The consideration of the final symptom of inflammation, the disturbance of function, which has been added in recent times, belongs to special rather than general pathology. It varies according to the seat of the inflammation, the disturbed function of the brain or heart differing from that of the liver or kidney. The clinical importance of this symptom of inflammation is greater than of all the rest, as it is the one whose presence is constant and indispensable. An inflammation may exist, as already stated, without heat, redness, or pain. The swelling may escape observation from the limited quantity of the exudation and other causative agents, or from the inaccessibility of the inflamed part to physical examination. The disturbance of function, however, becomes early apparent, and is present throughout the course of the inflammation. A knowledge of its nature enables the seat of the latter to be recognized, and its variations furnish a desired test of the efficiency of therapeutic agents. * * * * * The causes of inflammation may be divided into the traumatic, toxic, parasitic, infectious, dyscrasic or constitutional, and trophic. The traumatic causes are those which act mechanically, producing an injury to tissues by pressure, crushing, tearing, stretching, and the like. Others represent modifications in temperature, thermic agencies, and include extremes of cold as well as of heat. The chemicals whose action is direct, as caustic, include a third variety of the traumatic causes. Such chemicals are applied to surfaces, cutaneous or mucous, and comprise the active element producing the perforating ulcer of the stomach and duodenum, as well as such substances as potash or sulphuric acid which may have been swallowed intentionally or accidentally. The toxic group of causes is closely allied to the chemical variety of the traumatic agencies. It includes chemicals whose action is indirect, through absorption in a diluted form rather than from direct application in a concentrated condition. Such chemicals are derived from without, as arsenic, phosphorus, and antimony; or may be formed within the body, and the latter include the chemical products of putrefactive changes--in the urine, for instance--and, with considerable probability, certain of the active agents of blood-poisoning in septic diseases. It is not unlikely that some of the inflammatory affections met with among the so-called constitutional diseases, as rheumatism and gout, may owe their origin to the production of chemical substances within the body, excessive in quantity if not changed in quality.