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IV.

Remarks on the Difference between the Infectious Ophthalmia, and that produced by the Artful Application of Irritating Substances to the Eyes. By JOHN VETCH, M. D. Assistant Surgeon with Ophthalmia Detachments at Riding Street Barracks.

THE discovery of a system, which has existed among the men of the 28th regiment of foot, of producing, by the applica tion of irritating substances to their eyes, such a degree of ocular inflammation, as not only to exempt them from their duty, but even with the ultimate view of being discharged from the service, must naturally incline every person, more or less, to suspect that similar means have been employed in other instances where, from an affection of the eyes, the same objects have been accomplished, and even perhaps altogether to overlook, that it has been from the prevalence of a natural ophthalmia, that the minds of the men were in that instance led to perpetrate the deceit, and those of the medical attendants to receive the imposition.

To point out the difference between this factitious disease, and the infectious ophthalmia, which first appeared in the army during the Egyptian expedition, and in which it still prevails to a considerable extent, some leading facts are here briefly contrasted, in the hopes that they may be useful in assisting so necessary a discrimination, and to prevent, by a hasty belief that there exists no other than a factitious ophthalmia, the dereliction of those measures which, after the loss of much time, have been found sufficient to arrest the progress of the natural disease.

1. The affection of the eyes which prevailed in the 28th regiment of foot, and which has been proved in the greatest number of cases to have been caused by the wilful application of irritating substances to the eyes, was confined entirely to the privates and non-commissioned officers of the regiment.

Where the infectious opthalmia has prevailed, it has uniformly affected the women and children, in a proportion equal to that of the men: It has been frequently communicated to the officers, both military and medical. It has appeared among the inhabitants of the neighbourhood of the disease; it has also made its appearance among the children of the Royal Military Asylum, where for some time it prevailed to a considerable extent.

2.

* I am acquainted with four cases of the former, and two of the latter.

2. The counterfeit ophthalmia continued to present itself after the adoption of the most vigorous measures against the action of contagion or infection.

The progress of the infectious ophthalmia has been, in those instances with which I have been connected, effectually arrested by the removal of the affected, on the first appearance of the disease; their complete separation from the healthy as long as the slightest symptom remains; and the vigorous enforcement of every measure against the operation of infection.

3. In the counterfeit ophthalmia the inflammation was, for the most part, confined to one eye, and that almost always the right. In above 1000 cases of the infectious ophthalmia, I have met with but a very small number, not exceeding six, where both eyes have not been affected.

4. The counterfeit ophthalmia was sudden in its progress, having generally occurred and arrived at its acmé in the course of the night.

The infectious ophthalmia advances by a gradual and uniform progress after its first commencement.

5. In the counterfeit ophthalmia, the swelling was chiefly in the conjunctiva, and was not attended with much purulency. The tumefaction of the palpebræ, and great purulent discharge, are particularly characteristic of the infectious ophthalmia.

6. The artificial ophthalmia generally ceased as soon as the vision of the eye was rendered imperfect.

The infectious ophthalmia continues to harass the patient for months after the destruction of the eye, and the purulency and tendency to relapse, often remains for years after the total loss of sight.

7. As the counterfeit ophthalmia was generally confined to one eye, so was the loss of sight, a very small number of the 28th having lost both eyes.

From the infectious ophthalmia, a greater number have lost both eyes than one.

8. The eyes which were rendered unserviceable from the artificial ophthalmia, had seldom suffered much organic alteration.

Among the eyes which have been lost from the natural ophthalmia, a few are merely in consequence of a cloudiness of the cornea, and which may yet recover; but in by far the greater number, the organ is completely deformed, either by the forma tion of staphyloma, the complete evacuation of the humours, and a consequent flattening of the eye, from obliteration of the pupil, and adhesion of the iris with the cornea, cataract, amaurosis, and pterygion.

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The general facts which have been here selected, are sufficient to point out the existence of two separate affections, without rendering it necessary to enter into a description of the peculiarities, which, from its first commencement, characterize the infectious ophthalmia from every other inflammation of the eye. In all the occurrences of this disease, to which my observation has been directed, its appearances have been uniformly the same, in men, in women, and in children, and had even individual cases of a counterfeit nature presented themselves, although I might have remained ignorant of the imposture, their singularity must have excited my attention, more especially as, from the extensive experience I had, it has become very easy to distinguish a case of the prevalent ophthalmia from any other species of ocular inflammation; the truth I believe is, that the terror of the natural disease, whereever it prevails in its violent form, will be sufficient to deter the most resolute from tampering with their eyes. As the tediousness of the convalescence, and the frequency of relapse, may be considered as suspicious symptoms of the disease, I shall conclude these observations with stating that both, though in a great measure aggravated by particular situations, are the inseparable effects of an attack of the infectious ophthalmia, and that, in the cases of the men whose eyes are totally destroyed, and who wait with much impatience for the complete cessation of the disease, in order to receive their discharges, and return to their homes, the relapses are no less frequent, and the convalescence no less tedious, than with those who have escaped with their eyes uninjured.

V.

Remarks on Mr Ellis's Theory of Respiration.

By JOHN BOSTOCK, M. D. late President of the Edinburgh Medical Society, &c. &c.

MR ELLIS, in his late publication, on the changes produced in the atmosphere by respiration, objects to the hypotheses that have been formerly adopted on this subject, and substitutes in their place one which is, in several particulars, different from any that has hitherto been proposed. It appears to me, however, that he has not sufficiently established his point, either against

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the old hypothesis, or in favour of the new one; and I shall now beg leave, through the medium of the Edinburgh Journal, to state the reasons which induce me to retain my old opinion. The candid and liberal spirit which Mr Ellis has manifested in his work, will, I am confident, render it unnecessary for me to make any apology to him for my attempt to controvert his reasoning.

I shall begin, by briefly stating the theory of respiration which I regard as the most probable, and the one which I adopted in my Essay." The blood arrives at the right side of the heart, in a venalized state, loaded with a quantity of the oxide of carbon; as it passes through the pulmonary vessels, it becomes subjected to the action of the air contained in the bronchial cells; a portion of the oxygen is removed from the air, part of which, forming an intimate union with the oxide of carbon, is expelled in the form of carbonic acid gas, while the remainder is dissolved in the blood. It is here necessary to remark, that it is not oxygenous gas, but oxygene, which is supposed to be mixed with the blood. The caloric thus set at liberty is employed, part of it in maintaining the temperature of the lungs, which would otherwise be cooled by the admission of the external air; part of it in carrying off the aqueous vapour, and another portion in converting the carbonic acid into carbonic acid gas; but the greatest part of it is united, in the form of specific heat, to the arterial blood, which, by becoming arterialized, has its capacity for heat increased. The arterial blood is poured into the left cavity of the heart, and propelled through the arteries, into the extreme parts of the body. The oxygene which was dissolved in the whole mass of blood, during the circulation, gradually unites itself more intimately to a portion of the carbon in it, which it converts into the oxide of carbon, and thus the blood acquires the venous state. By this change its capacity for caloric is diminished; the specific heat which it obtained in the lungs, is given out in the capillary vessels, to keep up the temperature of the body, and the blood returns to the right side of the heart completely venalized. This hypothesis is nearly similar to the one which was proposed by M. M. La Grange and Hassenfratz; it received some modifications from Mr Allen of Edinburgh, and was delivered by him nearly in the form which I have stated above, in his admirable course of physiological lectures. It was, I believe, first published in my Essay on Respiration*.

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I must not omit to mention, that this theory was, in the year 1797, detailed in the valuable Thesis of Dr De la Rive of Geneva; but the circulation of medical theses is too limited to be considered as equivalent to publication.

I shall now consider the objections which Mr Ellis offers to this hypothesis: He observes, that the air and the blood, while they are in the lungs, are separated, both by the membrane which forms the air cells, and by that which forms the coats of the vessels, and that the air must pass through both these bodies before it can act upon the blood *. I may remark, in this place, that not only this argument of Mr Ellis's, but some other parts of his reasoning, are founded upon the mistaken opinion, that air is supposed to enter the blood, and to exist in the vessels. This, however, is not the case; the oxygen on the one hand, before it enters the arterial, and the carbonic acid on the other, after it quits the venous blood, mutually give out and receive a portion of caloric, which is necessary to reduce each of these bodies to the gaseous state. Oxygen, however, is supposed to enter the blood, according to the hypothesis which I have undertaken to defend; and improbable as it might à priori appear, that it should have the power of penetrating a compact membranous body, the fact has been so well illustrated by the experiments of Dr Priestley and others, that I cannot but consider it as one too well established to admit of any farther scepticism. He found that blood, when separated from the air by a bladder, was acted upon by it in the same manner as when no substance was inter posed between, and that a thick stratum of serum also permitted the action of the air, although a thin layer of water, saliva, or oil, as effectually prevented it, as if they had been separated by a solid body. In what way the action takes place, whether it be in consequence of the mechanical structure of membranous matter, which permits the oxygen to pass through its pores, or whether it be owing to its affinity for oxygen, which causes it, as it were, to become saturated with this substance, before it transmits it, it is not our business at present to inquire; it is sufficient to state, that oxygen and blood can act upon each other, through a membrane, which is very much thicker, and probably much denser, than that which separates the blood in the rete mirabile of the lungs from the air in the bronchial cells.

With respect to the actual change which takes place in air that has been exposed to the action of the blood, there can be no room for any difference of opinion; it is admitted on all hands, that it is diminished in bulk, that a part of its oxygen has disappeared, and that it has received the addition of a quantity of carbonic acid gas. The point in discussion is, to ascertain in what manner the carbonic acid gas is formed; and Mr Ellis endeaVOL. IV. NO. 14.

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vours

Inquiry, p. 117.