18 MANUAL OF EQUINE MEDICINE. 



In this variety the exudation contains the same elements as 

 does the fibrinous exudation. 



No coagulation occurs in this kind, no 'lymph' forms 

 and vascularizes. Any * lymph' which may be formed at 

 an early stage is destroyed. 



The irritation is more intense than that required to 

 produce a fibrinous exudation, and its action is more 

 prolonged. 



Suppuration may occur in the tissues in a circumscribed 

 form or abscess or in a diff'use manner, or its seat may be a 

 free surface, as a mucous membrane or the skin. In the 

 latter cases, when the epithelium is destroyed, with more or 

 less of the subjacent tissue, the process is termed Ulceration, 

 but when the deeper layers of epithelium remain it is termed 

 a purulent catarrh. 



Formation of an Acute Abscess. — Fluid and corpuscles 

 escape into the irritated tissue. The cells accumulate espe- 

 cially round the small veins, which thus form commencing 

 foci of infiltration. The infiltrations become denser and 

 denser, and spread by migration and transportation of cells 

 until the foci blend. In consequence of the extent of 

 injury and succeeding nutritive disturbance, the tissue ele- 

 ments die and disappear before the leucocytes. 



In the central parts of the diseased area no vessels are to 

 be seen, and no new ones are formed. 



From mutual pressure and absence of nutrition, the 

 central cells die and degenerate together with the inter- 

 cellular substance. Thus a cavity containing dead leuco- 

 cytes (pus-cells) is formed, and it is bordered by still living 

 infiltrated tissue. 



The process gradually spreads by thrombosis of the 

 vessels and consequent disintegration of the cells they 

 supply. An acute abscess almost always extends until it 

 bursts or is opened. 



