GENERAL PATHOLOGY. 19 



If the cavity be kept at rest and drained, the inflam- 

 matory cell-infiltration vascularizes, and the walls thus 

 become lined by granular tissue. 



This grows and stretches across the cavity, and then de- 

 velops into scar-tissue. In this manner the abscess is healed. 



Diffuse Sujpjpuration is a similar process going on in a 

 wider area. 



Suppuration is characterized by the formation of jpw5, 

 which from an otherwise healthy animal is thick, creamy, 

 opaque, yellowish-white, and slightly viscid, and has a 

 faint odour and alkaline reaction. The specific gravity 

 varies from 1030—1033. 



It contains about 10 — 15 per cent, of solid material, of 

 which two-thirds are albumen, the rest being fatty matter 

 and salts, such as are found in the blood. On standing, it 

 separates into a clear supernatant fluid, called ' liquor puris,' 

 and a dense yellow layer of pus-cells. 



Pus-cells are spheroidal, semi-transparent, more or less 

 granular motionless cells, usually containing a bi- or a tri- 

 partite nucleus. They are about ^sVir ^^ ^^ ^^^^ ^^ 

 diameter. 



The more recently escaped cells perform amoeboid move- 

 ments, and have the appearance of leucocytes. 



Ulceration. — Is due to the same molecular destruction of 

 the tissue on a free surface as was described above. Com- 

 monly, shreds of disintegrated tissue adhere to the floor of 

 a spreading ulcer. In more intense inflammation the shreds 

 may become much larger, and are thus transformed into 

 sloughs. 



Ulceration passes insensibly into gangrene, when death 

 becomes too rapid to permit of molecular disintegration of 

 the tissues involved. 



When the inflammation ceases, the round-celled infiltra- 

 tion on the floor becomes vascularized into granular tissue. 



