contained in a transparent capsule. The latter, in my experience, has been partially opake, presenting a dotted or mottled surface. The capsule appears in contiguity with the margin of the pupil, and as if projecting in it, and the opake spots upon it are most distinguishable when it is viewed laterally. The second usually resembles, in appearance, flakes of snow irregularly heaped, being visibly of a loose and broken texture, and the larger masses intersected by semi-transparent lines: the arrangement is sometimes regular and uniform, being either foliated or radiated. The capsule is sometimes semi-opake, but more frequently transparent. The third is the cataract of greatest bulk, impeding the motions of the pupil, having a heavy and dense appearance, uniformly opake, a clouded not a fleecy whiteness, and sometimes a greenish or dirty white tinge. The fourth appears deep seated, of a brown yellow, or amber colour, most dense in the centre; if entirely opake, flat upon the surface, over which the iris plays freely. The second and third species are most commonly met with; the first and fourth are comparatively rare.

The description of such appearances is difficult, and might appear over minute; but to an eye much accustomed they admit of ready distinction, and the distinction is of the highest importance, as the operation should be selected accordingly. To the first and second species, formerly regarded as incurable on account of their softness, the operation performed by the late Mr. Saunders is admirably adapted. To the two latter, the operation of couching or extraction is best suited.

In the description given the capsular opacity is not included; for when the capsule is completely opake, we can hardly judge of the texture of the lens. But where the complete opacity of the capsule exists, the lens is commonly diminished in bulk; it undergoes a waste after the opacity of the capsule, so as in process of time to become a membranous cataract. This I conceive to be owing to the obliteration of the vessels of the capsule, from which those of the lens are derived. When the capsular opacity is congenital, it is either purely capsular, or

only a very small piece of lens remains. When the capsule turns opake from injury, the lens is soon greatly reduced in bulk, as appears from the falling in or concavity of the iris which loses its support, and is demonstrated in the operation. This observation renders the operation with the needle appropriate to the cataract in which the capsule is opake, in cases which are not very recent. When the capsule of the vitreous humour is the seat of the opacity, I have not observed that the lens undergoes any diminution, nor have I yet ascertained the remediableness of this case. The membranous or purely capsular cataract is a form of the disease which appears to me to require a somewhat different operation.

The fluid cataract commonly requires only the central aperture of the capsule; it flows out into the anterior chamber, and mixes with the aqueous humour, which, by the absorption of the opake particles, in a few days recovers its transparency. It is to be observed, however, that this form of cataract requires to be treated with caution. I have seen two instances in which the simple discharge of the fluid was followed by severe inflammation, by which the process of absorption was arrested, as appeared from the permanently turbid state of the humour. This does not happen where the whole substance of the lens is changed. The milk-like fluid in these cases concealed a solid bed of lens, which, by the free laceration of the capsule, was set at liberty, and oppressed the iris.

The flocculent cataract readily undergoes solution in the aqueous humour when the capsule is freely opened, and its texture broken down by the needle.*

The attempt to procure a solution of the opake crystalline in the aqueous humour, was suggested by an accident, in which the crystalline being wounded, became opake, and was removed by this process. I have seen many examples of the same fact. Among the miracles recorded to have been wrought at the tomb of the Abbe Paris, is the gradual restoration of sight to a young man who became blind after a puncture of the eye with an awl, which caused the discharge of the aqueous humour. (See Paley's Evidences of Christianity, vol. I. p. 380.) This miracle admits of a more satisNo. 17.

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While any portion of the capsule preserves its connection, it continues to be nourished, and of course, resists absorption; but an insulated portion of capsule is dissolved and absorbed, like any other matter extraneous to the circulation. These facts are ascertained by the aperture in the capsule remaining ever after unchanged in dimension, and if it be equal to the natural aperture of the iris, so that its broken margin cannot be seen in the pupil, it will always appear upon dilating the pupil with the belladonna. If the aperture be made of a given size and figure, as for example, the figure of a small diamond, in the centre of the capsule, it will ever after retain its figure and dimensions. But where the aperture is ultimately of the full size of the pupil, it is evident that the portion of capsule that has disappeared, must have undergone solution and absorption with the lens. The transparent capsule is tense and contractile as well as delicate in texture, so that a wound made in it is enlarged by the retraction of its sides; but the retraction without loss of substance would be very insufficient to account for the magnitude of the aperture, and we continually see that a mere puncture or cut of the transparent capsule, from accidents with pins and scissars, unites by adhesion, forming an opacity. In the opake capsule, which has no contractility, it is still more decidedly proved, that the aperture of the size of the pupil must be produced by the laceration of the capsule in fragments, and the absorption of these fragments together with those of the lens.

The reasons why the operation of Mr. Saunders is objectionable in the two latter species of cataract are, first, the degree of force required to break down these cataracts with the needle, sufficiently to undergo a quick solution in the aqueous fluid; and secondly, the danger of dislocating the lens in the attempt. If the operation upon a cataract of firm consistence is conducted with the caution which experience dictates, the process of solution is tediously slow, and the operation must factory explanation than has yet been offered, as the familiar case of a cataract formed by the wound, and undergoing absorption.

be repeated many times; but this is the least evil. If the operator, after having opened the capsule in the centre, acts with the same freedom as upon the soft species of cataract, the unsupported lens falls forward, or revolves and turns edge foremost in the pupil, so as to put the iris on the stretch; or it passes entire into the anterior chamber. If he succeed in dividing it, large and solid masses will press upon the iris, wedge in the pupil, or pass into the anterior chamber, and the consequences be the same in kind though less in degree. Even where the operation is confined to the aperture of the capsule, and the lens has been scarcely touched, I have known the eye destroyed by the accidental falling of the lens through the aperture and pupil into the anterior chamber; a slow inflammation of the iris ensues, which not only produces the most distressing symptoms, but admits of little, if any alleviation, until the mechanical pressure is taken off. This event, so much to be desired, is unfortunately protracted, for the process of solution is arrested by an adventitious coating of lymph, which is effused by the inflamed vessels, and invests the extraneous body. This lymph becomes partially organized, and the case terminates in obliteration of the pupil and anterior chamber, or by the sympathy of the retina with the suffering iris and choroid, in incurable amaurosis. Having more than once observed the protrusion of the lens, and the consequent inflammation of the iris to ensue, where I had studiously endeavoured to prevent it, I was led to suppose this might be owing to the previous dilatation of the pupil by belladonna, by which the lens was deprived of support. I therefore omitted the previous use of the belladonna where the cataract was substantial and firm. It was then applied to the eyebrow an hour or two after the operation, with a view of preventing the adhesion of the pupil to the capsule of the lens; but under the influence of the belladonna, I repeatedly observed, that the unsupported lens came forward, and the symptoms of pressure commenced. I therefore deferred its employment until a time sufficient had elapsed for the renewal of the aqueous humour, which, I con

ceived, might resist the pressure of the lens. By this precaution the accident was effectually prevented, no symptom of inflammation followed, and the advantage of keeping the pupil circular was equally obtained. It may be right to observe here, that when the belladonna is used with this view, the interval of its application should be sufficient to admit of the recovery of the pupil, or it will be permanently dilated. With every precaution, however, the operation with the needle upon the full and firm cataract, is either distressingly tedious, or what is more to be objected to, destructive to the organ, and very trying to the health and spirits of the patient. In such cases I have, therefore, relinquished the operation, which was very ingeniously conceived, and for its simplicity appeared to me to deserve a full and fair trial of its merits. It is due to the projector of the operation to state, that its superiority was distinctly asserted by him only in the cases of soft and capsular cataract, as may be seen by a reference to his essay on that subject, in his posthumous work edited by Dr. Farre. At page 173 of the volume referred to, the editor observes, "In the adult, if the texture of the lens is nearly uniform and permeable, the cure is completed in a space of from three to five months; but if the texture is firmer and the nucleus large, the cure cannot be accomplished in less than seven months. On this account the author, who thought highly of extraction, and performed this operation with dexterity and success, was inclined to extract the lens when its texture was unusually hard. The editor cannot assert that he would ultimately have conceded thus much in favour of extraction. It was intended that such decision should result from a very long and impartial trial of both operations. With respect to the softer lens, or the capsular cataract, he was satisfied of the superiority of his operation."

In performing this operation for the soft cataract the operator may pass his needle through the cornea or the sclerotic. The former mode commands the advantage of giving no pain, exciting but slight inflammation, and ensures the laceration of