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 advice the moment the cough shows any disposition to become hard, or the breathing hurried. Next, when any sudden illness sets in with very high temperature and much general ailing, not to let the disorder of the head, or the delirium, make you shut your eyes to the import of the short cough, the dry eyes, the hurried breathing; and lastly, to remember that, grave though the symptoms may be, the tendency in pneumonia is to eventual recovery, and that in early life bronchitis is the graver of the two diseases.