=The prevention of fresh adhesions between the dura and the brain and between the scalp and the dura or brain.= ‘It is useless to talk about the prevention of fresh adhesions; they form in spite of anything that may be done’ (English). With this statement, I am in complete accord. It has been recommended that fresh egg-albumen, gutta-percha tissue, silver foil, &c., should be inserted beneath the dura or between the scalp and the brain. Experience shows, however, that all these substances are useless, being invaded or surrounded by granulation tissue, and, later on, absorbed by or enclosed in dense fibrous tissue. The formation of adhesions between the scalp and the dura or brain can, however, be effectually prevented by the insertion of plates, &c. (see below). The closure or protection of gaps in the skull. _Indications for operative treatment._ Large defects, post-operative or traumatic. Small defects situated over exposed portions of the skull or over the more important regional areas. Both large and small defects associated with chronic headache, insanity, Jacksonian epilepsy, &c. Certain congenital defects in the vault. Small defects, unless situated in exposed regions or associated with symptoms, seldom demand protection. Methods. _(a) The formation of bone-flaps, derived from neighbouring parts of the skull, from some other bone of the patient, or from the bones of a freshly-killed animal._ _(b) The interposition of plates of some foreign material between the scalp and the bone, or the insertion thereof into the osseous deficiency._ _(a) Bone-flaps. The osteoplastic method of König and Müller._ Two flaps are framed in the manner described below, and the two interchanged in position. A ⋂-shaped flap, comprising the whole thickness of the scalp, is turned down so as to expose the region of the deficiency, the margins of the incision lying about ¹⁄₂ inch outside the margin of the gap. The flap is dissected from underlying structures to which it may be adherent, care being taken to avoid injury to the blood-vessels entering at the base of the flap. A second flap is framed from the scalp immediately to one side of the first flap. This second flap corresponds in size and shape to the one already framed, but differs in that its base points in the opposite direction. It is also peculiar in that it consists of the whole thickness of the scalp plus the external table of the skull. The scalpel is carried down to the bone, and the margins of the incision retracted in such a manner as to allow of the application of the hammer and chisel. The external table is cut through along the line of the scalp incision and split away from the rest of the bone. The two flaps are now interchanged in position and sewn down with a few salmon-gut sutures. [Illustration: FIG. 59. THE KÖNIG-MÜLLER OSTEOPLASTIC FLAP. _a._, The scalp-flap; _b._, The osteoplastic flap; _g._, The gap in the skull.]