INTRODUCTION.

Pharmacology, from çapuazov, a drug, hóyos, a discourse, is a general term which properly includes all matters pertaining to the study of medicinal agents in the widest possible sense, embracing all of Materia Medica and Pharmacy, with so much of Therapeutics as relates to drugs. The term is however frequently employed in a more restricted sense, including only the physiological action of drugs; a subject to which the title Pharmacodynamics is much more appropriately applied.

Materia Medica is that branch of medical science which treats of the substances used as medicines, their origin, composition, physical characteristics, chemical properties, modes of preparation and administration, physiological and toxicological actions.

PHARMACODYNAMICS, from pápuaкov, a drug, divaus, power, is the proper title for that portion of the Materia Medica which relates to the physiological action of drugs, that is, the influence of drugs upon the healthy human body to modify its physiological activity.

TOXICOLOGY is another subdivision, and includes the effects of drugs when administered in poisonous doses, together with the study of the drug antagonists for the most dangerous symptoms produced, and the appropriate chemical antidotes.

Pharmacy is the art of preparing medicines for use and dispensing them on the order of the therapeutist. It includes a knowledge of the Materia Medica, an acquaintance with the theories and manipulations of chemistry, and an intimate practical knowledge of many special operations peculiar to itself.

Therapeutics, from @spansbst, to attend upon, includes all that relates to the science and art of healing; and embraces the application, not only of medicines to the alleviation or cure of disease, but of all other agents which may aid in the accomplishment of the same result. The operations of Nature herself, as well as of the substances described in the Materia Medica, and those of all other remedial measures, as food, climate, clothing, heat, cold, electricity, etc., are all embraced in the term Therapeutics, which may be divided into two grand divisions, viz. :

NATURAL THERAPEUTICS, including the operations of the Vis Medicatrix Naturæ,— the modes and processes of healing which occur independently of Art, for the spontaneous decline and cure of disease. There is no more completely established fact in science than that the living organism is in itself adequate to the cure of all its curable

disorders. This natural law enables the homoeopath to relate his sugar cures, aids the medical skeptic to hold to his infidelity, and helps all physicians out of more close places than most of them are willing to acknowledge before their clientele. This part of the subject is not taught in the schools except in connection with pathology, and by the chair of Theory and Practice of Medicine. It is deserving of a special chair and of more systematic treatment than it receives.

APPLIED THERAPEUTICS embraces the application by Art of agents foreign to the living organism, for the purpose of aiding Nature to restore the body to a healthy condi tion. This division is the portion of the subject which is taught separately and systematically in the schools, and therefore is alone considered in the following pages.

Other divisions of the general subject of Therapeutics employed in professional literature and conversation are those entitled "Empirical" and "Rational Therapeutics."

EMPIRICAL THERAPEUTICS is a term applied to the use of medicinal or other therapeutical agents for the sole reason that they have been tried previously with successful results in cases apparently identical with the one under treatment. By those who advocate this method it is styled the Therapeutics of Experience, and claimed to be an accumulation of means of combating disease simply by observation and experiment, independently of physio-pathological reasoning (Hartshorne). It was necessarily the original method in Therapeutics, has conferred many rich gifts upon medical science, and has been advocated by many great physicians, its latest and ablest expounder being the eminent and lamented Niemeyer.

The use of Opium to relieve pain,-that of Cinchona for malarial fevers,-of Colchicum in gout, of Potassium Iodide in syphilis,-of the Bromides in epilepsy,—of Codliver Oil in phthisis,-are examples of the empirical use of remedies. But, after all has been said for it that can be said, the fact remains that it is essentially an unscientific method, a mere elaboration of the prevailing popular habit of recommending Mrs. A. to use pepper tea, because it cured Mrs. B. of "the very same trouble." Permitted to reign supreme it would be destructive to all exactness in therapeutical progress. The so-called "experience" of one observer is too often overbalanced by the experience of another equally competent and trustworthy; and as few are encouraged to record their failures with remedies, there can be no scientific comparison of the failures with the reported successes. For this reason empirical methods would tend to a minimum degree of accuracy in a science which, in the very nature of things, can never be an exact one;-though undoubtedly such methods will always prevail to some extent.

RATIONAL THERAPEUTICS embraces the use of remedies for reasons based on a knowledge (1) of the pathological conditions present in the subject, and (2) of the physiological action of the agent employed. This method is the very antithesis of empiricism, and has been the leading idea in every revolt against empirical therapeutics in the past. Humoralism, Chemicism, Solidism, Stimulism, Galenism in the 2d century, Paracelcism in the 16th, and Hahnemannism in the 19th,-all originated in efforts to find a more rational system of administering medicines than the prevailing empiricism of the day.

The illustrious Albrecht von Haller, the father of Physiology and the author of the doctrine of Irritability, was the real originator of modern physiological therapeutics. In the preface to his Swiss Pharmacopoeia (circa A.D. 1755), occur the following remarkable directions:

"Nempe primum in corpore sano medela tentanda est, sine peregrina ulla miscela : odoreque et sapore ejus exploratis, exigua illius dosis ingerenda et ad omnes quæ inde contingunt affectiones, quis pulsus, quis calor, quæ respiratio, quænam excretiones, attendendum. Inde adductum phenominorum in sano obviorum, transeas ad experimenta in corpore ægroto."

"In the first place the remedy is to be tried on the healthy body, without any foreign substance mixed with it; having been examined as to its odor and taste, a small dose is to be taken, and the attention directed to all effects which thereupon occur; such as upon the pulse, the temperature, the respiration, the excretions. Having thereby adduced their obvious phenomena in health, you may pass on to experiment upon the sick body."

Forty or more years after these rules were laid down ex cathedra by Haller, the central idea contained in them was incorporated, as one of the main pillars, in a medical edifice then being erected in Germany. In the course of construction this pillar became so buried beneath a superstructure of palpable absurdities, that the medical profession, in its anxiety to steer clear of the whole mass, almost forgot the humble corner-stone, appropriated from the teachings of one of its own greatest chieftains. While, however, the masses of the profession, blinded by its prejudices, turned away from everything which savored of drug-experimentation, a few in every country were quietly working on the lines of the Hallerian dictum; and as a result of their labors, the present generation has seen the development of an idea, announced 130 years ago, but now inspiring the minds of teachers and students all over the civilized world. Medical Colleges are recognizing physiological drug-experimentation as a part of their regular curricula ;-laboratories are fitted up in many of the schools with costly instruments of precision, for the more exact prosecution of this study; and under the direction of such men as Wood, Ringer, Murrell, Brunton, Bartholow, Hildebrandt, Liebermeister, Husemann, Schmiedeberg, etc., systematic researches are being conducted upon the physiological action of every agent hitherto used in medicine. The alkaloids, and other component principles of vegetable drugs, are being subjected to the same rigid observation,—as also every new compound which chemistry gives to medicine. Journals, in every civilized country, teem with the results of these labors; and no medical student is permitted to pass the graduating ordeal until he has mastered the essential characteristics of the physiological action of the important medicaments. What has hitherto been the conviction of but a few, is daily growing into a fixed canon of professional belief, viz:—that physiological experimentation with drugs must be the basis of their therapeutical employment, and that all real advance towards the establishment of Therapeutics as a science, must be made upon the course laid down by Haller. Still, in the words of Brown-Séquard, "Therapeutics will cease to be empirical, only when this last kind of knowledge shall be fully obtained."

ADMINISTRATION OF MEDICINES.

Medicines may be introduced into the circulation by various routes, as the gastro-intestinal tract, the rectum, the respiratory tract, the veins and arteries, the subcutaneous cellular tissue, and the integument itself.

The Gastro-intestinal Route is the one most frequently employed, being the most convenient. The remedies, after being swallowed, find their way into the current of the circulation, through the walls of the gastro-intestinal blood vessels and the lacteals. When the stomach is empty and its mucous membrane healthy, crystalloidal substances in solution pass through the walls of its vessels with great rapidity. Colloidal substances (fats, albumen, gum, gelatin, etc.) require to be digested and emulsified before they can be absorbed.

The Rectum will absorb many substances applied in the form of Enemata or Suppositories. Those most suited to this route are the salts of the alkaloids in solution, especially those of Morphine, Atropine and Strychnine, the latter being absorbed more rapidly per rectum than by the stomach. Acid solutions, if not too frequently repeated, are also well administered by this channel.

The Respiratory Tract admits of the rapid absorption of medicinal substances through its extensive blood-supply. The inhalation of vapors or atomized fluids, the insufflation of powders into the nares, fauces, larynx, etc., and the use of a medicated nasal douche, are methods whereby this channel may be utilized.

The Veins are only used as a route of medication in emergencies, where the other channels are not available, and where immediate action is necessary to the preservation of life, the operation being a highly dangerous one. The injection intravenously of Saline Solutions in the collapse of cholera, diabetic coma, etc.,-Blood or Milk as a last resort in excessive hemorrhage, epilepsy, uræmia, the collapse of cholera, etc.,— and a solution of Ammonia for the bites of venomous reptiles, Hydrocyanic-acid poisoning, Opium narcosis, Chloroform asphyxia, etc., are the instances admitted in practice.

Arterial Transfusion has also been performed successfully in a number of cases, and is considered safer than venous transfusion when a large quantity of fluid has to be introduced into the circulation. A special apparatus is employed for these purposes, known as Aveling's Transfusion Syringe, but the ordinary Dieulafoy's aspirator slightly modified, may be used with safety and convenience. The danger of the operation lies in

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the liability of the introduction of air into the circulation, an occurrence which causes instant death in the human subject.

The Hypodermic Method is the introduction of medicines into the organism by injecting them into the subcutaneous areolar tissue, from which they are quickly absorbed by the lymphatic and capillary vessels.

The medicines must be in solution, of neutral reaction and freshly prepared, the usual menstruum being distilled water; though spring water filtered will answer just as well, and much better than distilled water which has been standing several days, and exposed from time to time to the air. The solution is to be injected beneath the skin, by a hypodermic syringe, care being taken to avoid puncturing a vein. The most suitable localities for the injection are the external aspect of the arms and thighs, the abdomen, the back, and the calves of the legs. On the external aspect of the thigh, just in front of the great trochanter, there is an area of some two inches square, over which the insertion of a fine hypodermic needle is not felt, so barren is the skin in that region of the sensitive nerve filaments.

After nearly filling the syringe with the solution to be used, the needle should be screwed on tightly; and with the instrument held in a vertical position, point uppermost, the excess of solution over the amount required should be ejected, thus expelling air-bubbles and filling the needle itself. A portion of skin should be grasped by the thumb and forefinger at the site selected for the injection, into which the needle should then be quickly inserted until its point has passed beneath the skin, when the piston may be pressed down slowly, delivering the solution so gradually as to avoid rupturing the tissue. If the solutions are freshly prepared with clean water, the needles kept clean and sharp, and the injection be made beneath the skin not into it, there will be no risk of producing abscesses with the agents ordinarily employed. Tablets for hypodermic use are prepared by the prominent manufacturers, each containing one dose. They may be readily dissolved in a teaspoon at the bedside, and are very convenient for the pocket, if put up in a case with a good hypodermic syringe, as may be obtained from Parke, Davis and Co., of Detroit. Their regular line of Hypodermic Tablets includes the agents named in the following list, put up in tubes of 25 each.

Parenchymatous Injection is the delivery of a medicine deeply into the tissues, either to affect a muscle itself or to locally influence some important nerve-trunk. The principal agents used in this manner are Strychnine for palsied muscles, Chloroform for sciatic and other neuralgias, and Salts of Cocaine for local anesthesia.

The Skin is an active absorbent of crystalloidal substances when its epidermis or cuticle is removed. By this route there are four methods of introducing medicaments into the circulation, viz.-the Enepidermic, Epidermic and Endermic Methods, and Inoculation.