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of inflammation. The rule would be meaningless had not experience taught us that there is very considerable danger lest the counter-irritant should aggravate the disease. It may be concluded, therefore, that a counter-irritant may aggravate the disease if applied during the first stage of inflammation, although this is by no means always the case.

There is a pretty general agreement in the opinion that counter-irritants tend to deflect the part towards health when applied during the second stage of inflammation; and more especially is this the case when the disease becomes chronic. Even here, however, the effect is not always beneficial. If a part in the second stage of inflammation is on the verge of breaking down into pus, the application of a counter-irritant may accelerate the process; and whether this event is or is not desirable, the deflection produced cannot be said to tend directly towards health. But counter-irritation is also used with marked benefit in cases which are not of inflammatory origin. Such cases as flatulent colic and partial paralysis of the bladder may be mentioned as examples. In these diseases the main symptoms arise from debility of the muscular coats of the respective organs, and it is important to remember that counter-irritants tend to restore health in such diseases.

There are two other important points which must be noticed in connection with the practice of counter-irritation. Quantitative differences may be observed in the effects according, first, to the proximity of the irritant to the seat of the disease; and, secondly, to the degree of irritation produced. If the irritant is placed too far from the seat of the disease, synovitis of the knee-joint for instance, it will have little or no effect; if at a moderate distance it may have a curative effect; and if too near it may aggravate the disease. Qualitative differences obscure to some extent the comparison, nevertheless it is readily seen that between no effect, a curative effect, and an aggravation of the disease there must be quantitative differences. The quantitative differences which arise from the degree of irritation are also considerably obscured by qualitative differences. But the fact of our dividing counter-irritants into rubefacients, vesicants, pustular counter-irritants, issues, &c., along with the fact that some are called milder, and others severer, counter-irri

tants, and that the former are used in acute and the latter in chronic cases, is alone sufficient to show that there are quantitative differences in the effects produced by different degrees of irritation. These are the main inductions which a survey of the effects of counter-irritants affords. How shall we interpret them?

Some would place the old maxim "Ubi irritatio, ibi fluxus," at the basis of any explanation of the action of counter-irritants. But although this maxim is perfectly true in so far as it is a statement of fact, it explains nothing unless it can be shown that the special flow of blood to the irritated part is accompanied by a special withdrawal of blood from the surrounding tissues. It cannot be shown that this is the case even when the part irritated and the part diseased have a direct vascular connection, and much less is it likely to happen when no such connection exists. But even if blood could be withdrawn from a diseased part, the effect produced would be very unlike that of counter-irritation. Imagine a practitioner giving the following instructions to his pupil :-Withdraw blood from organs during the second stage of inflammation, especially in chronic cases, and also from organs suffering from local debility, and this will tend to cure them. You exclaim, "How exceedingly false!" But let our imaginary teacher substitute counter-irritation for local blood-letting, and you are almost ready to exclaim, "How exceedingly true!" Practically the distinction between counter-irritation and local blood-letting is acknowledged, yet theoretically both are explained upon the same principle. Our precepts for the guidance of practice in local blood-letting are almost directly opposed to those for counter-irritation, but what are considered contraries in practice are regarded as identicals in theory. When I say that counterirritation and local blood-letting are regarded as contraries in practice, I am alluding to practice as it exists at the bedside, and as I can gather it from practical precepts, and not as I find it reflected in the classification of remedies. The practical precept warns us not to apply a counter-irritant near an actively inflamed organ, lest the disease be aggravated; but in classification counter-irritants are called antiphlogistics. The precept is the reflex of practice, the classification the reflex of theory.

NO. LXIX.

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Antiphlogistic, forsooth, when we are warned in the same breath not to employ the remedy in an early stage of inflammation. A counter-irritant might more properly be called a phlogistic than an antiphlogistic remedy.

The idea that counter-irritants are antiphlogistics has, however, got such a deep hold of the medical mind that those who see clearly that the flow of blood which takes place to a newlyirritated part will not directly diminish the flow of blood to the surrounding textures, endeavour to supply a machinery which they suppose to produce the same result indirectly. Such do not doubt that an artificial irritation does diminish the flow of blood to a diseased organ in its vicinity, and, since this cannot be explained upon hydraulic principles, it is supposed that it must be explicable by the indirect action of the nerves. Irritation of the sympathatic at a certain point induces a contraction of the surrounding minute arteries, and this of course lessens the supply of blood to the surrounding textures. It is difficult to understand how the minute arteries of the lungs should be specially contracted by the application of a counter-irritant to the surface of the chest; but admitting that such an action takes place, it would not account for the effects of counter-irritants. Contraction of minute arteries might be of some use in the first stage of inflammation; but a counter-irritant may aggravate the disease in this stage. On the other hand, what would be the use of contracting the blood-vessels in the second stage of inflammation, when a large number of the capillaries are already occluded? In this stage we want more, and not less, blood to the part. And lastly, in cases of debility, where counter-irritants are found so useful, it would be madness to endeavour to contract the blood-vessels even if it were possible.

The theory I advocate is, that a counter-irritant always tends to stimulate the neighbouring textures to increased activity, and that this stimulating action spreads along the parenchyma not merely when the tissues are continuous, but also when they are simply in contact. Let us attend to the successive changes which take place when a part of the surface is irritated, as for instance by the application of tartar-emetic ointment. In the centre there is a small cavity filled with pus. Surrounding this cavity there is a zone of tissue thickened by new deposit. Still

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further from the centre there is another red zone exhibiting vascular engorgement, and gradually fading into the colour of the surrounding skin. But it is not at all probable that the influence of the inflammatory centre ceases when we fail to recognise any engorgement of the blood-vessels with the naked eye. The overgrowth of hair which is found round oldstanding ulcers shows that a certain influence is propagated much further than the visible signs of inflammatory action. may, therefore be inferred that beyond the red zone by which an irritation merges into the healthy colour of skin, there is another zone the tissues of which are stimulated to increased action. But not only does irritation spread along the surface, but it also spreads inwards. That this is the case may be concluded from the fact that internal irritation has frequently been noticed to spread outwards to the surface. Witness the red and tender scrotum after injection of tincture of iodine for the radical cure of hydrocele. I have seen a red and tender spot on the skin of the upper lip corresponding to a long-continued ulcer on the internal surface. Again, in a post-mortem examination, a large patch of red and injected peritoneum has been found corresponding to the area of a blistered skin. There is also abundant evidence to show that irritation spreads from one tissue to another with which it is only in contact. In a postmortem examination it is rare to find indications of previous inflammation in the pleura costalis without indications of a corresponding action in the pleura pulmonalis. Occasionally, a patch of adhesion has been met with between the pleuræ opposite a single spot of tubercle in the lung. This shows that the irritation has spread from the tubercular centre to the pulmonary, and from the pulmonary to the costal pleura. In ulcerative stomatitis, the cheek and tongue opposite to the ulcerated gum generally become inflamed and ulcerated, and this has a like implication with the other instances adduced.

Let it now be granted that the transmission of irritation from one part to another is mainly an action of the parenchyma, that irritation will pass from one tissue to another with which it is contiguous, and that surrounding the irritated part there is an area stimulated to increased nutritive activity, several questions arise. Does the area of stimulated tissue extend far enough

and in a sufficiently short time to account for the action of counter-irritation? If so, is the intensity sufficient to produce the effects? and, lastly, is the quality of the action assumed of such a nature as to account for all the local effects counter-irritants are known to produce? There are no means by which we can measure how far the excitement of tissue extends round an irritated part. Dr. Beale has, however, made a very beautiful observation which shows how very sensitive the organism as a whole is to changes going on in a single part. He says that if one has only a slight catarrh, the bioplasm (protoplasm of others) over the entire body is increased. If such is the case there can at least be no difficulty in conceiving that the special excitement which surrounds an irritated part will extend sufficiently far, and in a sufficiently short time, to account for the action of counter-irritants.

But even if it be granted that this stimulated area extends far enough to account for the action of counter-irritants, it may be objected that the action is so very slight that it could not have any appreciable effect. If a blister is placed upon the chest of a healthy person, it produces no recognisable effect upon the lung beneath, and it may therefore be supposed that it cannot have a curative effect upon a diseased lung. This is an objection which may be urged against any theory of counterirritation; but a solution of the difficulty will be another argument in favour of the one advanced here. In a state of health the lung is in equilibrium with every part of the body, and it can therefore resist unusual incident forces of considerable intensity without a deviation from health being produced. When, however, a deviation from health is once produced in the lung, an unstable equilibrium is produced between it and the rest of the organism, and, as is usual in such a case, slight incident forces will produce large effects. In health, therefore, the effect produced by an irritation may be inappreciable, while in disease the effect may be very marked either for good or for evil.

The last question to determine is, whether the action assumed to spread along the parenchyma is of such a nature as to account for all the local effects of counter-irritation? The influence which I have supposed to proceed from the artificial irritation

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