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although unattended with any discharge, it became necessary to establish it as a law of the animal economy, that two morbid impressions could not subsist together in the same body, so that, a secondary and stronger one being promoted, the primary and weaker one necessarily ceased, “Aúw πóvwv,' says Hippocrates, “ ἅμα γινομένων, μὴ κατὰ τὸν ἀυτὸν τόπον, ὁ σφοδρότερος ἀμαυροῖ τὸν ἕτερον ;” and this assertion, gratuitous as it certainly is with respect at least to irritability, which has, as I have shewn, many totally independent mansions, however well founded it may be with respect to sensibility, which has but one, has been received since his time almost as an axiom; and while inflammation was considered to consist in increased action of the part affected, it was certainly a very convenient one. But inflammation is at present generally understood to consist, not in increased, but in diminished action of the capillary arteries of the part; so that our explanation of the benefit to be derived from revulsive remedies must be, toto cœlo, different from that formerly adopted, and must be founded upon the presumption that they communicate, not abstract a stimulus, and thus promote by the contraction of the dilated vessels, already, if necessary, freed by bloodletting of a part of their load: and this doctrine, however staggering it may be found, as directly opposed to preconceived opinions, is perfectly reconcileable to every unprejudiced view of the question, and either must be adopted, or the whole modern theory of inflammation must be entirely abandoned. The action also of those direct applications found most efficacious in the cure of inflammation is highly favorable to this view of that of indirect or revulsive remedies. "When such inflammation occurs in a superficial part, as the eyes, tonsils, or skin, the local applications in the forms of collyria, gargles, and lotions, from which we derive most benefit, are such as immediately irritate the dilated arteries: and, in the inflammation of a deep-seated part, some of the most efficacious local remedies, such as heat, electricity, and acu-puncture, manifestly act as direct and powerful stimulants;" and the only difference that seems to exist between the operation of these remedies and those reputedly revulsive is, that, what the former effect directly, the latter effect indirectly, or by sympathy.

c. Operation of Astringents.

Directly opposed in their sensible effects to the evacuant medicines are the astringents, the peculiar action of which seems to depend upon the constriction of the capillary arteries which they occasion, being generally (as blushing sometimes

immediately succeeds paleness,) followed immediately by a proportionate collapse; and this again (as a more or less permanent paleness frequently succeeds a blush,) by a more or less permanent constriction. That this is the case is rendered probable by the fact, that some of the strongest astringents, such as alum, if given in too large quantities to allow of this secondary constriction, prove, as I have before observed, not astringent, but relaxing. It must not, therefore, excite surprise that this class should contain many of the medicines commonly enumerated among the evacuants; since it may be easily inferred, from what has already been said, how slight a variation of circumstances may make the same medicine give rise, at different times, to directly opposite effects.

D. Operation of Stimulants, Sedatives, &c.

The stimulants and tonics appear to be analogous in their action to the several evacuant medicines already spoken of; and the sedatives, antispasmodics, and narcotics, to the astringents; inasmuch as the two former seem to produce, first a constriction, and afterwards a dilatation of the capillary arteries of the brain, and, consequently, first a diminished, and afterwards an increased evolution of the influence derived from this organ; and the three latter, in like manner, seem to produce, first, a diminished, afterwards an increased, and, lastly, a still more diminished evolution of this influence. The stimulants seem to differ from the tonics principally in their effects being more sudden and violent, and in the same degree more transitory, since both act apparently in exciting equally every organ of the body. Of those classes of medicines, however, which seem to lessen the action of the brain, those are called sedatives which diminish the stimulus sent from this organ, more particularly to the heart; those are called antispasmodics which diminish the stimulus sent from the brain to any of the muscles, whether of involuntary or voluntary motion; and those are called narcotics which at the same time diminish sensibility, the faculty of thinking, and the power of exciting voluntary motion.

E. Operation of Antacids, &c.

The two last classes of medicines which I have mentioned are the antacids and anthelmintics. Of these, the action of the former is directly chemical; while that of the latter is either chemical, as operating in dislodging the worms by dissolving the mucilage in which they are imbedded; mechanical, as operating by friction; or poisonous, as operating by directly killing them. Simple purgative medicines also fre

quently act as anthelmintics, and are commonly used to assist the action of those substances more properly so called; but to the operation of these medicines, as evacuants, I need not again revert.

4. Combination of Medicines.

Medicines, in order to adapt them to the various methods in which they are administered, are prepared, either separately or conjointly, in various forms, solid and liquid; but, in prescribing compound medicines, it is proper continually to keep in mind that the properties of the compound are by no means always the mean of the properties of the ingredients, but that, while sometimes these latter properties are corrected or neutralized by such combinations, at others they are considerably increased, and at others entirely new properties are superadded. It is sufficiently well known that two or more medicines of the same description given in combination frequently produce a much greater effect than the same dose of each individually would have done; and the influence exerted by one class of medicines upon those of a different character, not only generally but individually, is so infinitely varied, that it is almost impossible to say, a priori, what particular indications any such compound medicine is calculated to fulfil. It hence follows that we should be extremely cautious in excluding any medicine, however farraginous, the efficacy of which is supported by experience; and perhaps the old propensity for excessive complication in medicinal prescriptions, and for a vast choice of them, was not more reprehensible than is the modern one for excessive simplification and paucity. We know nothing of the specific properties of any medicine, whether simple or compound, but by its results; and we are no more justified in concluding that any composition is inadequate to effect the object for which it is administered, because its ingredients are respectively inert, than we should be in denying the violently explosive effect of gunpowder, because neither carbon, sulphur, or nitrate of potash, are severally possessed of that property. Nor is it unreasonable to suppose that a very slight variation of the ingredients of any compound medicine, or in their proportions, may sometimes make a considerable difference in its action. How can we tell, for instance, what new chemical compounds result from the mixture of ipecacuanha, opium, and sulphate of potass, in Dover's powder; or how the emetin, meconate of morphia, salt of potass, &c. mutually affect each other; and, if we cannot do so with respect to the compounds formed by artificially mixing different roots, gum resins, and

salts together, still less can we do so with respect to those roots and gum resins themselves, composed as they are of numerous principles put together by the hand of nature; and this reflection should make us very jealous of rejecting certain of these principles, in the presumption that they are inert, and of relying upon others, in the presumption that they alone are active. The ridicule thrown upon multifarious medicinal prescriptions by Pliny among the ancients, and by Montaigne among the moderns, is perhaps deserved; and it is probably true that "one might as well," as Dr. Baynard remarks, "prescribe the powder of an old-fashioned bedpost as some of the receipts of ancient authors;" but it is to be feared that we have gone, or at least are going, too far at present on the simplifying system: "Præstat," says Cicero, "copiâ quam penuria premi." If Nicolaus Myrepsis has admitted into his work too many compound medicines, the number of which is not very far short of three thousand, and if Dr. Huxham was too fond of a complication of numerous ingredients in his prescriptions, which sometimes contained, it is said, not fewer than four hundred substances, it may be doubted whether we have not recently gone into the opposite extreme. The three British Pharmacopoeias together do not contain in the present day more than fifty distinct compound medicines; but he who reflects as well on the endless diversities in the idiosyncrasies of the human body, as on the more or less specific action of every medicine, simple as well as compound, although he may not, like Van Mons, sigh for the restoration "to their primitive state of all those bizarres receipts whose credit time has spared," will yet certainly regret that the “novæ vires mixturâ variorum" of Gaubius, the new virtues of compounds, (which, as supposed by Dr. Ferriar, are analogous to the harmony of colours and of sounds,) the "tertium quid" of Shearman, or the adjective as well as substantive powers of Paris, should be sacrificed to a fastidious science, and that any compound medicine of acknowledged efficacy should ever be wantonly expunged and voted inert, because we cannot easily explain why it should be otherwise.

Before concluding these observations, I must observe, that they are deeply tinged,—particularly that portion relating to inflammation, with the views taught and inculcated by my talented friend, Dr. Fletcher, of Edinburgh. It is with much pleasure that I look back to the time I attended that gentleman's class, and with still more that I acknowledge how great has been the colouring his instructions have given to my own opinions and practice. The reader will

find some of the preceding doctrines ably supported, in a probationary essay by Dr. Fletcher, printed in 1829; upon which I have not hesitated occasionally to draw.

Dumfries, 1834.

Account of a Case of Pulmonary Consumption, in which nearly the whole of the right lung was converted into an immense vomica, attended with universal adhesion, and partial absorption of the pleural sac. Communicated to the Harveian Society, by WILLIAM STROUD, M.D., Physician to the Northern Dispensary, &c.

On the 31st of March, 1832, I was requested to visit, as a patient of the Northern Dispensary, James T***y, aged twentysix years, and formerly a domestic servant. I found him labouring under a severe pectoral complaint, of four months' continuance, which had been preceded by diarrhoea, and was ascribed to his having passed the two previous months in a damp house. He has a distressing, and convulsive cough, which disturbs sleep, and excites pain about the sternum, the head, and the inner sides of the thighs. His expectoration is very thick, and glutinous, but not copious. He is generally in bed, and feels best when lying down. On assuming the erect posture, the cough is aggravated; and, by an effort between coughing and vomiting, a yellow, puriform liquid is expectorated. Formerly he could not lie well on the right side, but can now lie with ease on either side, as well as on the back. The chest is much emaciated, and the ribs are conspicuous. In the right side, which is rather hollow, a pulsation can be perceived, on listening with attention; but it yields little sound on percussion, and no respiratory murmur, except under the clavicle. The left side is more resonant on percussion; and, except at its lower part, yields a tolerable respiratory sound. The action of the heart is moderate, the pulse at the wrist, in the recumbent posture, is one hundred, and feeble. He is very weak, and thin, has lately had at intervals several rigors, but has little fever, and no pain, except in the front of the chest, on coughing. A short time since, he was somewhat jaundiced; and, about a month ago, a quantity of viscid, blackish mucus, accompanied with tormina, was discharged from the bowels. The dejections, at the same time, were dark-coloured, but afterwards became yellowish, and the urine, which is not yet quite natural, was red, and turbid. His tongue is whitish in the middle, with red edges, he has little thirst, or appetite, and occasionally vomits his food. The abdomen bears pressure well, and exhibits no morbid appearance. About two years before his present complaint, he laboured for

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