Scientific features of modern medicine
Lee, Frederic S. (Frederic Schiller), 1859-1939
kt^^^avv ^ l5o <.«^,' CORNELL UNIVERSITY. ■ ,.>^/ — - THE THE GIFT OF ROSWELL p. FLOWER FOR THE USE OF THE N. Y. STATE VETERINARY COLLEGE 1897 Cornell University Library R 130.L47 Scientific features of modern medicine. 3 1924 000 285 845 V V Columbia ^Snt&ersitg %tttmz& SCIENTIFIC FEATURES OF MODERN MEDICINE THE JESUP LECTURES 1911 COLUMBIA UNIVERSITY PBESS SALES AGENTS NEW toek: LEMCKE & BUECHNER 80-82 Wb8t Z7th Stkeet LONDON : HENRY FROWDE Ahen Gobheb, E.g. TORONTO : HENRY FROWDE 25 BiOHHOHS St., W. COLUMBIA UmVEBSITT LECTURES SCIENTIFIC FEATUEES OF MODEEN MEDICINE BY FREDERIC Sf^LEE, Ph.D. DALTON PROFESSOR OF PHYSIOLOGY, COLUMBIA UNIVERSITY -ma THE COLUMBIA UNIVERSITY PRESS 1911 All rights reserved COFTBISHT, 1911, Bt the COLUMBIA UNITEESITT PEE88. Set up and electrot3rped. Published November, 191X. I So Li7 Notiooot) Wtnw J. 8. Cashing Co. — Berwick & Smith Co. Norwood, Mass., U.S.A. PREFACE An appointment to the lectureship founded by an appre- ciative .and generous patron of science, the late Morris K. Jesup, Es4., has given me an opportunity to present some of the striking features of modern medicine which illustrate its genuinely scientific character, its great ctange from the medi- cine of the past, and its hopeful outlook for the future. Obviously no attempt could here be made to survey its whole field; but I have endeavored, through a consideration of selected topics, to depict its spirit. Human beings may be divided into those who do, and those who do not, believe in the efficiency of medicine. The relative number of non- believers has always been small, and is doubtless much less now than in the days of the Greeks and of Moli^re, but their sentiments have ever been loudly proclaimed. It is hoped that these pages may be read by both classes. They may perchance help to fortify the believers, and, if not actually to convert the dissenters, at least to make their doubts appear less rational. The labors of a learned profession can easily be belittled by those who are less learned. I shall be gratified if what I have here written shall be instrumental in inducing laymen to study the human body and appreciate what men of medicine are now doing to maintain health and to prevent, diagnose, treat, and cure disease. When laymen do this, the influence of medical cults and healing sects is sure to decline. The lectures here published were delivered at the American Museum of Natural History in the city of New York during the months of February and March, 1911. As with previous lectures on the same foundation, the endeavor has been to present the subject matter clear-cut and in language that is Vi PREFACE not too technical for the intelligent layman. The latter is often eager to learn, but cannot be criticised if he finds the literature of science written in words that are foreign to his mother tongue. In a few cases I have taken the liberty of quoting from previous writings of my own, without acknowl- edging the repetition of my language. It has been found impracticable to reproduce the many illustrations that were helpful in the oral presentation of the lectures. My thanks are due to my colleagues, Professors Francis Carter Wood and Phillip Hanson Hiss, and Drs. W. A. Bas- tedo and H. H. Janeway, and to other friends, Drs. Simon Flexner, William Hallock Park, James Ewing, Alexis Carrel, Nathan W. Green, and Major F. F. Russell. Several of these friends have read critically portions of my manuscript and have ofEered helpful suggestions. FREDERIC S. LEE. Columbia TJhivbrsitt, October 1, 1911. CONTENTS Pass I. A Sketch of the Normal Human Bodt . . 1 II. The Nature of Disease. Methods of Diagnos- ing Disease 22 in. Methods of Treating Disease .... 42 rV. Bacteria and Protozoa and their Kelation to Disease 64 V. The Treatment and the Prevention of Infec- tious Diseases 86 VI. The Problem of Cancer and other Problems . 110 Vn. Features of Modern Surgery 132 Vm. The BdLE of Experiment in Medicine. The Public and the Medical Profession . . . 154 Index 177 SCIENTIFIC FEATURES OF MODERN MEDICINE I A SKETCH OF THE NORMAL HUMAN BODY In his profound book, "Of the Proficience and Advance- ment of Learning," Francis Bacon, writing at the beginning of the seventeenth century, speaks of medicine as follows : "Medicine is a science which hath been . . . more professed than laboured, and yet more laboured than advanced ; the labour having been, in my judgement, rather in circle than in progression. For I find much iteration, but small addi- tion." At that moment the world was standing at the threshold of a great medical advance. The circle of medie- valism had already been broken by the anatomist VesaHus and his contemporaries ; the physiologist Harvey was soon to announce the discovery of the circulation of the blood ; and the labors of men of medicine were thereafter to result in progression. During the seventeenth and eighteenth cen- turies progression was destined to be slow; during the nine- teenth it took on a sudden and unexampled acceleration. Three hundred years have now elapsed since Bacon wrote, and the progress has never been so swift as it is to-day. Each twelvemonth ends with a record of great achievements, and each new year begins with a clearer vision forward. Not- withstanding this we frequently meet with a distrust of the efficiency of medicine, a feeling that the physician knows far B 1 2 SCIENTIFIC FEATURES OF MODERN MEDICINE too little concerning disease -and its cure, and a tendency to turn toward strange cults, making fair promises. Such dis- trust is as old as medicine itself. Its cause is complex, and I shall not now try to analyze it.' I do not believe that it is justified. Doubting is indeed an entirely legitimate form of mental exercise. The man of science who is not a doubter has no claim to honorable standing. He who doubts not is dead to science. But not all doubts are equally estimable. There are those that betray much knowledge and those that betray little. Goethe and Browning did not contradict one another, although the one wrote, "Doubt grows with knowl- edge," and the other, "Who knows most, doubts not." Whatever distrust of medical potency may now exist, arises largely from ignorance of the human body and the present status of medical science. Among many persons this ignorance is extraordinarily great. It is strange to find thinking, reasoning, feeling men and women, who were born with their bodies, who have lived long lives and grown old with their bodies, who have clung to them in sickness and in health, for better, for worse, who have used them for every variety of human service, and yet deliberately hold themselves aloof from a knowledge of bodily affairs. I suspect that we have here an inheritance, through many generations, of the medieval notion of the vileness of the body, a notion which is out of keeping with the enlightened science of to-day. This science shows within ourselves wondrous mechanisms and adaptations, which ought to arouse a man's admiration if he possesses a truly esthetic sense. The medical profession is occasionally criticized for its alleged failure to take the laity into its confidence and to serve as teachers as well as practi- tioners of its principles. I shall not here discuss the question ' For a fuller discussion of this distrust, see p. 165. A SKETCH OF THE NORMAL HUMAN BODY 3 in how far a physician is morally bound to be a pedagogue. But in accepting the Jesup Lectureship, I was influenced largely by the thought that through it I might perhaps be of service to both the medical profession and an intelligent public by telling the public something of what medical leaders are doing. A recent writer has drawn a graphic picture of the three stages that appear in the history of medicine — those of dogma, of empiricism, and of modern science. Dogma was rife until the close of the Middle Ages ; empiricism charac- terized the Renaissance and the centuries immediately follow- ing ; while modern science is a matter of decades. However sharply differentiated are these stages, something of science characterized the earlier ones, while something of both dogma and empiricism, though forever dethroned, still persists. It would be fatuous to disparage the inheritance with which medicine entered upon its present stage, but one would be blind not to recognize its truly wonderful growth under the influence of the scientific spirit of our generation. The stimu- lus to this growth came partly from many extraneous and now familiar sources. The discovery of oxygen, the estab- lishment of the theory of the conservation of energy, the over- throw of the mystical doctrine of vital force, the discovery of protoplasm, the promulgation of the cell theory of organic structure, and the formulation of the theory of evolution — all contributed their share. The chief agents through which the great change has come are the laboratory, now little more than threescore and ten years old, and the method of orderly experimentation which the laboratory alone could foster. One of the first and most essential steps in the modem expansion was the acquisition of a better understanding of the human body in its normal condition of health. Here much 4 SCIENTIFIC FEATURES OF MODERN MEDICINE has been accomplished. Though human anatomy is still far from being a completed science, the gross structure of the body was appreciated early. When we submit the body to a physical examination, externally and internally, we find it to consist, first, of a number of easily recognized parts, which have long been known as organs. The existence of most of the organs of the human body were recognized before the Christian era. This knowledge was at first gained doubtless chiefly from observation of the bodies of men killed in battle. It was not until the famous school of Alexandria had reached the zenith of its glory in the third century before Christ that the human body became actually dissected for purposes of study. Later, dissection fell into ill repute, and it has required modern science to free it finally from obloquy and prejudice. If we proceed farther in our physical examination and look carefully at any one of the various organs, we find it to be composed of a small number of materials, varying in appearance and easily recognizable by the naked eye. To these materials the name tissues has been given, and we may distinguish such as muscular tissue, nervous tissue, connective tissue, epithelial tissue, bony tissue, fatty and cartilaginous tissue. Though the existence of tissues is plainly obvious to an observer, it was not until one hundred years ago that their structural significance was clearly recog- nized — first, by a French anatomist, Bichat, who classified them and pointed out their distribution within the body. It is easy now, in the days of powerful microscopes and in- tricate microscopical methods, to carry the physical exami- nation of organs and tissues into the realm of what was un- dreamed of by the ancients, and the significance of which has been appreciated only within the lifetime of still living men. But Bichat did not realize that all tissues are com- A SKETCH OF THE NORMAL HUMAN BODY 5 posed of recognizable particles, now called cells, of living substance, now called protoplasm. Moreover, cytologists do not stop here, but differentiate, within the cell, nucleus and cytoplasm, centrosome and chromosomes; the ultra- microscope is leading us on toward a sight of still smaller components ; theories of the physical structure of protoplasm are hotly discussed; and interchangeable states of solution and gelation are thought to occur within it. Living substance, in itself soft and delicate and gelatinous, is permeated throughout by non-living water and by non- living soUds, which are antecedents or products of cell activities. Having said this, I ought to confess that often it is a practical impossibility to decide what within a cell is living and what is not living. Moreover, when we attempt to submit the living substance and its contents to chemical analysis, our first step results in its death and chemical change, and we have no longer living, but only dead, substance in our test-tubes. We are thus at first baffled in our endeavor to determine the actual chemical structure of protoplasm, and indeed we are here still in the realm of hypothesis. But we are, nevertheless, making progress in learning the bricks or chemical cleavage products, which result from the demoli- tion of protoplasm and of which it is built up. All the various chemical substances are composed of comparatively few of the chemical elements. Only carbon, hydrogen, oxygen, nitrogen, sulphur, phosphorus, chlorine, sodium, potassium, calcium, magnesium, iodine, silicon, fluorine, manganese, and iron are known to occur in every hvunan body. But these are capable of entering into a long series of permutations and combinations with one another, the various organic com- pounds rarely possessing the simplicity of composition that occurs in inorganic 'nature. Thus we find many representa- 6 SCIENTIFIC FEATURES OF MODERN MEDICINE tives of the ever interesting group of proteins, huge molecules containing hundreds, or even thousands, of atoms, which seem to be arranged in most intricate patterns. For no protein has this pattern yet been fully made out, but it is believed that many of the atoms are grouped into the so- called amino-acids, and that the protein molecules represent still more intricate groupings of these groups, in themselves complex. Besides a considerable number of proteins there occur in protoplasm starches and sugars and fats of various kinds and compositions, water, and various salts. The salts probably exist, in part at least, as ions, electrically charged atoms or groups of atoms, which are chemically combined with the proteins, thus adding to the latter's complexity. The scientific physician must understand not only the morphological and chemical structure of the bodily machine, but the way in which it acts. However complex structure appears to be, it is simple when compared with function. The modern physiologist looks upon the body as a machine, a machine in which physical and chemical processes are con- stantly occurring in orderly sequence and in which energy, no more created here than elsewhere, is being constantly changed from one form to another. Function is thus the expression of physical and chemical principles, and it is the physiolo- gist's endeavor to resolve the vital phenomena of organs, tissues, and cells into their physical and chemical compo- nents. He has already gone a long way in doing this ; but, as might be expected of the science of the life process, every problem solved leaves other problems awaiting solution, and with every mystery mastered still other mysteries lure and baffle. Let me enumerate some of the chief functions of the body. The heart by the force of its beats, which are contractions of A SKETCH OF THE NORMAL HUMAN BODY 7 its muscular walls, moves the blood, receiving it from the veins and propelling it along the arteries. The actions of the heart's valves, the sequence of activity and the dynamic rela- tions of its parts, and its regulation by the nervous system are fairly well understood. We can point with reasonable cer- tainty to the spot at which the beat originates, but we are not agreed as to the nature of the stimulus which sets it off four thousand times during each hour of our Uves, or whether the stimulus acts primarily on nervous or muscular tissue. The lungs serve to introduce oxygen into, and to remove carbonic acid from, the blood. For this purpose the lungs and chest act together like a bellows, the moving power residing in the muscles of the walls and floor of the chest, which are under the control of the nervous system. We understand much of the pneumatic conditions and the nervous relations of the process, but we are still trying to learn in what manner the exchange of oxygen and carbonic acid between the air and the blood occurs. The successive steps in the digestion of food occurring in the stomach and intestine are recognized in the main. From earliest times the liver has been misunderstood, often maligned, and always the subject of hypothesis. The phys- iology of to-day recognizes in it a considerable number of important functions. Like certain parts of a plant's body, its cells serve as a storehouse for such of the body's starch as is not needed for immediate use, and on the demand of the tissues they give this out to the blood in the form of easily transported sugar. The liver is, in fact, the body's "sugar trust" — without, however, employing the peculiar methods that have made famous its modern namesake. It manu- factures and give to the intestine bile, which is an important aid to the digestion and absorption of fats, and an important 8 SCIENTIFIC FEATURES OF MODERN MEDICINE medium for the removal of certain waste products of the tissues' activities. It manufactures and gives to the kidneys urea, another waste product, whose prompt removal from the body is essential to health. To some extent the liver is capable of protecting the body by rendering inert a variety of poisonous substances, such as those that may have been pro- duced within the intestine in the course of digestion, those that may have been caused by disease germs, and even stich poisons as strychnine, morphine, and metallic salts, which may have been taken by the individual with good or evil intent. Various as are the known activities of the liver, it is probable that future research will reveal still others of great importance. The pancreas manufactures and sends to the intestine a liquid which contains three ferments capable of digesting proteins, fats, and starches, respectively. The kidneys and their connected organs remove from the body a variety of chemical substances, both organic and inorganic, which are the end products of the body's chemical changes, and the retention of which would be harmful. Glands are an endless source of interest. We know that from them appear characteristic liquids ; but why, from the uniform store of materials in the blood supplied to all glands in common, the salivary glands secrete saliva, the glands of the stomach gastric juice, the liver bile, and the kidneys urine, and as to what physical principles are involved in the passage of the widely different components of these various juices through the gland cells, we are much in doubt. Within only a few years we have learned that besides producing and excreting through their ducts their characteristic juices, glands give back to the blood equally characteristic sub- stances, many of which are indispensable to the continued A SKETCH OF THE NORMAL HUMAN BODY 9 activity of other organs and to life itself. This process has come to be known as internal secretion, and the same term is applied to the substances thus produced. Thus the liver gives to the blood sugar and urea. The pancreas gives to the blood, apparently only through the activity of certain peculiar groups of its cells, a substance which, in some way still to be determined, plays an important r61e in the chemical changes undergone by sugar within the body. Re- moval or serious disease of the pancreas results in the accu- mulation of sugar in the blood and its constant loss from the body in the urine, which are the striking symptoms of dia- betes. An internal secretion of unknown nature seems to come from the kidney. The peculiar bodies called the thy- roids appear to produce a substance which is of great im- portance to certain nutritive activities of the brain. The absence of this substance may lead in the young to the pe- culiar form of idiocy called cretinism, and in the adult to a disease known as myxedema, both of which are characterized by symptoms of mental deterioration. An excess of thyroid secretion, on the other hand, may lead to an equally distress- ing disease, known as exophthalmic goiter. Still other organs yield equally striking internal secretions. In fact, internal secretions seem to constitute one of the chief media by which parts of the body act upon other parts, often in the most profound and unexpected ways. One of the most active fields of research in physiology to-day is that which deals with the chemical changes under- gone by the body in the process of living. Half a century ago this was largely a matter of speculation. Now we 10 SCIENTIFIC FEATURES OF MODERN MEDICINE recognize that, with its living and its non-living substances inextricably intermingled, the body constitutes an intensive chemical laboratory in which there is ever occurring a vast congeries of chemical reactions ; both constructive and de- structive processes go on ; new protoplasm takes the place of old. We can analyze the income of the body and we can analyze its output, and from these data we can learn much concerning the body's chemistry. A great improvement in the method of such work has recently been secured by the device of inclosing the person who is the subject of the ex- periment in a respiration calorimeter. This is an air-tight chamber, artificially supplied with a constant stream of pure air, and from which the expired air, laden with the products of respiration, is withdrawn for purposes of analysis. The subject may remain in the chamber for days, the composition of all food and all excreta being determined, and all heat that is given off being measured. Favorable conditions are thus established for an exact study of many problems of nutrition. The difficulties increase when we attempt to trace the successive steps in the corporeal pathway of mole- cule and atom. Yet these secrets of the vital process are also gradually being revealed. When we remember that it is in this very field of nutrition that there exist great popular ignorance and a special proneness to fad and prejudice, we realize how practically helpful are such exact studies of metabolism. I have likened the body to a machine. A more fitting simile would be that of an intricate industrial plant, in which varied machines work to produce a certain output. The first essential in such an establishment is order. The work of each machine must be methodical ; its raw material must be supplied in just the right quantity and at just the right time ; A SKETCH OF THE NORMAL HUMAN BODY 11 its products, both useful products and wastes, must be removed promptly and taken to their destinations; and a harmonious adjustment of the labors of the respective parts of the plant must be continually maintained, if confusion and chaos are not to reign. The human body possesses two mechanisms for the maintenance of order and harmony among its varied parts, — the blood cir- culating through heart, arteries, capillaries, and veins, and conveying material substances, and the nervous system conveying immaterial nervous impulses. Nothing illustrates so well the relations of bodily functions as a consideration of these two systems. The blood consists of a liquid part, the plasma, and a large number of minute, floating cells, or cell-like particles, called corpuscles. The plasma is capable of holding in solution a great variety of solid substances. It is the medium by which food and drink and drugs are conveyed to all portions of the organism, carbonic acid to the lungs, and other wastes to the excretory glands. Products of protoplasmic action which are the result of internal secretion and are to be used elsewhere than in their place of origin, are shipped by way of the plasma to their destinations. Those toxic products of ex- cessive activity that are known as fatigue substances are transported by the plasma to all tissues, and thus make it possible that the fatigue of a working organ may be extended even to those that have been resting. Whatever a tissue requires it receives from the store available in the blood plasma, and whatever it is to give up passes to the same medium. The blood corpuscles are of three kinds — blood plates, red corpuscles or erythrocytes, and white corpuscles or leucocytes. The blood plates are a comparatively recent discovery, and 12 SCIENTIFIC FEATURES OF MODERN MEDICINE their functions are not yet well understood. The very abun- dant erythrocytes have long been known for their power of absorbing large quantities of oxygen, and in the course of evolution they seem to have become differentiated for the express duty of conveying to the tissues this essential gas. That this power is adapted to the bodily needs is shown by the fact that life in high altitudes, where the actual oxygen con- tent of the air is relatively low, leads to a marked increase in the number of erythrocytes, and thus to an increased power on the part of the blood of absorbing oxygen. Until recent years the leucocytes have been regarded as humble and insig- nificant members of the organic colony, but they have now risen to a dignity that is surpassed by few other cells. Like the amoeba they possess the power of independent motion, and like nomads they wander at will. I say "at will" fanci- fully. We have no reason to believe that leucocytes possess consciousness. When it pleases them they allow themselves to be carried along in the blood stream, but ever and anon they forsake the blood-vessels, push their way through the walls, and roam up and down among the tissues. It is pos- sible that they act as carriers of food, such as fats and pro- teins, when these substances are ready to enter the tissues after the digestive ferments have dealt with them. They assist in the peculiar and often life-saving process of coagu- lating blood. They seem to be factors in maintaining the desired chemical composition of the blood plasma. They probably manufacture substances that are destructive to bacteria. And, lastly, they engulf worn-out body substance, living bacteria, and other matter foreign to the body, should such be present, and thus protect the body from harmful agencies.' • See also pp. 45, 77 and 79. A SKETCH OF THE NORMAL HUMAN BODY 13 Pumped by the heart, the blood circulates in arteries, capillaries, and veins throughout the body to its remotest parts and back again to the heart. In the thin-walled cap- illaries its liquid plasma exudes into the interstitial spaces of the tissues, accompanied by numbers of leucocytes, and the two together constitute the lymph. It is only through the lymph that the exchange between blood and tissue is effected. Even with the elaborate blood system with its many func- tions the diversified body without other agency would still be unable to live a unified life. To harmonize, correlate, and unify is the special function of the nervous system. Without a nervous system oiu- members might exhibit a certain de- gree of spontaneity, but it would be the spontaneity of un- bridled license, and anarchy would soon put an end to us. For more than two thousand years men have been endeavor- ing to fathom the mysteries of brain and nerve, and their ultimate problems seem now as enigmatical as ever. Even a rational idea of the structural basis of nervous action has been acquired only within three decades, and there are some biologists who are still skeptical of this. According to the prevalent conception, the nerve-cell, now called neurone, is the imit of nervous structure. Like other cells, it possesses a central, nucleated body of microscopic size, but unlike other cells, there extend far outward from its body in various direc- tions dehcate filaments. The numerous, comparatively short, and much-branched filaments are called dendrites; the few, comparatively long and little-branched, axones. A human nervous system, with its brain, spinal cord, ganglia, and nerves, is a mass of neurones. The bodies of the neurones and their dendrites lie mostly within the brain, spinal cord, and ganglia, in more or less definitely localized masses. 14 SCIENTIFIC FEATURES OF MODERN MEDICINE The axones are mostly collected together into definite bundles or tracts, of which some lie within the brain and spinal cord, but many extend outward and, as the constituent nerve-fibers of nerves, reach all parts of the body. Through the nerves all organs and tissues are in communication with, the brain or spinal cord, and only through the brain or spinal cord do organs and tissues possess the possibility of communicating with one another. Neurones, while often in contiguity and seemingly inextricably mingled, do not appear to be actually continuous with one another. Their number is legion, and through them the infinitely complex work of the nervous sys- tem is performed in an orderly, methodical manner. The messages which they transmit are called by the physiologist nervous impulses. Many theories of the nature of nervous impulses have been proposed, and though no theory is wholly satisfactory, we believe that in them certain physical, prob- ably electrical, and chemical processes are involved. Each nerve-fiber seems to conduct impulses in one direction only. Outside the brain or spinal cord certain of the fibers conduct only from the tissues and toward the central nervous system, while certain others only in the opposite direction. Every organ seems to possess both of these afferent, or centripetal, and efferent, or centrifugal, fibers, and thus is able both to send and to receive impulses. Incoming impulses inform the brain or cord of the physiological state of the particular organ from which they come; they may give rise to sensations, and are then called sensory. The most striking functions of pm-ely sensory nerves are those of the so-called special senses. Outgoing impulses are never in themselves sensory, although the brain actions that inaugurate many of them may be accompanied by conscious acts of the will. They inform the organs or tissues what to do under the circumstances. The A SKETCH OF THE NORMAL HUMAN BODY 15 following is a classification of the known varieties of nerve- fibers, according to their functions. Afferent Efferent Excitatory Inhibitory : Excitatory Inhibitory : Sensory: controlling sensations of sight, hearing, smell, taste, pressure, temperature, pain, etc. Reflex: inducing reflex actions through efferent fibers. inhibiting reflex actions. Motor: supplying voluntary mus- cles, the heart, and the muscles of arteries, stomach, intestines, etc. Secretory : supplying salivary glands, glands of the stomach, and the pancreas, sweat-glands, etc. inhibiting the activities of the muscles and glands. Within the brain and spinal cord the various nerve-fibers, grouped into different bundles, offer definite routes for the conduction of nervous impulses. In some the impulses pass upward, in others downward, in still others from side to side. Through them the organs and tissues communicate with the various parts of the brain and spinal cord, and these in turn communicate with one another. A single act, however simple it may appear to be, usually involves many nervous phenomena. Thus the voluntary contraction of one's biceps muscle means the ti'ansmission, not only of excitatory impulses to the biceps itself, but of inhibitory impulses to its antagonist, the triceps; other excitatory and inhibitory impulses to adjacent muscles for the purpose of inducing in them just the right degree of ten- 16 SCIENTIFIC FEATURES OF MODERN MEDICINE sion in order that the biceps may be aided ; dilating impulses to the arteries of the various contracting muscles and con- stricting impulses to arteries elsewhere, in order to supply the muscles with more blood ; impulses to the heart to beat more strongly, in order that the demands of the arteries for blood may be met ; increased naotor impulses to the muscles of respiration; increased secretory impulses to the sweat- glands and dilating impulses to their arteries; and perhaps other nervous impulses to other organs. If, moreover, we realize that with each one of these separate actions special afferent nervous impulses go to the nervous system announc- ing the nature and extent of the action, we may in our be- wilderment well wonder why a mere innocent contraction of the biceps does not bring in its train an attack of nervous prostration. Gay critics of the medical profession, anti- this, and anti-that, who wonder why the problems of health and disease have not been solved long ago, have little con- ception of the intricacies of the human body. One of the greatest achievements of the modern physiology of the nervous system has been the exploration of the various parts of the brain and spinal cord and the discovery that each part has its own specific work to do. The parts that are composed chiefly of the bodies of nerve-cells are known as nerve-centers, and it is customary to picture the brain and cord as consisting largely of innumerable centers connected with one another by tracts of nerve-fibers. Along the whole length of the cord there is a series of such functional centers, which deal with the activities of the muscles of the trunk and limbs and some of the abdominal organs. The bulb, or medulla oblongata, is a mass of most important centers dealing with such essential features as breathing and the actions of the heart, the arteries, and the glands. In the much-folded A SKETCH OP THE NORMAL HUMAN BODY 17 outer layer, or cortex, of the cerebrum lie the innumerable centers whose activities are accompanied by consciousness, and here we locate the volitional factors of locomotion, the movements of arms, hands and fingers, speech, sight, hearing, taste, smell, and touch. Here also are mediated the psychic processes of perception, conscious memory, the association of ideas, and the thousand and one features of mental life. A scientific cerebral phrenology has thus replaced the doctrine of cranial bumps and excrescences, which was advocated so strenuously by Gall and Spurzheim seventy-five years ago, and which impressed so many of our fathers. Yet there is still much unknown territory lying within the skull, and cerebral geography offers to the intrepid explorer prizes of infinitely greater importance to the human race than those won, however gallantly, by Nansen, Scott, and Peary. In this rapid and very incomplete sketch of the structure and functions of the normal human body, I have endeavored to give to you something of the spirit of modern physiology and to impress you with the variety and complexity of our bodily machine. Unless one learns it step by step one may be overwhelmed with the intricacy of it all. We should bear in mind that the intricacies of both structure and function are the result of a long evolution. Of the mode of origin of the earliest rudiments of organs we can only speculate, but it may conceivably have been a more rapid process than their subsequent change into complicated mechanisms. Loco- motion, even in the unicellular forms, required contractile protoplasm. When the primitive organism became so large that it could not obtain sufficient food by direct absorption from its environment, it may have been a simple matter to infold and produce a primitive alimentary canal. A simple system of tubes permeating the body and containing a nutrient 18 SCIENTIFIC FEATURES OF MODERN MEDICINB liquid soon followed. A simple method of nervous commu- nication between the parts originated early, and along with it certain simple sense-organs. Thus in the more simple of the ccelenterates we find muscular, alimentary, circulatory, and nervous systems already begun, and ready for the subse- quent long process of development. Within the walls of the circulatory system a localized aggregation of muscle cells formed a simple heart. An extension of the surface tissues became a respiratory gill. Glands secreting digestive ferments appeared in connection with the ahmentary canal. Other glands communicating with the surface of the body carried off waste products. An aggregation of neurones performed the simple function of a primitive brain. Nerves were multi- plied, and nervous functions became more diverse. New sense-organs appeared, by which the organism could acquaint itself with the various forms of energy in the external world. A change from the original aquatic to a terrestrial life involved the appearance of lungs and other profound transformations. Simultaneously with the ever increasing complexity of struc- ture came physiological differentiation and physiological integration — the greater the differences within the body, the greater became the correlation between the parts. And so, step by step, through ages of trial, now advancing, now receding, the intricacies of form and function that we find most completely developed in man's body slowly appeared. In surveying the working of a human body there is one topic which has been of absorbing interest to physiologists, physicians, and philosophers of all ages, and at the present time, with its many systems of mental healing, is much attracting the attention of the lay public. This is the prob- lem of mind, its nature, the relation of mind and body, and the possibility of their mutual influence. To consider this A SKETCH OF THE NORMAL HUMAN BODY 19 topic is to enter a field of many and diverse opinions, where speculation has always been rife, where experimentation is difficult, and where superlative uncertainty is still supreme. To the naive thinker, mind and body are two distinct entities, dififerent in nattire — the one spiritual, the other material — and each capable of existing and acting apart from the other, and of inducing, modifying, and arresting activity in the other. To the physiologist this view presents insurmountable diffi- culties. Neither introspection nor extrinsic observation nor laboratory experimentation reveals to him a mind outside a nervous system. He associates human consciousness only with the cortex of a himian cerebrum, and only when the cortical neurones are active, — in sleep and other forms of unconsciousness mind no longer exists, except when dreams interpose their feeble and fantastic images. Every mental phenomenon has its neural counterpart, although the vast majority of neural processes are devoid of a mental accom- paniment. It is a favorite attitude of physiologists thus to look upon mind as a sign of brain activity, as only one of the several phenomena by which cerebral neurones manifest their activity, albeit mind seems more mysterious than the phenomena which we call physical, such as changes in tem- perature, in electrical state, and in chemical composition, all of which are manifest when brain cells act. This hypothesis does not postulate the nature of mind, but it regards mind as an accessory phenomenon, or epiphenomenon, and not as the supreme inhabitant of the cerebral protoplasm. If this hypothesis be true, we must alter our naive ideas concern- ing the interaction of body and mind. Thus bodily changes may madify mental action, but only by modifying brain action. So, too, the brain through the nerves may modify bodily action. But the mind itself, a sign of brain activity, 20 SCIENTIFIC FEATURES OF MODERN MEDICINE cannot influence matter, and thus can never be the directing agency of either brain or body. All supposed influence of the mind over the body is thus reduced to brain influence, which, however, may be mirrored in mental acts. Such an hypothesis, whatever its future, appears to me to be the most fruitful working hypothesis for the physiologist at the present time, and it would appear to clarify the now puzzling field of psychotherapy. We ought not to leave the consideration of the activities of the human body without a glance, however brief, at the problem of the nature of vital actions in general and their control. From the beginning of human speculation — and that means from the beginning of the human race — down to the era of modem science, when speculation has been forced to give way to demonstration, it was thought that a peculiar power resided in the body which was immediately responsible for bodily actions. This power was variously believed to be material and immaterial. The doctrine which lived longest was that of the pneuma, or spirits, which were conceived as matter in an extremely tenuous state, permeating the body and directing the grosser matter of which the body is com- posed. The Greek physicians, five hundred years before Christ, beUeved in the spirits, as did their successors in both Greece and Rome. All through- the Middle Ages the spirits held sway, but after the Renaissance had set men free from slavish tradition, there entered doubts and a lack of agree- ment as to what constitutes the directing power in vital ac- tions. Various immaterial agencies were then invoked — the anima or soul, the archeus, the ether, the nervous prin- ciple. But these in turn gave way with the advent qi a final form of the general doctrine. This was the hypothesis that vital actions are manifestations of a specific force, differing A SKETCH OF THE NORMAL HUMAN BODY 21 from the forces of inorganic nature, but peculiar to living things, and hence called vital force. The belief in a vital force was almost universal from about the middle of the eighteenth to the middle of the nineteenth century. But toward the end of the period the great advance of physics and chemistry and the application of the new discoveries to living processes profoundly shook the existing belief in regard to the nature of vital phenomena, and led, by the middle of the last century, to the practical abandonment of the doctrine of vitalism. Thus ended the endeavors to explain vital actions by means of a single mysterious principle, and men turned their atten- tion to the discovery of the physical and chemical phenomena, which were, and are still, recognized as the essence of the mani- festation of life. The question of vitalism or mechanism is not yet beyond the sphere of debate, but the mechanistic mode of interpreting the phenomena of nature has proved to be the one under which the most rapid progress in discovery has yet been made. One of the scientific features of modern medicine, therefore, is no longer to regard the human body as a thing of mystery, which will forever be inexplicable, but to believe that every part of it, sooner or later, will give up its secrets — to the same extent at least that non-living nature will yield hers. II THE NATUEE OF DISEASE. METHODS OF DIAGNOSING DISEASE In the last lecture I endeavored to present a picture of the human body in a state of health, healthy as to both structure and function. To-night I intend to devote the hour to a subject which is popularly less inviting, but to the man of science not less interesting, namely, that of the body in the throes of disease. By disease we customarily mean that condition in which bodily function or bodily structure exhibits a deviation from what has come to be regarded as the normal. 