Again, we read, the nervous system may be in a condition that repels sleep; a judicious and well-directed narcotic, in as much as it affords the means of indirectly giving power to the body, may be correctly considered as a stimulant." The distinction is not clear between stimulants and tonics in this place. Stimulants give increased action; tonics give power; but, according to the author's own words, "action is not power.' We fully agree with the author, when, he says, we must at once perceive how imperfect must be every classification that does not acknowledge pathology as its foundation.” This is sound, orthodox doctrine.

"From the too common error of mistaking action for power, and of regarding that which is, in fact, only borrowed, for an actual increase of capital, the practitioner has often concluded, that debility and stimulants (I use the terms according to their popular acceptation) constantly stand towards each other in the relations of disease and remedy; the same false reasoning will also lead him to conclude that a debilitated patient can never bear depletion, forgetting that the weakness may be the effect of disease, the removal of which can alone restore strength. The practical applications of these views are as numerous as they are important, and we shall have frequent occasion to refer to them."

Where the debility is real, where it is the effect of previously impoverished diet or of long-protracted disease, accompanied by great inanition of the capillaries, then we would have a poor opinion of that man's practice who would have recourse to depletion; but when the debility is only apparent, when it is oppression and not debility, that really exists, such oppression being occasioned, as so frequently happens in fevers, by the congested and adynamic state of the lungs, in which the blood is but imperfectly arterialized, then the brain, being thus supplied with such deteriorated blood, becomes oppressed, as does the entire nervous system with it-here to employ stimulation would but tend to overload still further the already congested capillaries of the brain, and so to oppress the nervous system that the powers of life must of necessity ultimately decline. Here the obvious indication is to employ depletion, by which means the lungs, brain, and other organs which may be in a state of congestion become relieved of the load which oppresses them. The lungs, thus relieved, become better able to arterialize the blood; and this improved blood becomes better adapted for the restoration of the functions of the nervous system. The great point in such cases is carefully to distinguish real from apparent debility.

We now come to the interesting subject of Narcotics, which our author defines to be "substances which, in moderate doses, occasion a temporary increase of the actions of the nervous and vascular systems, but which is followed by a greater depression of the vital powers than is commensurate with the degree of previous excitement, and which is generally followed by sleep." When large doses are taken, the symptoms of diminished sense and motion follow so rapidly, that the previous stage of increased action is very obscure, or not at all perceptible. This two-fold effect of narcotics now seems to admit of explanation from the fact that they, or at least the principal one, opium, contain both stimulant and narcotic properties combined, the former depending on the presence of narcotine, the latter on that of morphia. The circumstance that the narcotic principle

is generally combined with either a stimulant or a sedative renders it peculiarly necessary to distinguish it from both the one and the other of these; this fact it is which has occasioned the contradictory and unsatisfactory reports of the value of the different narcotic remedies. It is rather surprising that our author makes no allusion whatever to the co-existence of these different principles, the more so as it is on a knowledge of it that the judicious employment of them depends in the treatment of disease. Thus opium, which contains a stimulating principle combined with the narcotic, will not suit those cases of disease in which hyosciamus, which contains the narcotic combined with a sedative, would be applicable. If we want to administer a narcotic to a person who exhibits the symptoms of pyrexia, as hot skin, thirst, delirium, &c., we should prefer hyosciamus or some sedative narcotic to opium, by which no doubt the patient will be put to sleep, but sleep from which he is likely to awaken feverish and unrefreshed, whilst a sedative narcotic would have cooled and refreshed him. There is, however, something in the action of opium, which we must admit stands very much in need of elucidation.

We next come to the consideration of CONTRA-STIMULANTS, or SEDATIVES. It has been the custom to identify these and narcotics, and to place them in the one category; however, as our author well observes, whoever has carefully observed and compared the effects of these agents must withhold his assent to such an alliance. "A sedative, in whatever dose it may be given, is never followed by the slightest indication of excitement: it directly and primarily depresses the powers of life, whereas a narcotic in small doses never fails to increase the vital force." In fact, a sedative produces its effects by repressing the nervous influence, and thereby diminishing the action of the heart and other organs. Some will have it, however, that there is no such thing as a direct, primary sedative; but that the sedative effect was only the secondary result of exhaustion from stimulus. To this conclusion they are led from the state of stupor which is observed to supervene on intoxication after the use of fermented liquor; as also from opium, which is observed to be stimulant in small quantities, before enough of it is taken to produce stupor. A state of exhaustion being thus observed to follow intoxication or any other abuse of stimulus, it has been taken as a matter of course that every sedative effect must be secondary, and the consequence of previous stimulation.

Our author's observations on the physiological effects of sedatives, as well as of their application to the treatment of disease, are not so copious as he might have made them. Substances of this class, when taken in a large dose, are observed to produce great anxiety and despondency of mind, and to render the nervous system so depressed that it becomes incapable of directing the muscles-hence the giddiness and staggering so often observed after the use of cigars in excess: the retina itself is often so much affected, that the individual cannot see distinctly : we know the same effects may be produced by severe hæmorrhage. We know that coma may arise from either plethora or inanition; its treatment must evidently depend upon which of these two different and opposite states have occasioned it; if it arise from inanition, as it sometimes does in the case of children, depletion would be mischievous, and we must have recourse to stimulants; whereas, if it be occasioned by congestion, the

opposite line of practice is indicated. A knowledge that opposite states may give rise to the same symptoms is of the utmost importance in the practice of medicine.

Sedatives, contra-distinguished from stimulants, diminish the injection of the brain, at the same time repressing nervous influence; whilst stimulants, by exciting the heart's action, and also increasing the discharge of nervous influence, increase the injection of the brain: hence when stupor or delirium comes on from sedatives, inanition is the proximate cause, whilst congestion is the proximate cause when stimulants produce such symptoms.

Antispasmodics.-These, our author defines to be, "substances which are supposed to possess the power of allaying the inordinate action of muscular structures." The necessity of establishing a distinct class of substances, as capable of specifically controlling spasmodic action, is, to say the least of it, very questionable.

Before we can determine how far we are justified in recognizing any class of bodies capable of controlling spasm, we must first know what spasm is. Spasm has been defined to be a temporary, irregular, and involuntary action of muscles, attended with more or less pain, and followed by exhaustion. "The general cause would appear to be morbid impressions upon the nervous system, of which the following are the principal exciting causes.

1. Irritation of the nervous centres.

2. A loss of balance between the nervous and sanguineous system. 3. Irritation in the primæ viæ.

4. Cold.

5. Excessive muscular re-action excited by over-extension.
6. A laborious effort to expel foreign matter."

Thus, then, it is to the cause of spasm, viz. the cause of nervous irritation, and not to the inordinate muscular action itself, that the physician is to direct his attention. Indications of a plethoric or inflammatory condition of the brain or spinal marrow are to be met by depletion; whilst symptoms indicating sanguineous inanition, as spasm may arise from those opposite states, is to be combated by the appropriate treatment. Narcotics, from their power of allaying irritation and pain, are found to be very efficacious in the treatment of spasm. Spasm, in fact, depends on a variety of causes, and in order to treat it judiciously, the cause must be first ascertained-purgation, venæsection, tonic treatment, stimulation, sedatives, narcotics, will, in their turns, serve to allay it, according to the causes on which it may depend.

The influence of the mind in encreasing or allaying spasm must not be left out of consideration in the treatment of this affection. There is nothing more likely to produce spasm, than an excessive degree of sedative action-thus excessive hæmorrhage, the action of lead, sour fruit, &c., are frequently followed by spasm. This circumstance will point out the indispensable necessity of investigating the cause, and absurdity of prescribing for mere symptoms-sedatives, narcotics, stimulants, &c., may evidently be indicated according to the cause.

Tonics. We now come to Tonics, which the author defines to be "substances, whose continued administration gives strength and vigour to the body, without producing sudden excitement, or subsequent depression."

Of course this definition is a make-shift-it does not contain in it that great essential of a good definition, namely, adequacy-but, to say the truth, it is not so much the author as the nature of his subject we have to blame.

"When the vital movements have been accelerated by a stimulant beyond a certain point, the consequence will be a corresponding collapse, as already explained, and an interval must elapse before the exhaustion can be supplied, and the natural balance re-established through the agency of the vital stimuli; not so, however, with Tonics, for as they act slowly, and yet progressively, time is allowed for the full operation of the vital stimuli to supply an influx of power which shall, at least, equal the demand for it, and consequently no collapse can take place but more than this is effected; for, since the reanimating or restorative functions will necessarily partake of the general excitement, they will be urged with increasing activity, and thus, as it were, by an ascending scale, will the energies of every part be gradually and permanently increased, and the general standard of strength raised. To ensure, however, this desirable result, we must be careful so to regulate the application of the vital stimuli, by a judicious system of medical training, as shall insure the full benefit of their revivifying influence. Such is the theory by which I propose to explain the operation of tonics, and the phenomena will be found to correspond with it; thus to the above conditions there must evidently be a limit; when the powers of the system have been urged to a certain amount, or as far as may be consistent with its well-being, the tonics assume the character of an excitant; the vital stimuli are no longer adequate to the demand made upon them, and indications of collapse present themselves."

This is rather metaphysical; and will, perhaps, scarcely suit the tastes of the plain matter-of-fact kind of folks now going. With this portion of the profession at the present day tonics are substances, which are neither stimulant nor sedative; they neither call forth actions, like the former, nor do they repress them, like the latter; their action is directed to the nervous system which they enable to generate the nervous influence, by which the entire system is invigorated. Tonics give strength, stimulants call it forth. There are occasions, no doubt, where stimulants produce tonic effects, viz. when, by stimulating the digestive organs, they enable them to perform their functions more vigorously; the new nourishment thus taken into the system, acts upon and strengthens the nerves as well as the other parts; but this does not prove that tonics are stimulants; we know there may be occasions where the employment of a purgative may be followed by tonic effects. We see sometimes the employment of a tonic followed by an increase in the strength and quickness of the pulse, with headache, &c. and this is set down as the effect of a stimulating property of the tonic; this, however, is the result of morbid sensibility of the stomach, occasioned by the tonic disagreeing with it, and not of any stimulant power inherent in the medicine. There is no class of medicines which go farther to prove the principle that medicines are relative agents, than tonics-venesection-emetics-purgatives-may prove tonic, according to the state of the system.

The therapeutical use of tonics, in the treatment of chronic inflam mation, has not been adverted to by our author, though that is an extremely important part of their use in the practice of medicine; he has not touched upon the matter. The efficacy of tonics, however, in the

treatment of chronic inflammations is undoubted. Bark, iron, mercury, nitrate of silver, are, all of them, found serviceable in the removal of chronic inflammations ; an effect which they seem to produce by their power of giving healthy tone to the capillary vessels of the affected part, when conveyed to them through the circulation-the efficacy of bark in the treatment of erysipelatous inflammation, when the acute stage has passed by is well known-the beneficial effects of mercury in effecting the resolution of chronic inflammations, is also universally recognised. Even in acute inflammation, when the acute stage has been subdued, it may happen that the powers of the system are so depressed, that the patient appears likely to sink: in such a case, the exhibition of tonics becomes of the utmost importance. Rheumatic inflammation in the fibrous and other tissues, the capillaries of which are very minute, are most effectually treated by mercury, iodine, arsenic, antimony, &c., introduced into the capillaries through the medium of the circulation. Analogy would incline us to consider that tonics are indebted for their efficacy in relieving inflammation to their astringency, that is, we consider them to produce an astringent effect on the relaxed capillaries of the affected part.

We now come to a class of medicines very near akin to Tonics, namely, Astringents, which our author defines to be "substances which, when applied to the living body, corrugate and condense its fibres; and at the same time exert a tonic influence through the medium of its living principle."

From this definition it would appear, that very little difference exists between astringents and tonics; in fact, none whatever, if we admit that tonics produce their effects by constringing the capillary vessels.

Astringency is readily recognised by the organs of taste; the papillæ of the tongue become corrugated, and a sensation of roughness is communicated to the taste. Astringent substances are found in the mineral and vegetable kingdoms-thus, the mineral acids are found to be astringents, many of the metallic salts, also, especially those of iron, zinc, copper, and lead; some of the earths, also, combined with acids, as alum. The vegetable kingdom affords the greatest number of astringents; this principle is found to depend on a peculiar proximate principle called Tannin, or Tannic Acid, characterised by its forming with animal gelatine an insoluble compound, (Leather,) and with the salts of the peroxide of iron precipitates of a deep blue colour. With this acid there is another acid found almost universally associated, viz. Gallic Acid, which also precipitates the peroxide of iron, but not gelatine; this acid also possesses astringency. It has been recently ascertained that tannic acid is readily convertible into gallic acid by the absorption of oxygen. Some even maintain that, whatever gallic acid is obtained from galls is formed by the action of air on their tannic acid.

The modus operandi of vegetable astringents, has been explained by some on the principle of their action in tanning. May we not account for their effects on morbidly secreting surfaces in the same way as we No LXXVII,

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