WOUNDS 



405 



stance, and organization having been thus established, repair is completed 

 by the growth of a layer of cuticle over the united parts. This mode of 

 healing is unattended by any local or general disturbance, and illustrates 

 what takes place in "healing by the first intention". 



Healing by Blood -clot. — Healing by blood-clot differs but little 

 from that just described. It occurs when, in consequence of the edges 

 of a wound not being brought immediately into apposition with each 

 other, the space between them becomes filled with blood-clot, into which 

 white blood corpuscles and plasma cells soon penetrate. 



By a process of development the latter are resolved into fibrous tissue, 

 which, as in healing by the 

 first intention, form the 

 j)ermaneut bond of union 

 between the divided parts. 

 These two modes of union 

 can only be eftected where 

 the lips of the wound are 

 undisturbed and all causes 

 of irritation are excluded. 



Healing by Granula- 

 tion. — If, instead of heal- 

 ing by one of the three 

 methods referred to above, 

 an incised wound lie left 

 open, it is noticed that the 

 surface soon becomes coated 

 over with a pale, glairy sub- 

 stance composed of white 

 blood cells in the midst of 



a quantity of sticky albuminoid matter, which together have passed out 

 of the ])lood- vessels of the part. Sooner or later, according to the 

 extent of damage the tissues have sustained, small, raised points begin 

 to appear here and there above the glairy film, until the entire surface 

 of the wound is dotted over with little, rounded, fleshy-looking granules, 

 or, as they are termed, granulations. These by enlarging coalesce or 

 run one into another, and having formed a continuous layer on the 

 surface of the wound, begin again to throw out granulations as before, 

 and by a repetition of the process the breach is filled in and repair is com- 

 pleted (fig. 410). As the granulations grow and mature they soon begin to 

 shrink, and in doing so draw the sides of the gaping wound together. At 

 the same time they lose their red colour, become dense and firm in con- 



Fig. 4in. — Wound Healing by Granulation 



1, Discharge. 2, Margin of sore. 3, New epithelium at edge 

 of sore. 4, Epithelium unaffected by the wound. 5, Blood- 

 vessel. 6, Deep organizing layer beneath granulation, 7, Hair. 



