Whether the term self-limited can or cannot with propriety be applied to pneumonia and other acute inflammations, as pericarditis, etc., has been a mooted question. If it be so, it appears to the writer to be true in a different meaning of the word self-limitation from that in which it is applied to variola or typhoid fever. Yet some nosologists deny this distinction, and regard pneumonia as strictly a lung fever. Some of the facts supporting this view belong to the history of pneumonia as complicating malarial fever; _e.g._ in the winter fever of some parts of our Southern States. It must be admitted, however, that the inflammatory process, though morbid, is generally eliminative or corrective of a disturbing cause which produced it, and, unless that cause is continued or repeated in action, a limitation belongs to the succession of stages, ending either in resolution or in adhesions, serous accumulation, suppuration, or gangrene. 2. It is not necessary to dwell here upon the significance in prognosis of the patient's original constitution and hereditary or acquired {169} predispositions, or on that of results left by previous attacks of illness. These are all obviously of importance. In a member of a family predisposed to consumption a bronchial attack following exposure may be much more dangerous than in others. So also a cause of mental agitation may produce insanity in a person who inherits a tendency thereto or who has before had an attack of mental derangement, while it would be innocuous to another who has no such proclivity. A second or third attack of delirium tremens is much more dangerous to life than a first attack. On the other hand, if yellow fever occurs at all in a patient who has before had it, the course of the disease is apt to be milder than usual. The most striking example of the influence of previous disease is seen in the comparative mildness of varioloid--_i.e._ small-pox modified by the system having been placed under the action of the vaccine virus. 3. Most important of all data in prognosis are, in most cases, the indications of the present state of the patient's system as to the performance of the organic functions, his sum of energy, and vital resistance and persistence. Especially must these indications be regarded comparatively; that is, ascertaining whether, in a period of weeks, days, or, sometimes hours (in malignant cholera even of minutes), the patient's general condition has been and is gaining or losing in the evidences of strength and healthy function of the great organs.