NAEVUS  , a

term in surgery signifying that form of tumour which is almost entirely composed of enlarged blood-vessels . There are three principal varieties: (r) the capillary naevus, consisting of enlarged capillaries, frequently of a purplish colour, hence the term " port-wine stain "; (2) the venous naevus, in which the veins are enlarged, of a bluish colour; (3) the arterial naevus, in which there is distinct pulsation, it being composed of enlarged and tortuous arteries . The naevus can be lessened in size by pressure . It genetaily occurs in the skin or immediately under it; sometimes it lies in the mouth in connexion with the mucous membrane . It is often congenital, hence the term " mother's mark," or it may appear in early childhood . It often grows rapidly, sometimes slowly, and sometimes growth is checked, and it may gradually diminish in size, losing its vascularity and becoming fibrous and non-vascular . This natural cure is followed by less deformity than a cure by artificial means . Various methods are used by surgeons when an operation is called for: (1) the tumour may be excised; (2) a ligature tightly tied may be applied to the base of the tumour; (3) inflammation may be set up in the growth by the injection of irritating agents, —in this way its vascularity may be checked and the formation of fibrous tissue encouraged; (4) the blood in the enlarged vessels may be coagulated by the injection of coagulating agents or by electrolysis .