PHARMACOLOGIA. ON THE OPERATIONS OF MEDICINAL BODIES, AND ON THE CLASSIFICATIONS FOUNDED ON THEM.

Medicinal Substances are those bodies, which, by due administration, are capable of producing certain changes in the condition of the living system, whereby its morbid actions may be entirely removed, or advantageously controlled.

In adopting this definition we intentionally exclude those alimentary substances which are more immediately subservient to the support of life, and to the repair of that diurnal waste, which the exercise of its functions so inevitably occasions.

It has been generally supposed, that substances whose application does not produce any sensible action upon the healthy system, cannot possess medicinal energy; and, on the contrary, that those bodies which occasion an apparent effect in health, must necessarily prove active in the cure or palliation of disease. Under certain limitations we may perhaps venture to assent to this general proposition; but it cannot be too forcibly or too frequently impressed upon the mind of the medical practitioner, that Medicines are frequently but relative agents, producing their effects in reference only to the state of the living frame; we must therefore concur with Sir Gilbert Blane in stating, that the virtues of Medicines cannot be fairly essayed, nor beneficially ascertained, by trying their effects on sound subjects, because that particular morbid condition does not exist which they may be exclusively calculated to remove;^[127] thus in certain states of debility, Tonics may excite the system when languid, by their sympathetic influence upon the primæ viæ, while in a robust condition of the body, the effects of the same agents may be wholly inappreciable.

The Modus Operandi of remedies, or the general principle upon which they effect salutary changes in the morbid states of the body, is involved in considerable obscurity, and has given rise to much ingenious 68speculation and scientific controversy. It would seem that the immediate impression of a remedy may depend upon mechanical, chemical, or vital agencies; and that the sanative impulse thus occasioned may either be Absolute, or Relative;—Primary, or Secondary;—Local, or General;—Direct, or Sympathetic;—Permanent, or Transient;—thus certain purgatives will occasion intestinal excretions in every condition of the body, and may therefore be justly considered as absolute agents; while diuretics, since they generally require for their success, a certain state of the living system, may with equal truth be denominated relative in their operation. That the obvious effect of a remedy may either depend upon its Primary, or upon its Secondary and incidental operation, will at once be apparent by inspecting the diagram which exhibits the classification of diuretic medicines; the same scheme will also shew that remedies may be local or general in their effects, and may excite an action in distant organs, either by entering the circulating mass, and being thus brought into contact with their textures;—by occasioning an impulse conveyed through the nervous system,—or by exciting a local impression upon the stomach and primæ viæ, and thus arousing their energies through the mysterious medium of sympathetic^[128] communication.

That certain bodies are capable of evading the assimilating functions, and of entering, unchanged, into the circulating current, either through the branches of the thoracic duct, or of the vena portarum, is a fact which admits of chemical demonstration; many of the alkaline salts are thus conveyed to the kidneys, and being excreted from the blood by its vessels, are to be easily detected in the urine by appropriate reagents; I have made many experiments upon this subject, and am prepared to state some results which may perhaps explain the occasional value of such bodies as medicines. Some essential oils, particular bitter principles,^[129] and certain colouring matter,^[130] seem also capable of passing the barriers of digestion, and of circulating to the remote parts of the body; Mercury, and several of the other metals, would likewise appear, under certain circumstances, to possess a similar privilege, and the former to be able moreover to facilitate the absorption of other bodies with which it may be associated, as I shall hereafter more fully exemplify.

In some instances, the medicinal body undergoes a partial decomposition by the digestive organs, in transitu, by which some of its constituents escape into the circulation, while the others are completely digested, and converted into chyle; this occurs with saline compounds into which vegetable acids enter as constituents. See Potassæ Acetas. It is also stated 69in the history of Diluents, that there is reason to believe that Water may under particular circumstances suffer decomposition, and transfer its elements for the formation of new compounds, furnishing oxygen to some, and hydrogen to others. There is likewise reason to suppose, that in particular conditions of the digestive functions, a remedy may be at once rendered inert by its entire decomposition.^[131]

That an impression made upon the stomach by a medicinal agent, should be the means of exciting an action in the distant parts of the machine, will not appear extraordinary when we consider how universal a sympathy and control this central organ exercises over every function of the body; imbued with exquisite and diversified sensibilities,—subjected to the first and coarsest impressions of our various ingesta,—stretched occasionally to an enormous extent by the unrestricted indulgence of appetite,—disturbed by the passions,—exhausted by volition, and debilitated by intense thinking; in short, assailed by numerous foes from without, and harassed by various revolutions from within, can we feel surprised that the aberrations of this viscus should give origin to the greater number of maladies with which we are afflicted, or that those medicinal applications should be effective that are directed for their cure, through the medium of its sympathies?

A dose of Ipecacuan, by exciting the stomach, will abate both the force and velocity of the heart in its vital motion, and affect the whole series of blood vessels, from their origin to their most minute ramifications, as is evinced by the pallor of the skin under its operation, as well as by its efficacy in arresting hemorrhage; so the brain, when disordered by vertigo, frequently derives instantaneous relief from the administration of a tea-spoonful of æther in a glass of water. The stomach however is not in every case the medium of sympathy; a substance may excite a powerful impression upon a distant part, by the instrumentality of the nerves, without any concurrence of the stomach; thus, the Belladonna, by coming in contact with the Tunica Conjunctiva of the eye, will occasion immediate dilatation of the Iris, although no other part of the system is in the slightest degree affected.

But there is yet another mode by which remedies may be made to exert a sanative effect upon particular organs of the body, through the medium of what Mr. Hunter called contiguous sympathy, and whose existence 70appears to depend upon the mere proximity and contiguity of parts, without any relation to the distribution of the nerves; thus it is, that relief is afforded to a deep-seated inflammation, by scarifying the nearest external surface; while we know from long experience that the thoracic or abdominal viscera, when similarly affected, receive corresponding relief from the same topical use of bleeding, blistering, or fomenting.

With respect to the Modus Operandi of medicines the following classification may be established.

The Particular Organs of the Body may be excited into action, through four distinct and different modes of communication.

I. By the actual contact of the appropriate remedy.

1. Conveyed by absorption, WITHOUT DECOMPOSITION.

Internally. a. through the branches of the Thoracic duct.

b. through the branches of the Vena Portarum.^[132]

Externally. c. through the branches of divided blood-vessels.

d. through the branches of Lymphatics.^[133]

2. Conveyed by absorption, WITH DECOMPOSITION, by which one or more of its constituents are developed, and pass into the circulating current.

II. By an impulse conveyed through the instrumentality of the nerves.

III. By the sympathetic control exerted by the stomach on distant parts.

IV. By the operation of contiguous sympathy, or of that which is excited by the mere proximity and continuity of parts.

And it is important to observe, that these are frequently antagonist operations, and consequently, that remedies, although they should occasion the same apparent effects, unless they act through the same medium, are not SIMILAR agents, but on the contrary, are generally medicinally incompatible with each other; for an illustration of this truth, the practitioner may refer to the observations which I have offered under the history of diuretics.

The difficulty of justly appreciating these phenomena, in every instance, has furnished a powerful objection against the validity of any classification of medicinal substances which is founded on their supposed modes of operation; and it must be acknowledged that, if we are unable to assign to remedies their primary action, or to distinguish this from their more obvious, though perhaps secondary effects, we shall frequently be 71compelled to place similar medicines under opposite heads, and to include those of very dissimilar characters under the same artificial division; an error which has contributed more generally to embarrass and misguide our practice than any other therapeutical fallacy, and it was the conviction of this truth which induced me to introduce the present chapter, and to impress the importance of its subject upon the attention of my practical readers.

It is probable that, in philosophical strictness, no two medicines in our Materia Medica are perfectly similar, although they recede from each other by such insensible shades of gradation that we may with practical advantage admit their parallelism; at the same time, it must be ever kept in remembrance, that those Medicines only are practically similar, whose operations have been found by experience to continue similar under every condition of the human body; and which, moreover, owe such similarity to modes of operation which are compatible with each other, and consonant with the general indications of cure.

The importance of admitting this proposition will be frequently illustrated in the sequel; and it may be observed in this place, that every classification in which it is not recognised as a leading principle, must be as imperfect in its execution, as it will be unjust and erroneous in its views.

Before I proceed to any farther discussion upon the present subject, it will be necessary to offer a synoptical view of an arrangement of medicinal bodies founded upon the basis of their operations, in order that I may be better enabled to illustrate the observations which it is my intention to introduce: for this purpose I shall present the reader with three different classifications of this kind; the first being that proposed by Dr. Cullen,^[134] and which is now admitted to rest on principles nearly altogether false, but the investigation of which will afford many useful lessons of practical importance; the second classification is by Dr. Young;^[135] and the third is that proposed by Dr. Murray,^[136] which, from its simplicity and strict conformity with the views I intend to offer, will be adopted as being the most eligible for the occasion.

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CULLEN’S ARRANGEMENT OF THE MATERIA MEDICA.

Medicamenta agunt in

Solida. Simplicia.

Astringentia.

Tonica.

Emollientia.

Erodentia.

Viva.

Stimulantia.

Sedantia.

Narcotica.

Refrigerantia.

Antispasmodica.

Fluida. Immutantia.

Fluiditatem.

Attenuantia.

Inspissantia.

Misturam.

Acrimoniam Corrigentia.

In Genere.

Demulcentia.

In Specie.

Ant-acida.

Ant-alkalina.

Antiseptica.

Evacuantia.

Errhina.

Sialogoga.

Expectorantia.

Emetica.

Cathartica.

Diuretica.

Diaphoretica.

Menagoga.

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CLASSIFICATION OF THE MATERIA MEDICA BY Dr. YOUNG.

I. Chemical Agents.

1. Caustics.

2. Antiseptics.

3. Antidotes.

4. Demulcents.

5. Diluents.

II. Vital Agents.

A. Supporting Strength.

1. Nutrients.

B. Causing Action.

Partial & Transient. 1. Expergefacients.

2. Excitants.

3. Calefacients.

4. Sudorifics.

5. Errhines.

6. Sialogogues.

7. Expectorants.

8. Stomachics.

9. Emetics.

10. Cathartics.

11. Chologogues.

12. Hydrogogues.

13. Simply Propellents.

14. Anthelmintics.

15. Diuretics.

16. Carminatives.

17. Emmenagogues.

18. Epispastics.

19. Suppuratories.

20. Sorbefacients.

21. Astringents.

Permanent. Tonics.

C. Diminishing Action or Sensation.

Primarily 1. Narcotics.

2. Sedatives.

3. Nauseants.

4. Diaphoretics.

Secondarily Exhaurients.

III. Insensible Agents.

Specifics.

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CLASSIFICATION OF REMEDIES BY Dr. MURRAY.

A. General Stimulants.

a. Diffusible. { Narcotics.

Antispasmodics.

b. Permanent. { Tonics.

Astringents.

B. Local Stimulants.

Emetics.

Cathartics.

Emmenagogues.

Diuretics.

Diaphoretics.

Expectorants.

Sialogogues.

Errhines.

Epispastics.

C. Chemical Remedies.

Refrigerants.

Antacids.

Lithontriptics.

Escharotics.

D. Mechanical Remedies.

Anthelmintics.

Demulcents.

Diluents.

Emollients.

With respect to the classification of Dr. Cullen, we may commence our objections by stating, that the very basis upon which it rests is a mere gratuitous assumption, viz. that certain medicines act on the fluids of the body. With the exception of a very few substances, it is now generally admitted that medicines produce their effects by acting on the living materials of which our organs are composed, and not by modifying the specific gravity, or chemical composition, of the fluids which they may happen to evacuate. The origin of this latter opinion is to be traced to the exploded notions of the humoral pathologists, and to the exclusive doctrine of the earlier chemists; for as the former recognised a depraved condition of the fluids as the source of every disease, so did the latter imagine that every remedy operated by producing a chemical change upon its composition; and the remedial value of a medicinal substance was estimated by its effects upon inert matter. Thus were experiments made with different substances upon the blood, and other fluids of the body, in order to deduce, from the results, the nature and extent of their powers as agents upon the living frame; for instance, the spirit and salt of hartshorn, as they were found to render the blood more fluid, when added to it, out of the body, 75were indiscriminately administered in almost every complaint, with a view to dissolve that “lentor of the fluids” which was regarded as the more general source of disease. For similar reasons, a tribe of medicines were introduced into practice under the title of Antiseptics, for the prevention of a process which very probably never takes place in the living body: the powers of these supposed agents were, as usual, inferred from their effects in resisting and preventing the putrefaction of dead matter.

Nor is the distinction assumed by Dr. Cullen, between the action of remedies on the Simple and Living solids less hypothetical. Tonics and astringents may certainly exert a beneficial effect upon the animal fibre, but not by any immediate action on its materials, but through the agency of its living principle.—“Medicamentum non agit in cadaver.”

The classification of Dr. Young, although it presents many points of interest and value, is not altogether free from objection; his classes in some instances are perhaps unnecessarily sub-divided, without a sufficient regard to the primary and secondary operations of the substances which they include. The arrangement of Murray has been adopted in the present inquiry, not as being less objectionable, in a general point of view, but as one which from its simplicity, is better calculated, as a frame-work, if I may so express myself, for the display of those particular facts, the knowledge of which I consider essential for the successful administration of medicinal agents, and for the full comprehension of those practical doctrines which it is the exclusive object of this work to inculcate.

Dr. Murray observes that, in this arrangement, he places in the first division those substances which exert a GENERAL STIMULANT operation on the system. Of this there are two sub-divisions, the Diffusible and the Permanent; the former including the class of Narcotics, with which may be associated, as not very remote in their operation, the class of Antispasmodics; the latter comprising two classes, viz. Tonics and Astringents. Through these there is a gradual transition from the most highly diffusible stimulant, to those most slow and durable in their action.

A second division comprehends Local Stimulants, those, the action of which is determined to particular parts of the system. Such are the classes of Emetics, Cathartics, Emmenagogues, Diuretics, Diaphoretics, Expectorants, and Sialogogues; with which may be associated the classes of Errhines and of Epispastics, founded on direct local application.

The remaining classes include substances which do not operate according to laws peculiar to the living system. To one division may be referred those, whose effects depend on the Chemical changes they produce in the fluids or solids; the classes which may be established on this principle are Refrigerants, Antacids, Lithonthriptics, and Escharotics. To another division belong those, the operation of which is purely Mechanical, as Anthelmintics, Demulcents, Diluents, Emollients, and certain Laxatives.

Under the above classes, says Dr. Murray,^[137] may be comprehended all those substances which are capable of producing salutary changes in the human system, and which are used as remedies. I have stated my reasons for adopting this as a general basis of classification, although I shall deviate very considerably in the subordinate divisions of the plan, in the hope of establishing some distinctions that may tend to practical utility.

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1. GENERAL STIMULANTS.

The four classes comprehended under this first division, are Narcotics, Antispasmodics, Tonics, and Astringents.

Although these remedies differ very essentially in the degree and permanence of their action, as well as in the character of their apparent effects, yet, as it is conceived that their primary operation is stimulant, they are considered as possessing sufficient general similitude to sanction their arrangement under one comprehensive division.

NARCOTICS.

Synon: Sedatives. Anodynes. Hypnotics. Soporifics.

Substances which, in a moderate dose, 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.

The relative intensity of these primary and secondary effects varies in the different narcotics,^[138] and even in the same narcotic in different doses; in some cases, especially if the quantity administered be considerable, the symptoms of diminished sense and action follow so immediately, that the previous stage of increased action is very obscure, or not in the least perceptible, while in other cases, the operation of the substance is more particularly directed towards the heart and arteries, and syncope succeeds its exhibition. These facts have led many physiologists to deny the stimulant nature of these bodies, and to consider their primary operation as one of a depressing kind, whence they have bestowed upon them the name of Sedatives; in referring to the classification of Cullen and Young, we shall find that the arrangement of these substances has been directed in strict conformity with such a view of the subject; but it may be asked, how the increased excitement and exhilaration which so obviously follow the use of these bodies, in small doses, can be reconciled with that theory which considers them as absolutely and primarily sedative? In order to combat an argument so fatal to his hypothesis, Dr. Cullen summons to his aid the potent intercession of his tutelar deity, the Vis Medicatrix, a power which he supposes to preside over our living body, and with anxious vigilance, to resist the invasion of every thing that is noxious, or hostile to its health and well being; with such assistance it was not difficult to explain any paradox in physiology, and the anomalies attending the agency of narcotic medicines were accordingly, in the school of Cullen, easily reconciled with the views of a favourite theory. He supposed that whenever a sedative was applied in a moderate dose, the Vis Medicatrix took the alarm, and excited all the powers of the system, in order to throw off the noxious application, and that thus indirectly arose those peculiar symptoms of increased action; but when the dose was more considerable, he contended that the preserving power 77of the system was silenced, and unable to offer any salutary resistance, and consequently that universal depression immediately followed; but there is no direct evidence in support of the existence of such a power, and still less of its influence upon such occasions; it is far more philosophical to refer the operation of narcotics to a peculiar stimulating power, remarkable for the extreme rapidity with which it exhausts the energy of the nervous system. No one will deny the stimulating powers of alcohol, and yet a very large draught of this liquor will occasion extreme exhaustion without the occurrence of any signs of previous excitement; nor will any one be disposed to question the depressing influence of opium, and yet small doses have enkindled excitement and sustained the powers of life, under circumstances of extreme and alarming exhaustion.^[139]

From the celerity with which narcotics produce their effects, it is reasonable to suppose that they act upon the nervous system through the sympathetic relations of the stomach, although in some instances it is highly probable that these bodies are actually absorbed into the circulation; I am inclined to think that this occurs with opium, as death is accelerated in cases of persons poisoned by it, by the adoption of those measures which are best calculated to promote its absorption: (see Opium.) A still more striking proof is furnished by the fact of opium, when externally applied to ulcers, producing all its constitutional effects, such as costiveness, head-ache, nausea, &c. Whether the effects of spirituous potations are to be attributed to the introduction of alcohol into the blood, or to the sympathies existing between the stomach and brain, is still a question of doubt. Dr. Cooke^[140] relates a case, on the authority of Sir A. Carlisle, of a person who was brought dead into the Westminster Hospital, in consequence of having drank a quart of gin for a wager, and that upon examination, a considerable quantity of a limpid fluid was found within the lateral ventricles of the brain, distinctly impregnated with gin. I very well remember the case, for it occurred during the period that I held the situation of Physician to that hospital, but it is very doubtful whether such an absorption occurs under ordinary circumstances. We well know the facility with which certain odorous bodies enter the circulation, and are developed in distant organs; it is therefore very possible that the apparent odour of the gin, which has been sometimes recognized in the secretions, may depend upon the presence of the flavouring ingredients, independent of the alcohol?

At one period, substances supposed to possess narcotic virtues were placed about the bed to obviate watchfulness; the plant Anethum, or Dill, was very commonly suspended over the head for such a purpose, while in modern times the Hop has been introduced into the pillow.

In concluding the history of Narcotics, it may be observed, that there is, perhaps, no class of medicinal bodies, the individuals of which are less disposed to bend and conform to an artificial arrangement; each would seem to have its own particular mode of operation, and to affect sensibility in its own peculiar manner; and hence the practitioner will often find that, after the failure of one narcotic, the administration of another will induce sleep.

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ANTISPASMODICS.

Substances which have the power of allaying the inordinate action of muscular structures, and of assuaging pain, without occasioning that state of insensibility which characterises the operation of narcotics.

There are certain medicinal bodies which would appear to exert a specific control over spasmodic action, from whatever cause it may have originated, such are Assafœtida, Galbanum, Musk, Castor, Ammonia, Valerian, &c. To such remedies the term antispasmodic more exclusively belongs, but in a more general view of the subject we must admit that this class branches, by indefinable gradations, into narcotics and tonics; for since spasm may be connected with the most opposite states of the body, it is very evident that many of the individuals included in the class of antispasmodics, can only be relative agents: spasm, for instance, may arise from excessive irritability, as from teething, wounds, worms, &c. in which case a narcotic would prove beneficial; or it may depend upon a state of general debility, the proper remedy for which would be the administration of an Aromatic Stimulant, or the assiduous exhibition of some permanent tonic.

TONICS.

Substances, whose continued administration gives strength and vigour to the body.

It is very justly admitted, that a state of permanent tension in the fibres of the body is necessary for the existence of life, and that any undue departure from such a condition is followed by debility. Thus, Sir Gilbert Blane observes, that no muscle, whether voluntary or involuntary, can act unless its fibres are previously in such a state, that if divided they would shrink by their own resiliency, leaving an interval between the cut extremities; the same may be said of the vascular system in all its ramifications, in order to give play to their contraction in grasping and propelling their contained fluids. It appears that there are certain medicinal bodies that have the power of affecting this state of tension, and when their effects contribute to its restoration, they are properly denominated Tonics. We are not, however, to consider them as producing such a change by any mechanical operation upon the matter of which the fibre is composed, but by a direct action upon its living principle; it seems probable that certain poisons may thus produce sudden death by their agency on the vital principle, by which the tension of the heart and whole arterial system is immediately relaxed. In this point of view, Tonics, like the other remedies which we have described, may be relative or absolute in their operation. Venesection, purgation, or whatever will, under certain conditions of the body, occasion a salutary change in its vital powers, may produce a corresponding alteration in the tension of its fibres, and consequently fall under the denomination of a tonic remedy: but independent of the state of the body, there would seem to be certain substances that act as specific stimuli upon the living fibre, and are in certain cases indispensable for the maintenance of its healthy tone; such are vegetable bitters, which produce a powerful effect upon the digestive organs, and by nervous sympathy, 79upon the rest of the system. Bitter Extractive,^[141] seems to be as essential to the digestion of herbivorous, as salt is to that of carnivorous animals; it acts as a natural stimulant, for it has been shewn by a variety of experiments that it passes through the body without suffering any diminution in its quantity, or change in its nature. No cattle will thrive upon grasses which do not contain a portion of this vegetable principle; this fact has been most satisfactorily proved by the late researches of Mr. Sinclair, gardener to the Duke of Bedford, which are recorded in that magnificent work, the “Hortus Gramineus Woburnensis.” They shew, that if sheep are fed on Yellow Turnips, which contain little or no bitter principle, they instinctively seek for, and greedily devour any provender which may contain it, and if they cannot so obtain it they become diseased and die. We are ourselves conscious of the invigorating effects of slight bitters upon our stomach; and their presence in malt liquors not only tends to diminish the noxious effects of such potations, by counteracting the indirect debility which they are liable to occasion, but even to render them, when taken in moderation, promoters of digestion. The custom of infusing bitter herbs in vinous drinks is very ancient and universal; the Poculum Absinthiatum was regarded in remote ages as a wholesome beverage, and the Wormwood was supposed to act as an antidote against drunkenness. The Swiss peasant cheers himself amidst the frigid solitude of his glaciers, with a spirit distilled from Gentian, the extreme bitterness of which is relished with a glee that is quite unintelligible to a more cultivated taste. With regard to the natural use of Bitter Extractive, it may be laid down as a truth, that it stimulates the stomach,—corrects putrefying and unwholesome nutriment,—promotes tardy digestion,—increases the nutritive powers of those vegetable substances to which it is united,—and furnishes a natural remedy for the deranged functions of the stomach in particular, and through the sympathetic medium of that organ, for the atony of remote parts in general; and I shall hereafter shew, that in its medicinal applications it certainly imparts additional activity to many remedies, while it renders the stomach and system more susceptible of their salutary energies. As an essential ingredient in the provender of herbivorous animals, it may I think be admitted as a fact, that its importance is in an inverse ratio with the nutritive powers^[142] of the food, and we accordingly find, in conformity with that universal scheme of self-adjustment and compensation, which influences all the operations of nature, that cultivation, which extends the nutritive powers of vegetable bodies, generally diminishes their bitterness in the same proportion; the natural history of the Potatoe offers a good illustration of this fact, for the roots of this useful plant which have been so greatly improved 80by culture, are in their wild state both small and bitter.^[143] Gummy matter, which seems to result from the first change of the sap, is undoubtedly rendered more digestible and nutritive by the presence of a bitter; pure gum is not very much disposed to yield to the assimilative functions; “it frequently passes through the bowels,” says Dr. Chapman,^[144] “very little changed, as I have witnessed a thousand times.” We see therefore the value of the bitter principle, in the economy of the Lichen Islandicus, which is intended as the food of animals in northern latitudes; we are told that boiled linseed constituted the sole diet of the people of Zealand during a scarcity of long continuance, on which occasion, symptoms of great debility occurred, attended with those of dyspepsia; so again Professor Fritze, in his Medical Annals, states that vegetable mucilage, when used as a principal article of diet, relaxes the organs of digestion, and produces a viscid slimy mucus, and a morbid action in the primæ viæ, an effect which analogy shews might be obviated by the addition of bitter extractive. For the same reason animals that feed in marshy lands, on food containing but little nourishment, are best defended from the diseases they are liable to contract in such situations by the ingestion of bitter plants.^[145] Upon these occasions nature is very kind, for the particular situation that engenders endemic diseases is generally congenial to the growth of the plants that operate as antidotes to them.

I have offered these views upon the subject of Bitter Extractive, from a conviction that they will essentially contribute to the establishing of just and philosophical notions, respecting the necessity and modus operandi of many vegetable tonics.

As the action of tonics is gradual, so their operation is not followed by that exhaustion consequent upon the use of diffusible stimulants.

The substances which compose the class of tonics are derived from the vegetable and mineral kingdoms; those of the former are generally bitter, and produce their effects by a primary action on the stomach, and are not absorbed into the circulation, as experiments upon Bitter Extractive have most fully demonstrated; those derived from the mineral kingdom, comprehending several of the metals, appear in some instances to pass into the circulation, although several of them, like the vegetable tonics, act primarily on the primæ viæ; I apprehend this observation applies to the nitrate of silver, which certainly possesses considerable powers as a tonic in certain cases of dyspepsia, for which it may perhaps be indebted to the bitterness which distinguishes it.

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AROMATICS.

Substances of a fragrant smell,^[146] which produce upon the organs of taste a peculiar sensation of warmth and pungency, and occasion, when swallowed, a corresponding impulse upon the stomach, which is rapidly communicated to the remote parts of the body.

The vegetable bodies which constitute the class of aromatic stimulants are very intimately related with that of tonics; indeed in the most efficient vegetables of the latter kind, the two qualities are generally blended, and the transition from these to the more pure bitters and aromatics is so imperceptible, that it is extremely difficult to arrange them in different classes; Dr. Murray has accordingly in his classification not attempted to separate substances which are so intimately connected. Aromatic Stimulants, however, in a practical point of view, must be distinguished from tonics, as the former are valuable for the rapidity, the latter, for the permanency of their effects. Their characteristic properties appear to depend chiefly, if not entirely, on an essential oil which, when extracted from the vegetable, exhibits all its aromatic power in a very concentrated form.

Medicines of this kind, when administered for the purpose of dispelling wind from the alimentary canal, have been termed Carminatives.^[147] They would seem to act by imparting energy to the distended and weakened muscular coat of the stomach, by which the accumulated gas is propelled through the upper orifice; for this viscus, like the bladder, when greatly distended, becomes unable to relieve itself, partly in consequence of the exhausted state of the over-stretched fibres of its muscular coat, and partly perhaps from a contraction of the Cardia, or upper orifice; for it has been already stated that a loss of power, and spasmodic action, are often the simultaneous results of debility.

ASTRINGENTS.

Substances which, when applied to the human body, corrugate and condense its fibres, and at the same time, exert a tonic influence through the medium of its living principle.

Astringency in any substance may be at once recognised by the organs of taste; its power in corrugating the papillæ of the tongue, and in imparting a sensation of harshness and roughness to the palate, being too peculiar to be mistaken; this is a fortunate circumstance, for there does not exist any one chemical test by which we can invariably detect the property of astringency, since it is found to reside in many different classes of substances: thus, acids, especially the stronger mineral ones, are powerfully astringent; so are many of the metallic salts, as those of iron, zinc, copper, and lead; and some of the earths, when combined with acids, of which alum is a striking example. The vegetable kingdom, however, 82furnishes the greater number of astringent remedies; and chemistry has shewn that this property uniformly depends upon a peculiar proximate principle, characterized by its power of forming an insoluble compound with animal gelatine; to this principle the name of Tannin has been given. As tannin generally exists in union with gallic acid, and as the latter body is known by its property of striking an inky blackness with the salts of iron, solutions of this metal were long, but erroneously, regarded as the proper test of vegetable astringency; the fallacy of this is at once shewn by the habitudes of Catechu, one of the strongest of our astringents, but which, nevertheless, will not yield the smallest degree of blackness to the solutions of iron, because it contains only tannin, the true principle of astringency, without a trace of its usual associate the gallic acid. From the power which these substances possess of astringing, and condensing the animal solids, their medicinal properties are supposed to arise, and we may perhaps, in this instance, admit such a mechanical explanation; but astringents possess also some power over the living principle of the matter which they astringe, for they are capable of acting as permanent stimulants, of curing intermitting fever, and of obviating states of general debility. Astringents would seem to moderate the morbidly increased secretions of distant parts, and to restrain hemorrhage, by their corrugating influence upon the primæ viæ,^[148] which is extended by sympathetic action to the vascular fibre; it is not difficult for any person to conceive the possibility of such a sympathy, who has ever experienced the thrilling and singular feeling which is produced over the whole body, by the acerb taste of the sloe-juice. As however the primary operation of these bodies, by their actual contact with the animal fibre, must be much more powerful than that which can result from the mere sympathy of parts, we find that the efficacy of astringents is principally displayed in the cure of diarrhœa, or serous evacuations from the intestinal canal; their operation, in checking profuse fluor albus, gleet, and the inordinate secretions of other distant organs, is much less striking and unequivocal, and it is a question whether in many of such cases the benefit arising from their use may not depend upon their tonic powers. As the morbid excess of different evacuations may arise from various and opposite states of the living system, so may the individuals of the other classes become astringents; and we are bound to admit upon this, as we have on other occasions, the existence of absolute and relative remedies.

Narcotics, at the head of which stands opium, will frequently assume the character of astringents, by diminishing the irritability upon which increased discharges depend. In Diarrhœa, an astringent, properly so called, diminishes the flow of those acrid fluids into the intestines, by which their peristaltic motions are præternaturally increased, and it consequently represses the diarrhœa; a narcotic, under similar circumstances, might not repress the flow of the acrid matter to which I have alluded, but it would render the bowels less susceptible to its stimulus, and would therefore produce the same apparent alleviation, although by a very different mode of operation. There is yet a third species of remedy, which 83may operate in restraining a diarrhœa of this description; not by stopping the flow of acrid matter, nor by diminishing the irritability of the intestinal organs, as in the instances above recited, but, simply, by acting chemically upon the offending matter, so as to disarm it of its acrid qualities; such, for instance, is the nature of absorbent and testaceous medicines. In the cure of hemorrhage, if it be active, that is to say, connected with a state of strong tonic contractility of the blood-vessels, a very different remedy will be required as an astringent, than in cases of passive hemorrhage, in which the vascular fibres are in a state of relaxation or collapse. Sir Gilbert Blane has offered some valuable remarks upon this subject, with a view to settle the difference of opinion which has arisen respecting the treatment of flooding after child-birth. (Medical Logic, Edit. 2d. p. 100.)

Astringents are capable of being exclusively used as local applications, and when they are so employed for the purpose of stopping hemorrhage, they are termed Styptics.^[149] With respect to these latter agents it must be confessed, that great popular error still exists, much of which has evidently arisen from deductions drawn from the effects of such remedies upon inferior animals; thus have several substances gained the reputation of Styptics, from the result which may have followed their application to the wounded and bleeding vessels in the extremities of the horse and ass; whereas the fact is, that the blood-vessels of these animals possess an inherent power of contraction which does not exist in those of man, and to which alone the cessation of the hemorrhage, fallaciously attributed to the Styptic, is to be wholly attributed. In many cases an application may owe its styptic qualities to its power of coagulating the blood around the orifice of the wound; in this way the contact of heated metal will sometimes arrest the flow of blood from a cut surface.

LOCAL STIMULANTS.

This Second Division comprehends those medicinal substances, which have been generally classed under the head of Evacuants; for, as they stimulate particular organs, so do they occasion by their local operation, an increased secretion, or evacuation from them.

EMETICS.

Substances which excite vomiting, independent of any effect arising from the stimulus of quantity, or of that occasioned by any nauseous taste or flavour.

Before we can determine the modus operandi of emetics, it will be necessary to take an accurate view of the phenomena and pathology of vomiting. 84It is an important fact that any extraordinary stimulus applied to the stomach, instead of increasing its motions, as it would in other instances, actually inverts them: the wisdom of such a peculiar provision is manifest; it is intended to prevent the protrusion of the food into the duodenum before it has undergone those necessary changes in the stomach, by which it is prepared for the more elaborate process of chylification. The act of vomiting, however, is not effected, as Dr. Haygarth formerly supposed, by the sole influence of the stomach; the brain is an important accessary: Dr. Majendie goes so far as to attribute the operation of vomiting, exclusively, to the agency of this latter organ upon the abdominal muscles, and regards the stomach as a mere passive instrument in the act;^[150] this doctrine was supported in an elaborate experimental memoir, presented by this indefatigable physiologist to the Royal Institute of France in the year 1812.

Although we shall not be disposed to receive this theory in its full extent, yet we cannot hesitate to admit that the influence of the nervous system is indispensably necessary for producing vomiting; and we accordingly find that this act will not take place, however forcibly the stomach may be goaded by emetics, where the energy of the nervous system is suspended, as in cases of profound intoxication, or in violent wounds and contusions of the head; while if the brain be only partially influenced, as by incipient intoxication, or by a less violent blow upon the head, its irritability is increased instead of being paralysed, and vomiting under such circumstances is excited by the slightest causes: the fact of such opposite results being produced by the same impulse in different degrees of intensity, is no less curious than instructive. Dr. Richard Harrison, in his Gulstonian Lecture before the College of Physicians, treated the subject of vomiting with much ingenuity, and I am disposed to adopt the views which he offered. He observed, that although the experiments of Majendie sufficiently testify the importance of the pressure of the abdominal muscles upon the stomach in the act of vomiting, and which can only be explained by the influence of the brain and nervous system, yet that he has attributed too much to their agency; “it appears to me,” continued he, “that vomiting may be explained in the following manner:—the irritation of the stomach makes a call upon the brain for the aid of the diaphragm and the abdominal muscles, in order to expel its contents; the diaphragm then becomes contracted and fixed, the ribs drawn down, and the abdominal muscles drawn inwards, so that the stomach is pressed on all sides by voluntary muscles, which, together WITH ITS OWN CONTRACTION, expel the contents.” Now it must be obvious that where the brain, from oppression or injury, is unable to transmit its influence to these muscles,^[151] and disregards the call of the stomach, vomiting can only be excited with difficulty, or it will be prevented altogether.

85Under such circumstances venesection may in some cases prove a powerful adjuvant, by unloading the vessels of the brain, and thus restoring to the nervous system its necessary excitability; where its powers have been paralysed by the operation of a narcotic, a copious draught of some vegetable acid, or the affusion of cold water upon the surface of the body may impart efficiency to an emetic; the operation of Nightshade and some other narcotic poisons may be adduced in farther illustration of this subject;—an excessive dose of the Atropa Belladonna produces symptoms of alarming stupor, and so difficult is it to evacuate the stomach under such circumstances, that as much as fourteen grains of Tartarized Antimony have been administered without effect: now if in such a case a copious draught of some vegetable acid be given, the emetic will be more likely to succeed: here then we perceive, that the brain, being paralysed by a narcotic poison, is unable to lend its aid to the muscles requisite for the operation of vomiting, until its energies are restored by the anti-narcotic powers of a vegetable acid. The practical precaution which this view of the subject affords, is extremely important,—not to allow the apparently inactive state of the stomach to induce us, inconsiderately, to augment the dose of an emetic: for although the stomach, for the reasons just stated, may be unable to void its contents by vomiting, it may nevertheless retain its sensibility, and be therefore liable to inflammation: Dr. Harrison has reported a case of this kind, where the practitioner, in attempting to excite emesis in an epileptic patient, by a very large dose of sulphate of zinc, produced an inflammation in the viscus that terminated fatally.

Vomiting may also be produced by the primary operation of certain agents upon the brain, by which its energy is disturbed, as by narcotics, or by the motions of swinging, whirling, and sailing: in such cases, the series of actions necessary for the establishing of vomiting, commences in the brain, and is propagated by nervous sympathy to the stomach.

When an emetic is taken into the stomach, an interval of twenty minutes or longer, usually passes without any apparent effect; an uneasy sensation, which we term nausea, is then felt, and this continues to increase until vomiting begins; here then we perceive are two distinct stages, each of which is marked by its own proper symptoms; the relative intensity and duration of which will be found to vary according to the nature of the exciting causes; thus some Emetics, as Sulphate of Zinc, act without occasioning much nausea, while others, as Tobacco excite it to a degree which is far greater than is proportioned to their emetic power: this is a fact of great importance in directing us in the selection of an Emetic, for we shall find that in some diseases it is a great object to avoid that state of system which invariably accompanies nausea, while in others it affords the best mode of answering an important indication of cure.

Nausea would seem to depend upon the exertions of the stomach and muscles, not being proportioned to the effects of the brain, in order to produce vomiting. Where this balance however is maintained, as during the operation of an ordinary emetic, the following are the symptoms which characterise the two stages;—while the nausea only is present, the countenance is pale and shrunken, the pulse feeble, quick, and irregular, and there is a feeling of cold; but as soon as vomiting commences, the face becomes flushed, the pulse quicker and stronger, although it seldom returns to its natural standard, until some time after the vomiting has ceased. 86A degree of languor, a disposition to sleep, and a general moisture upon the skin, are the circumstances which occur after the total cessation of the paroxysm.

The feeble state of the circulation, as indicated by the pulse, and the general coldness and languor experienced during a paroxysm of nausea, are to be ascribed to those sympathetic relations by which the brain, stomach, and heart, are reciprocally influenced.

The advantages to be obtained from the administration of an emetic in the cure of disease, may either depend upon its primary, or secondary operations, that is to say, upon the mere evacuation of the stomach, or upon those changes which occur in distant parts from sympathy; and the judicious practitioner, in the selection of an emetic, will always be guided by the nature of the indication which he intends to fulfil; if his object be to evacuate the stomach quickly and completely, he will avoid those emetics that are distinguished by their nauseating tendency, as in cases of disease which depend on a disordered state of stomach, connected with undue distention, and the presence of acrid and indigestible matter; if, on the other hand, his intention be to influence some remote organ through the sympathetic powers of the stomach, an emetic of an opposite tendency may be better calculated to answer such indications: in some cases, he is to seek a beneficial result from the mechanical action of the diaphragm and abdominal muscles, by whose pressure the gall-bladder and hepatic ducts are emptied of their contents, and hence jaundice, arising from the obstruction of biliary calculi, has been suddenly removed by the concussion of an emetic: a similar pressure upon the thoracic viscera may occasion expectoration, and relieve the bronchial vessels in cases of asthma, catarrh, and croup.

Vomiting, when produced by the operation of a mild emetic, does not appear to exhaust the excitability of the stomach, but on the contrary to increase its tone; for we generally find the process of digestion is carried on more vigorously afterwards; although it is probable that, by frequent repetition, a different result would be obtained, and we should find that its motion would become liable to inversion by slight stimuli: we may therefore question the propriety of that practice which is so strenuously recommended by Hippocrates,^[152] and other ancient physicians, to administer emetics frequently to those in health, in order to prevent the incursions of disease.

The benefits arising from the secondary effects of an emetic are numerous and extensive. It has been observed that during nausea the force of the circulation is considerably abated, hence the use of these remedies in hemorrhage; and, as the energy of absorption is generally in an inverse ratio to that of the circulation,^[153] we frequently obtain from a nauseating 87dose of an emetic, considerable assistance in the treatment of anasarca, and other dropsical swellings. Those medicines that are liable to produce at once, full vomiting, without any previous stage of nausea, are of course less calculated to fulfil such indications. In the same manner we should select a nauseating emetic, when our object is to promote the passage of a gall stone through the ductus communis, for the nausea so excited will relax the duct, while the mechanical concussion tends to push the obstructing matter forward. On the other hand, whenever our object is to evacuate the stomach, and to prevent absorption, we must take care to cut short the nauseating stage; a precaution which is highly important in the treatment of a case of poisoning. The state of the stomach produced by vomiting is very frequently extended, by sympathy, to the vessels of the skin; in consequence of which, a diaphoresis not unusually follows the operation. In the different varieties of febrile disease, this circumstance stamps additional value upon the class of Emetics; while, at the same time, that they eject any offensive matter which may be present in the stomach, they thus control the accelerated circulation.

From the violent muscular exertions which take place in the act of vomiting, the administration of an emetic may be very injurious in certain 88states of the body. In consequence of the pressure applied to the descending aorta, and the interrupted circulation through the lungs, from impeded respiration, the blood returns with difficulty from the head during a paroxysm of vomiting, and in plethoric states of the body, or in cases of determination of blood to the cerebral or pulmonary organs, the act of vomiting cannot be considered as free from danger. The concussion of an emetic may also produce mischief in the advanced stage of pregnancy, and in hernia and prolapsus uteri; while in extreme debility, there is the danger of a syncope being produced, from which the patient may never recover, as I once witnessed in the last stage of Phthisis, where an emetic was imprudently given, with the intention of dislodging the pus with which the lungs were embarrassed.

By violent and protracted retching, a person will sometimes become jaundiced; the stomach, diaphragm, and abdominal muscles, are, under such repeated efforts, apt to be rendered, to an eminent degree, irritable; so that at each effort of the former to discharge its contents, the latter will frequently be thrown into strong spasmodic contractions, and the liver together with the gall bladder will be suddenly caught, and, as it were, squeezed in a powerful press; in consequence of which the bile will regurgitate, and be carried into the Venæ cavæ; for Haller has shewn with what facility a subtle injection, when thrown into the hepatic duct, will escape by the hepatic veins; and upon which Dr. Saunders observes, “I know this to be a fact, for I have ascertained by experiment, that water injected in the same direction, will return by the veins in a full stream, though very little force be used.” When a jaundice is thus produced it will gradually disappear without the aid of any medicine; the kidneys are the principal means by which all unnecessary bodies are extracted from the circulating mass, a portion of bile will therefore under such circumstances be eliminated in every discharge of urine.

The different emetics employed in practice are derived from the vegetable and mineral kingdoms, some of which appear to produce their effects by an immediate impression upon the nerves of the stomach, while others require to be absorbed into the circulation before they display their energies. Ipecacuanha would seem to act primarily on the stomach, but Tartarized Antimony has been found, by experiment, to occasion vomiting, when injected into the veins of an animal; while the other mineral emetics, viz. the preparations of Copper and Zinc, undoubtedly operate on the stomach, and without inducing much nausea.

CATHARTICS:

Medicines which quicken or increase the evacuation from the intestines, or which, when given in a certain dose, occasion purging.

These remedies, from a general difference in their modes of operation, have been classed under two divisions—Laxatives and Purgatives. The former operate so mildly that they merely evacuate the contents of the intestines, without occasioning any general excitement in the body, or even stimulating the exhalant vessels of the canal; the latter produce a considerable influx of fluids from these vessels, and extend their stimulant effect to the system in general; and where these effects are very violent, the purgative is further distinguished by the epithet Drastic. Laxatives then may be said to empty the bowels simply, and to carry off extraneous 89matter, which is out of the course of the circulation; but purgatives, as they occasion a constitutional effect, may be made subservient to very important purposes. The effects of a purgative may depend upon three different modes of operation; viz.

1. By stimulating the muscular fibres of the Intestines, whence their peristaltic motion is augmented, and the contents of the bowels more quickly and completely discharged.

2. By stimulating the exhalent vessels, terminating in the inner coat of the intestines, and the mouths of the excretory ducts of the mucous glands; by which an increased flow of serous fluids takes place from the former, and a more copious discharge of mucus from the latter; the effect of which is to render the fæcal matter thinner and more abundant.

3. By stimulating the neighbouring viscera, as the Liver and Pancreas, so as to produce a more copious flow of their secretions into the intestines.

It appears that different purgatives have very different powers in relation to the several modes of operation above specified; some medicines, for example, urge the bowels to evacuate their contents by an imperceptible action upon the muscular fibres, and little or no increase of serous discharge attends the evacuation, such are Manna, Sulphur, and Magnesia; there would seem, moreover, to be certain bodies that have the property of increasing the peristaltic motions by operating as mechanical stimulants upon the fibre; it would not be difficult to derive many illustrations of this fact, from the history of herbivorous quadrupeds, and I have been disposed to consider the harsh and coarse texture which certain grasses assume in moist situations, as a wise provision in Nature to furnish an increased stimulus to the intestines of the animals who feed upon them, at a time when their diminished nutritive qualities must render such a result desirable; but the operation of a mechanical laxative may be demonstrated by a more familiar example; the addition of bran to our bread, constituting what is known by the name of Brown bread, induces laxative effects, merely from the mechanical friction of the rough particles, or scales of the bran, upon the inner coats of the intestines, for the wheat without the bran in bread is not particularly laxative.^[154] Other cathartics stimulate the fibres to a much greater degree, and the effects are either confined to a part of the canal, or communicated to the whole range of the intestines, from the duodenum to the extremity of the rectum; Aloes will furnish a good example of the former, and Colocynth may be adduced as an instance of the latter mode of operation. Other cathartics, again, direct all their stimulus to the exhalant vessels, and are accordingly distinguished by the force with which they produce serous evacuations; and for which they were formerly denominated Hydragogues, such are Saline Purgatives, and certain vegetable bodies to be hereafter described. Dr. Cullen has even supposed that some of these medicines may act solely in this way, and 90without increasing directly the peristaltic motion; there is, however, as Dr. Murray very justly remarks, no proof of such an hypothesis, and it seems scarcely probable that any substance should act as a stimulant on these vessels, without at the same time stimulating the mobile fibres of the intestines. Mercurial Purgatives appear to possess, in an eminent degree, the power of exciting the functions of the liver, and of thereby occasioning an influx of bile into the intestines. From the indications which cathartics are capable of fulfilling, their utility in many diseases must be apparent; the extent of their importance and value were, however, never justly appreciated until the valuable publication of Dr. Hamilton on this subject, in which the author has pointed out with more precision than any preceding writers had done, the therapeutic principles which should regulate their administration. His practice has clearly proved that a state of bowels may exist in many diseases, giving rise to a retention of feculent matter, which will not be obviated by the occasional administration of a purgative, but which requires a continuation of the alvine stimulant, until the healthy action of the bowels is re-established. Since this view of the subject has been adopted, numerous diseases have received alleviation from the use of purgatives that were formerly treated with a different class of remedies, and which were not supposed to have any connection with the state of the alvine evacuations; thus in fever, the peristaltic motion of the intestines is diminished, and their feculent contents are unduly retained, and perhaps, in part, absorbed, becoming of course a source of morbid irritation; this fact has long been understood, and the practice of administering cathartic medicines under such circumstances has been very generally adopted; but until the publication of Dr. Hamilton, physicians were not aware of the necessity of carrying the plan to an extent beyond that of merely emptying the primæ viæ, and they did not continue the free use of these remedies through the whole progress of the disease.

Cathartics are essentially serviceable also in several diseases of the class Neuroses, which are generally intimately connected with a morbid condition of the alimentary passages; Chorea and Hysteria have been very successfully treated in this manner. The diseases incident to puberty in both sexes are also best relieved by a course of purgative medicines, and their effects in Chlorosis have conferred upon many of them the specific title of Emmenagogues.

But the therapeutical utility of Cathartics extends beyond the mere feculent evacuations which they may occasion. In consequence of the stimulating action which some of them exert upon the exhalent vessels, they abstract a considerable portion of fluid from the general current of the circulation, and are, on that account, beneficial as Anti-phlogistics. For the same reason they may act as powerful promoters of absorption, for there exists an established relation between the powers of exhalation and absorption, so that when the action of one is increased, that of the other is augmented.

Certain Purgatives, as I have just stated, exert their influence upon the neighbouring organs, and are calculated not only to remove alvine sordes, but to detach and eliminate foul congestions from the biliary ducts and pores.

With such facts before us, it is impossible to concede to the opinion of Dr. Hamilton,^[155] that the different species of purgative medicines do not 91possess distinct powers over the different species of matter to be evacuated; on the contrary, there is reason for reviving the ancient theory, too inconsiderately abandoned, and which acknowledged these different distinctions in the operations of cathartic medicines, under the appropriate names of Hydragogues, Cholagogues, &c.

The importance of cathartic medicines having been shewn, and the distinctions in their modes of operation established, it only remains to say a few words upon the subject of their abuse. All the remedies of this class, but more especially those of considerable power, require caution in their administration, even in those diseases where they are indicated by peculiar symptoms, especially if there be any tendency to inflammation, or to extreme debility, although this latter symptom is often rather apparent than real, and is at once removed by the brisk operation upon the bowels; during pregnancy and immediately after delivery, and during the flow of the menses, the prudent practitioner will use a discretionary caution in their exhibition. The too frequent use of these medicines will induce marasmus, and render the bowels so morbidly irritable, that purging is easily excited by the ordinary stimulus of our aliments; while in some habits the contrary obtains, and the resource to which the valetudinarian flies for relief only increases the torpor of the intestines, and confirms his costiveness.

The mode of adapting, combining, and administering Cathartics, will present subjects for our future consideration.

EMMENAGOGUES:

Medicines which are capable of producing the Menstrual discharge.

As Amenorrhœa, or retention of the menses, is generally the effect of a morbid state of the body, it follows that remedies capable of acting as Emmenagogues can only be relative agents, unless indeed we are disposed to accede to the opinion so generally maintained in the writings of the older physicians, but now generally discarded, that certain substances exert a specific^[156] action upon the uterus. It may certainly be asserted without fear of contradiction, that there are many substances which, when received into the stomach, have their stimulant operation more particularly determined to one part than to another; alkalics, for example, to the kidneys; cantharides to the bladder; mercury to the salivary glands, &c. Reasoning therefore by analogy, it was not unphilosophical to conclude, that similar medicines might exist with respect to the uterus; but experience has negatived the supposition, there being no proof of any of the substances styled Emmenagogues producing their effects by any specific influence upon the uterine system. If the term Emmenagogue be assumed conventionally, according to this view of the subject, it may be retained without any fear 92of error, otherwise it would be wiser to remove the name from our classification.

The suppression of the catamenia usually depends upon a debilitated state of the body, although it is sometimes the consequence of a plethoric diathesis; in the former cases tonics, in the latter, venesection may display the powers of an emmenagogue; upon which occasion, I have frequently derived the greatest benefit by cupping the patient upon the loins. Where the disease occurs in young women, about the age of puberty, it is very generally connected with extreme debility of the system; the preparations of iron, bark, and other invigorating medicines, are accordingly the most likely to succeed in its cure. Whereas in full florid habits, when the catamenia are suddenly suppressed, Laxatives, Diaphoretics, or blood-letting, afford the surest means of relief.

There are two other classes of medicine which may occasionally prove emmenagogue—Acrid Purgatives, which act upon the rectum, and hence by contiguous sympathy upon the uterus, as Aloes, &c. and Stimulating Diuretics, as Cantharides, the Turpentines, &c. which are supposed to excite the womb, sympathetically, by their stimulus upon the bladder. Nor is the advantageous influence of mercury to be overlooked, which, in cases of morbid action in the secreting functions, prove a Herculean remedy.

DIURETICS:

Medicines which increase the urinary discharge.

This effect is produced by very different modes of operation; and as some of them are mutually incompatible with each other, it is essential that we should understand the modus operandi of each individual of which the class consists, in order that we may direct its application with precision.

There is undoubtedly no tribe of medicinal agents more precarious in their nature and effects than that of Diuretics; this fact in a great measure depends upon the uncontrollable character of the organs upon which they act, but it must at the same time be admitted, that their failure frequently depends upon their modes of operation being directly incompatible with the state of the system at the time of their administration.

The following classification may perhaps serve to bring together the principal facts which are known upon the subject, and at the same time to display them in an order which is calculated to demonstrate their practical bearings and relations.

DIURETICS,

Arranged according to their supposed Modes of Operation.

CL: I.—MEDICINES WHICH ACT PRIMARILY ON THE URINARY ORGANS.

1. By stimulating the secreting vessels of the kidneys, BY CONTACT.

a The medicines not undergoing any decomposition in transitu.

931. Potassa.

2. Potassæ Nitras.

3. Oleum Terebinthinæ.

4. Juniperus Communis.

5. Cantharides.

b The Medicines undergoing decomposition in transitu.

1. Potassæ Acetas.

2. Potassæ Super-tartras.

3. Scilla Maritima.

4. Colchicum Autumnale.

5. Copaifera Officinalis.

6. Spartii Cacumina.

CL: II.—MEDICINES WHICH ACT PRIMARILY ON THE ABSORBENTS, AND SECONDARILY ON THE KIDNEYS.

Mercury.

CL: III.—MEDICINES WHICH ACT PRIMARILY ON THE STOMACH AND PRIMÆ VIÆ, AND SECONDARILY ON THE ABSORBENTS.

1. By diminishing arterial action, and increasing that of Absorption.

1. Digitalis.

2. Nicotiana.

2. By increasing the tone of the Body in general, and that of the absorbent system in particular.

Bitter Tonics, &c. &c.

3. By producing Catharsis, and thereby increasing the action of the Exhalants directly, and that of the Absorbents indirectly.

1. Elaterium.

2. Jalap, &c. &c.

C. 1. Of Medicines which act Primarily on the Urinary Organs.

1. By stimulating the secreting vessels of the kidneys, by actual contact.

a The substance not undergoing any decomposition in transitu.

It is easy to imagine that any substance which is capable of entering the current of the circulation, and of stimulating the kidneys by a direct application to their secerning vessels, may occasion a more copious urinary discharge; in this manner the different saline^[157] preparations, Potass, 94Soda, Nitrate of Potass, &c. are brought to the kidneys in the course of the circulation, and exciting the vessels to an increased action, promote the secretion of a larger proportion of watery fluid from the blood, in consequence of which, the absorbents are indirectly stimulated in order to supply the deficiency, and in this manner dropsical swellings are reduced.

Water, as a simple diluent, will promote the action of the kidneys, and it is very judiciously remarked by Dr. Cullen, that by withholding the use of fluids in dropsy, you will diminish the quantity of fluids secreted, and allow the secretories of the kidneys to fall into a state of inactivity and collapse. This is a sufficient answer to those who defend the practice of enjoining an abstinence from all drinks in dropsy.

b. The diuretic remedy undergoing decomposition IN TRANSITU.

The digestive organs appear to possess the power of readily decomposing all saline compounds into which vegetable acids enter as ingredients, and of eliminating their alkaline base, which, being in the course of the circulation, carried to the kidneys, excites them into action, and promotes the excretion of urine; and it is probably in this way that the Acetate, Citrate, Super-tartrate, and other analogous combinations of Potass and Soda prove diuretic: on the other hand, it is equally evident that salts containing the mineral acids are not under the control of the decomposing powers of the chylo-poietic organs, and consequently do not undergo any changes in transitu, although some of these salts, as I have just stated, especially the more soluble ones, are absorbed entire, and prove diuretic. Sulphate of Potass, from its insolubility, is not readily absorbed, and its composition will not allow the developement of its base; we perceive therefore that it has not any tendency to produce an influence upon the urinary secretion.

Certain vegetable bodies likewise appear to occasion diuresis by a similar mode of operation, and it is worthy of notice that these medicines generally contain a bitter principle, which is probably separated by the analysing powers of the stomach; as exemplified in Scilla maritima; Colchicum autumnale; Lactuca Virosa; Gratiola officinalis; Spartium Scoparium (Summitates); Juniperus communis; Copaifera Officinalis (Balsamum,) &c. The stimulant powers of a bitter vegetable principle upon the primæ viæ, have already been fully noticed under the consideration of Tonics, (page 78), and it is reasonable to suppose, that an analogous principle, if introduced into the circulation, may exert a corresponding impulse upon the organs with which it comes into contact.

It particularly merits attention, that the diuretic operation of any body that acts by being absorbed, is at once suspended if catharsis follows its administration, whether in consequence of the largeness of its dose, its increased solubility, or from the effect of its combination with some purgative; for it is a law, that the processes of assimilation, and absorption from the duodenum, are arrested, or very imperfectly performed during any alvine excitement; the different effects of the saline compounds of the alkalies with tartaric acid, elucidate the truth of this law in a very striking manner—thus, Super-tartrate of Potass, or Cream of Tartar, in well regulated doses, acts, as we all know, upon the kidneys; the tartaric acid being, as I suppose in this case, abstracted and assimilated by the digestive process, and 95at the same time the alkaline base (Potass) eliminated, and subsequently carried into the circulation; but if we increase the solubility of the compound, by reducing it to the state of a neutral tartrate (soluble tartar), or by combining it with Boracic acid, or some body that has a similar effect; or what is equivalent to it, if we so increase the dose^[158] of the cream of tartar, that full catharsis follows its administration, then diuresis will not ensue, since no decomposition can take place under such circumstances, nor can it be carried by absorption into the circulation. Nitre and those salts which are carried to the kidneys without previous decomposition in transitu, are subject to the same law; for, if we combine them with purgatives, their presence can no longer be recognised in the urine, as I have ascertained by experiment. Oil of Turpentine in doses of two fluid-drachms, may so excite the urinary organs as to produce even bloody urine; whereas a fluid-ounce will scarcely occasion any apparent influence upon those functions, because the increased dose acts upon the bowels, and consequently prevents its passage into the circulation.

Sulphate of Magnesia does not readily produce any diuresis, because it operates upon the bowels, but the experiments of Vitet and Bracy Clarke have shewn, that if this saline compound be administered to the horse whose bowels are not easily affected by purgatives, it acts powerfully upon the kidneys;^[159] and I will take occasion in this place to observe that, on account of the inirritability of the bowels of the horse, diuretic medicines are more certain in their operation, than in the human subject; a fact which, in itself, shews the importance of attending to the state of the bowels, during a course of those diuretics which require to be absorbed before they can produce their specific effects.

Equally necessary is it to attend to the state of the vessels of the skin, for if during the administration of a Diuretic, these vessels be excited by external warmth, its action may be diverted from the urinary organs to the exhalants on the surface, and occasion diaphoresis; but if the surface of the body be kept cool, this diversion will not occur: so greatly indeed does cooling the surface determine to the kidneys, that the usual diaphoretic medicines may, by an attention to this circumstance, be converted into powerful diuretics.

C. II. Medicines which act Primarily on the Absorbents, and Secondarily on the Kidneys.

It has been shewn, in the former division, that by increasing the action of the kidneys, we diminish the quantity of water in the blood, and consequently occasion an extraordinary action of the absorbents to supply the deficiency, whence dropsical accumulations disappear; it remains to be stated that an operation, which may be considered the converse of the one just described, is not unfrequently established: the absorbent vessels, in 96this case, are first roused to extraordinary action, and the blood therefore becomes surcharged with serous matter, in consequence of which the kidneys are stimulated, and it is eliminated through the urinary passages: so that in the former case the absorbent may be said to be called into action by the kidneys, while in the latter, the kidneys are obviously subservient to the increased energy of the absorbent system. The preparations of Mercury are perhaps the only medicinal bodies which we can strictly consider as specific stimulants to the absorbent system; and of their power in directly acting upon these organs there are such ample proofs, that it is unnecessary to adduce any additional evidence upon the subject. In instances of increased absorption from the agency of other medicines, the effect must be considered as rather arising from their secondary than primary operations; the most important of which will constitute objects of inquiry in the succeeding divisions of the subject.

C. III. Medicines which act Primarily on the Stomach or System, and Secondarily on the Urinary Organs.

A Diuretic effect is very frequently occasioned by substances which act on the stomach and primæ viæ, producing a peculiar state of these organs, which sympathetically affects the whole body, and more particularly the absorbent system, and the vessels concerned in the secretion of urine from the blood. As this primary influence upon the stomach, and the effects to which it gives rise in remote parts, are very different in their character, according to the nature of the remedy employed, and the state of the system at the time of its administration; the present attempt to investigate and generalize these relations, and to adopt them as the basis of a classification, may ultimately lead the practitioner to some distinctions of practical utility.

1. By diminishing Arterial Action, and increasing that of Absorption.

It would appear that the action of the vessels employed in the circulation of the blood, and the energy of the absorbents are, to a certain extent, antagonist powers; the experiments of Majendie demonstrate that the absorption of a poisonous substance is retarded by a plethoric, and accelerated by a depleted state of the sanguineous system; the fact is practically established by numerous phenomena in pathology. Dr. Blackall has very satisfactorily shewn the existence which subsists between increased arterial action and diminished absorption. Hence it follows that remedies capable of controlling the circulation may affect the activity of absorption, increase diuresis, and cure dropsy; in this manner the Digitalis Purpurea acts as a sorbefacient, and it may be remarked that it seldom or never produces its diuretic effects, without a concomitant reduction of the frequency of the pulse; its power too appears only when it is administered in dropsy; in a state of health it will reduce the pulse, but not increase the discharge of urine. Tobacco has also somewhat analogous powers in promoting absorption, and its operation is accompanied with a corresponding depression of vascular action. Venesection, upon the same principle, may occasion, in certain cases of dropsy, a discharge of the accumulated fluid.

97 2. By increasing the tone of the Body in general, and that of the Absorbent System in particular.

That diminished absorption, and the consequent accumulation of serous fluids in the cellular texture, and different cavities, frequently depends upon general debility is very obvious, whence fevers, whether of the intermittent, or continued kind, which have been long protracted, are followed by œdematous swellings. In states of extreme debility the exhalant vessels would seem, from their laxity, to permit the thinner parts of the blood to pass too readily through them; this is proved by the circumstance that palsied limbs, in which such a laxity may be presumed to exist, are frequently affected with œdema, and the truth of this explanation is still farther corroborated by the advantages which accrue on these occasions from the mechanical support of pressure from bandages. In such cases, those remedies which are capable of renovating the vigour of the body can alone prove of any signal service. Dr. Blackall presents us with an illustrative case of this nature, on the authority of Mr. Johnson of Exeter, in which the tonic powers of well fermented bread occasioned in the space of a few hours an effect so powerfully diuretic, as to have cured sailors on board of the Asia East Indiaman, who had been attacked with Dropsy, in consequence of the use of damaged Rice.

Thus then do Diuretics, in some cases, cure by Evacuating, while in others, as in the instance above cited, they Evacuate by curing.

A case has lately occurred in my own practice, which not only affords a striking illustration of the present views, but is well calculated to convey to the inexperienced practitioner a very instructive lesson of caution. A man of the age of thirty-five, of the most dissolute habits, was attacked after a debauch of several days’ continuance, with inflammatory symptoms in the chest; a very large quantity of blood was suddenly abstracted, and the bleeding was repeated after the interval of a few hours. The respiration became laborious, and I was desired to visit the patient; I found that little or no urine had been evacuated since the attack, and that there were evident symptoms of effusion, the legs were swollen, and the difficulty of breathing was rapidly increasing. Under these circumstances I directed a large dose of Ammonia with some stimulating diuretics, which were to be repeated at short intervals. On the following day the distressing symptoms had subsided, a large quantity of urine had passed, and the patient expressed himself greatly relieved; unfortunately, however, in consequence of a slight increase of his distress in the evening, an injudicious friend in attendance, took more blood from the arm—the dropsical effusions rapidly increased, and life was extinguished in the course of three days by confirmed Hydrothorax.

3. By producing Catharsis, and thereby increasing the action of the Exhalants directly, and that of the absorbents indirectly.

It has been already stated, under the consideration of Cathartics, that certain medicines of that class excite the exhalants of the alimentary canal, and occasion a very copious discharge of serous matter: by this operation the blood is deprived of a large portion of water, and the absorbents are thus indirectly stimulated to supply the deficiency; Elaterium, and some other hydragogue cathartics, may be thus employed with extraordinary 98success for the cure of certain forms of Dropsy, where the vital powers of the patient can sustain the violence of the remedy;—in the whole circle of medicinal operations there is nothing more wonderful than this, that an impression made on the internal surface of the primæ viæ, by a few particles of matter, should thus convey by magic as it were, an impulse to the most remote extremities, rousing their absorbents to action; and, in case of œdema there, awakening the sleeping energies of these vessels, which like millions of pumps at work, transmit the morbid fluid to the intestines and urinary passages, effecting a detumescence of the hydropic limbs in the course of a few hours, and thus affording a striking illustration of the sympathetic action of medicines, and an instructive example of the operation of those of the sorbefacient class.^[160]

The observations which I have thus offered will lead the practitioner to select the particular diuretic which is best calculated to fulfil the indications of each individual case; and they will at the same time point out those which cannot be administered in combination, without a violation of the law of medicinal compatibility. With respect to the general efficacy of these medicines it may be stated, that where the disease originates from organic affections of the chylo-poietic viscera, it will not be cured by the mere evacuation of the water by diuretics; but that where it has taken place from diminished absorption, these remedies may be reasonably expected to effect a cure.

DIAPHORETICS.

The term Diaphoretic has been applied to those medicines which increase the natural exhalation of the skin, and when they act so powerfully as to occasion sweating, they have been commonly distinguished by the name of Sudorifics, but as no difference exists between these remedies, but in the degree of force with which they act, we may very properly comprehend the whole under the general title of Diaphoretics: the fluid effused is also in both cases similar, but in the one it is discharged more slowly, and is carried off by the conducting^[161] power of the air, in the insensible form of vapour, while in the other case it is so copiously effused from the exhalant vessels, as to appear in the liquid form.

As obstructed perspiration may depend upon very different, and even opposite states of the system, so may the most adverse medicines fall under the denomination of diaphoretic remedies.

In some affections, a deficient diaphoresis may be associated with increased vascular action, and in others, with a slow languid circulation.

99Diaphoretics may be considered as operating, either by directly stimulating the cutaneous capillaries;—by increasing the general action of the vascular system;—by relaxing the morbidly constricted mouths of the perspiratory vessels;—or, lastly, by producing at once both the latter of these effects.

In conformity with the plan adopted on other occasions, I shall proceed to investigate the powers of this class of medicines, according to their supposed modes of operation.

DIAPHORETICS

Occasion their effects—

I. By Stimulating the Cutaneous Capillaries.

A. By external application.

The Stimulus of Heat, Frictions, &c.

B. By Medicines which enter the circulation and stimulate the cutaneous vessels by contact.

Mercurials—Sulphur.

C. By Medicines which act on the surface sympathetically, through the medium of the Stomach.

Cold Drinks, &c.

II. By Increasing the General Action of the Vascular System.

Violent Exercise—Ammonia—Guaiacum—Alcohol—Warm Bath.

III. By relaxing the morbidly constricted mouths of the Perspiratory Vessels.

Antimonials—Cold Affusion—Venesection—Saline Diaphoretics.

The action of the cutaneous vessels may be augmented by heat, without necessarily increasing, at the same time, that of the heart and arteries; hence it is that heat is, of itself, often sufficient to produce sweating, while it generally accelerates the operation of a sudorific medicine. To this general proposition, however, there are some very important exceptions; and, indeed, in certain conditions of the cutaneous surface, the stimulus of heat will be even found to impede, rather than to promote, diaphoresis; thus in the hot stage of a continued fever, there would seem to exist a peculiar constriction of the perspiratory vessels, accompanied with extreme heat and dryness. In such a state, remedies of the third class must be applied, or conjoined with those of the former. The warm bath may be said to partake of all the qualities upon which our classification is founded; it will stimulate the cutaneous capillaries,—increase vascular action, generally, and, by its emollient powers, relax the morbidly constricted mouths of the perspiratory vessels. During the ardent heat of fever, the external application of cold is the most efficient sudorific, as the valuable reports of Dr. Currie have very satisfactorily established.

Although the external application of cold was not often employed in the hot stage of fever, until within the last thirty years, yet the administration of cold drinks appears to have been practised by the ancients, as an expedient to produce perspiration. Galen, and his immediate disciples, as well as the physicians of the sixteenth century, seem to have frequently 100administered cold water for the purpose of exciting sweat in fevers.^[162] Celsus also describes the beneficial effects which arise from copious draughts of cold water in ardent fevers, “fereque post longam sitim et vigiliam, post multam satietatem, post infractum calorem, plenus somnus venit, per quem ingens sudor effunditur, idque præsentissimum auxilium est.”^[163] Cold water, when introduced into the stomach in the hot stage of fever, must produce its diaphoretic effect through the sympathetic relation which subsists between that organ and the skin. Nauseating doses of Antimony, and of other emetics, occasion a relaxation of the surface from the same mode of operation, and in this latter case, if the force of the circulation be at the same time increased by tepid diluents, the diaphoretic effect is more certain and considerable.

Alcohol, Guaiacum, and other powerful stimulants, produce their effects by merely accelerating the circulation; but in employing such remedies for the purpose of exciting sweat, we must be careful to adapt them to the circumstances of the case, and to the degree of action which prevails. In all febrile diseases attended with much increased heat, or connected with local inflammation, diaphoretics of this description must be very cautiously administered, for by accelerating the circulation they might counteract any benefit which they would otherwise confer by relaxing the vessels of the skin. In the whole history of medical opinions there is scarcely a theory which has proved so fatal in its practical applications as that maintained by Van Helmont, and his disciples, viz. that acute diseases were to be cured by expelling some morbific matter, after its proper concoction—a theory which suggested the administration of the most stimulating sudorifics, together with high temperature^[164] in every grade of febrile exacerbation. The fatal effects of such a practice during the seventeenth, and early parts of the eighteenth centuries, are incalculable, and may be very satisfactorily contrasted with the beneficial results which have accrued, in the same diseases, in the present age, from the use of diaphoretics of the refrigerant kind.

Saline Diaphoretics, as they readily pass with the chyle, may be supposed to enter the circulation, and be thus brought to act, directly, on the cutaneous vessels; at the same time it seems extremely probable that such remedies may also occasion an impression on the stomach, which is sympathetically communicated to the vessels of the skin; they have undoubtedly little or no influence on the general vascular system, and neither augment the force nor the velocity of the circulating current.

It is not, however, in febrile affections alone that this class of remedies proves highly beneficial; the very intimate sympathetic connection which subsists between the functions of the lungs and skins, renders the use of such medicines particularly advantageous in the cure of the diseases incident to the former of these organs; a fact upon which we shall hereafter offer some remarks under the history of Expectorants.

So again, in the treatment of bowel affections, in consequence of the 101intimate relation which exists between the cutaneous capillaries and those of the internal organs, gentle diaphoretics offer a valuable resource in their cure. How frequently do Diarrhæa, Enteritis, &c. ensue from the sudden suppression of perspiration by cold?

From the influence which these medicines exert upon the extreme vessels of the skin, they are also highly serviceable in various obstinate cutaneous affections, as Herpes, Lepra, &c.

As evacuating the serous part of the blood must necessarily have an indirect effect in promoting absorption, Sudorifics have been occasionally exhibited in Dropsy, especially in that form of the disease called Anasarca. It has been already observed that cases too frequently occur in which the discharge of urine cannot be increased by art; upon such occasions practitioners have sometimes had recourse to a trial of Sudorifics,^[165] but from the great difficulty which generally exists in exciting sweating in such affections, the indication has rarely been fulfilled. Where however a sudorific does succeed, it is less liable to debilitate than the other alternative of a drastic purgative.

There is still another point of view in which the therapeutic importance of Diaphoretics may be considered. It is generally acknowledged that by cutaneous transpiration a portion of excrementitious matter is ejected from the system; hence by the failure or imperfect performance of this function, a deleterious fluid is retained which may give origin to disease; to such a cause may perhaps be attributed the generation of Calculi, and other diseases of the urinary system, as we shall have occasion to notice under the head of Lithonthryptics.

The increased efficacy which these medicines derive from combination with each other, will form a subject of interesting enquiry in the succeeding essay.

EXPECTORANTS.

Medicines which are supposed to be capable of facilitating the excretion of mucus from the breast, ex pectore, that is, from the trachea, and cells and passages of the lungs.

If the term Expectorant be intended to express a medicinal substance which has the power of promoting the expulsion of fluid from the lungs, by some specific action on the parts concerned, we can have no hesitation in at once rejecting the word, and denying the existence of such remedies: if, however the term be received, conventionally, as comprehending 102all those substances which are capable, according to the state of the system in each particular case, of producing expectoration, it will be extremely proper to recognise, and practically useful to retain, such a class of medicinal agents. In order that their modus operandi may be correctly understood, the following classification is submitted to the reader.

A CLASSIFICATION OF EXPECTORANTS,

According to their supposed Modes of Operation.

CL: I—MEDICINES WHICH INCREASE PULMONARY EXHALATION, AND THEREBY DILUTE THE MUCUS IN THE FOLLICLES OF THE LUNGS.

a. By removing constriction of the Pulmonary Exhalant vessels.

Blisters.

Venesection.

Nauseants.

b. By stimulating these vessels by the actual contact of a medicinal substance.

Allium.

Scilla?

The different Balsams.

fœtid Gums.

c. By stimulating the top of the trachea, and thereby increasing the action of the exhalant vessels of the lungs, by a species of Contiguous Sympathy.

Stimulating Lozenges, Linctusses, The Inhalation of certain vapours, &c.

CL: II.—MEDICINES WHICH DIMINISH THE INORDINATE FLOW OF FLUID INTO THE LUNGS, AND RENDER THE EXPECTORATION OF THE REMAINDER MORE EASY.

a. By removing the debility of the Exhalants.

Sulphate of Zinc.

Bitter Tonics.

b. By increasing the power of the Absorbents.

Digitalis.

Nicotiana.

c. By determining to the skin by gentle diaphoresis.

Tartarized Antimony.

d. By exciting serous discharges from the bowels.

Saline Purgatives.

CL: III.—MEDICINES WHICH OPERATE, MECHANICALLY, IN PROMOTING THE REJECTION OF ACCUMULATED MUCUS.

a. By stimulating the muscles of Respiration.

Ammonia.

b. By exciting vomiting, and thereby compressing the thoracic viscera.

Emetics.

103 I. Of Medicines which increase Pulmonary Exhalation.

a. By removing constriction of the Pulmonary Exhalant vessels.

There can be no doubt but that, in certain states of disease, the exhalants of the lungs, like those of the skin, are affected by a spasmodic constriction, in consequence of which the usual quantity of fluid for the lubrication of these parts, is not effused, whence a train of morbid phenomena arise; this appears to happen in Pneumonia, Asthma, and certain other diseases of the pulmonary organs. In order to remove such a constriction, remedies of the Antispasmodic class may be exhibited with advantage; nauseating doses of Tartarized Antimony, or of Ipecacuanha, are likewise calculated to fulfil the same indication, by an operation analogous to that by which Diaphoresis is produced. If the term might be allowed we should call such remedies Pulmonary Diaphoretics. It is in this way that Venesection, Blisters, and other anti-phlogistic remedies, may in certain states of the lungs restore a healthy excretion from these vessels.

b. By stimulating the Pulmonary Exhalants, by the actual contact of a medicinal substance.

There certainly appear to be substances which enter the circulation, and are more peculiarly determined to the pulmonary vessels, since their odour is to be distinctly recognised in the air that is expired. Garlic may be adduced as an example of this kind; so penetrating is its odorous principle, that if it be only applied to the soles of the feet it may be perceived in the breath. Such substances may stimulate the exhalant vessels through which they pass, and by this stimulus the secretion may be increased, and the mucus contained in the follicles diluted, so as to be poured out in a less viscid form, and consequently in a state to be more easily brought up by expectoration.

c. By stimulating the top of the trachea, and thereby increasing the activity of the Exhalant vessels of the lungs, by a species of contiguous sympathy.

The salutary operation of those various remedies, which are allowed to pass slowly over the fauces, sufficiently establish the fact which is here announced. In this manner I apprehend that much benefit may arise from the use of a Linctus, and I am satisfied from experience that certain cases of hoarseness are to be frequently removed by such an application of stimulating syrups.

The inhalation of certain vapours will also enable us to make a more direct application to these parts; as, however, it is my intention to dedicate a chapter to the consideration of this form of remedy, it is unnecessary to dwell upon it in this place.

104 II. Of Medicines which diminish the inordinate flow of fluid into the lungs.

a. By removing the debility of the Exhalants.

It not unfrequently occurs in persons either debilitated by age or disease, that the exhalant vessels of the lungs lose their tone, and pour out a larger quantity of fluid than is necessary for the lubrication of these organs; this is particularly observable in the disease called humoral asthma, and in the catarrh of old persons: if this excess be restrained by strengthening the tone of the system generally, or by astringing these vessels in particular, the expectoration of the remainder will be rendered much more easy. According to my experience, sulphate of zinc displays considerable powers in moderating this effusion of fluid, and it appears to produce this effect by increasing the tone of the exhalant vessels of the lungs; several medicines also, which are included in the former division of this classification, may, by stimulating these organs, not only promote the exhalation when it is too scanty, but repress it when it is too abundant.

b. By increasing the power of the Absorbents.

In some cases, the mucous inundation may not depend upon any fault in the exhalants, but upon a torpid state of the pulmonary absorbents: our remedy for this evil is to be found amongst that class of medicines which have the power of promoting absorption, as small doses of some mercurial preparation, Digitalis, and perhaps Nicotiana, &c.

c. By determining to the skin by a gentle diaphoresis.

It is evident that an increase of the cutaneous exhalation is generally attended with a relative diminution in the other serous excretions of body; this is so obvious with respect to our urinary discharge, that every person must have noticed the variation of its quantity at different seasons of the year: in like manner the exhalation from the lungs, although less capable of becoming an object of observation, is not less affected by the state of the cutaneous discharge; hence medicines capable of promoting it, are calculated to diminish the quantity of serous exhalation from the lungs; and it is upon this principle, that well regulated doses of the compound powder of Ipecacuan], frequently furnish the oppressed asthmatic with a valuable resource.

d. By exciting serous discharges from the bowels.

Upon the principle announced in the preceding section, the operation of a saline cathartic may relieve the pulmonary organs when loaded with a preternatural accumulation of fluid, and consequently assist expectoration. On the contrary, if the exhalation be deficient, this class of remedies may increase pulmonary irritation, and check expectoration, a fact which coincides with the concurrent testimony of many able practitioners.