46

ELEMENTS OF MATERIA MEDICA.

results. The appearance of a cutaneous eruption is sometimes a signalfor the disappearance of an internal affection; and vice versa, the disap-pearance of a cutaneous disease is sometimes followed by disorder ofinternal organs. Here, again, we have another remedy suggested,namely, the production of an artificial disease of the skin, as by blisters,by an ointment containing tartar emetic, or by other irritating applications ;—a suggestion the advantage of which experience has frequently verified.I might bring forward numerous other examples to prove the fact (which,however, is so well known as to require little proof,) that action in onepart will often cease in consequence of action taking place in another.Diseases, then, appear to have what Dr. Pring ( Principles of Pathology,1823, p. 352, et seq.) calls a curative relation with respect to each other;and we shall find that the greater part of our most valuable and certainremedies operate on the principle of counter-irritation ; that is, they pro-duce a secondary disease which is related to the primary one. Dr. Parry(Elements of Pathology and Therapeutics, 2nd edit. 1825,) calls this the“ cure of diseases by conversion." Let us offer a few examples:—vomit-ing is a powerful means of relief in bubo, and also in swelled testicle.John Hunter says, he has seen bubo cured by a vomit. I have fre-quently seen the progress of swelled testicle in gonorrhoea stopped bythe exhibition of full doses of tartar emetic. Now it is very improbablethat the benefit arises from the mere evacuation of the contents of thestomach. The only plausible explanation to be offered is, that theemetic sets up a new action in the system, which is incompatible withthat going on in the groin or in the testicle. If this notion be correct,emetics act in these cases as counter-irritants. The efficacy of purga-tives, in affections of the head, is best accounted for by supposing thatthey operate on the principle of counter-irritation. Blisters, cauteries,issues, moxa, and other remedies of this kind, are universally admittedto have a similar mode of operation.

Even the efficacy of blood-letting, in inflammatory affections, is betterexplained by assuming that this agent induces some new action incom-patible with the morbid action, than that it is merely a debilitant. Theimmediate effect sometimes produced on disease, by this remedy, is soremarkable as hardly to admit of the supposition of its acting as a mereweakening agent. One full blood-letting will sometimes put an imme-diate stop to ophthalmia; and I have sometimes seen, even while theblood was flowing, the vascularity of the eye dimmish, and from thattime the disease progressively declined. When to this fact we add thatthe same disease is often successfully treated by other different, andeven opposite remedies, such as mercury, and stimulant applications, wefind a difficulty in explaining their beneficial agency, except by sup-posing that they influence disease by some relation common to all ofthem. This view of the counter-irritant operation of blood-letting issupported by Dr. Clutterbuck, ( Lectures on the Theory and Practice ofPhysic, published in the Lancet, vol. x. 1826,) Dr. Pring, {op. cit. pp. 465-8,) and others. The term counter-irritant is, however, objectionable,since literally it expresses that the secondary disease should be a state ofirritation,—a term hardly applicable to the condition caused by blood-letting. But this, as well as other remedial agents (mental impressions,for example,) agrees with the counter-irritants, commonly so called (blis-ters, &c.) in influencing diseases only by an indirect relation ; it would