Veterinary medicines : their actions and uses : with a copious appendix on the diseases of the domesticated animals

Front matter

BOSTONIA “ CONDITA A.D, ae Bund :

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Preface To The First Edition

Durine the four years in which I have lectured on Materia Medica at the Edinburgh Veterinary College, I have endeayoured in vain to find a suitable text-book for my class. The meagreness and inaccuracies of the published works on veterinary medicines are such as to have compelled me to use Christison’s Dispensatory, or some other of the excellent works on human Materia Medica. But although such text-books furnish the veterinary student with a knowledge of the preparation, properties, and adulterations of medicines, they necessarily contain a considerable amount of matter of comparatively little importance to him; and they further afford him no information concerning the general actions, uses, and doses of medicines when administered to the various domesticated animals. A text-book, epecially designed for veterinary students, is therefore a desideratum, and I have endeecncaeed to supply it by the publication of this volume.

The contents and arrangement of the work are as follows. The general actions and uses of veterinary medicines, and the more important pharmaceutical preparations, are treated of in the Introduction. The rest of the volume is occupied with the consideration of the medicines used in veterinary practice; the points chiefly dwelt upon being their natural history, preparaal PREFACE.

tion, properties, and most common impurities and adulterations ; their general actions on the various domesticated animals ; and their uses, doses, and medicinal forms. ‘The several drugs are discussed in alphabetical order according to their English names. Other arrangements of a more scientific nature might have been adopted. The articles of the Materia Medica might, for example, have been classified, as has been done by Pereira and others, according to their natural history relations,—the vegetable substances being grouped under the natural families to which they belong; the mineral, according to their chemical affinities. But such an arrangement, while conveniently associating medicines with similar external characters, and similar actions, requires for its satisfactory study a considerable knowledge of botany and chemistry, and is, besides, somewhat defective on account of the botanical relations of certain plants, and the chemical relations of certain drugs, being as yet insufficiently ascertained. On the other hand, some authors and lecturers discuss medicines according to their general actions; but such a method, though possessing certain practical advantages, frequently necessitates the consideration of the same medicine under several different heads. These systems being thus objectionable, I have preferred an alphabetical arrangement as the most convenient, especially in a work of reference.

From the detailed manner in which the actions, uses, and doses of medicine are considered, and from the original matter regarding aconite, tartar emetic, and other drugs, I trust that the volume may be found useful, not only to students as a text-book, but also to practitioners as a book of reference. From its practical nature it may further be serviceable to agriculturists and others who are in the habit of treating simple and incipient cases of disease without professional aid.

PREFACE. vil

The works which I have chiefly consulted in the preparation of this volume are,—Professor Christison’s ‘‘ Dispensatory” and “ Treatise on Poisons ;” the late Professor Pereira’s ‘‘ Elements of Materia Medica ;” Mr Headland’s Essay on the “ Actions of Medicines”—being the Fothergillian Prize Essay for 1852 ; the “ Edinburgh Pharmacopeeia ;” Professor Hertwig’s ‘* Praktische Arzneimittellehre fiir Thierirzte,” Berlin ; and Moiroud’s “‘ Traté Elémentaire de Matiére Médicale ou de Pharmacologie

Vétérinaire,” Paris and Tolouse.

EpinpurGH VETERINARY COLLEGE,

15th December 1853.

Preface To The Second Edition

WirTH the view of embodying in the present edition the most important facts and observations which have been elicited in the field of Veterinary Materia Medica since the original publication of this work, in 1854, I have carefully revised every portion of it, and have introduced much new and important practical matter in many of the articles. Those especially on Arsenic, Digitalis, Lead, Nux Vomica, and Valerian, have been largely added to. In the revision of the Chemical and Pharmaceutical portions of the volume, I have been aided by my friend Dr Murray Thomson, a chemist of much practical experience and scientific skill.

The chief difference, however, between this and the preceding edition consists in the introduction of a copious Appendix, con- — taining short notices of the causes, nature, symptoms, and treatment of the more common diseases of the domesticated animals,— an addition which I trust. will render the volume more useful to students, young practitioners, and amateurs.

Weston Parx, January, 1859.

VETERINARY MEDICINES:

THEIR

ACTIONS AND USES,

Introduction

Verertmnary Marerta Mepica, in the extended sense of the term, treats of every agent, material or immaterial, which is used for the cure of disease or injury, or for the preservation of health, among the domesticated animals. A subject of such scope would evidently require for its full consideration a treatise far exceeding the limits of the present work ; and it is my intention, therefore, to confine my observations solely to that branch of Veterinary Materia Medica, which is sometimes styled Veterinary Pharmacology, or the description of the medicines or drugs used in the cure of disease among the domesticated animals.

As the different medicines thus used possess many actions in common, and are prepared by the same pharmaceutical processes, I purpose making, in two preliminary sections, a few remarks on the general actions of medicines, and on the more important operations of pharmacy. The body of the volume _ will treat of the medicines themselves; and, in the present edition, there will be added an Appendix, containing a brief and popular notice of the Nature, Symptoms, Causes, and Treatment of the more common diseases of the domesticated animals,—an addition which will, I believe, be specially serviceable to agriculturists and amateurs, as well as to junior students of Veterinary Medicine.

A

Section I. On The General Actions And Uses Of Medicines

Every medicine is endowed with certain inherent characteristic actions, which distinguish it as decidedly as its physical and chemical properties. Thus, some medicines act on the bowels, causing purgation ; others on the kidneys, stimulating the secretion of urine; and others on the brain and nervous system, causing insensibility ; in fact, there is no part or organ of the body, except the spleen and pancreas, which is not influenced, and that often in several different ways, by some medicinal agent. It is impossible, however, to explain why a medicine should act in one way rather than in another; why, for example, aloes is purgative, and not diuretic, narcotic, or anesthetic ; or why chloroform is anesthetic, and not caustic, diuretic, or purgative. ‘The student must therefore endeavour to conceive of these actions, or dynamical effects of medicines, in the same manner as he does of their more familiar properties of colour, odour, taste, or density.

In order to facilitate the discussion of the general actions and uses of medicines, I shall divide this section into the following heads :—

I. The manner in which medicines establish their actions.

Ul. The manner in which medicines are believed to cure disease.

III. The arrangement of medicines according to their physiological actions.

IV. The circumstances which modify the actions of medicines.

i it i, i a

ACTION OF MEDICINES.

Oo

I.—THE MANNER IN WHICH MEDICINES ESTABLISH THEIR ACTIONS.

Some medicines, as demulcents, caustics, and astringents, have merely a local or topical action—soothing, irritating, corroding, or altering the animal tissues, but not extending their influence beyond the part to which they are first applied. Others, either with or without such a local effect, have a remote or indirect action on organs at a distance from the part with which they are first brought in contact. Medicines which act thus remotely or indirectly are thought to produce their effects in either or both of the two following ways :—(a) They are absorbed into the circulation, and carried by the blood to remote organs ; or, (b) The impression, which they produce on the parts with which they are first brought in contact, is transmitted along the nerves to other parts. This latter mode of operation is sometimes called action by sympathy.

(a.) The great majority of medicines appear to act in the former of these two ways, being taken up by the blood-vessels from the surface of the mucous membranes, skin, or other part to which they have been applied. Thus, most medicines given by the mouth, after having, if solid, undergone solution in the acid gastric juice or alkaline bile, pass, by a process of endosmose, into the capillary veins which ramify on the surface of the stomach and intestines, enter the general circulation by the mesenteric and portal vessels, and are thus carried to all parts of the body, altering, it may be, the nutritive processes of various organs and tissues, and at length expelled through some of the excretory channels, as the skin, kidneys, or bowels. The rapidity with which most substances are thus absorbed and make the round of the circulation is almost incredible. Professor Hering, of the Veterinary College, Stuttgardt, found that yellow prussiate of potash injected into one of the jugular veins of a horse appeared in the other in twenty-five seconds, and was exhaled from the mucous and serous membranes in a few minutes ; and also that chloride of barium injected into the jugular vein of a dog reached the carotid artery in seven seconds. Dr Blake observed that chloride of barium and nitrate of barytes traversed the whole circulation of a dog in nine seconds, and that of a horse in twenty seconds; and a similar rapidity of distribution doubtless obtains with substances which cannot easily be detected in the blood.

(0.) The other hypothesis, regarding the action of medicines, is that they owe the development of their effects to the production of some nervous impression on the part to which they are first applied, and its subsequent transmission to remote organs by means of the nervous system. A recent modification of this theory, advanced by Messrs Morgan and Addison, assumes that the nervous impression is produced, not upon the part with which the medicine is first brought in contact, but on the interior of the blood-vessels after partial absorption. Part of the evidence in support of those hypotheses is derived from the fact that some poisons operate with such extreme rapidity as to render it doubtful whether there could be time for their being absorbed and making the round of the circulation. Thus anhydrous prussic acid, conia the alkaloid of hemlock, and aconita the alkaloid of aconite, when injected into the veins, applied to the cellular tissue, or given by the mouth, produce almost instantaneous effects, and death in a few seconds. It appears, however, that the strongest evidence in favour of the theories under consideration consists in the effects of local injuries in producing constitutional disturbance. For example, a blow on the region of the stomach sometimes causes fatal swooning; distension of the stomach often produces hiccough ; the presence of worms in the intestines sometimes induces epilepsy; and a local injury frequently causes fever and constitutional disturbance of all the more important organs of the body. In such cases the connection between cause and effect obviously depends on the transmission of nervous impressions only. And if topical causes are thus productive of remote effects, it is surely fair to infer that medicines and poisons may operate in a similar manner.

In fine, although it would appear that most medicines are absorbed, and actually conveyed to the parts on which they act,

ACTION OF MEDICINES. i and that such absorption and actual contact are essential to their action, yet it is highly probable (though nut yet positively ascertained) that some substances, especially the more active poisons, astringents, and emetics, owe their effects to the production of a nervous impression, and its propagation to remote organs. Nor is it at all improbable that, under different modifying influences, certain substances will operate sometimes in one, and sometimes in the other of these two ways.

II.—THE MANNER IN WHICH MEDICINES ARE BELIEVED TO CURE DISEASE.

Every medicine, as already stated, is possessed of certain inherent and distinctive dynamical effects, which are exerted both in health and disease, and are termed its physiological actions. When however, appropriate medicines are administered for the treatment of any curable disease, they are said to call forth another and secondary series of actions more variable, uncertain, and limited than the physiological, but springing from them, and leading directly to the mitigation or cure of the malady, ‘These are usually called therapeutic or curative actions, and may perhaps be better understood from the following illustrations :—A dose of aloes, or of any other purgative, administered during a simple febrile attack caused by the presence of irritating matters in the intestines, induces, first, its usual physiological effect, namely, purgation; this removes the cause of irritation, or excites the so-called therapeutic action, and is hence succeeded by restoration to health. Again, a diuretic given in a case of simple anasarea, or watery effusion in dependent parts, usually establishes, in virtue of its primary or physiological effect of increasing the secretion of urine, a secondary or therapeutic action, namely, the draining away of the effused fluid, and the consequent cure of the case. With some medicines it is not difficult to trace the cure, first to the therapeutic, and then to the physiological. action, and to note each stage distinctly ; with many others, however, it appears impossible, even with the utmost care and ingenuity, to discover any properly marked difference between the physiological and therapeutic actions on the one hand, and the therapeutic actions and the cure on the other. Indeed, there appears little use for complicating our ideas of the actions of medicines by regarding them as two-fold; for a physiological action, more or less obvious, is the source and origin of every cure, while the so-called therapeutic action is merely the physiological action exercised in or modified by disease, and specially applied to its alleviation or removal.

Many hypotheses have been propounded in explanation of the manner in which medicines cure disease. But the two which are most deserving of credit, and which together appear sufficient to account for the action of most, if not all, medicines are,—lIst, The antipathic ; and 2d, The allopathic mode of eure.

Ist. Medicines act antipathically (dvri, anti, opposite; and mafos, pathos, a disease), or, in other words, they produce a condition diametrically opposed to the disease in which they are administered. It is thus that astringents are effectual in diarrhoea; purgatives in torpidity of the bowels; and stimulants in depressed states of the system. In these, and in all other cases where an antipathic cure is effected, the physiological action of the medicine overcomes the morbid condition, because it counteracts it by a superior and directly antagonistic force. This mode of cure is specially adapted to the treatment of symptoms and local diseases.

2d. Medicines act allopathically (#)Xos, allos, another; and ma0os, pathos) or produce an effect, which, though itself unnatural, overcomes the disease to be cured ; or, in other words, they occasion a short, simple, and manageable disease, which subdues that which originally existed. Nature herself frequently removes maladies in this way. Thus a spontaneous diarrhea often relieves internal congestions ; and copious perspiration, febrile attacks. In a similar manner blisters relieve pleurisy, purgatives alleviate local inflammation, and diuretics drain away cedema or dropsy.

But about sixty years ago another method of cure was propounded by the German physician, Hahnemann, who taught that the cure of a disease is effected by the administration, in small

ACTION OF MEDICINES.

doses, of medicines which would induce, if given to a healthy subject in large quantity, symptoms similar to the disease. This is the doctrine of homceopathy (épo10s, homoztos, like or similar ; and dos, pathos), the principles of which are enunciated in the aphorism, similia similibus curantur. According to this doctrine, cinchona cures ague and intermittents, because it produces such febrile symptoms when given to healthy individuals in considerable doses; aconite is the appropriate remedy for reducing inflammatory fever, because in large doses it produces symptoms which are thought to resemble inflammation ; and strychnia is the best remedy for palsy, because in large doses it appears to produce paralytic symptoms. It is only, however, in a few exceptional cases that any similarity can be detected between the symptoms produced by large doses of the remedy and those of the disease for which it is given. No known medicines, for example, are capable of developing symptoms such as those of thick-wind, roaring, pleurisy, strangles, or hydrophobia, yet fifteen or twenty remedies are prescribed for each of these diseases. Glanders, farcy, and consumption, are treated by aurum, arsenicum, and bromine, but none of these medicines develop symptoms similar to the diseases for which they are used. Again, the disciples of Hahnemann, treat diseases the most dissimilar in their nature and symptoms by the same remedy. Thus Mr Haycock, in his “ Elements of Homceopathy,” employs arsenic as the appropriate remedy in mange, bronchitis, enteritis, diabetes, strangles, tetanus, rheumatism, ophthalmia, poll-evil, glanders, and other thirty diseases; whilst he prescribes aconite in thirty-two diseases, beginning with papular eruptions, including most affections of the respiratory and digestive organs, and ending with ophthalmia and glanders. An * accurate similarity ” between the symptoms of the disease and those of the remedy, is, however, regarded as essential to the success of the homeopathic treatment; but where is the similarity between arsenic and these forty diseases, for which it is prescribed, or between aconite and the thirty-two diseases in which it is considered so efficacious. These and many other such instances cannot be established without straining simi-

INTRODUCTION.

larities which, to ordinary eyes, are imperceptible, or at best but very remote.

Hahnemann, in his “ Organon of Medicine,” translated by Mr Dudgeon of London, and accepted by English homeeopathists as their standard authority, states, that “the symptoms of each individual case of disease must be the sole indication—the sole guide to direct us in the choice of a curative remedy,” (p. 120). Now symptoms, although sometimes requiring special treatment, are but the visible signs and results of derangement and disease ; whilst their removal, which is all that is aimed at in homeopathic treatment, does not always ensure the removal of the conditions on which they depend. Thus, rheumatism, pleurisy, enterites, worms, and many other disorders frequently remain unchecked after their symptoms have been relieved. Instead of thus vainly attempting the removal of symptoms, it were therefore more rational at once to remove, as is attempted by allopathists, the morbid condition—the. source of the evil. Causé sublatd, tollitur effectus. No curative system, directing its efforts, as homoeopathy does, merely against the symptoms of disease, — can ever rest upon a safe or scientific basis; for it is notorious that under varying modifying influences, the same diseases sometimes induce very dissimilar symptoms, and would consequently, according to this new system, require dissimilar treatment. On the other hand, cases of disease essentially different sometimes manifest similar symptoms. Thus, stupor and vertigo, result sometimes from an excessive and sometimes from a deficient quantity of blood sent to the brain; difficulty of breathing from too much as well as from too little blood circulating through the lungs; vomiting from irritation of the stomach, or from direct derangement of the functions of the vagus nerve; diarrhcea from crudities in the alimentary canal, or irritant matters in the blood. Now, in these cases similar symptoms, although depending upon unlike morbid conditions, must, according to homeopathy, be combated by the same remedies; for, it is written: “ Diseases are cured by such medicines as have the power of producing, in - healthy individuals, symptoms similar to those which characterise the diseases themselves,” (Haycock’s Elements, p. 20). No ~ provision, let it be remarked, is here made for cases in which the same symptoms result from different or opposite conditions ; and yet we not only find the same symptoms produced by very’ different diseases, but also by the most opposite remedies. Strychnia and prussic acid, for example, although totally dissimilar in their modus operandi and general action, both induce convulsions, and should therefore, according to the tenets of homeopathy, be equally suitable for the cure of convulsive diseases.

If the principles or foundations of homceopathy be false and imperfect, as 1 have endeavoured to show, the superstructure based on such a foundation cannot be otherwise than weak and tottering. The following important facts and doctrines of homeeopathy, exhibit perhaps more clearly than any arguments, the extravagancies and inconsistences of the system :—The homeopathic doses are so small that they are often undetectible either by the microscope or by chemical analysis, and are sometimes so inconceivably minute that the mind can form no idea of them. It is admitted, even by homeeopathists, that millions of such doses may be swallowed by a healthy individual without inconvenience, ‘but in disease the system is believed to become so susceptible of their action, that much risk is incurred by their insufficient dilution. Medicines, such as charcoal, sand, and carbonate of lime, which, in ordinary doses of several scruples or drachms, have only a slight mechanical effect, when given in fractional parts of a grain, are thought to produce very powerful effects, and cause many hundred symptoms. Charcoal, for example, is said, when given to man in very minute doses, to produce 930 distinct symptoms; oyster shell, 1090 symptoms; and the ink of the cuttlefish, 1242 symptoms. The extraordinary powers supposed to be conferred on these and other medicines, even when given in doses of inconceivable minuteness, are chiefly ascribed to the magic influence of careful and continued triturations and often repeated shakings, performed according to most precise directions. Little difference of activity is believed to exist between different dilutions of the same medicine; and it is said, that if the medicine be well selected, it matters little whether the tenth, hundredth, or thousandth of a grain be used. There is probably some truth in this observation; for, with most medicines, especially when administered to the lower animals, all the dilutions mentioned would be equally harmless. The admixture of different medicines with one another, is said to neutralise the effect of all; but, if this be the case, homceopathic drugs must always be without effect (which is very probable), for all medicines contain adulterations and impurities, which, though small in amount, must of course acquire great potency by the triturations above mentioned.

But homeeopathists assert that, in spite of the errors which their opponents discover in the system, it is nevertheless very successful in the cure of disease. In judging, however, of homeceopathy as a system of practical medicine, it must ever be regarded as made up of two distinct parts—1st, The original and peculiar part of the system, consisting in the use of medicines selected in accordance with a law embodied in the axiom sumilia similibus curantur, and administered in infinitesimal doses, usually varying from one grain to one-millionth of a grain, and earefully prepared according to certain precise directions; and 2d, Attention to diet and regimen—the only effectual and rational part of homceopathy—the true source of all its boasted cures—and that very department of medical treatment which has been insisted upon from the most ancient times by all scientific and successful practitioners, both of human and veterinary medicine. The value of the first part of the treatment, viz., of medicines given homeeopathically, has never been satisfactorily shown, and never can be so, until two series of cases, as nearly as possible alike, be treated, the one in the usual homceopathic fashion, the other with the same attention to diet and regimen, but without the globules. If, in a sufficient number of well regulated experiments, the former method proves itself superior to the latter, then of course it would be fair to infer that the medicine had some real curative effect. But no such superiority has been observed where impartial observations have been made. Tn a few experiments made at the Edinburgh Veterinary College, as to the treatment of pleuro-pneumonia and other diseases according to these two modes of cure, it appeared, that those cases which were treated by diet and regimen alone were as speedily and effectually cured as those treated with the globules in addition, so long as these globules were given in homceopathic doses. I say, so long as the doses given were homeopathic ; and this, [ think, is an important fact; for many of the medicines, which are used homeeopathically, are, in ordinary medieinal doses, capable of producing prompt and often powerful effects, and become effectual means of cure, in virtue of their physiological properties, but not in virtue of any homeopathic actions.

But though the principles of homceopathy are unsound, and though its practice among the lower animals has not been more successful than that of many more modest modes of treatment, still it has done some service to the cause of practical medicine, by showing more forcibly than before the great power of the vis medicatrix nature, and the inestimable importance of regimen and diet as auxiliaries to tle medical treatment of disease. Further, it has aided in the advancement of a more rational system of veterinary practice, by discountenancing those copious — and repeated bleedings, and large and reiterated physickings, which were often indiscriminately prescribed for all patients ; and it has also acted beneficially in elucidating various subjects connected with therapeutics, and in inducing the opponents, as well as the supporters of homeeopathy, to institute numerous and eareful observations on the actions of remedies both on man and the lower animals.

i11.—THR ARRANGEMENT OF MEDICINES ACCORDING TO THEIR PHYSIOLOGICAL ACTIONS.

The comparatively obvious nature, regularity, and certainty of the physiological actions of medicines, render these a valuable means of arranging or classifying the different articles of the materia medica ; and it is found that the arrangements or classifications so made, though confessedly imperfect, on account of our present defective knowledge of therapeutics, are of much practical utility. I have, therefore, subjoined a tabular view of hy INTRODUCTION.

a physiological classification which I have sometimes adopted in my lectures, and in which I have grouped medicines, classed and denominated according to their physiological actions, into three great divisions of mechanical, chemical, and vital agents— a plan followed by Dr A. T. Thomson and many other authors.

TABLE OF THE DIFFERENT CLASSES OF MEDICINES, ARRANGED

ACCORDING TO THEIR PHYSIOLOGICAL ACTIONS.

I1.—MEDICINES WHICH ACT CHIEFLY AS MECHANICAL AGENTS.

Examples :—

Demulcents. | Protect the tissues from | Solutions of gum, albu- | the action of irritants. | men, and gelatine. Diluents. | Dilute the fluids, Water, and mild watery fluids.

IIi.—MEDICINES WHICH ACT CHIEFLY AS CHEMICAL AGENTS.

| | Examples :—

Antiseptics. Prevent or arrest putre-| Common salt, _ spirits, faction. | tannin.

Disinfectants. | Absorb, alter,or destroy | Chlorine, sulphurous

| contagious matters. acid, ozone. ;

Antidotes. | Counteract poisons. Dilute alkalies for acids.

Hydrated sesquioxide of iron for arsenic, ete.

Caustics. Destroy the animal so-|Strong acids, metallic lids, and decompose | salts, as nitrate of silthe fluids. ver, butter of antimony.

Acids. Counteract alkalinity. | Sulphuric, nitric, and

hydrochloric acids.

Antacids. | Counteract acidity. Alkalies and alkaline earths.

IlI.—MEDICINES WHICH ACT CHIEFLY AS VITAL AGENTS,

Examples :— ( Rubefacients, Cause redness of the skin.} Alcohol, turpentine. Vesicants. Cause discharge of se- | Cantharides, boiling warum from the skin. ter. a4 Suppurants. Cause discharge of pus; Croton oil, Tartarised 2 from the skin. _aptimony. a Errhines. | Irritatethe mucous mem-}| Veratrum aibum, en- Z brane of the nostrils. phorbium. sia Stomachics. Promote digestion. Ginger, cardamoms,. voag | latile oils. as 1 Emetics. Cause vomiting. Tartarised antimony, a sulphates of zine and . copper, common salt. 5 | Ecbolics. Induce contractions of| Ergot of rye, savin, can- So the uterus, and expul-| tharides, i sion of its contents.

Aphrodisiacs. Stimulate the generative | Phosphorus, cantharides organs and the venereal} peppers. ( appetite,

ACTION OF MEDICINES.

as Cathartics. Evacuate the bowels. Aloes, croton, oils, jalap. a5 Expectorants, Increase the secretions | Ipecacuan, balsams, aie of the respiratory mu-| gum-resins, AS cous membrane. 32d } Diaphoretics. Increase the perspira-| Warm clothing, acetate a§s tion. of ammonia, ethers. ao Diuretics. Increase the secretion of | Turpentine, resin, nitre. ea urine.

Bs Sialogogues. Increase the salivary se- | Mercurials, iodine, pun- 7 ( eretions. gent-tasted bodies, as { Tonics. Improve the appetite; Cinchona, quinine, sul- Ces) | and increase the gene-| phates of iron and eo4 ral vigour. copper. eos 4 Calefacients. Stimulate the circulating | Volatile oils, ammonia, aaa system. alcohol. a3 Nerve stimulants.| Stimulate the nervous | Nux vomica, large doses At system. of calefacients. dat [ oes | ie E 8 4 Astringents. Constrict muscular fibre. | Oak bark, tannin, alum. 2233 | S78 | Emollients. Soften the tissues. Poultices, fomentations, “ie moistened spongivuase¢ piline. eS 38 | Refrigerants. Lower animal heat. Cold air, cold water, ice, a gs saline and _ etherous { : matters. ( Sedatives. Depress both the circu-| Aconite, prussic acid, latory and nervous| digitalis. systems. 2 Narcotics. Pass from the blood to} Opium, Indian hemp, Ba the nerves and nervous} belladonna. 23 centres, and act so as =3 first to exalt nervous a3 + force and then to de- ES press it; and have also 25 | a special action on the th intellectual part of the brain. (Headland.) Anesthetics. Diminish sensibility to | Chloroform, ether, naphpain, and to external| tha, coal gas. q impressions.

To familiarise the student with the names, general actions, and therapeutic applications of these different physiological classes of medicines, I shall briefly notice them in the order in which they occur in the above table.

DEMULCENTS.

Demulcents (demulceo, I soften) sheath and protect the tissues from irritants. Gums, mucilage, sugar, starchy matters, gelatine, albumen, fats, and oils, as well as cotton, thin leaves of gutta percha, and oiled silk, are familiar examples of this class of remedies. ‘They are chiefly used to take the place of the natural demulcents, as the tears, mucus, or skin, where these are defective or wanting; to defend external sores from the injurious action of the air, or of acrid secretions; and to lubricate the mucous membranes, and protect them from irritating and poisonous matters.