WOUNDS OF THE SKIN. 457 



twenty-four hours after the wound has been inflicted. Of all do- 

 mestic animals, however, the horse is the least prone to such union, 

 being more disposed to the formation of pus. 



(2) By granulation, which is the common form of healing in raw, 

 exposed sores, in those containing foreign bodies and septic and in- 

 fecting ferments; also in torn and contused wounds. In this form 

 the w^ound becomes covered w ith a layer of embryonic cells, of which 

 the superficial ones degenerate into pus cells, and thus the surface is 

 kept moist by a layer of Avhitisli, creamy pus. In the deeper layer of 

 cells minute loops of capillary blood vessels start up, causing the small 

 rounded elevations known as granulations. In this way the deeper 

 layer of cells receiving a blood supply is transformed into connective 

 tissue, and from its surface new loops of blood vessels start into the 

 layer above, and thus layer after layer of new tissue is formed, and 

 the breach caused by the wound is gradually filled up. The new tis- 

 sue as formed undergoes a steady contraction, drawing in the ad- 

 jacent skin over the woilnd, and hence large wounds healed in this 

 way have the skin more or less puckered around them. 



(3) By secondary adhesion, in which, two granulating lips of a 

 wound having been brought together and kept in apposition, union 

 takes place through the medium of the cells, as in primary adhesion. 



(¥) By scabbing, in which the exudation on the surface of the 

 wound dries ujd into a firm scab, under which the process of repair 

 goes on by the development of tissue from the deeper cells, as in ad- 

 hesion. 



Treatment. — In treating clean, incised wounds, attempts should be 

 made to secure healing by primary adhesion, even in the horse. 

 Bleeding should first be arrested, or nearly so, by applying a cold 

 or hot sponge, or by tying bleeding vessels, and the lips of the wound 

 should then be closed accurately, without any twisting or overlap- 

 ping. In small wounds pieces of sticking plaster may be used, the 

 lips of the wound having first been smoothly shaved, so that they 

 may adhere firmly. In larger wounds the wound may be sewed with 

 a curved surgical needle and a silk thread dipped in a solution of 

 carbolic acid. The stitches may be continued from end to end of 

 the wound and the thread prevented from slipping and loosening 

 by a knot at each end ; or the stitches may be independent, the two 

 ends being tied together across the wound. In such cases they may 

 be one-quarter to one-third inch apart ; or the lips of the wound may 

 be pinned together, the pins in a simple skin wound being inserted 

 one-eighth inch from the edge, and when both lips have been trans- 

 fixed in this way a thread (or hair) carried successively around the 

 two ends of the pin and made to describe a figure 8 will hold the 

 wound close. When the stitching is not continuous from end to end 



