Lastly, there are still other types of chronic inflammation attended with the formation of fibrous tissue on such a liberal scale as to suggest analogies with new growths. The best known of these are the systematic forms of fibromatosis met with in the central nervous system and in the peripheral nerves--_neuro-fibromatosis_; in the submucous coat of the stomach--_gastric fibromatosis_; and in the colon--_intestinal fibromatosis_. These conditions will be described with the tissues and organs in which they occur. In the _treatment of chronic inflammations_, pending further knowledge as to their causation, and beyond such obvious indications as to help the tissues by removing a foreign body or a piece of dead bone, there are employed--empirically--a number of procedures such as the induction of hyperæmia, exposure to the X-rays, and the employment of blisters, cauteries, and setons. Vaccines may be had recourse to in those of bacterial origin. CHAPTER IV SUPPURATION Definition--Pus--_Varieties_--Acute circumscribed abscess--_Acute suppuration in a wound_--_Acute Suppuration in a mucous membrane_--Diffuse cellulitis and diffuse suppuration-- _Whitlow_--_Suppurative cellulitis in different situations_--Chronic suppuration--Sinus, Fistula--Constitutional manifestations of pyogenic infection--_Sapræmia_--_Septicæmia_--_Pyæmia_. Suppuration, or the formation of pus, is one of the results of the action of bacteria on the tissues. The invading organism is usually one of the staphylococci, less frequently a streptococcus, and still less frequently one of the other bacteria capable of producing pus, such as the bacillus coli communis, the gonococcus, the pneumococcus, or the typhoid bacillus. So long as the tissues are in a healthy condition they are able to withstand the attacks of moderate numbers of pyogenic bacteria of ordinary virulence, but when devitalised by disease, by injury, or by inflammation due to the action of other pathogenic organisms, suppuration ensues. It would appear, for example, that pyogenic organisms can pass through the healthy urinary tract without doing any damage, but if the pelvis of the kidney, the ureter, or the bladder is the seat of stone, they give rise to suppuration. Similarly, a calculus in one of the salivary ducts frequently results in an abscess forming in the floor of the mouth. When the lumen of a tubular organ, such as the appendix or the Fallopian tube is blocked also, the action of pyogenic organisms is favoured and suppuration ensues.