_Varieties in the method of Flap Extraction._--Jacobsen of Königsberg in every case gives chloroform. He always makes his flap in the boundary line of the cornea and the sclerotic, through a vascular structure, and he believes that union is on this account more rapid, and after extraction removes that portion of the iris which appears to have been most exposed to bruising during the exit of the lens. The operation of extraction may in many cases be either preceded or followed by iridectomy, as proposed by Mooren, Von Graefe, and others. The following operation seems to diminish the risks to a very great extent:-- _Professor Von Graefe's Operation._--The lids are separated by a speculum, and the eyeball is drawn down by forceps placed immediately below the cornea. The point of a small knife, of which the edge is directed upwards, is inserted at a point fully half a line from the margin of the cornea near its upper part, so as to enter the anterior chamber as peripherally as possible. The point should not be directed at first towards the spot for counterpuncture; nor till the knife has advanced fully three and a half lines within the visible portion of the anterior chamber, should the handle be lowered and the point directed so as to make a symmetrical counterpuncture, which will give the external wound a length of four and a half or five lines. As soon as the resistance to the point is felt to be overcome, showing that the counterpuncture is effected, the knife must at once be turned forward, so that its back is directed almost to the centre of the ideal sphere of the cornea, whether the conjunctiva is transfixed or not, and the scleral border is divided by boldly pushing the knife onwards and again drawing it backwards. This portion of the operation is concluded by the formation of a conjunctival flap a line and a half or two lines in length. A section thus made is almost perpendicular to the cornea, a circumstance much facilitating the passage of the lens, and the line of incision is nearly straight, so that the wound does not gape. The iris should be excised to the very end of the wound, and the capsule most freely opened by a V-shaped laceration. Any lens, even the hardest, may then be removed without the introduction of an instrument into the eye, but Von Graefe's experience shows it to be advisable to assist the evacuation by the hook in about one case in eight. In a certain number of cases the lens will escape without difficulty when the operator presses on the posterior lip of the wound, especially when the back of the spoon is made to glide along the sclera; should this not occur, Von Graefe uses a peculiar blunt hook, or occasionally, though rarely, a spoon. A compressing bandage is applied, and replaced at intervals.[88]