The discharge does not always consist of laudable purulent matter. Pus formed in the diseased part itself has particular characters, according to the tissue involved; thin and greyish in bones, opaque and caseiform in cellular tissue, flocculent in serous, and greenish and thready in mucous membranes; it is said to be reddish in the liver, and yellowish-grey in muscles. Its sensible properties are various, often very offensive when proceeding from a cavity containing decayed bones, and it degenerates in consequence of disturbance of the constitution, or of the part affected. It is also frequently suppressed, in consequence of over-action in the vessels of the part, or from debility, partial or general. Suppression of a purulent discharge is to be regarded as an untoward symptom, fraught with considerable danger, being generally followed by the most violent constitutional disturbance. Certain cases would seem to warrant the belief that a species of metastasis occurs; that the matter is absorbed, and again deposited in some other part, perhaps of the utmost importance in the animal economy. The danger arising, when the pus is not separated from the blood, has already been adverted to. No wonder, if from any cause it does not escape by its accustomed channel, that an effort should be made to deposit it somewhere else, for the temporary relief of the system. The most vascular parts are commonly chosen, as the lungs, spleen, and liver. In the cavities of joints, also, matter is often found in great quantities. This is sometimes indicated by the occurrence of tenderness and swelling for only a short period previously; but, in other cases, its presence has never been suspected. In purulent collections, after wounds from accident or operation, on the suspension of the discharge, the patient becomes affected with severe constitutional irritation, and gradually sinks; the existence of purulent depôts in the viscera of the chest or abdomen, being perhaps not indicated by any, unless very equivocal, symptoms, and these appearing only a short time before dissolution. A late writer has endeavoured to connect this with inflammation of the veins; but such an opinion is not borne out by observation, although the two circumstances may occasionally coexist. In many cases the veins of a limb are found filled with pus, yet their coats present no marks of inflammatory action having existed in them. Their mouths are open in the wound, from failure of that healthy action by which they would have been closed by coagulated lymph, and the matter appears to be taken up by them as secreted. From the discharge varying according to the state of the system, the latter can in general be accurately ascertained by examination of the sores which afflict the patient.