important therapeutic agents, but to a knowledge of the relation which exists between the chemical constitution of a substance and its physiological effects. Already a considerable amount of work of this kind has been accomplished. The physiological action of the various anesthetics (such as chloroform, chloral, alcohol, &c.), of narcotics (such as morphia, narceine, narcotine, codeine, and many others), and of alkaloids (such as strychnine, brucine, nicotine, atropine, hyoscyamine, physostigmine, muscarine, veratrine, aconitine, digitaline, santonine, ergotine, and quinine) has been carefully studied. The celebrated research of Professor Crum Brown and Dr. Thomas R. Fraser, upon the physiological action of the methyl-, amyl-, and ethyl-substitution compounds of certain alkaloids, in which they showed that a change in chemical composition was attended by a change in physiological action, opened up a new field of discovery. The investigations of Dr. B. W. Richardson on the action of homologous series of alcohols and ethers, and the observations made by Professor Dewar and myself on the action of the chinoline and pyridine series of bases, and their substitution compounds, all tended to illustrate the same general truth. Nor must I forget to mention an interesting series of investigations made by Professor Gamgee, of Manchester, and his pupils, communicated to our Section and at the present meeting, on the action of various compounds of the rare metal vanadium, on the action of chromium salts, and on the differences between the physiological actions of ortho-, meta-, and pyro-phosphoric acids. Here, again, we had a further illustration of the important facts that the physiological action of any active substance is affected (1) by the number of atoms in the molecule and its complexity of structure, and (2) by the degree of stability of the molecule. That is to say, the more complex the molecule, the more intense and prolonged will its action probably be; and, on the other hand, if the molecule of a substance tend readily to break down or split up while circulating in the blood, it will act more intensely than if it held firmly together for a considerable time. These generalizations are merely tentative. We have not yet sufficient data to entitle us to term them general laws. Now no one can glance over any work on organic chemistry without seeing on every page the names of substances regarding the physiological action of which we know nothing. I would not have these investigated in a promiscuous manner, with the vague hope of coming upon something new. Here, as elsewhere in science, we must be guided so far by the light cast upon the unknown by former discoveries, and by those general laws which have been formulated by previous investigators. Nor is the mere discovery of new poisons any thing but a sorry task," unless the research lead us to an agent likely to be of therapeutic value, or to the enunciation of an important general principle. But former experience warrants us in hoping, nay in expecting, that new useful agents will yet be discovered. I need not refer to the practical applications of chloroform and ether, as these are too well known to need any eulogy from me; but I may be allowed to direct attention to chloral, first discovered by Liebig in 1832, and known for many years merely as the ultimate product of chlorine upon alcohol. It was only a few years ago that Liebreich, of Berlin, pointed out its important physiological action, and it is now recognized as a therapeutic agent of the highest value. Its use, no doubt, has often been sadly abused, and people have often trifled with a powerful physiological agent even to the loss of their lives; but when we think of the hours of pain which many a weary sufferer has escaped by its use, we cannot but regard it as a boon to humanity. Here the physiologist must go hand in hand with the chemist. The chemist in his laboratory prepares the substances, and builds up new compounds by those wonderful synthetic processes which are now the glory of his science; it is then the duty of the physiologist to investigate the actions of these. By united work, who can foretell what may be accomplished? For example, may we not hope to see the day when such a substance as quinine, or a substance having similar therapeutic properties, may be produced artificially; or, may we not obtain an anaesthetic as potent and even less dangerous than those at present employed? Nor have we yet investigated the physiological action of the active principles of thousands of plants, many of which may prove to be of great value. Let us remember the well-known words of Shakespeare, as Romeo-the love-stricken Romeo-repairs to Friar Lawrence's cell, "when grey-ey'd morn smiles on the frowning night." The old friar thus soliloquizes:— "I must up-fill this osier cage of ours With baleful weeds and precious-juiced flowers. Many for many virtues excellent, None but for some, and yet all different. In herbs, plants, stones, and their true qualities: Within the infant rind of this weak flower Romeo and Juliet, Act II. Scene 3. I cannot help noticing here, in passing, that Shakespeare appears to have conceived the notion of the physiological antagonisms of drugs, which is generally regarded as quite modern, although the practice of using antidotes has been followed from the earliest times. Thus in the interview between the Queen and Cornelius, the physician, in Cymbeline, she says: 66 Having thus far proceeded, (Unless thou think'st me devilish) is't not meet That I did amplify my judgment in Other conclusions? I will try the forces Of these thy compounds on such creatures as We count not worth the hanging (but none human), To try the vigour of them, and apply Allayments to their act, and by them gather Their several virtues, and effects."-Cymbeline, Act I. Scene 6. RELATION OF PHYSIOLOGY TO MEDICINE. I may now be permitted to say a few words regarding the present position or attitude of physiological science. I am in the habit of thinking of physiology, not only as a physical science in itself, but as having a direct relation to two other sciences-medicine and psychology. Carrying out this idea, were a sculptor to form a group, he might represent physiology, on the one hand, dispensing gifts and affording assistance to medicine, and, on the other, pointing upwards to psychology as the greater sister of the three. Abandoning metaphor, there can be no doubt physiclogy is most intimately connected with these sciences. First of all, with regard to medicine (and by this term of course I mean the whole art of detecting and curing disease), there arem any problems which physiology alone can solve. The origin of disease, the steps of the changes by which organs and tissues become so altered as to produce what is called a diseased state, the effects of one diseased organ upon others which are healthy, the actions of remedial substances, both in the healthy and in the diseased condition, are all physiological processes, many of which cannot, in the present condition of society, be thoroughly investigated by a practitioner, who is often too busy a man to engage in this kind of work. Such labour must be handed over, to a large extent, to a special class of men. They must investigate, experiment, and work up the subject in the laboratory-either the physiological laboratory of the university or school of medicine, or of the hospital or infirmaryas the business of their lives, and from time to time announce the results. These results must be checked by past experience, or by a knowledge of cases apposite to the point, by the men who come into daily contact with patients, and their verdict, so far as any practical benefit is concerned, must usually be regarded as final. IMPORTANCE OF SYSTEMATIC INVESTIGATION OF DISEASES. In the present state of science, we have not reached that subdivision of labour, nor need it be ever absolutely complete. Many of the best contributions to physio logical and pathological science, during the past twenty years, have been from men busy in practice. Such busy men will, no doubt, always be found in the ranks of the medical profession, and they will contribute so far to the advancement of medicine; but in the future, much scientific work, as a basis of the practical treatment of disease, must be done by men specially devoted to the laboratory, the pathological theatre, and the clinical ward. The origin and progress of those diseased processes which cause cancer, tubercle, rheumatism, and gout, with all their attendant evils, the discovery of the poisons which produce fever in its manifold forms, the modes of counteracting these poisons so as to arrest the progress of fever at an early stage, and the investigation of those diseases which destroy thousands of our domestic animals, are all subjects which must be investigated more systematically and on a larger scale than has yet been done. Such stupendous work can scarcely be left to individual effort. To carry it on requires men, time, and money; and these can only be supplied by the aid of governments, or municipalities, or by private munificence. Already excellent work has been done by Professor Burdon Sanderson and his coadjutors, by Dr. Klein, and by Dr. Thudicum, for the Medical Officer of the Privy Council, and by Professor Rutherford, Dr. Braidwood, and others, at the instance of the British Medical Association; but still the amount of aid given is small alongside of what is lavished, for example, in warlike experiments. Compared with what is needed for the manufacture, testing, and equipment of an 80-ton gun, designed to destroy human life and property (no doubt on the theory that it is for the ultimate welfare of the State to do so), a small sum would be necessary; but authorities do not yet see the vast importance of inquiries of this kind, and consequently consider two or three thousand pounds per annum sufficient. We accept gratefully what help is given; but we look for more. I hope to see the day when Government will equip and thoroughly furnish a body of men for the investigation on a large scale of the genesis of such diseases as tubercle or of typhus fever, both of which kill in Great Britain alone thousands of people annually, just as they have sent out a 'Challenger' expedition to explore the depths of the sea, or have at present a number of brave men engaged in the attempt to discover the North Pole. To strike at the rcot of one of those great maladies that afflict the human race, such as cancer, tubercle, or fever, would confer an inestimable blessing on humanity, and honour on the Government that proposed and carried out the undertaking. RELATION OF PHYSIOLOGY TO PSYCHOLOGY. As I have said, physiology is intimately connected with psychology, or of the science of the mind; and as this department of physiological work has lately been my chief study, I may be allowed to refer to it a little more in detail. Psychology may be divided into two parts :-first, all those phenomena which we may include under the term mind properly so called, such as feeling, volition, and intellectual processes; and second, the phenomena which are associated with, and which indicate the alliance between, mind and matter. Every mental act may be regarded in the present state of knowledge as having a double aspect-on the one side it is known to our consciousness, and on the other side it is the result of a number of physical processes occurring in the brain. THE METHODS OF PSYCHOLOGY. In the investigation of mental phenomena, two modes of inquiry have been hitherto followed. First, that of introspection and reflection, in which the investigator looks within himself for the facts of his experience; and second, that of the examination of physiological processes which coincide with sensorial or mental changes. It is evident that the first of these methods, usually called the subjective, is open to the objection that by it a mind attempts to observe its own operations, and that the proceeding is somewhat analogous to asking a machine to investigate its own mechanism. This objection, urged in other words by Comte, Maudsley, and others, may be answered by replying that the subjective method does not attempt to explain the physiological phenomena concomitant with mental states, but the laws which regulate these mental states themselves. Suppose a complicated machine possessed consciousness, I can readily understand that by the exercise of this consciousness it might be unable to discover the relation and mechanism of its own parts, because in attempting to do so the machinary would be so interfered with as to prevent normal action; but it might still be able to study the products of its operations. I do not, therefore, decry this old method of psychological research, as it is so much the fashion to do in these days. Apart altogether from the philosophical speculations and systems of philosophy founded upon them, I think. many data accumulated by such men as Locke, Berkeley, David Hume, Thomas Reid, Dugald Stewart, Thomas Brown, Sir William Hamilton, and James Mill have as good a right to be considered correct as some of the quasi-metaphysical conceptions of modern physical science. Subjective inquiry carried on by such men cannot be given up as a mode of psychological research. It may not carry us much further than it has done, but it has rendered good service already, and may possibly do more. But, on the other hand, the objective method appears to me to be the one which, in future, will be principally cultivated; and it is for this reason that, as a physiologist, I wish especially to refer to it. It is the business of physiology to supply psychology with information regarding physical processes occurring in the nervous system; and it is one of the special features of the physiology of the present day to direct attention to the physical side of mental phenomena. No doubt Aristotle, Hobbes, and Hartley incorporated into their psychological theories much that was purely physiological; but in their days the physiology of the nervous system was in a crude state, and, consequently, did not lead to great results. In comparatively recent times, a new inductive and experimental department of science has arisen, the nature of which is indicated by the term physiological psychology, and which is being diligently cultivated by numerous workers, both at home and abroad. In our own country the writings and researches of Herbert Spencer, Alexander Bain, Dr. Laycock, George Henry Lewes, Dr. Maudsley, Dr. Carpenter, Alfred Barratt, and James Sully, and on the continent those of Fechner, Helmholtz, Wundt, Hermann Lotze, Taine, Donders, Plateau, and Dalboef, have excited much interest, and have led to the formation of a new school of thought. I think it right to mention here specially the name of Professor Laycock, who has done more, in my opinion, in this field of inquiry than any other member of the medical profession of this country in our time. His teaching has largely contributed to our present humane methods of treating the insane; he has attracted year by year some of the best students of the University of Edinburgh to this important department of medical practice; and his earlier writings incontestibly show that many years ago, and prior to most of the writings of those great men whose names I have just enumerated, he not only recognized the value of physiological research with regard to mental phenomena, but made important contributions himself. Physiology has thus encroached on psychology, and is attempting to supply from the objective side an explanation of at least the simpler mental phenomena. As a proof of awakened interest in this department, one of the features of the past year has been the appearance of Mind,' a quarterly journal of psychology, edited by my able friend Professor Croom Robertson of University College. In the prospectus of this journal it is stated that "psychology, while drawing its fundamental data from subjective consciousness, will be understood in the widest sense, as covering all related lines of objective inquiry. Due prominence will be given to the physiological investigation of nerve-structure." This quotation indicates the view which the editor takes of the relation of the two sciences, and already valuable papers have appeared on subjects connected with physiological psychology, from the pens of Sully, Lewes, Wundt, and others. Now a certain class of thinkers are alarmed by work of this kind. They are afraid of the tendency "to represent the mental fact as a physical fact," and they are inclined to shut their eyes to the physical facts connected, undoubtedly, with psychological processes, and to be contented with the study of subjective phenoBut as most admit that there are two aspects in which mental phenomena mena. may be viewed, why should not both be looked at carefully? If it be also admitted that it is impossible to connect any physical process (supposing we knew it) occurring in brain-cells with an act of consciousness, what is the use of taking a one-sided view of the phenomena in question? Why not study both sides of the problem, and give up the attempt at reconciliation, which is entirely beyond the pale of our faculties? This mystery of mind and matter has puzzled thoughtful men from the earliest times. Some have attempted a reconciliation. They have reasoned in a circle, so that most people, after perusing their works, are no nearer an ultimate solution than they were at the beginning. We always come back to this view of the case, namely, that every fact of mind has two aspects, a physiological and a psychological. That is one way of looking at the problem, and it is the one which, in the present state of knowledge, personally I prefer. But there is another. Thus, as has been well argued by Mr. George Henry Lewes in his recent work, Problems of Life and Mind,' two very different descriptions may be given of one and the same mental activity. The one may be expressed in the language of psychology, which is the language we commonly use to describe our feelings; the other may be stated in the language of physiology, a language intelligible only to those acquainted with the present state of physiological research. He says, "All that we have to guard against is the tendency to mistake difference of aspect for difference of process, and to suppose that changes in feeling can exist independently of changes in the organism, or that any change in the organism can be effected otherwise than by some previous change." This way of stating the question may be more satisfactory to some minds. At all events it is a fair attempt to solve the puzzle of our present state of existence, in which we are constantly brought face to face with the antithesis of object and subject. Abandoning these speculations, which are fruitless in practical effects, let me now endeavour very briefly to indicate the lines of inquiry in the domain of physiology along which progress has been and may be made in the attempt to solve psychological phenomena; and I wish it to be understood that I do not take these in any logical order, but merely adduce them by way of illustration. It will also be my aim not so much to describe what has been done in the past, as to indicate what remains to be done in the future. RESEARCH IN PHYSIOLOGICAL PSYCHOLOGY. First of all, then, it is quite evident that all researches on the general physiology of the great nerve-centres are of paramount importance. Such researches as those of Hitzig, Fritsch, and Ferrier on the excitability of the cerebral hemispheres, supplying new ideas regarding the mechanism of the brain as a compound organ; of Wundt on central innervation and consciousness, in which he discusses in a manner never before attempted, the phenomena of reflex excitation; of William Stirling on the summation of excitations in reflex mechanisms; of various French physiologists on the mode of action of ganglia in Insecta; and of many others, are all recent important contributions to this department of science. Here, however, we have to confess that we have little accurate information regarding the minute structure of the parts involved, and consequently no anatomical basis on which to found our views. We have a general idea of strands of nerve-fibres and groups of nerve-cells of various forms, but we have no precise knowledge of the relative quantity of these, or of the relation of one group of nerve-cells to another group. We are unacquainted with any peculiarity in structure, for example, by which even an accomplished histologist could identify three microscopical sections as respectively portions of the brain of a man, of a monkey, and of a sheep. All this has still to be work out. Every little area of brain-matter has to be surveyed and carefully described. Supposing this were done in the case of the human brain, and of the brains of the higher animals, the same must be attempted with the brains of animals lower in the scale. I can then conceive a grand collection of facts which may throw light on the intricate working of different kinds of brains, and, perhaps, afford a rational explanation of certain simple psychological characters. |