y expelled.

In _pneumonia_ or inflammation of the lung-substance the process is
different. A portion of one or other lung, sometimes of both, becomes
overfilled with blood, or congested, and though the air-tubes themselves
are not the special seat of the congestion, yet the air-cells are
pressed on by the surrounding swollen substance, and the entrance of air
into them is impeded. If the mischief goes further the substance becomes
solid and impervious to air, and lastly it becomes softened, its
structure destroyed, and infiltrated with matter; the affected part
becomes really an abscess, though not bounded by the distinct limits
which would shut in an abscess of the hand or the foot. Inflammation,
and the formation of an abscess anywhere is, as we know, attended by
fever and much general illness, and inflammation of the lung is of
course attended by fever and general illness in proportion to the
importance of the organ affected. To these, too, must be added all the
disturbance inseparable from any ailment which gravely interferes with
breathing.

In the great majority of instances inflammation of the lung-substance
does not go on to the last stage, and recovery is not only possible, but
probable, from congestion and solidification of the organ. Pneumonia,
too, usually attacks only a portion of one lung, while in bronchitis the
air-tubes of both are always involved. Hence of the two, serious
bronchitis is more to be dreaded than serious pneumonia.

Bronchitis is always developed out of previous catarrh, though there is
a wide difference between the duration of the preliminary stage and the
occurrence of serious symptoms in different cases; while it may be laid
down as a general rule that the severity and danger of an attack are in
proportion to the rapidity of its onset. An attack of pneumonia, or
inflammation of the lung-substance sets in, as a rule, more suddenly,
with fever, a temperature of 103 deg. to 105 deg., general distress, headache,
not unfrequently delirium; the urgency of which symptoms, the hurried
breathing and the short, dry, hacking cough, and the tearless eyes are
too often misinterpreted, and the state of the chest not examined.

The doctor, of course, skilled in auscultation, will listen to the
chest and give to all these symptoms their true signification. The
lesson for the parent to bear in mind is never to neglect in a child the
symptoms of what may seem to be but a common cold, but to seek for