We have had occasion already to notice that the various phenomena of inflammation are not always present in every case, and one or other of them may be so pronounced as to give its character to the inflammation. Hence, names have been given according as the inflammation shows certain special characters. It may, however, be remarked that hyperemia is a nearly constant accompaniment of inflammation, and in slight acute inflammations it may be almost the only phenomenon. Exudation is also of almost constant occurrence. Indeed, in the examination of the tissues after death, the presence of leucocytes or round cells is often the most definite evidence of the existence of an inflammation.

In the various forms of inflammation now to be mentioned, it is not to be supposed that a classification of inflammations is attempted. These are merely names in current use which call for explanation.