MORTIFICATION. 59 



The final act in the separation of dead tissue is that of 

 tilceration of portions of living tissue, which are in immediate 

 contact with the dead. A groove is formed by this ulceration, 

 which circumscribes and entrenches the dead part, and then, 

 gradually deepening and converging, undermines it, till, reach- 

 ing its centre, the separation is complete, and the slough falls 

 oft', or is dislodged by the discharge of the ulcerated living 

 surface. Concomitant with this process of destruction, one of 

 repair is set up ; as the ulcerated groove deepens, so do granu- 

 lation cells rise from its surface, so that, as one might say, that 

 which was yesterday ulcerating is to-day granulating ; and thus, 

 very soon after the slough has separated, the whole surface of 

 the living part, from which it was detached, is covered with 

 granulations, and proceeds like an ordinary ulcer towards healing. 

 There is one peculiarity in mortification, namely, mortification 

 hy contact. Thus a spot of mortification of the size of a five- 

 sliilling piece is discovered upon a portion of intestine, sur- 

 rounded by perfectly healthy structures, until the portion of 

 the intestine in immediate contact with the gangrenous spot 

 is examined. This will be found to be gangrenous also, 

 although, when divested of its convolutions, it may be several 

 feet from the originally mortified spot, the intervening length 

 of gut being free from mortification. 



