(From a photograph lent by Dr. Stopford Taylor and Dr. R. W. Mackenna.)] _The tertiary ulcer_ may be situated anywhere, but is most frequently met with on the leg, especially in the region of the knee (Fig. 42) and over the calf. There may be one or more ulcers, and also scars of antecedent ulcers. The edges are sharply cut, as if punched out; the margins are rounded in outline, firm, and congested; the base is occupied by gummatous tissue, or, if this has already separated and sloughed out, by unhealthy granulations and a thick purulent discharge. When the ulcer has healed it leaves a scar which is depressed, and if over a bone, is adherent to it. The features of the tertiary ulcer, however, are not always so characteristic as the above description would imply. It is to be diagnosed from the "leg ulcer," which occurs almost exclusively on the lower third of the leg; from Bazin's disease (p. 74); from the ulcers that result from certain forms of malignant disease, such as rodent cancer, and from those met with in chronic glanders. _Gummatous Infiltration of the Skin_ ("Syphilitic Lupus").--This is a lesion, met with chiefly on the face and in the region of the external genitals, in which the skin becomes infiltrated with granulation tissue so that it is thickened, raised above the surface, and of a brownish-red colour. It appears as isolated nodules, which may fuse together; the epidermis becomes scaly and is shed, giving rise to superficial ulcers which are usually covered by crusted discharge. The disease tends to spread, creeping over the skin with a serpiginous, crescentic, or horse-shoe margin, while the central portion may heal and leave a scar. From the fact of its healing in the centre while it spreads at the margin, it may resemble tuberculous disease of the skin. It can usually be differentiated by observing that the infiltration is on a larger scale; the progress is much more rapid, involving in the course of months an area which in the case of tuberculosis would require as many years; the scars are sounder and are less liable to break down again; and the disease rapidly yields to anti-syphilitic treatment. [Illustration: FIG. 41.--Ulceration of nineteen year's duration in a woman æt. 24, the subject of inherited syphilis, showing active ulceration, cicatricial contraction, and sabre-blade deformity of tibiæ.] _Tertiary lesions of mucous membrane and of the submucous cellular tissue_ are met with chiefly in the tongue, nose, throat, larynx, and rectum. They originate as gummata or as gummatous infiltrations, which are liable to break down and lead to the formation of ulcers which may prove locally destructive, and, in such situations as the larynx, even dangerous to life. In the tongue the tertiary ulcer may prove the starting-point of cancer; and in the larynx or rectum the healing of the ulcer may lead to cicatricial stenosis.