As a result of healing of the granulating surface there is what is known as a _cicatrix_ or _scar_. This is composed of fibrous tissue, probably more or less distorted by virtue of its contractility, and of epithelial covering furnished from the margin of the original ulcer, constituting a thin, glistening membrane, applied closely to the scar tissue beneath, without intervening fat or tissue which permits of the play of the one upon the other. When this epithelial surface is abraded it is repaired with difficulty, and a raw or ulcerating scar is difficult to heal. Manifestation of perverted epithelial outgrowth is frequently provoked at these points by the action of continuous irritation. In consequence there is what is generally recognized as the _transformation of a chronic ulcer_, or the site of one, _into an epithelioma_, or possibly, by similar irritation of the connective-tissue elements, into a sarcoma. This is the so-called cancerous degeneration of previous ulcers, and is noted occasionally. The lesion is one which often requires disfiguring, or even mutilating operations in order to get rid of the malignant disease (Fig. 12.) All the scars thus resulting are liable to undergo a fibrous and degenerative change to which is given the name _cicatricial keloid_. It is marked by increase in size and density, by reddening which denotes increased vascularity, and extension into surrounding previously healthy tissue. By these changes a given scar is made much more prominent and disfiguring. It cannot be prevented by any ordinary treatment, and is often the _bête noir_ of surgeons. (See also under Fibroma, and chapter on Diseases of the Skin.) The surface of a superficial scar while thus covered with epithelium shows a complete lack of all the other skin elements. No hair grows upon such a surface, because the original hair follicles are destroyed; neither is it moistened by perspiration nor anointed by sebaceous material, because the secretory glands have also disappeared. It is a surface which often needs more or less protection, especially when in exposed situations.