_Ulcers due to Imperfect Circulation._--Imperfect circulation is an important causative factor in ulceration, especially when it is the _venous return_ that is defective. This is best illustrated in the so-called _leg ulcer_, which occurs most frequently on the front and medial aspect of the lower third of the leg. At this point the anastomosis between the superficial and deep veins of the leg is less free than elsewhere, so that the extra stress thrown upon the surface veins interferes with the nutrition of the skin (Hilton). The importance of imperfect venous return in the causation of such ulcers is evidenced by the fact that as soon as the condition of the circulation is improved by confining the patient to bed and elevating the limb, the ulcer begins to heal, even although all methods of local treatment have hitherto proved ineffectual. In a considerable number of cases, but by no means in all, this form of ulcer is associated with the presence of varicose veins, and in such cases it is spoken of as the _varicose ulcer_ (Fig. 14). The presence of varicose veins is frequently associated with a diffuse brownish or bluish pigmentation of the skin of the lower third of the leg, or with an obstinate form of dermatitis (_varicose eczema_), and the scratching or rubbing of the part is liable to cause a breach of the surface and permit of infection which leads to ulceration. Varicose ulcers may also originate from the bursting of a small peri-phlebitic abscess. Varicose veins in immediate relation to the base of a large chronic ulcer usually become thrombosed, and in time are reduced to fibrous cords, and therefore in such cases hæmorrhage is not a common complication. In smaller and more superficial ulcers, however, the destructive process is liable to implicate the wall of the vessel before the occurrence of thrombosis, and to lead to profuse and it may be dangerous bleeding. These ulcers are at first small and superficial, but from want of care, from continued standing or walking, or from injudicious treatment, they gradually become larger and deeper. They are not infrequently multiple, and this, together with their depth, may lead to their being mistaken for ulcers due to syphilis. The base of the ulcer is covered with imperfectly formed, soft, œdematous granulations, which give off a thin sero-purulent discharge. The edges are slightly inflamed, and show no evidence of healing. The parts around are usually pigmented and slightly œdematous, and as a rule there is little pain. This variety of ulcer is particularly prone to pass into the condition known as callous. In _anæmic_ patients, especially young girls, ulcers are occasionally met with which have many of the clinical characters of those associated with imperfect venous return. They are slow to heal, and tend to pass into the condition known as weak.