If the injury has been very slight, observation of the area on the following day will show no change beyond a slight dilatation of the vessels and a great accumulation of cells in the tissue.
Everyone has experienced the effect of such changes as have been described in this simple experiment.

An inflamed part on the surface of the body is redder than the normal, swollen, hot and painful.

The usual red tinge of the skin is due to the red blood contained in the vessels, and the color is intensified when, owing to the dilatation, the vessels contain more blood.

The inflamed area feels hot, and if the temperature be taken it may be two or three degrees warmer than a corresponding area.

The increased heat is due to the richer circulation.