Studies in the Osteopathic Sciences The Physiology of Consciousness: Volume 3 Louisa Burns, M.S., D.O., D.Sc.O. 1911  
  CHAPTER I.  
  THE FUNCTION OF THE NERVOUS SYSTEM.  
 
    The only duty of the nervous system is to unify diverse structures. Unicellular organisms make direct reply to environmental changes. Each variation in the surrounding fluids is met by changes in the activity of the cell which adapts its internal conditions to those changes, unless these be so great and so destructive as to preclude the possibility of adaptation, and thus the possibility of continued life. The series of internal changes which make reply to the external changes is life, in Spencer’s use of the term. In answer to variations in any environmental factor the unicellular organism makes such movements or displays such inactivity as best serves the needs of the organism as an individual of a certain race. The history of the race determines the answer to each external change, and each answer writes a new sentence in the history of the race. Having no diverse structures, the unicellular organism needs no nervous system.

    Among multicellular organisms, many are composed of cells which are alike in physiological activities. Great colonies of bacteria, molds, algae, or certain organisms of different races, may live together, each cell living its own life. The cells may be all of a kind, or they may be alike in function, or they may be of different kinds, and live together in symbiosis. In such cases each cell lives its own life, answers the demands of its own environment, secures its own foods and uses the energy therefrom in its own way, reproduces itself, and perhaps may ultimately die from the lack of water, or food, or oxygen, or other requirements of life. These structures have no nervous system, and need none. Having no diverse structures, no method of unification is required.

    Among some molds and bacteria, as well as in other types of life, there may be found diverse structures with no nervous systems. The occurrence of spores, the formation of structures especially adapted to the reproduction of the species, display the beginnings of specialization. The volvox, for example, has upon its outer aspect cells which are in contact with the environment of the individual, and these are concerned with the so-called vegetative functions of the individual. The cells centrally placed are not in contact with the environmental food supply, and these are concerned with reproduction. The external or vegetative cells act according to their environment, which is the environment of the individual; the central or reproductive cells act according to their environment, which is made in part of the vegetative cells and in part of the fluids which bathe them, until the dissolution of the colony sets all the cells free, and the reproductive cells begin the formation of the new individual. Thus, even in organisms of a certain degree of complexity, the reaction of individual cells to the environment of individual cells is sufficient for the maintenance of life.

    Plants of even greater complexity of structure may live very long lives without any appearance of a nervous system. Here, also, the cells act as units, each making its own reply to its own environment. The effects of the environmental changes upon the external cells, or of one cell upon its neighbor, of the circulating fluids upon the different cells, are sufficient to initiate those metabolic changes needful to the preservation of the individual and the race. Unity of activity is secured only through the unity of the different structures, and the unity of the forces of osmosis, gravity, and the like, acting upon the entire plant.

    With the greater differentiation of parts characteristic of the more complex animals, with their larger bodies, capable of motion, bulky and awkward as they are compared to the simpler animals, the reactions produced in the surface cells by the environmental conditions become altogether inefficient. If an individual is to retain the power of replying efficiently to the surrounding changes--and this is the essence of life—it must act as a unit, even though it be composed of millions of different cells, and even though it be capable of any one of hundreds of different responses. It is in meeting this demand for unity of action that the nervous system is found in function. The only function of the sensory organs is to translate the environmental changes into the language of nerve impulses; the only function of the motor mechanism is to translate nerve impulses into the language of action. The function of the neurons of the ganglia of invertebrates and of the ganglia and central nervous system of vertebrates is to relate the incoming and the outgoing impulses in such a way as best to conserve the requirements of the individual and his kind.

    The sea anemone is rather a simple animal, yet it has a better nervous system than many other animals. In the sea anemone the food is secured through the contraction of tentacles which surround the oral aperture. The stimulation of the surface of any one of its tentacles by particles which may or may not be of food value causes the contraction of almost or quite the entire ring of tentacles. It is evident that the contraction of the single tentacle stimulated would rarely entangle the prey. The tentacles must act as a unit, in answer to a single stimulus at one point. The unity of action is secured through the activity of a ring of nervous ganglia around the oral aperture, which transmits the stimulation received by one tentacle to the muscles of all the tentacles. Only in the unified activity of the tentacles can life be preserved.

    The beginnings of structures specialized for the performance of nervous functions are found among sponges. These have retractile processes, whose manner of action resembles muscle activity to a certain extent. At the origin of each of these processes lie one or more stellate cells, resembling nerve cells, which send a prolongation into the retractile process. Stimulation of the stellate cell causes the retraction of one or more of the processes, and stimulation of the process itself may cause retraction. The stellate cells have irregular prolongations, which are shorter and seem to be more or less closely intermingled.

    The hydra has a double ring of nerve fibers around the periphery of the bell of the animal, which are associated with the muscles and also with the ectodermal cells. Within this ring of fibers nerve cells are placed. The processes of the nerve cells are intermingled, so that nerve impulses probably are transmitted with facility.
In the flat worms a structure resembling a brain appears. This resemblance is only superficial, and there is no homology between the invertebrate ganglia and the vertebrate brain, except as all nervous structures present a certain homology with all other nervous structures. A large ganglion lies near the head end of the body of the flat worm, and two cords of nerve fibers with small ganglia scattered throughout their length extend through the body.

    Nerve cells lie scattered among the cells of the ectoderm, and these are sensory I function. The fibers from these sensory cells are intermingled with the fibers from the ganglia. This peripheral position of sensory cells is found among vertebrates only in the olfactory region of the nasal mucous membrane.

    The earth worm has two ganglia placed at the head end, above the pharynx, and from these pass two gangliated cords. The ganglia are placed segmentally, and are more or less independent. The earth worms studied by Darwin took the sharp bilobed leaves of the Scotch fir by the united broad base, and thus were able to use them without harm from the sharp points. This humble animal is thus cited as indicative of a certain degree of mentality among the lower animals. It is a little difficult to see that this habit is more indicative of mentality than is the activity of certain unicellular organisms, which, meeting any obstruction, usually turn to the right, but which, meeting further obstructions for a number of times, finally turn to the left.

    The nervous systems of invertebrates in general present modifications of this general structure. There is usually a large cephalic ganglion or a pair of ganglia, which may be apparently formed from the fusion of two or more ganglia. From the cephalic ganglion or ganglia nervous cords, containing ganglia scattered among the fibers, pas through the length of the body. The sense organs present a few resemblances to the vertebrate sense organs, but they present more striking differences. It is not possible even to say what specific energy of sensation is carried by certain invertebrate sense organs. The gangliated cord is usually more or less completely segmented, and the various ganglia may act more or less independently. The invertebrate nervous system seems to perform the same functions which are performed by the vertebrate nervous system. The nerve cells of invertebrates show about the same evidences of fatigue, the accumulation of chromophilic masses resembling the tigroid substance, and pigment granules like those found in the vertebrate cell, as yellow pigment. Invertebrate nerve cells are much alike through all the different ganglia. The sensory cells placed among the epithelium present a few differences, but the nerve cells of the invertebrates do not show anything like the variations of structure which vertebrates possess.

    The same invariable function is present throughout, the unification of diverse structures.

    The ultimate source of energy for all living structures is found in changes in their surroundings. Among lower forms of life this statement simply means that foodstuffs, oxygen, water, etc., must be supplied to each cell upon the surface of the organism. Each cell uses these materials for its own metabolic needs, and casts the wastes away into that same surrounding medium. The individual cells of higher organisms are subject to the same need of a constantly-renewed food supply, and of a constant removal of the wastes of metabolism. Currents of water supply these needs among the simpler types of living beings, currents of sap supply the same needs of vegetable cells, currents of blood and lymph supply the same needs among the higher animals. Organisms may move toward the food, probably impelled thereto by chemotaxis or the tropisms. No nervous system is needed for this answer of each cell to the changes in its own surroundings.

    Animals of yet greater complexity, having nervous systems of more value, seek food, water and other needfuls with every appearance of forethought. This appearance of forethought, of purposive reaction, is due to the coordinating activity of the nervous system. The “bridges of protoplasm” carry the stimulation derived from the needs of the deeper tissues to the muscles concerned in the movements of the body; they carry the stimulation derived from the presence of stuffs fit for food to the structures capable of catching and eating and digesting that food. These same bridges of protoplasm enable the animal to travel in search of food and of other requirements, thus greatly increasing the available sources of energy. Thus the need of food impels the muscles to increased activity, though this increase in the activity of the muscles must increase its own waste and its own danger from starvation.

    The unity of the individual with his racial history has not always a beneficent effect. The perpetuation of the racial instincts, through the intermediation of the nervous system, may perpetuate death rather than life to many of the individuals of the race. As one instance of this tragical repetition of racial history the flight of the white butterflies may be considered. From a headland on the coast of New Zealand every year hundreds of butterflies wing their endless way out over the sea. They fly endlessly, die of fatigue, and drop into the waves. It is supposed the habit is a survival of the habits of ancestors who found an island somewhat farther north, to which they retreated for the summer. But history knows no such island. It must be that some racial history is perpetuated in this fearful and suicidal journey. The flight of the butterflies has been made the subject of much beautiful writing, but no poem ever written of that flight can even faintly shadow the grandeur of the lesson it shows, the absolute, essential and unquestioning unity of the individual with his race.

    Animals with well-developed nervous systems are able to unify their activities according to the demands of the year. Squirrels store nuts, other animals store other foods, so that the animal of today’s plenty reacts to the environment according to the needs of the winter’s scarcity. Through the intermediation of the nervous system the animal unifies its summer’s work with its winter’s hunger.

    Animals build nests. Animals with well-developed nervous systems make provisions for the young whom they have never seen. Birds in captivity, hatched in an incubator, still build nests, though no other bird, not even a mate, is to be found. Instincts are preserved through the activity of the nervous system, and thus animals react to their present environment according to the needs of the race. Thus the race is unified in needs and in action. The building of homes or nests, the storing of supplies for future needs, the building of dams by beavers, the migration of birds, seals and other animals, are instances of the manner in which organisms are unified in time. Only animals with well-developed nervous systems keep such complex instincts from generation to generation. Whether the custom of making provision for the future is actuated by conscious forethought or not, the fact that such customs prevail enables the animal of the year to react to the environment of the year, the individual of the race to react to the needs of the race. The nervous system, guided by the forces which perpetuate wise reactions, unifies the individual with the environment of the race through wide changes of time.

    Animals with no nervous systems, and those whose reactions are inefficient, are unable to avoid danger, either for themselves or for their neighbors. Animals with well-developed nervous systems avoid danger in many ways. Many animals run from the object feared. This activity is secured through the activity of the nervous system. Others erect the exoskeleton and assume a frightful appearance. This reaction is secured through nervous activity. Others pass into a condition resembling hypnotism, in which apparently all motion becomes impossible. This is secured through the action of the higher nerve cells inhibiting the action of the lower centers. Such animals are said to “feign” death in order that they may escape the attack of other animals which refuse food already dead. The reaction enables others to remain unnoticed by their enemies. In many instances the reactions characteristic of fright have for their purpose the salvation of other individuals of the race. The “lame” mother quail is a familiar object to most country children. The “lameness” disappears with remarkable celerity when the pursuer has been enticed away from the nest or the young; that is, when the inhibitions of the higher centers are exhausted. The various calls of different animals in the presence of danger serve the same purpose, the protection of other individuals of the same race. Thus, in securing safety, the animal is enabled to act according to the needs of the whole race—the animal is unified in danger and in safety through nerve activity.

    In the presence of injury to any part of the body, repair is often facilitated through reflex action. The overactivity of the heart muscle leads to the reflex lowering of blood pressure, and thus to the relief of the heart. The taking of foods of a certain character leads to the increase of the enzymes for the digestion of that class of foods. The presence of the fatigue toxins leads to the decreased activity of the nervous system, and thus to the rest of the body. Pain in any joint leads to the inhibition of the muscles moving that joint. In deficient light the pupils are dilated, in excessive light they are contracted. The ear is partly preserved from injury through the activity of the intrinsic muscles of the ear. The phenomena of inflammation, secured in the most efficient activity through the intermediation of the nervous reflexes, lead to repair and recovery.

    All of these reactions are for the good of the individual and the preservation of his life, as a rule. Each may be a source of danger under certain conditions. If it should be granted that under certain conditions the maintenance of the life of an individual is secured at too great a cost, then the biological relationships are apparent. When the reaction to abnormal conditions becomes inefficient, then these same reactions make for the speedy destruction of the individual, and the race is saved from the perpetuation of the unfit. As a result of the reactions, when they are efficient, the safety of the individual is secured; by the same reactions, when they are unable to save the individual, the race is preserved. The efforts toward adaptation cease only with the death of the individual. The race is thus unified in injury, disease, and the forces which make for increased powers of adaptation and repair.

    Far more than among animals, mankind is unified in time. The man provides not only for the year’s needs, but for the needs of himself and his family for many years. The organized man, through governments, provides for the needs of the people for many generations ahead. The destruction of the forests, the provisions for reforestation, the building of highways, of canals, of parks and playgrounds, all are proofs of the function of the nervous system in unifying the activities of individuals in accordance with the needs of others, though these others may be separated by generations from those who plan for their well-being.

    Through the action of associative memory man is unified in his own experiences. The teachings of childhood modify the actions of the old man, and through his teachings, in turn, modify the actions of others. Teachings which are shown to be wise are thus perpetuated without the need for the long processes of racial development through the activities of the nervous system of man.

    Through the processes of associative memory, also, the experiences of others may modify the reactions of any individual. By means of language, itself a manifestation of nerve activity, the individual is enabled to be unified with his fellows in experiences. Thus each person who is associated with others may gain from his neighbors the wisdom which may enable him to react to his environment in a much more efficient manner than would be possible if only personal experiences were able to modify his actions.

    Through the use of the written language and other expressions of men of ancient times the person of today is able to react to the environment of today with a wisdom gained from the experiences of all the past ages. By means of history, the experiences of the past may make today’s reactions better adapted to the good of the individual and his race.

    By means of associative memory, and by the use of the neurons concerned in variously relating the elements of experiences, the individual is enabled to modify his reactions in accordance with the future, as he imagines it. He is able to foresee the effects of causes and thus to modify today’s activities in such a manner s to prevent those disasters which perhaps never have been experienced, either by himself or by others. The ills never experienced may be avoided only through the activity of associative memory, the power of dissociating and recombining the elements of experience.

    Through the action of associative memory, also, the sharing of the experiences of others is made possible. This is true not only in securing the benefits of the experience of others, but also in sharing their troubles. As the activity of the nervous system secures a certain degree of adaptation and compensation in the presence of bodily injury or disease, so in the disease, or pain, or injury of members of the race, by means of the cerebral activities one person shares the pain and makes whatever reparation is possible when any suffer. This unity of the race in suffering is seen most notably in the presence of great disasters. How long after the San Francisco disaster before offers of help were received? How long after the Galveston flood, of the Johnstown flood, or the eruption of Mount Pelee before help was on its way to the sufferers? How long after any suffering is brought clearly before any really humane person before assistance is given? Only when there is a lack of the clear vision is there any delay. The altruistic feeling and action represents the highest and most perfect development of the nervous system. By this means the race is unified in its needs and in its resources.

    True, this unification fails at times. Always the failure is due to the lack of the normal activities of the nervous system in its activities. Many ills of others are unknown to us; it is for us to develop the power of seeing more clearly. Many times the means of communication are faulty. Since means of communication can result only from the use of natural resources by the powers of the cerebral cortex in activity, the lack of exact knowledge of one’s fellow man can be only due to the fact that not yet have the associative processes reached their fullest development.

    Some years ago there was a famine in India. This story is told of that famine. We of America were sufficiently developed and altruistic to try to send food to the sufferers. We sent a shipload of corn. Corn is good food—for us. Unfortunately, the famine-stricken people were not acquainted with corn; they did not know how to cook it, did not like it, and a great part of the corn was wasted or thrown away Our altruism, our feeling of unity, was sufficient to impel the aid, but the unifying process failed to make that aid efficient, because of our ignorance of real conditions. Also, they were unable to appreciate the value of the food sent, because they had been so long set apart, and were thus so poorly at one with the rest of the world, that they were permitted to die of starvation. More complete knowledge, more complete “sympathy” in the literal sense, would have been possible only through more efficient activity of the cortical neurons.

    Only through the unification of the race in the truest sense can the saying reach its fullest truth: “He hath made of one blood all the nations of the earth.”
Through the activity of the nervous system the race is unified in inheritance Among animals, only those traits are perpetuated which are characteristic of individuals of at least a certain degree of fecundity. Among savages the statement is almost as true. The more highly developed the race, the less is the inheritance of race limited by the fecundity of the people possessing the highest characteristics. Among people who think most and think best, the best thought is the thought of all. Teachers are often childless, yet they modify the thought of the next generation in a way which few parents even think of. Childless men plan playgrounds and parks, model tenements and schools, and all that makes for governmental betterment. Childless women teach children and their mothers, provide better conditions for the physical and the mental development of children now living and their children’s children. And while tomorrow’s children must be born of today’s physically-fit parents, yet they inherit today’s strongest thought, though it be the thought of the childless; and their environment is planned by today’s loving forethought, though it be the forethought of the childless. Civilization at its best is a function of the nervous system by means of which the race is unified in its needs in its labors, in its powers and in its inheritance.

    The ultimate source of energy is found in the environment of the body. Through the activity of the nervous system in governing the body’s use of the energy so derived other sources of energy may be discovered. Among mankind this power is developed highly. The sensory impulses are employed more and more efficiently in the use of the various sources of energy with which the world abounds. This use of natural forces is possible only in the presence of a nervous system of great complexity and efficient function.

    So far as the nerves of common sensation are concerned, the environment of the body is of the same size as the skin of the body. By means of these nerves and the impulses which they carry the body acts as a unit in the use of foods, the activities of the different parts of the body are coordinated, certain dangers are avoided, and the body is protected from certain abuses, as of overwork, etc. In injury or disease the body is enabled to recover or to adapt itself to a surprising amount of abnormal conditions. By means of motion the knowledge of one’s environment may be considerably increased merely by the use of the common sensations. Through pain the individual is enabled to guard against injury; through taste and smell he is able to provide against suffocation and poisoning under certain conditions. Through smell, also, one is able to secure a certain amount of information. Yet the best possible use of these sensations alone must leave the person with a very poor knowledge of a very small world.

    The sense of hearing increases the environment to a considerable degree. By means of this sense the individual is enabled to react to an environment which is limited only by his acuteness. Through the action of the association cells and the memories stored and interpreted in them the sense of hearing may become a source of information, a source of energy and of wisdom in the determination of reactions, whose value is scarcely to be estimated. Through this sense, too, the experiences of other individuals become immediately and frequently available. This sense is a very valuable agent in increasing the possibilities of unification of individuals.

    The sense of sight probably adds greater size to the human environment than does hearing. By means of sight the environment of the educated individual reaches to the limits of the universe as seen with the largest telescope, on the one hand, and to the limits of microscopic vision on the other. Even if one’s experience with these instruments be limited, the experiences of others may be imposed upon a comparatively scanty personal experience by means of the powers of associative memory. Thus the educational value of the experiences of others may serve to add efficiency, and unity, and wisdom t the reactions of any one whose nervous system is capable of delicate perceptions, clear mental visions and wide associational processes. The mental outlook of an ignorant man may be broadened by the beauty of the nightly sky; but as he sees more and more clearly the relation of stars and planets, of meteors and comets, his mental horizon becomes proportionately broadened. Acted upon by the broader environment, he reacts to broader environment. This is the essence of what is called mobility in life and character.

    This is the meaning of education in the widest sense, that the sensory nerves be made more and more delicate, so that constantly-decreasing environmental changes may initiate constantly-increasing knowledge and delicacy of reaction; that the associational processes may become constantly more complex in interpretation, and then, through understanding, constantly more simple in significance; that the balance between the fact of today’s environmental variations may be interpreted more wisely in today’s answer; that all experiences may be present in increasing vividness in consciousness, so that today’s reactions may make for the best good of the individual and his race through all of the tomorrows. Thus education lessens self-seeking and narrow seeing; it shows the great, and real, and permanent good rather than the narrow, and transient, and individual gain.

    Through the activity of the associational neurons the facts of daily experience are quickly and correctly classified. By means of this reaction the sensory impulses are made to yield the greatest possible energy value and knowledge value. In this way, by the constant classification of facts as they present themselves, the ultimate reaction, the ultimate expression of judgment, is more suitable to the daily demands, better adapted to the real value and meaning of life, and better fitted to conserve the best interests of the individual and his kind. The individual who thus classifies his experiences, who makes best use of the facts as they present themselves to himself personally and to himself through the experiences of others, makes the wisest judgment, the most forceful reactions, and lives the longest, strongest and finest life. Be he “butcher or baker or candlestick maker,” or “doctor, lawyer, merchant, chief,” he is of the best and happiest; though he may not become famous, he is sure to be fameworthy.

    Unicellular organisms make very slight reply to the changes which occur in their surroundings. If these changes are not very pronounced, they may be able to live for a time, or even indefinitely. If the changes are more pronounced, they may adapt themselves to the variation, and yet maintain life. This is seen in certain lake shores of the Western mountains and plains, where slowly-changing saltiness of water has been for ages associated with slowly-changing characteristics of the living organisms which live therein. Among plants, also, no great reply is made to environmental changes, save the changes which the plant itself undergoes in order to maintain its life in the presence of those changes which occur in climate, food, water, etc. Under the influence of the developing nervous system, the reply which is made to an adverse environment may modify the environment. Animals of comparatively simple structure build homes, thus varying the environment of their own bodies, and providing a suitable environment for their young Animals of greater complexity, with more efficient nervous systems, build more efficiently and provide more suitably for the future. These reactions, when they are controlled by the inherited and tropism-guided nervous system, set temporary circumstances aside, and act without regard to those conditions not present with their ancestors. An instance of this is shown in a report of the life of a beaver, captured when very young, and kept for a time in an office in a skyscraper. At the proper time he built dams of the books, footstools and other small articles in the room, which was, of course, placed hundreds of feet above water mark.

    Mankind, in whom the action of the nervous system is associated with consciousness, gives more forceful answer to his environmental changes. Should the factors of the environment affect him adversely, he simply changes the environment. Not only dos he adapt his metabolic processes in such a manner as to become able to withstand those changes, as do animals and plants, but he builds larger homes, warms them with fire, provides thicker clothing, makes ice for hot weather, compels artificial breezes with an electric fan, plants trees to modify the winds and the rainfall, levels hills, fills valleys, tunnels mountains, digs canals, dredges rivers and harbors, and in a thousand ways he changes the very face of the earth He projects his own personality into the inanimate world. To the man guided by the normally active nervous system the forces of nature lengthen his arm, strengthen his muscles, convey his judgments and his diets to the most distant countries; the whole worldful of inanimate force is simply an instrument for the expression of his own personality. Through the agency of the nervous system the will of man is unified with the forces of the universe.

    All these things are only the beginning. What has been achieved is only a foundation for the future’s building. The unification of the race is not complete; it is only beginning to become complete. The forces of nature are not yet subjugated. We still crawl on the surface of the earth; we still get in one another’s way. Even yet we misunderstand, and quarrel, and go to war. Even yet we often fail to give the danger signal when we see impending harm. Even yet we pretend and imitate, see falsely, and act according to the demands of a mean and narrow environment. Human eyes must be opened more widely, ears must be tuned more keenly, association processes must be more delicately coordinated and adapted to wider environments and more forceful reactions. Future wisdom based upon more wholesome nervous activities must break down the barriers of ignorance, and narrowness, and injustice, until a unified humanity lives fully and rejoices in a universe of subjugated power.