Popular Science Monthly/Volume 25/June 1884/Editor's Table
|←Arnold Henry Guyot||Popular Science Monthly Volume 25 June 1884 (1884)
THE PROGRESS OF MENTAL SCIENCE.
IT is gratifying to remark the steady and assured advance of psychological research on the objective or corporeal side, or what is now better known as mental physiology. Without denying the validity of the old method of studying the mind by introspective observation, or that there are regularities and uniformities in the changes of consciousness thus revealed which are the proper subject-matter of science, it is still true that this method does not reach down to the conditions which give law to mental operations, and can not deal with the most fundamental questions of psychical science. It is the organic side of mind which determines mental phenomena, and the science of mind is, therefore, radically incomplete until the nervous system is made the basis of exploration in its manifestation of psychical effects. It can hardly be said that there was anything entitled to recognition, as a proper science of mind, until the bodily conditions and concomitants of feeling and thought became an essential part of the study, and, when that was done, the progress of knowledge upon the subject was clear, decisive, and in the highest degree important. To appreciate the latest phase of this interesting research, it will be desirable to recall some of the signal steps of advancement which have been made in recent years in this line of investigation.
Throughout past ages, from the ancient classical period onward, although philosophy was ever busy with questions concerning the nature and powers of the soul, nobody dreamed that it had a fixed and definite working relation to the universe through the living mechanism with which it was associated. The anatomy and physiology of the last century, however, prepared the way for the successful elucidation of the subject, and the first great step forward was made by Sir Charles Bell about the year 1825, in establishing the double action of the nervous system, or that impressions from the external world pour in upon the brain through one set of nerve-lines, while all the mandates of volition controlling human activity are transmitted outward along another system of nerve-lines. This was a triumph of anatomy and experimental physiology, and a very striking fact, yet the profound significance of the discovery could not be at all appreciated at the time, as it derived its chief importance from the train of disclosures that grew out of it.
It was at first supposed that all peripheral impressions are sent directly to the brain or sensorium, and that all commands of the will are also transmitted uninterruptedly from the brain to the muscles. But about 1840 Dr. Marshall Hall made another capital step of progress by establishing the reflex function of the spinal cord, or by showing that the spinal centers have a control of muscular movements and organic processes independent of the brain. The element of automatism in the working of the living machinery was here brought out, and it was discovered that there are self-working systems in the living economy, by which important gradations of effect are secured. The lower and simpler centers of the spinal system control the fundamental processes of organic life, involving the action of the heart, and the respiratory and digestive apparatus. It is as if these could not be intrusted to the higher organ of volition, which, becoming exhausted, sinks daily into inaction and unconsciousness, but must be committed to specific centers which act with automatic certainty and never sleep.
Pursuing this line of inquiry, a third important step was taken by establishing the separate and automatic functions of the sensory ganglia at the base of the brain and the summit of the spinal column. Impressions from the surface reaching the spinal centers are passed upward to the sensory ganglia, and there give rise to sensations and emerge into consciousness, reflex action being here extended to conscious movements. Dr. Carpenter did much to unravel this branch of the subject about 1850, and his work on "Mental Physiology," published within a few years, will be found full of interesting and important information in relation to it. The problems entered upon were, of course, of great complexity, obscurity, and difficulty. Dr. Laycock had carried the doctrine of reflex action into the cerebral hemispheres, and shown its importance in the higher operations of the mind; and it yet remains a sharply debated question among nervous physiologists how far the principle of automatism extends in the higher realm of our psychical life.
It was thus gradually established that all mental operations, all thought, feeling, instinct, and volition, are the results, first, of the activity of the primary nervous elements, cells, and fibers, by which nervous influence is accumulated and discharged; and, second, of the interaction of numerous automatic centers variously endowed, but communicating with each other solely by the transmission of nervous force. The gain thus secured to mental science on its practical and progressive side was very great. The subject took its place among the definite and experimental science of the natural world. Nothing is so vague as the conception of mind from the metaphysical point of view. Quantitative results are unattainable by that method, and all limitations are scorned by it as degrading to the dignity of spiritual being. But in inquiring into the functions of the nervous system we are at once deeply involved in the physiology of limitations. Mind-force can not come from nothing, any more than other forms of force, and here as elsewhere one effect is at the expense of another. Thinking and feeling exhaust the mechanism, and we are involved with practical questions of waste and repair, exercise and rest, food, blood, nutrition, and the hereditary qualities of the nerve-centers.
Here also the study of mind widens out into the comprehensiveness of a true science by including all the grades of animal life as objects of psychological study. For here as well as everywhere else the higher is to be interpreted by the lower, the complex by the simple, and no animate creature is so far down in the scale that it does not illustrate some phase of mind which has a bearing upon the mental problems of higher beings. The introspective method of course breaks down here. Confined to the adult mind, it excludes the minds of children, and therefore the study of the laws of mental growth; confined to the human mind, it excludes those of all inferior beings. Yet when it becomes a question of determining the properties of nerve-centers, the nature of reflex action, of instinctive movements, and all forms of the laws of intelligence, then comparative psychology makes invaluable contributions to mental science.
And there is still another division of the study of mind of supreme importance, to which very little was or could be contributed by the old method, but which is making marked progress by the more recent methods of investigation: we refer to the subject of insanity. When we come to mental derangements, introversive study is obviously fruitless, and so long as that was pursued nothing was known of the nature of insanity. Mental disease in its basis and causation is bodily disease, and the multitudinous forms of mental weakness, degeneracy, and aberration are to be studied as effects of corporeal infirmity or disease of the nerve-structure. The light thrown upon the science of mind through the manifestations of mental failure has been of great importance, and physiological investigation has now brought us to another and very significant aspect of the subject.
For all scientific men the doctrine of evolution is established, and its highest interest to them is that it is constantly giving new clews to the interpretation of nature and opening new avenues to productive research. This doctrine teaches that the grades of life have arisen in past ages through the operation of laws by which the higher have been derived from the lower. But if this be true, then the nervous systems of animated beings are to be regarded as products of evolution, so that the hierarchy of nervous centers of which we have spoken has been built up by the successive attainment of higher and higher levels of organization. Man, as the latest product and highest term of evolution, combines in his organism the various automatic systems successively reached in the long course of organic development. Biology works out the great laws of upward and divergent unfolding, but there is another side to the phenomena which it is the business of pathology to investigate. Corresponding to the progressive and upward changes of evolution, there are the downward and retrogressive changes of dissolution, by which the constructive work is reversed and undone. But, if we have a true theory of the way the nervous system of man has been evolved, will not that theory afford guidance concerning the order of dissolution, and throw light upon the nature of nervous maladies and mental derangement? This question has been answered affirmatively. We print a lecture by Dr. J. Hughlings Jackson, the first of a course before the Royal College of Physicians in London, on the "Evolution and Dissolution of the Nervous System," in which the subject is treated from the point of view here indicated. Dr. Hughlings Jackson is not only an eminent practitioner in the department of nervous diseases, but he is an able philosophical student of medical subjects, and, although the Croonian lectures are addressed to medical men, the one we print will be found of general interest as opening a new chapter of original investigation in this important field of research.
It is announced in the papers that Mr. Andrew Carnegie has given the sum of fifty thousand dollars to the Bellevue Hospital Medical College of this city, for the erection and equipment of a building to be devoted to original investigations on subjects connected with the progress of medicine and the prevention of disease. Mr. Carnegie is well known as a man of large liberality who has accumualted a fortune by his own enterprise, and uses it generously in the promotion of projects of public and private beneficence. "We have before had occasion to observe the wise discrimination of his contributions, but in this case he has undoubtedly devoted his money to the noblest use for which money can ever be expended. The endowment of hospitals and dispensaries for the immediate relief of suffering is, of course, highly commendable, and they are so obviously necessary, and their benign results are so direct and palpable, that sympathetic charity is ever ready to lend them support. But that is a more far-sighted and efficient benevolence which provides for the extension of medical knowledge, the research into the causes and conditions of disease, and the increase in the resources of medical art, by the systematic scientific investigation to which we owe all the progress that has yet been achieved in this important field. There has never been a time in the history of medicine when the need of independent original research was so great as now, when the questions demanding elucidation were so numerous and so grave, and the encouragements to their pursuit so promising. The sciences of observation and experiment have done much for the world in many ways, and the medical art has fully shared in the advantages they have conferred; but work in this direction is modern, and that which has been accomplished is as nothing to what yet remains to be done. It is well for the medical colleges to teach what is known, but they need to know a great deal more, and it is certainly high time that we should have a class of professional investigators in this country so thoroughly qualified and prepared for their work that our students will not have to go to Europe after the facilities for profound and exhaustive research. Mr. Carnegie's gift, by establishing an ample and well-appointed laboratory for the experimental study of important medical subjects, will favor the progress of American science, at the same time that it promotes those interests of humanity that are wider than nationalities. The questions to be taken up in such an institution and that are now in most urgent need of solution are many, and one of them was so well stated by a writer in a morning paper that we quote it:
Histological investigations—that is, by means of the microscope—have within late years shed much light on the heretofore occult processes taking place in the different parts of the body in health and disease, and, quite recently, scientific developments in this field of study have shown the vast importance of these investigations, together with experimental researches, as regards our knowledge of micro-organisms. Already it has been demonstrated that several of the infectious diseases are caused by specific parasitic bacteria, and it is more than probable that investigations now in progress will lead to further discoveries rendering preventable and controllable many diseases which occasion much human suffering and contribute largely to mortality. It is, perhaps, not extravagant to say that the discoveries already made, conjoined with those which are foreshadowed, will prove of greater importance in their influence on the science and practice of medicine than any since the great discovery of the circulation of the blood by Harvey.