FOREIGN substances which can be left in tissues have been used for some time in various fields of surgery. Relatively nonirritating materials, such as metal plates, screws and wire, have been used in the open reduction of fractures, but these rarely cause trouble unless infection is present. Silk, cotton and nylon used for ligature are usually introduced in such small amounts that they become clothed in varying amounts of fibrous tissue and lead to no further trouble. Surgical gut, though more irritating to the tissues, is completely absorbed. Large amounts of gauze, usually in the form of sponges, accidentally left in the tissues usually result in some complicating reaction sooner or later. Gauze packs are used sometimes to promote adhesions and, when they have accomplished this purpose, are removed with impunity. However, there are occasions when such packs are used for purposes of hemostasis, but their removal may initiate fresh