8. _Collis’s operation_[78] (Figs. 53 A and B).—This proceeding is somewhat similar to Stokes’s as regards the utilisation of every portion of the soft tissues. On the inner side the knife is carried along the margin of the cleft (_a b_), but stops short at the mucous membrane, allowing this portion to be turned, as on a hinge, backwards to increase the thickness of the raw surface. On the outer side a prolabial flap (_e f_) is made from above downwards, starting at the centre of the margin, whilst the rest is turned upwards to form a flap attached above (_c d_). This latter is then drawn across and adapted to the upper part of the inner margin with its apex upwards, whilst the lower flap is drawn across and implanted on the lower portion with its apex downwards. In actual practice this is complicated and tedious, but the principal objection to it as well as to Stokes’s operation lies in the fact that there is no provision for restoring the shape of a distorted nostril. [Illustration: FIG. 53.—Collis’s operation. No tissue removed. Inner margin is pared by incision _a b_, but left attached by mucous membrane, and hinged backwards. Outer margin is transfixed, and flaps _c d_ and _e f_ are cut; _c d_ is turned up and attached to _a g_; _e f_ is turned down and attached to _b h_. (_Mason._)] In the severer forms of harelip, where either the cleft is broad or the nostril much flattened, other modifications may be necessary; such, for instance, as that practised by Dieffenbach, the essential principle of which consists in making additional incisions horizontally below, and even skirting around the ala nasi, with the object of so loosening the tissues as to bring them more readily into apposition. I have never practised this, and cannot help thinking that the difficulty often experienced in bringing a flattened nostril into position would be rather increased than otherwise. Free undercutting of the cheek tissue will probably be found much more efficacious. In alveolar harelip with projection of either segment of the alveolus it may be necessary to excise the projecting portion, or to reduce its bulk in order to prevent undue tension on the flaps. In many it is sufficient merely to excise the milk tooth, whilst in others a part of the bony margin may need removal with cutting pliers. Any such step, when obviously necessary, should be carried out as a preliminary operation. OPERATIVE TREATMENT OF DOUBLE HARELIP. This subject naturally resolves itself into the discussion of two points, viz. the method of treatment of the os incisivum, and that of the soft parts.