18 INFLAMIMATION. 



When the local injury is so intense as to destroy the vitality of 

 the affected part at once, that part becomes surrounded with a 

 zone of inflamed tissue, from which it eventually separates, leav- 

 ing behind it a granulating surface. To understand this process 

 of demarcation and separation, it is in the first place to be borne 

 in mind that the exuded liquid contains the fibrine-producing 

 elements of the blood, and that contact with dead substance at 

 once determines coagulation of all such fibrinogenous liquids. 

 Accordingly, the first step in the process of reparative separation 

 is the formation, in contact with the dead part, of a more or less 

 solid stratum of fibrine, in which stratum the production of new 

 capillaries and granulation tissue commences." 



LOCAL SYMPTOMS OF INFLAMMATION. 



Bedness. — In the lower animals this symptom can only be seen 

 in the white parts of the body, such as the white skin of the 

 heels of some horses, and upon the visible mucous membranes. 

 It arises from an increased quantity of blood in the part, both 

 in the capillaries and in the large vessels ; and when the con- 

 gestion is excessive, particularly if it be due to some mechanical 

 cause or obstruction, the redness is increased by the passage of 

 the red corpuscles through the walls of the capillaries without 

 rupture. The corpuscles, in passing through the vessel, become 

 constricted in their centre, so as to assume an hour-glass shape. 

 This passage of the red corpuscles can be seen in the frog's web 

 after ligature of the femoral vein. In some cases the redness 

 may be caused by extravasation of blood, but generally it de- 

 pends on engorgement. The redness of inflammation is more or 

 less vivid ; deepest in the centre, gradually shading off towards 

 the edges of the inflamed part, and partly removable by pres- 

 sure ; but if extravasation be present, its margin will be more 

 defined, and the colour is not removable by pressure. 



The aspect of the redness may differ according to various 

 circumstances ; if the capillary networks of the part be uniformly 

 distended, the injection will appear as an uniform deep blush ; 

 if, on the other hand, they are moulded in the form of viUi or 

 folds of nmcous membrane, the surface will have the appearance 

 of a pile of red velvet. In fibrous structures the redness" has 

 a streaky appearance. The redness does not depend upon the 



