PRINCIPLES OF VETERINARY SURGERY 317 



ganic repair and cicatrization. The fixed cells attached to 

 the surface of the fibrinous layer proliferate simultaneously 

 with the accumulation of leucocytes at the periphery, thus 

 constituting a sac. The accumulated blood is rapidly mod- 

 ified. The serum absorbs and the coagulum remains cling- 

 ing to the walls of the sac, and dries up, or else the corpus- 

 cles become dissolved, and leave a sac that fluctuates in- 

 definitely. In time their coloring matter becomes dissolved 

 and destroyed, leaving the liquid contents brown, then yel- 

 low, and finally amber colored, in which event, the case be- 

 ing old, the exact origin of the lesion will be difficult to de- 

 termine. 



3. Contusions of the Third Degree. — In contusions of 

 the third degree the tissues are deeply impaired. The mus- 

 cles are crushed and torn, infiltrated or separated by haemor- 

 rhage, and the skin covering the injured area readily be- 

 comes necrotic. Tendons are ruptured, aponeuroses torn, 

 nerves crushed, vessels ground, and the whole area trans- 

 formed into an irregular focus impregnated with a liquid 

 that exudes at the surface, and if infection intervenes death 

 is quite certain. 



Contusiojis of the third degree include primary serous 

 effusions. This lesion consists of an ovoid tumor of limited 

 height, but extending over a considerable surface, and is 

 frequently encountered on a level with and slightly behind 

 the coxo-femoral articulation. It is cold, indolent and very 

 fluctuant, and any force applied to its surface produces an 

 undulating movement which spreads over its entire area. 

 The skin is markedly detached and the contents are easily 

 displaced. Primary serous effusions are rather common in 

 the horse in places where the muscles are enveloped in a 

 strong aponeurosis such as exists in the region of the but- 

 tocks. They are not entirely absent in the ox, in which ani- 

 mals they are encountered on the other side of the stifle. 



