AND HIS DISEASES. 3 



part in which these changes are going on, must be carefully 

 noted as diagnostic of the different stages in the progress of 

 the inflammation. 



1st. The Heat. — This is an invariable symptom, being 

 always present to a greater or less degree. It is produced 

 by the more rapid oxidation going on, consequent on the 

 increased quantity of blood circulating in the parts imme- 

 diately surrounding. 



2d. Eedness is due to the increased determination of 

 blood to the part, the distension of the hitherto invisible 

 capillaries with red blood, and sometimes, when extensive, 

 to the extravasation of blood from the bursting of the thin 

 walls of the vessels. 



3d. Pain. — The pMn in an. inflamed part is almost the 

 first and most characteristic symptom. It is due to the 

 tension of the tissues, and implication of the nerves and nerve 

 centres. The degree of pain varies according to the seat of 

 the infiamination and the degree of its intensity : the more 

 sensitive the part, the more painful will it be under inflam- 

 mation. Thus, it is sharp and cutting in inflammation of 

 serous membranes, dull and gnawing in diseases of bones, 

 and burning in inflammation of the skin. When matter is 

 forming, the pain becomes throbbing and intense. 



ith. The swelling is due to the vascular engorgement and 

 the exudation of serum in the first place, and afterwards the 

 formation of fibrin, and in the latter stages to the development 

 of matter. The.other concomitant symptoms of inflammation 

 will be noticed when we come to treat of local inflammations, 

 or inflammation of particular organs. 



Inflammation, though regarded as a disease, is the prin- 

 cipal agent which nature employs in repairing or rebuilding 

 parts which have been injured by accident or disease. Thus, 

 when a fracture has taken place, the ends of the bones have 



