lo Dec, 1908.] Discines of the Blood. 753 



the exuded fluid is either reabsorbed by the blood vessels or is removed by 

 the lymphatic vessels, or, if on a free surface by being discharged from 

 it. Croupous inflammation may also terminate in resolution, the process 

 in this case in\olving the solution or liquefaction of the exudate and its 

 removal by absorption as in the case of serous and catarrhal exudates ; 

 or ENCAPSULATION may occur by the formation round the exudate of a wall 

 of fibrous tissue resulting from a zonary productive inflammation. 



Caseation, a process by which the exudate and tissues become 

 changed into a cheesy looking mass consisting of dead cell debris and 

 organic salts, is also a common termination of croupous inflammation in 

 some animals and particularly in fowls. The termination of a productive 

 inflammation can scarcely be said to occur; in that, the newlv formed and 

 organized tissue is seldom whollv removed. It usuallv undergoes a 

 shrinking process called cicatricial contraction. Surface inflammation 

 may end in ulceration, a process in which there is a tendencv to the pro- 

 duction of molecular death or necrosis of the tissues involved, and which 

 therefore results in the gradual destruction of tissue. 



The TREATMENT and control of inflammation in various tissues and 

 organs will be touched on wherever inflammatorv diseases are discussed 

 throughout this treatise. 



Thrombosis. 



By Thrombosis is meant " the coagulation of the blood within the 

 blood vessel during life. The product is called a thrombus in opposition 

 to a coagulum or clot which is the result of post mortem coagulation " 

 {Qreen). Thrombosis is most common in veins aiid is usually due to in- 

 jury or disease of the vessel wall. Rupture, tearing, twisting or ligature 

 of a vessel will cause a thrombus to form at the seat of the injurv; or the 

 presence of a foreign body (an embolus) in the vessel will txcile throm- 

 bosis. 



Thrombosis mav result in permanent obliteration and "cording" of 

 the vessel, as seen oftentimes in the jugular vein after the operation of 

 blood-letting. Frequently however the thrombus undergoes softening and 

 is removed by the blood stream without any permanent injury being sus- 

 tained by the vessel. 



Thrombosis of the iliac arteries is an occasional cause of obscure hind 

 limb lameness in the horse. 



Embolism. 



" Embolism is the impaction of solid substances, circulating in the 

 -blood, in vessels which are too small to allow them to' pass. A mass 

 thus arrested is termed an embohis " (Green). Fragments of thrombi 

 or of inflammatorv or tumour growths, parasites and their eggs, globules 

 of fat and of air and masses of micro-organisms are amongst the common 

 sources of emboli. They are carried along by the current of the blood 

 stream until thev become blocked in a narrowing vessel or at a bifurcation 

 or by a vein valve. Acting as a foreign body they cause the formation 

 of a thrombus which frequently extends both in front and behind as far 

 as the junction of the blocked vessel with some other through which the 

 blood is flowing. In small vessels they cause a complete stoppage of the 

 circulation and hence they have often serious results ; as for example when 

 the blood vessels of the brain are concerned. 



