M. _Dupré_, Surgeon to the Hospital of _Hôtel-Dieu_ at _Paris_, a Person well vers'd in these kinds of Operations, hath observ'd, that after the same manner as Cataracts were form'd in a very little space of time in perfect Maturity; it happen'd also very often, that the Cataracts which were suppos'd to have got up again, were not the very same with those that were couch'd, but rather a new _Pellicula_ or little Skin, which sometimes hath its Origine in the top of the _Uveous_ Tunicle, and is caus'd only by a very considerable Relaxation of the Excretory Vessels from the Sources of the Aqueous Humour which in filtrating permits the running {218} of many heterogeneous Parts, the Encrease of which produceth a new Cataract. _Of other Operations in the Eyes._ Sometimes a sort of purulent Matter is gather'd together under the Corneous Tunicle; so that to draw it out, the Eye must be fixt in a Posture with the _Speculum Oculi_, and after a small Incision made therein with a fine Lancet, is to be press'd a little, to let out the Matter; but if it be too thick, it may be drawn forth by sucking gently with a small Tube or Pipe, having a little Vial in the middle, into which the Matter will fall as it is suck'd out. Sometimes a small Tumour ariseth in the Eye, which being ty'd at its Root with a Slip-Knot, to streighten it from time to time, will at length be dissolv'd: But if the Tumour lie in the Hole of the Apple of the Eye, this Operation must not be admitted, lest the Scar shou'd hinder the Passage of the Light. Sometimes also a somewhat hard Membrane, call'd _Unguis_, appears in the great corner of the eye, which when it sticks thereto, may be cut off by binding it; this is done with a Needle and Thread, which is pass'd thro' the Membrane, and afterward ty'd. If the Eye-Lids are glu'd together, a crooked Needle without a Point may be threaded, and pass'd underneath 'em; then the ends of the Thread may be drawn, to lift up the Eye-Lids, and they may be separated with a Lancet. {219} If the Hairs of the Eye-Lids or Eye-Brows offend the Eye, they must be pull'd out with a Pair of Tweezers or Nippers; and when any small, hard, and transparent Tumours arise in the Eye-Lids, they are to be open'd, to let out the corrupt Matter. * * * * * CHAP. IV. _Of the Operation of the _Polypus_._