ulcerates the cornea. Unless when in great quantity," says he, "the matter is generally absorbed in proportion as the inflammatory symptoms are alleviated; but if it remains a long time, it sometimes ulcerates the cornea, or becomes inspissated into a tough light-coloured mass, which remains after all the inflammatory symptoms have disappeared." P. 49. This position, however, we are not disposed to admit. Authors, indeed, have talked of the corroding power of matter, as if it were a mineral acid or a caustic solution; and ascribed the progressive ulceration and wasting of soft parts, and even of bones, to this power. But whence does matter come? Is it not an effect of disease in the solid parts ? Were matter the cause of ulceration, there could be no ulcers previously to its formation. The reverse is the case. The solids become discased, and matter is formed. If they become sound again, a stop is put to its formation. If they continue diseased, or increase in discase, there is a correspondent production of matter. Matter, therefore, is an effect, and not a cause, of ulceration. 66 On these principles we cannot admit that matter lodged in the anterior chamber " ulcerates the cornea." The cornea But these abscesses" (viz. of the anteis, indeed, diseased. rior chamber)" are commonly the effect of violent ophthalmia occasioned by blows or injuries of the eye-ball." p. 50. How, then, can the cornea escape ulceration?-Or how can matter be collected in the anterior chamber without a morbid condi tion of the adjacent parts? And is not this morbid condition, especially if it be progressive, sufficient to account for the ulceration of any of these parts? "If it (the matter) remains a long time, it sometimes ulcerates the cornea;" or, more properly, if the affection continues a long time, the cornea gets more and more diseased, and at last becomes ulcerated. The seventh chapter relates to ulcers of the cornea. These have been divided by some authors into a number of species. But as, in this author's opinion, these divisions are not founded on any specific differences in the nature of the disease; and as, instead of elucidating the subject, and assisting us in our inquiries, they lead to erroneous conclusions, and render more complex a subject in itself simple, he omits mentioning them, referring those who wish for information on the matter to the works of Wallis, Maitre-Jan, Mauchart, and Rowley. The most frequent variety of ulcer of the cornea is that which remains after the cornea has suppurated and burst, either in consequence of a pustule or of an abscess: they also take place from the formation of abscesses or collections of purulent matter betwixt the layers of the cornea; from wounds of the The eornea; and from the action of corrosive substances. following cases are worthy of notice. The first, a woman, in whom, by a violent attack of inflammation, the cornea was destroyed, and cane off in large sloughs.: a transparent tumour was formed by a prolapsus of the vitreous humour through the opening of the cornea, by which means she was enabled to see with considerable distinctness for several days, until the vitreous humour began to be absorbed and the eye-ball to collapse. The second, a man some time ago under Mr. Thomson's care, in the Royal Infirmary of Edinburgh. He had a cancerous sore on the under eye-lid, which, in spreading, inflamed the eye-ball, and ulcerated nearly the whole cornea. Through this ulcer a portion of vitreous humour was exuded, forming a large transparent tumour, which enabled him for several days to distinguish minute objects with tolerable distinctness. The eighth chapter treats of wounds of the cornea; and the ninth, of foreign bodies adhering to the cornea. When a foreign body once adheres to the cornea, all attempts in rubbing the eye-lids, or winking and shutting them, forcibly tend more to imbed it firmer rather than to remove it. From the external layer of the cornea being soft and yielding, the foreign body, if it be small, soon forms to itself a seat; and the constant flow of tears, and disposition to shut the eye-lids, produced by its irritation, soon bring on a violent inflammation, which never abates until the body is either removed by art, or comes away by a tedious process of suppuration. It sometimes happens, however, that after a body is imbedded in the cornea, a layer of a new substance is formed over it, so that it does not excite any inflammation, but remains through life in a kind of sac. The author has observed this process begin and be completed, in a case where a small portion of the iris had been pushed through an ulcer of the cornea. The cornea near the prolapsed iris became obscure, and the opaque matter was daily effused from the circumference towards the centre of the opening, so as finally to cover the prolapsed iris 0 completely that it appeared afterwards like a common speck of the cornea. In another case, he found a piece of whinstone, inclosed in a sac of cellular membrane, lying close to the sclerotic coat, which had remained for ten years prior to the person's death, without his experiencing the least uneasiness from it, or even suspecting its presence. In the tenth chapter we have an account of the ossification of the cornea, and in the eleventh of the speck of the cornea. 1. Of the Varieties of the Speck of the Cornea;-2. Of the Formation of Specks of the Cornea ;-3. Appearances of Speck en Dissection;-4. Causes of Specks of the Cornea. ulcerates the cornea. Unless when in great quantity," says he, "the matter is generally absorbed in proportion as the inflammatory symptoms are alleviated; but if it remains a long time, it sometimes ulcerates the cornea, or becomes inspissated into a tough light-coloured mass, which remains after all the inflammatory symptoms have disappeared." P. 49. This position, however, we are not disposed to admit. Authors, indeed, have talked of the corroding power of matter, as if it were a mineral acid or a caustic solution; and ascribed the progressive ulceration and wasting of soft parts, and even of bones, to this power. But whence does matter come? Is it not an effect of disease in the solid parts? Were matter the cause of ulceration, there could be no ulcers previously to its formation. The reverse is the case. The solids become discased, and matter is formed. If they become sound again, a stop is put to its formation. If they continue diseased, or increase in discase, there is a correspondent production of matter. Matter, therefore, is an effect, and not a cause, of ulceration. On these principles we cannot admit that matter lodged in the anterior chamber "ulcerates the cornea." The cornea is, indeed, diseased. But these abscesses" (viz. of the anterior chamber)" are commonly the effect of violent ophthalmia occasioned by blows or injuries of the eye-ball." p. 50. How, then, can the cornea escape ulceration?-Or how can matter be collected in the anterior chamber without a morbid condi tion of the adjacent parts? And is not this morbid condition, especially if it be progressive, sufficient to account for the ulceration of any of these parts? "If it (the matter) remains. a long time, it sometimes ulcerates the cornea;" or, more properly, if the affection continues a long time, the cornea gets more and more diseased, and at last becomes ulcerated. The seventh chapter relates to ulcers of the cornea. These have been divided by some authors into a number of species. But as, in this author's opinion, these divisions are not founded on any specific differences in the nature of the disease; and as, instead of elucidating the subject, and assisting us in our inquiries, they lead to erroneous conclusions, and render more complex a subject in itself simple, he omits mentioning them, referring those who wish for information on the matter to the works of Wallis, Maitre-Jan, Mauchart, and Rowley. The most frequent variety of ulcer of the cornea is that which remains after the cornea has suppurated and burst, either in consequence of a pustule or of an abscess: they also take place from the formation of abscesses or collections of purulent matter betwixt the layers of the cornea; from wounds of the eornea; and from the action of corrosive substances. The following cases are worthy of notice. The first, a woman, in whom, by a violent attack of inflammation, the cornea was destroyed, and cane off in large sloughs.: a transparent tumour was formed by a prolapsus of the vitreous humour through the opening of the cornea, by which means she was enabled to see with considerable distinctness for several days, until the vitreous humour began to be absorbed and the eye-ball to collapse. The second, a man some time ago under Mr. Thomson's care, in the Royal Infirmary of Edinburgh. He had a cancerous sore on the under eye-lid, which, in spreading, inflamed the eye-ball, and ulcerated nearly the whole cornea. Through this ulcer a portion of vitreous humour was exuded, forming a large transparent tumour, which enabled him for several days to distinguish minute objects with tolerable distinctness. The eighth chapter treats of wounds of the cornea; and the ninth, of foreign bodies adhering to the cornea. When a foreign body once adheres to the cornea, all attempts in rubbing the eye-lids, or winking and shutting them, forcibly tend more to imbed it firmer rather than to remove it. From the external layer of the cornea being soft and yielding, the foreign body, if it be small, soon forms to itself a seat; and the constant flow of tears, and disposition to shut the eye-lids, produced by its irritation, soon bring on a violent inflammation, which never abates until the body is either removed by art, or comes away by a tedious process of suppuration. It sometimes happens, however, that after a body is imbedded in the cornea, a layer of a new substance is formed over it, so that it does not excite any inflammation, but remains through life in a kind of sac. The author has observed this process begin and be completed, in a case where a sina!l portion of the iris had been pushed through an ulcer of the cornea. cornea near the prolapsed iris became obscure, and the opaque matter was daily effused from the circumference towards the centre of the opening, so as finally to cover the prolapsed iris so completely that it appeared afterwards like a common speck of the cornea. In another case, he found a piece of whinstone, inclosed in a sac of cellular membrane, lying close to the sclerotic coat, which had remained for ten years prior to the person's death, without his experiencing the least uneasiness from it, or even suspecting its presence. The In the tenth chapter we have an account of the ossification of the cornea, and in the eleventh of the speck of the cornea.1. Of the Varieties of the Speck of the Cornea;-2. Of the Formation of Specks of the Cornea ;-3. Appearances of Speck on Dissection;-4. Causes of Specks of the Cornea. 1. The great varieties in the degree of the obscurity, as well. as those which occur in the shape, the mode of formation, the relative position, and extent of corneal specks, have induced some authors to consider them as distinct species, and to distinguish them by particular names. As the meaning, however, of these names is very ambiguous, there being scarcely two authors who use the same word to denote the same variety of the disease; and also, as it will appear, that there is such a close resemblance between some, and such a similarity of character in all the forms in which specks appear, the author thinks that these arrangements are not only useless but incon-sistent. Instead, therefore, of introducing a variety of names, or attempting to arrange in a systematic manner the varieties of this morbid alteration of structure, he considers it, in whatever form it may appear, or in whatever degree, under the general name of obscurity of the cornea, or corneal speck. The first and most simple variety or form of corneal speck is when a particular part of the cornea loses its natural transparency, and appears clouded; objects appearing to the patient as if seen through a mist or smoke. In a second form of this affection the opacity is of a darker shade, giving the. cornea a bluish, or in some parts a white milky appearance. And in a third, the cornea becomes of the opaque, glistening, white colour of common pearl, and the opacity generally extends through the whole of the lamella of the cornea; so that if even several of those layers, which are external, be removed,.. the remaining ones continue to form a complete obstruction to the entrance of light. Besides these forms of corneal speck, there are instances where the cornea acquires a very peculiar mottled appearance; and, in other cases, the opacity, instead of being formed towards the central part of the cornea, or at some distance from its circumference, begins at the place of the junction of the cornea and sclerotic coat, and gradually extends towards the centre of the cornea, forming au opaque ring around its circumference. 2. Specks, most commonly, are either preceded or accom-. panied by inflammation of the cornea. In some instances, however, the cornea acquires a very remarkable degree of obscurity, when the inflammatory symptoms are apparently mild, and where there is very little perceptible redness. The author has observed several instances of this kind, and in all of them the obscurity came on by very slow degrees, and was attended by no pain. 3. When the cornea is examined after death, no change of structure can be observed in those cases where there had been a mere cloudiness or general opacity during life; and even |