he may safely be
put to regular work.

PNEUMONIA, OR LUNG FEVER.

Pneumonia is inflammation of the lungs. The chief varieties of pneumonia
are catarrhal--later discussed in connection with bronchitis, under the
name of broncho-pneumonia--and the fibrinous or croupous variety. The
latter form receives its names from the fact that the air spaces are
choked with coagulated fibrin thrown out from the blood. This causes the
diseased portions of the lungs to become as firm as liver, in which
condition they are said to be hepatized. As air is excluded by the
inflammatory product, the diseased lung will not float in water.

The inflammation usually begins in the lower part of the lung and
extends upward. The first stage of the disease consists of congestion,
or engorgement, of the blood vessels, followed by leakage of serum
containing fibrin from the blood vessels into the air passages. The
fluids thus escaping into the air cells and in the minute branches of
the little bronchial tubes become coagulated.

The pleura covering the affected parts may be more or less inflamed. A
continuance of the foregoing phenomena is marked by a further escape of
the constituents of the blood, and a change in the membrane of the
cells, which becomes swollen. The exudate that fills the air cells and
minute bronchial branches undergoes disintegration and softening when
healing commences.

The favorable termination of pneumonia is in resolution that is, a
restoration to health. This is gradually brought about by the exuded
material contained in the air cells and lung tissues being broken down
and softened and absorbed or expectorated through the nostrils. The
blood vessels return to their natural state, and the blood circulates in
them as before. In the cases that do not terminate so happily the lung
may become gangrenous (or mortified), an abscess may form, or the
disease may be merged into the chronic variety.

Pneumonia may be directly induced by any of the influences named as
general causes for diseases of the organs of respiration, but in many
instances it is from neglect. A common cold or sore throat may be
followed by pneumonia if neglected or improperly treated. An animal may
be debilitated by a cold, and when in this weakened state may be
compelled to undergo exertion beyond his strength; or he may be kept in
a badly ventilated stable, where the foul gases are shut in and the pure
air is shut out; or the stable may be so open tha