I. Incubation. The first section of the diagram corresponds to the period of Incubation, the time between the exposure to an infectious disease and its development. This period may last from a few minutes to a few days, weeks, months or even years. During this stage morbid matter, poisons, microorganisms and other excitants of inflammation gather and concentrate in certain parts and organs of the body. When they have accumulated to such an extent as to interfere with the normal functions or to endanger the health and life of the organism, the life forces begin to react to the obstruction or threatening danger by means of the inflammatory processes before described. II. Aggravation. During the period of Aggravation the battle between the phagocytes and Nature's antitoxins on the one hand, and the poisons and microorganisms of disease on the other hand, gradually progresses, accompanied by a corresponding increase of fever and inflammation, until it reaches its climax, marked by the greatest intensity of feverish symptoms. III. Destruction. This battle between the forces of disease and the healing forces is accompanied by the disintegration of tissues due to the accumulation of exudates, to pus formation, the development of abscesses, boils, fistulas, open sores, etc., and to other morbid changes. It involves the destruction of phagocytes, bacteria, blood vessels, and tissues just as a battle between contending human armies results in loss of life and property. The stage of Destruction ends in crisis, which may be either fatal or beneficial. If the healing forces of the organism are in the ascendancy, and if they are supported by right treatment which tends to build up the blood, increase the vitality and promote elimination, then the poisons and the microorganisms of disease will gradually be overcome, absorbed or eliminated and, by degrees, the tissues will be cleared of the debris of the battlefield. IV. Abatement. The absorption and elimination of exudates, pus, etc., take place during the period of abatement. It is accompanied by a gradual lowering of temperature, pulse rate and the other symptoms of fever and inflammation. V. Resolution or Reconstruction. When the period of Abate-ment has run its course and the affected areas have been cleared of the morbid accumulations and obstructions, then, during the fifth stage of inflammation, the work of rebuilding the injured parts and organs begins. More or less destruction has taken place in the cells and tissues, the blood vessels and organs of the areas involved. These must now be reconstructed, and this last stage of the inflammatory process is, therefore, in a way the most important. On the perfect regeneration of the injured parts depends the final effect of the acute disease upon the organism.