, acute cases there are a sufficient
number of peculiarities to enable us to make a positive diagnosis. There
are, however, many cases in which the disease is restricted to small areas,
or to the interlobular tissue, or in which the changes are still
imperfectly developed, or else so far advanced that doubts may arise as to
the true nature of the affection. In such cases all obtainable facts,
including the history of the case, the symptoms during life, and the
pathological changes observed on post-mortem examination must be taken into
consideration. Only one who has made a careful study of the disease is
fitted to decide in such cases.

Other kinds of lung disease, because of certain features common to most
lung diseases of cattle, may be confounded with pleuropneumonia. The
inflammation of the connective tissue between the lobules is not
infrequently observed in so-called interstitial pneumonia and may lead to
the formation of whitish bands intersecting the lung tissues in various
directions. On the cut surface these bands may give rise to a decide