The constitution of pus, which is subject to constant change, depends upon the form of the disease, the locality and the condition of the patient. When pus is of a yellowish-white color, of the consistence of cream, and composed of a great number of pus globules, it is called "healthy," "pure," or "laudable." When pus is thin, reddish and mixed with blood, it is termed "sanious" pus, and is common to diseases of the bones, irritable ulcers, etc., and is also frequently mixed with particles of fibrin, and dead tissue. In chronic and cold abscesses the pus-corpuscles become pale and watery, showing that they are undergoing solution; the pus from epithelial tumors, indolent ulcers, and phagedenic ulcers, is thin and sanious, and contains more or less dead tissue, which prevents the repair.

Thin, watery, acrid pus is termed "ichorous," and is common to chronic ulcers, bone diseases, etc. Thin, watery pus from inflamed mucous membrane, is termed "muco-pus." Thin, watery pus, containing fibrin and coming from serous membranes, is termed "sero-pus." Thick, ropy pus from syphilitic abscesses, is termed "gummy pus." Sanious pus, containing flakes of coagulated fibrin, common to chronic abscesses, and bone disease, is termed "curdy" or "cheesy" pus.