An important clinical distinction is drawn with reference to the duration of an inflammation. Acute inflammations are those whose course is rapid, whose progress is associated with graver disturbances of function, and with a greater prominence of the cardinal symptoms. The chronic forms occupy more time in their progress, the functional disturbances, though severe, are injurious more from their protracted persistence, than their temporary violence, while redness, swelling, heat, and pain are symptoms of trifling prominence. The exudation in acute inflammation, if recovery takes place, is rapidly removed from the place of its origin, while in the chronic variety it tends to become a part of the region in which it lies, or, if removed, slowly disappears, and may be constantly replaced. Acute inflammations may become chronic, and the chronic variety is liable to acute exacerbations. The distinction between acute and chronic inflammations is essentially one of convenience, and, when considered from the anatomical point of view, relates rather to the persistence of the results. These may be {54} present as a variously modified exudation or as a degenerated condition of the parenchyma of the organ or tissue affected. Inflammation terminates in resolution, production, or destruction. For resolution to occur it is necessary that the causes of inflammation cease to act, either by their removal or their isolation, and that their results be removed. With the removal of the results there is often associated the removal of the cause. That such may take place it is necessary that the function of the vessel walls be so restored that the exudation ceases to escape. Inflammatory products already outside the vessels, if present on surfaces with external outlets, are carried along in the course of the excretions. If they lie within the cavities of the body not opening externally, their removal is accomplished through the medium of the circulating lymph and blood, by absorption. The liquid portion of the exudation becomes a part of the circulating fluids of the body. The fibrin is converted into a granular detritus, which eventually disappears from the place of its formation. The leucocytes may return to the blood-vessels or enter the lymphatics; the latter course probably being the one taken by the larger number of the corpuscles. Many undergo a fatty degeneration, and as they lie in lymph-spaces their conversion into an emulsion permits a removal of the mechanical obstruction to the flow of lymph through the spaces in which they were accumulated. The red blood-corpuscles are destroyed, their pigment being dissolved by the surrounding fluid and removed in the course of the circulation and excretions, or it becomes transformed into granules or crystals, which may remain in the place of their formation, or be transferred, within amoeboid cells, to remote parts of the body.