investigations have been made by the above-named chemists. Lecanu also investigated the varieties which may be shewn in healthy urine, according to age and sex.

The quantity of urine passed in the 24 hours, and its colour, are frequently of importance. A diminished quantity of the urine passed in 24 hours is under circumstances a sign particularly of acute diseases; an excessive increase of the urine, if permanent, is oftentimes indicative of serious diseases. A dark-coloured, flaming or fiery red urine commonly indicates an inflammatory affection; a dark brown red is generally observed in typhus. But the urine may also be coloured blood-red or brown-red by bile-pigment, which is easily detected by its re-action with nitric acid; the latter constantly indicates an affection of the liver; a blood-red urine commonly contains blood; there is then for the most part found in it a sediment of blood-corpuscles, which are recognized with the microscope; but should a little blood be contained in the urine and this in a state of solution, it may be discovered by adding nitric acid, which occasions a precipitation of coagulated albumen coloured red by hæmatine. This bloody urine indicates a bleeding in the kidneys, bladder, urethra, or, in the case of women, of the uterus. Blood flowing from the urethra comes in drops. If the blood is discharged in masses after clear urine, it comes from the bladder, and in that case it often stops up the passage from the bladder by coagulation; if the blood is distributed through the urine, partly dissolved, and not in very large quantity, it comes from the kidneys; if it be dark, and mixed with mucus and pus, it owes its origin to an ulcer. The presence of stone-colic shews that the blood has been poured out during the descent of a renal calculus.

Blue urine has been observed, though not frequently; in the majority of cases it probably owes its origin to the use of certain medicines; black urine has likewise been observed; the connexion however is not yet known between the colouring matter and the morbid process; greenish urine indicates, according to Prout, an oxalic acid diathesis; sediments of oxalate of lime form, or mulberry calculi pass away; a urine, which is pale-coloured, and has a bias to green, frequently indicates the presence of albumen, which is readily detected by heating to boiling or by nitric acid. In this case the urine is not perfectly clear, but slightly opalescent; its quantity may be increased, diminished, or natural. The oxalic-acid diathesis of the urine indicates, according to Prout, functional disturbances in the chylopoietic system; albuminuria ordinarily indicates dropsy and an affection of the kidneys. The re-action of the urine is important for the physician. Natural urine, it is well known, has an acid re-action: the quantity of free acids in the urine and the intensity of the re-action may encrease to an extraordinary degree in diseases, more particularly in rheumatism, gout, in disturbances of the digestive organs, and in certain stages of typhus; to judge correctly of the intensity of the acid re-action, reference must be had to the quantity of the urine; the greater or less acid re-action is known by the effect of the urine on litmus paper of a weak blue colour, which becomes coloured so much the more rapidly and the more deeply reddened, the greater the acid contents of the urine are. Urine with a neutral re-action commonly forms the transition from the acid to the alkaline re-action, and vice versa. The alkaline

some change during their transit and final exit from the body. It was a maxim of Cullen's, that with respect to vegetables, and also some animal substances, "it is often a certain portion of them only that can be subjected to our digestive organs, while the medicinal part of the same is hardly affected, and therefore it may be alleged that their operation on the interior parts is not prevented by the powers of digestion.' Our author lays claim to the merit of having been the first who attempted to give to this vague proposition a more definite form, or to examine the laws by which such decompositions may be governed. Since his having done so, writers on the Materia Medica have accepted the theory, and it now very generally enters into all speculations regarding the operation of medicinal bodies.

Our author adopts the classification of Dr. Murray, with a few additions of his own.

His classification is as follows;-A. GENERAL STIMULANTS. B. CONTRA-STIMULANTS. C. LOCAL OR SPECIAL STIMULANTS. D. CHEMICAL REMEDIES. E. MECHANICAL REMEDIES. F. ALTERATIVES. Under each of these six heads he arranges several classes. The first of these heads he sub-divides into a. Diffusible, and b. Permanent. To the Diffusible belong Exhilarants, Narcotics, and Anti-spasmodics, and to the Permanent, Stimulants, Tonics, and Astringents. The physiological correctness of this arrangement has been frequently disputed; it has been found, however, extremely difficult, nay even impossible, to substitute one wholly free from objection. We have often thought, that, if the primary effects of medicinal substances could be made the criterion of classification, much confusion might be avoided; we are well aware, however, that a serious objection could be made here also, as the primary effect itself is variable, depending, as it frequently does, on the quantity administered. The truth of the maxim, that medicines are mere relative agents, appears no where so striking as in the case now before us; let the system be languid and oppressed from intestinal accumulations, the operation of a purgative will, by unloading the bowels, relieve the state of languor and oppression, and so exhibit all the effects of a stimulant; let the brain or the lungs be congested, venesection will, by removing this state, arouse the powers of the system, and so act the part of a stimulant.

"The two most essential processes of animal life," says our author, are nutrition and excretion, and these are exclusively performed by capillary vessels; suppose the balance of their circulation to be disturbed; mercury, by restoring and equalizing it, might, in certain cases, prove a true stimulant." In this small compass there is some physiology which may admit of question. In the first place, we are told that " the two most essential processes of animal life are nutrition and excretion it is usually taught that nutrition and excretion are by no means processes of animal life, but of vegetative or organic life-letting that, however, pass, what means the balance of their circulation being disturbed"? -what precise idea is to be annexed to these words? what can, properly speaking, unequalise the circulation? we know that the circulation may become quicker or slower, stronger or weaker, or more or less irregular, in a part, but it cannot be unequal; the blood must be sent equally to every part of the body, passing as it does from the heart through a single canal-the aorta.

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. 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

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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.