752 Jouryial of Agriculture. [lo Dec, 1908. 



The successive stages in tiie prcx:ess of inflammation are : Dilatation 

 of the vessel with acceleration of the flow of blood (the stage of congestion 

 or hypersemia). The dilatation continues but retardation of flow shortly 

 commences. This is followed by oscillation of practically stagnant blood 

 which culminates in actual stasis or stoppage of flow. In severe inflamma- 

 tion a further stage may be reached, that of thrombosis or clotting of the 

 blood within the vessel. From the time retardation commences the con- 

 comitant process of exudation may proceed. Through the stretched but 

 unruptured wall of the dilated vessel the fluid of the blood (liquor san- 

 guinis) commences to exude and it may be accompanied by the exudation 

 or diapedesis of white corpuscles. At a later or more severe stage exuda- 

 tion of red corpuscles may occur. 



Inflammation is always accompanied by certain physical signs, viz., 

 redness, heat, swelling, pain, tenderness and impaired function. The 

 redness and heat depend upon the increased quantity of blood contained 

 in the inflamed part. The swelling is due mainly to the exudation of 

 flui'd and corpuscles into the tissues of the inflamed part. Pain and 

 tenderness are due to the pressure exerted by the exuded material on the 

 sensory nerve filaments of the part and perhaps in some measure to chemical 

 irritation of them. Impaired junction is a result of the injury and 

 lessened vitality of the inflamed tissues and is proportional to the damage 

 sustained by the functional cells of the part. 



There are certain varieties of inflammation which are frequently 

 referred to in the description of diseases and which therefore it will be 

 advisable to indicate briefly : — 



(i) Catarrhal inflammation in which the exudate is watery olr 

 " mucoid" and has little or no tendency to coagulate; a good example is 

 the inflammation of the mucous membranes of the nasal and respiratory 

 passages in an ordinarv " cold " or catarrh. 



(2) Croupous inflammation, the exudate in this case containing the 

 fibrin-forming elements of the blood along with white corpuscles so that 

 it coagulates readily and forms a firm infiltrate in the tissues or deposit 

 on the surface involved. 



(3) Diphtheritic inflammation somewhat similar to croupous, occur- 

 ring usually on mucous surfaces and differentiated by the fact that the 

 coagulated exudate never becomes vascularized but quickly undergoes 

 necrosis or death, forming on mucous surfaces what is known as a " false 

 membrane. ' ' 



(4) Serous inflammation occurring usualh' on serous membranes but 

 also in other tissues when the irritation is slight, and in which the serum 

 of the blood is alone exuded. 



(5) Fibrinous, productive or proliferative inflammation, which 

 occurs mostly in connective tissues and in which the exudate shows a 

 tendency to Ix'come organized or vascularized and to develop into fibrous 

 tissue through the exuded white cells becoming transformed into connective 

 tissue fibres. Thickenings of tendons, callous swellings, tumour-like 

 growths from collar pinches and the encapsulation or encysting of tuber- 

 cular or other growths are all good examples of this variety of inflamma- 

 tion. 



(6) Suppurative inflammation is perhaps not strictly a variety of 

 inflammation, as suppuration only occurs when the inflammatory exudate 

 becomes contaminated with suppurative organisms. 



Terminations of Inflammation. — Serous and catarrhal inflammations 

 usually terminate bv resolution, that is, the exudation ceases and 



