Thus, in regard to Asiatic cholera, we have the scientific infection experiments of Professor Thiersch, and others, performed on a few mice; and, on the other hand, the popular experiments which were performed on a half million human beings in London, during the cholera epidemics of 1848-49, and 1853-54, by the water companies. M. Villemin has gained information of incalculable value concerning the causes and nature of tubercle from his laboratory experiments on other animals than man, and has been followed by others who have extended and developed his discoveries. Professor Gerlach, of Hanover, has, in a similar manner, studied the transmissibility of tubercle from animals to man by eating their flesh and drinking their milk. The popular experiments, performed by milk-dealers serving their customers, which lead us to suspect that tuberculosis might be transmissible through milk, are performed daily upon thousands of human beings. The scientific experiments which have made us certain of the fact were conclusive when they amounted to half a dozen. Thus, without making any account of the relative value of human beings and animals, the scientific experiments are vastly more economical than the popular. They have the further advantage of being precise and exact, while the popular experiments very often have in them sources of ambiguity which lessen their usefulness for teaching. The principal problems to be solved in preventive medicine are how, by cross-breeding or otherwise, to convert a short-lived or constitutionally enfeebled stock into a long-lived or vigorous one, which has hardly yet become a practical question; and how to avoid or resist the extensive interferences which shorten life, on which much has been learned by vivisection, and much remains to be learned. Of the investigations in the latter line, which have led to results of momentous value, are cited the diversified researches of Pasteur and others on germs, and their specific applications to the diseases of domestic animals and man; Drs. Klebs and Tommasi Crudelli's examinations into the intimate cause of marsh-malaria; Dr. Grawitz's studies of the conversion of ordinarily harmless microphytes into agents of deadly infectiveness; Dr. Lister's applications of Pasteur's discoveries to the antiseptic treatment of wounds; Professor Semmar and Dr. Krajewski's discovery of inoculation against septicemia; and Dr. Schüller's contributions to the treatment of tubercular and scrofulous affections, on the basis of their microphytic origin. No work has been performed of more promise to the world than these various contributions to the knowledge of disease, its cure and prevention; and they are contributions which, from the nature of the case, have come, and could only have come, from the performance of experiments on living animals.

The controversy about vivisection which is now going on, though at first sight appearing

like a retrograde movement, will, in all probability, end in a substantial advance of the interests of medicine. The public, including even the mass of the opponents of vivisection, have only to be properly informed of the immense service it has been made and may yet be made to render to the health and happiness of mankind, to be willing to give to suitably qualified experimenters all the liberty of research they require. The present contest is, in most of its aspects, a repetition of the old battle which was formerly waged against the dissection of human bodies. Many of the stock-arguments which were then employed in opposition to the direct study of human anatomy are now made to do duty over again against the study of physiology through the analogies exhibited in the structure of animals. Now, as then, discussion is destined to result in enlightenment, and vivisection will eventually be recognized as a legitimate method of investigation.

The most important step in therapeutics, and probably the most important in the whole history of that branch of the science, consists in the adoption of a definite physiological aim in the use of remedial measures, of the practice of administering medicines with a definite purpose to produce a distinct physiological effect, instead of employing particular drugs with a vague idea that general favorable results have been remarked from their use. This principle is the necessary result of the clearer definition of disease and of the action of drugs. When the aggregate symptoms presented by a disease were analyzed, one generally assumed a causal relation to the others which singled it out as the object of therapeutical attack. Or, again, the urgency of certain symptoms, or the irremediable character of the essential lesions, rendering other treatment of no avail, gave a purely symptomatic aim to the whole plan of treatment. The principle of this method is that no true progress in therapeutics can be made if more than one drug is employed, since a favorable result can be attributed to no single drug-so that only a single drug is to be administered for a single intention. Where no definite therapeutic indication can be observed no drug is to be used. This is the modern justification of "expectant" treatment. But disease is seldom a single pathological condition, with a single essential symptom, which a single remedy can relieve. The latest tendency in therapeutics is to revert cautiously and partially to the combination of remedies, still following pathological indications, but not submitting the whole plan of treatment to a single dominant symptom; and this tendency may be plausibly referred to the more constructive or synthetic mood which seems of late to have come over medicine. It may be illustrated in the modern treatment of consumption, in which, in place of the sedative treatment that sent sufferers to a moist, relaxing climate, a stimulating and bracing plan of open-air life has been adopted. The former method was

the treatment of symptoms-that is, of the cough; the latter is the treatment of the essential disease, by improving the constitutional powers. There can be no doubt of the value of the one-drug treatment of disease, nor that it is strictly scientific and has largely contributed to the advance of therapeutics. It is essentially the definite basis of therapeutics, and, in appropriate cases, gives the chief successes of medicine. But where disease is a complex condition, the treatment must also be complex; and, even where a single cause can be defined, its effects and results give to the affection a complex character.

Improvement in the methods of treatment of the insane has been manifested in the discarding of the system of mechanical restraint, and the substitution of judicious mental control; in the tendency to prefer for all classes of patients public to private institutions, which is illustrated by a bill that was introduced into the British Parliament in 1881, to facilitate the extension of the privileges of the public institutions to private patients; and in the increasing esteem with which the treatment of lunatics in private families is regarded.

The essential aim of therapeutics may be stated as being the induction of a physiological process for the remedy of disease. The more nearly this induced process assumes a definite chemical or dynamic form, the more positive and direct is its action; and recent advance has greatly tended toward the statement of many therapeutical problems in chemical or mechanical terms. At the same time, the influence of the nervous system is so constant and direct in every process of the body, that these problems must always be distinctly physiological, and can not be stated as purely chemical or mechanical. The nervous element is, however, neutralized as an interrupting element, in many cases, by its very constancy, by reason of which it is present alike on either side of the equation, both in cause and effect. But if therapeutics has been thus simplified in one direction, it has made use of more complicated physiological processes in another direction. Some of its most certain and remarkable effects are obtained by acting upon the nerve centers in the brain and spinal cord, by which these effects are normally induced. Nervous influence is thus subordinated to, in place of disturbing, the therapeutic plans. Very striking in this connection are the results obtained by the precisely localized and measured action of heat and cold upon the central nervous system.

The growing identification of therapeutics with physiology is also seen in the hygienic treatment of disease. Not only are hygienic measures used for general purposes of advantage, but distinct applications of hygiene are employed for a distinct physiological effect. Schemes of dietetics, for instance, are not only used with negative precautionary aims, but with positive remedial intentions. By the

prevalence of certain climatic conditions, natural or artificial, physiological states of the body are induced, and may be calculated upon as distinctly curative. Exercise may be so ordered that particular secretions and processes shall be stimulated, while others are unaffected. This mode of treatment has largely displaced the use of drugs, and has greatly diminished the expectation of specifics, if not the desire for them.

The advance of chemistry has produced some new remedies of importance, which have not, however, been derived from the organic side of the science. No connection has been traced between the chemical composition of the essential principle of a secretion and a chemical remedy; and while chemical stimulants and depressants have been demonstrated for every organ, their action has not been explained by any law of chemical or physical constitution. The rule established by Rabuteau, that the therapeutic energy of soluble metallic salts is in direct ratio with the atomic weight of the metal contained in the salt, suggests probabilities of the enunciation of such laws in the future.

The relation of electricity and disease has been well investigated; a precise code of electro-therapeutics has been established, and clear results of considerable value have been obtained; but it can not be said that electricity has been as successfully applied in the remedial as in the diagnostic section, and a feeling of disappointment in regard to its influence on disease has been produced.

Important advance has been made in the principles of the administration of drugs, especially in the matter of their application to the part they are designed to affect as directly as possible. By the subcutaneous injection of the active principle of drugs, the effect is more localized and less constitutional disturbance is produced than when the administration is by the mouth. Moreover, the remedy acts more quickly, and enters sooner into the general circulation; and the risk of decomposition before absorption, which is incurred by admixture with the digestive fluids, is avoided. The method of direct application is also exemplified in the inhalation of suitable substances by smoking in a pipe or cigar. So much doubt has been cast by physiology upon the absorbing power of the skin, that external treatment by lotions and ointments has been greatly restricted.

Special study has been given to the employment of anæsthetics. A considerable number of substances have been used more or less extensively, and their physiological effects have been closely compared. A smaller quantity of the inhalent has been found to be sufficient, and happier results-in view of the slight danger to life incurred in ordinary inhalationshave been obtained by the method of "mixed narcosis," or the subcutaneous injection of narcotics before the administration of the in

curs in a wound; that it is his fault if even the slightest reaction or redness is developed in it, or if an amputation is not healed by first intention"; and, speaking of the simplification of processes that has attended the employment of this method, he remarked that "it would appear that in association with anæsthetics and the bloodless method antiseptic surgery has deprived all important operations of their terrors." While for the forty years previous to the adoption of the antiseptic treatment fatal wound-diseases raged, patients with compound fractures most frequently died of them, and even those with the slightest injuries often succumbed to them, and erysipelas and abscesses were matters of daily occurrence, and during later years hospital gangrene became very prevalent and fatal, now, operations are conducted which would have been regarded then as madness, or as crimes; and even young doctors are able with impunity to venture upon operations which the most daring surgeon did not think of. While Dr. Volkmann and his predecessor in the hospital with which he is connected had experienced a loss of forty per cent of the cases, of compound fracture that they had treated, and Dr. Volkmann's last cases before he adopted the antiseptic treatment had all died of pyæmia or septicemia, he has since lost none from wound-diseases and only two from other causes out of 135 cases of compound fracture, and only four or five per cent in direct consequence of the operations out of 400 cases in which the larger limbs were amputated. Thus amputation of the larger limbs has become almost free from danger; certainly less dangerous than many small operations were formerly, the mortality of which was never discussed. The adoption of the antiseptic system has made it possible to counteract the noxious qualities of the "infected air" of hospitals, and to perform operations in the most crowded institutions of large cities almost as safely as in the open country. With the aid of the new method, operations of an increasingly formidable character are carried on with diminished mortality and almost assured safety, and are made to confer life and health upon thousands who must otherwise have suffered for years or have miserably perished. Among the most striking operations of this kind may be named the extirpation of deep-seated and important organs, such as the pancreas, spleen, kidney, and thyroid gland; the removal of a part of the stomach and pylorus by Billroth, and of a part of the small intestine by a surgeon of Strasburg, both with perfect recovery. The operation of cutting for stone has been practically abolished since the introduction of Bigelow's method for crushing the stone and securing its removal by natural ways, at a single operation, a method which Dr. Erichsen says has effected a complete revolution, and has wholly changed the character of lithotrity, and which, he adds, there is every reason to believe "constitutes one of those real advances

in a method which marks an epoch not only in the history of the operation itself, but in the treatment of the disease to which it is applicable." The larynx has been more than once successfully removed and replaced by an artificial voice-organ; and the use of the laryngoscope has made the easy removal of morbid growths and foreign bodies an every-day proceeding. In regard to the treatment of aneurisms, the ligature and compression still have their partisans, and improvements in either process seem to keep pace with those in the other. Compression was most in favor a few years ago. The invention of improved ligatures, made of various kinds of animal tissue and applied with antiseptic precautions, once more inclined the balance of professional opinion in their favor; but now again the practice of compression has received renewed strength from the employment of Esmarch's elastic bandage. Wounded joints are now freely opened and successfully treated. Among new operations in plastic surgery may be named skin-grafting, and the transplantation of the cornea of the eye.

In the category of the development of medicine by the adoption and absorption of means and principles of other arts and sciences, may be placed the adoption of new drugs whose action has been investigated, either by physiological experiments or by study of their chemical effects. The isolation of the active principle of a drug is a decided approximation to scientific precision; but the clinical gain from this source is not always indubitable, for the entire drug is often seen to act with more advantage than the simple alkaloid, even though the alkaloid is practically the therapeutic power of the drug. It is not yet clear whether this difference is due to the chemical or molecular condition in which the active principle is present in the plant, or to the modifying influence of other slightly powerful substances. The vegetable kingdom has supplied the great bulk of the recent additions to the list of drugs, and chemistry has given some most important remedies, but the animal kingdom, where many favorite remedies were formerly found, is now hardly regarded. A great power has always been recognized in the enlightened practice of hydropathy, but it can not be said that its therapeutic function has as yet been definitely established. Good results have been obtained in the application of gymnastics for its decided remedial value in particular affections as well as, and quite distinct from, its beneficial effect as exercise and in the culture of the physical powers. Many nervous and muscular disorders, and other disorders in which the main defect seems to be in the controlling power of the brain, are certainly benefited by such treatment; and the brain can often be thus educated so as to establish a normal functional action in the place of one that is aberrant or altogether wanting. The study of climatology has been carried on without yield