Finally there are numerous plastic methods which have been resorted to in various parts of the body, most of which are made to comprise, first, the absolute eradication of the diseased tract, and, later, the closure of the wound thus made by transplantation or sliding of flaps, or any other plastic expedient which may be considered best. These, as well as the special treatment made necessary for particular forms of sinus and fistula, will be dealt with under their proper headings. CHAPTER IV. ULCER AND ULCERATION. The term _ulcer_ pertains to surfaces, and should be defined as a _surface which is or ought to be granulating_, _i. e._, _healing_. While an ulcer may be the result of ulceration, it is not necessarily so, the term _ulceration_ being one of very loose significance and applied to many different processes. The idea underlying ulceration is _infection_, and, when limited to its proper significance, the term should never be used for a process in which infection and consequent breaking down of tissue do not virtually comprise the whole process. Therefore, it is to be distinguished from certain disappearances of tissue alluded to under the head of Atrophy or Interstitial Absorption. It is not correct to say that the sternum ulcerates away, making room for a growing aortic aneurysm, the question of infection here not being raised. These distinctions should be accurately maintained and constantly borne in mind. ULCERS. The causes of ulcers may be-- A. _Traumatic_; B. _Local_; or, C. _Constitutional_. A. =Traumatic.=--This includes all surfaces which are granulating and healing more or less rapidly, or are displaying a disposition toward healing, and which may have been produced by _wounds_, _burns_, _frostbites_, etc. These include also ulcers due to _pressure_, as from splints, bandages, orthopedic apparatus, or from _external friction_. Ulcers which form around _foreign bodies_ may also be included under this head, their essential cause being traumatic. It should include also destruction of the surface by various _chemical agencies_, such as strong caustics, and the consequences of intense _heat_ or _cold_, including burns and frostbites. B. =Local.=--1. Among local causes may be mentioned _local infections_, with tissue death in consequence, such as occur in tuberculous, cancerous, leprous, syphilitic, and other specific manifestations where surfaces are involved. 2. _Tumors_, either benign or malignant, whose blood supply is cut off and whose surface is thereby predisposed to infection.