194 PRINCIPLES OF VETERINARY SURGERY 



could not retain a clot as effectually as one located in the re- 

 cesses of muscular tissue, and if the part were kept in motion 

 by walking, moving about the stall, etc., the accumulating 

 clot would be repeatedly cast off and thus prevented from ex- 

 erting its plugging propensities. A wound of the palatine ar- 

 tery, which is located between the bony and the fibrous 

 palate, both of which are unyielding structures, always 

 bleeds profusely. There is no suitable cavity to gather an 

 effectual coagulum, and the motion of the tongue constantly 

 wipes away the clot as fast as it forms. 



In the large wound this influence is no small part of the 

 natural hsemostasis. The coagulum fills every recess of the 

 traumatic cavity and even heaps up above the level of the 

 skin. When several hours old it is quite effectually or- 

 ganized and is not as easily dislodged as during the first 

 stage of the bleeding. In a favorable wound not subjected 

 to much motion, especially jerking, sudden motion or fric- 

 tion, the coagulability of the blood is nature's greatest pro- 

 tection against death from hsemorrhage. It is also of equal 

 value, in fact, it is indispensable, in permanently obturating 

 the lumen of ligated vessels after the ligature has sloughed 

 away and before the blind channel is obliterated. 



b. The Contractility of the Vessels. — The blood vessels, 

 especially the arteries, are very elastic. When cut they 

 retract into the walls of the traumatic cavity, diminish in 

 caliber, and the tunica intima recedes. By retracting into 

 the tissues, the formation of a formidable plug of coagulated 

 blood is facilitated ; by diminishing in caliber, the blood- 

 current is narrowed; and by receding of the tunica intima, 

 its rough subjacent stroma is exposed to the out-fliowing 

 blood and thus gathers particles of coagulated blood, which 

 still further diminish the size of the out-pouring current and 

 often entirely obturate the lumen. The contractility of the 

 blood vessels, acting in conjunction with the coagulability 



