Popular Science Monthly/Volume 24/March 1884/Study: Physiologically Considered
THE ultimate element by means of which those processes that constitute the mind are carried on, is the microscopic cell of the gray matter of the brain. These gray nerve-cells, with the delicate tissue in which they are imbedded, form a layer, from one sixth to one twelfth of an inch in thickness, on the surface of the brain. This area would be small, were it not disposed in folds or convolutions which greatly increase its extent. It is upon the number and quality of these nerve-cells, and the systematic exercise of their function, rather than upon mere size or weight of brain, that the mental capacity of the individual depends.
The activity of the nerve-cells of the brain, in other words, depends partly upon their inherent vitality or vigor of constitution, and partly upon the quantity and quality of their blood-supply. They may be stimulated into unwonted activity by an effort of the will or the spur of excited consciousness; but even in these cases, should the strain last any length of time, the blood-supply is quickly and largely increased.
Skeptics may cavil, but the solid fact remains that strength of intellect, like that of muscle, is frequently inherited. Capacities differ from the beginning. For this reason, children can not be expected to make equal progress under any system of teaching, any more than horses upon a race-course. But, by persistent and judicious training, the strength, speed, and endurance of all may be increased through a steady and gradual development.
In order that the teacher may utilize his efforts to the best advantage, he should understand the laws of the mind's development, and the influences that modify and regulate its activity. Mental philosophy deals with the former—to explain some of the latter is the object of this paper.
The brain-substance may be touched, and even cut, with little or no consciousness of sensation; yet the gray nerve-matter is very delicate in construction, and exquisitely sensitive to changes in its blood-supply. Like other organs, it is exhausted by continued activity, and needs rest in order to recuperate its vitality. All tissues wear more or less by work; that is, molecules of their cell-substance die and become foreign matter, which must be cast off and replaced by new material. This new material is absorbed by the cells from the blood, through the thin walls of the minute blood-vessels in their vicinity. Through the walls of the same vessels the cast-off matters pass in the opposite direction into the circulation and are washed away by its current. While the tissue is hard at work, the process of disintegration is at a maximum, and that of repair at the opposite extreme—consequently the waste is produced more rapidly than it can be carried away, and accumulates. As ashes in a stove interfere with combustion, it impedes the current of thought, and lessens its intensity. But, during repose, the opposite conditions obtain—repair is at its maximum, and waste almost or entirely suspended. The blood has been busy all night ridding itself and the tissues of all impurities, and is richly charged with oxygen. The brain, and consequently the mind, is fresh and vigorous after the night's repose; the damages have been all repaired, and the débris cleared away. It is a matter even of common observation that at no other time is the mind so sharp, clear, and strong, as in the morning.
Concrete ideas tax the mind but lightly. The more abstract ideas become, the more difficult is their comprehension, and the greater the nervous strain involved in their contemplation. For this reason, the abstruse studies should be taken up during the forenoon session, as the faculties of the mind are then in the most favorable condition to grapple with their difficulties.
Of all school-studies, mathematics requires the strongest grasp of mind, and the closest exercise of the reasoning powers and the judgment. In abstruseness and difficulty of comprehension, geometry, algebra, and arithmetic, rank in the order enumerated. Rhetoric, including grammar and composition, comes next. In every school and college, therefore, these subjects should be taken up during the morning session.
The mind learns by means of impressions made upon the gray nerve-cells, through the senses, of which sight is the most vivid and durable in its effects. Hearing ranks next, but its impressions are less vivid and more fleeting. Further, they are recalled to the memory less readily and distinctly. We all remember what we see longer than what we hear. Hence the most reliance should be placed upon the eye as an avenue of instruction, and the teacher should make use of it whenever practicable. When an impression is made upon a nerve-cell, it is said to retain it "in potency" that is, it is capable of renewing it by an exercise of the memory. Now, the clearness and permanence of a mental impression depend—(a) upon its vividness; (b) upon the frequency of its repetition; and (c) upon the inherent vigor of the nerve-cell.
To obtain vividness of impression, the teacher's language should be clear and simple; his descriptions of processes and objects sharp and vivid; he must present the same ideas again and again, in order to fix them permanently in the memory. The inherent vigor of the mind can be strengthened by systematic exercise, just as the muscles of a blacksmith's arm become strong and brawny by years of daily toil at the clinking anvil.
Throughout animated nature, a period of repose succeeds one of activity, both recurring in regular alternation. The vegetable world grows and blooms; then, for a season, all the vital processes stand still. Work brings weariness, which rest must dissipate. So is it with the tissues of the body; and the younger and more delicately organized they are, the sooner does toil exhaust them. Brain-matter is the most delicate of all our tissues, and nearly one third of the pure blood thrown out by the heart at each contraction goes to supply it. A tissue, when at work, has its blood-supply largely increased. When the mind is actively engaged in study, the circulation in the brain is full and active, the temperature is raised, even the face is flushed; and the more difficult the study, the more these effects are intensified. After a time, the brain becomes so engorged with blood that its activity is depressed and its energies begin to flag. The younger a pupil is, the sooner does his mind grow tired. Between the ages of six and seven, the lessons should not exceed ten minutes' duration, as young children are unable to keep their attention fixed upon one subject for a greater length of time. It may be laid down as a safe rule, that close mental application for an hour and a half will tire out the majority of pupils, and leave them unfit and indisposed to proceed further without a relaxation of at least ten or fifteen minutes.
Here the forenoon recess is indicated—not, as some imagine, simply to kill time, but as a positive physical necessity, not for the pupil alone, but also for the teacher. The worry and mental strain of governing a roomful of nervous, restless children, and teaching at the same time, no one can fully realize without actual experience.
How should recess be spent by the pupil? To reply to this, his physical condition must be considered. As the blood is contained in a series of closed vessels, it is evident that, if the circulation be increased in one portion, it is correspondingly diminished in another. When the brain is engorged, some other portion of the economy must be under-supplied. By a wise provision of Nature, the surplus is drawn from the tissue that is least active in this case, from the muscular system. The indication is to relieve the congested brain, and this is best met by muscular exercise, as a tissue in action has its blood-supply largely increased. The muscular system is of considerable extent, and the exercise that brings the most muscle into action is the most beneficial.
Therefore, daring recess, nothing can take the place of active exercise in the open air.
But if the temperature is very low, recess had better be taken indoors, for the intense cold exhausts the vitality by drawing largely upon the heat-supply. By constringing the cutaneous vessels, it congests the internal organs and weakens the heart, while it requires some time to restore the equilibrium of the circulation. In rainy weather, the result is still more detrimental. In a climate like ours, exposure to rain is at all times fraught with danger to health, and particularly when one sits still in wet or damp garments for any great length of time. No recess out-doors, on a bitterly cold or rainy day, should be the rule, and gymnastic exercises, calisthenics, motion-songs, etc., should take its place. Every grammar-school should have one room fitted up as a gymnasium. There is a certain amount of nerve-energy that is accustomed to find outlet in the muscles, and, if unduly repressed, it will often break through the strictest discipline and cause the teacher much annoyance. It must not be forgotten that muscles were not created to be kept still during waking hours, and, when kept at rest an hour or two, a surplus of energy accumulates, which recess gets rid of legitimately. It also serves another purpose admirably. Of all sedatives of the nervous system, muscular exercise is the most efficient, because physiological. It quickens the circulation, and stimulates the heart and all the vegetative functions.
After exercise, the muscles—of the hand and forearm particularly—are subject to rhythmic, automatic waves of contraction; that is, there is a tremor beyond the power of the will to control. So that writing and drawing, which require great steadiness of the hand and fingers, should never be taken up after recess, or at the commencement of the afternoon session. Of the elementary studies, mental arithmetic involves the closest application of the highest powers of the mind—drawing at once upon memory, reason, and judgment—and this may be taken up advantageously from half-past eleven to twelve. Breakfast digestion is then nearly if not quite completed, and intense application is least detrimental to the vegetative system.
The morning meal is usually light in material and amount; dinner, partaken of soon after noon (except in the largest cities), is the principal meal. It is "solid," in a physiological not less than in a popular sense, for it is most generous in amount, and usually rich in nitrogenized matters—flesh-meat, puddings, eggs, etc. After its ingestion, the digestive organs are taxed to their utmost capacity, and soon become loaded and distended with blood. The digestive system is quite extensive, and is richly supplied with blood-vessels, which are imbedded in rather loose tissue, so that they may dilate, to accommodate the sudden influx from the outlying portions of the body, together with the newly-absorbed products of digestion. The brain is thus deprived of its full supply; and if, by reason of severe study, it draws upon the circulation, the digestive organs are robbed of their needs, and their efficiency interfered with seriously. Intense application at this time does harm in another way. All the functions of the body are under nervous control. The digestive organs are mainly innervated by the pneumogastrics—two nerves arising from the lower portion of the brain, near the base. Now, the thinking portion of the brain being situated on the convex surface, deep and perplexing thought robs the roots of the pneumogastric nerves of their circulation, and in this way depresses their influence. Lacking the proper nervous stimulus, the digestive juices become scanty in amount; peristalsis is enfeebled; the liver—that refinery where the crude products of digestion are purified and elaborated loses tone, and allows the peptones to pass unchanged into the general circulation, giving rise to much discomfort and mental depression. Thus are laid the foundations of dyspepsia, that common complaint of students; and in the higher institutions of learning, where the course is difficult and protracted, many, after graduation, return home invalids—often only to die.
The products of digestion are taken up by two different sets of vessels. The fatty matters, in the form of an emulsion, go almost directly to the right side of the heart; while the others, before entering the general circulation, pass through the liver. A portion of the refuse is excreted here; the rest, remaining in solution in the blood, is carried to other organs to be gradually eliminated. So that, during digestion, the blood is not only charged with impurities from the alimentary canal, but also with newly or imperfectly formed material.
The brain, then, being deprived of its full blood-supply, and the blood itself being impure and impoverished, it may at once be seen that the mind is not very active after dinner, and by no means fitted for severe study. Hence the lighter subjects—reading, geography, history, writing, drawing, music—should occupy the afternoon session, as these subjects involve chiefly the imitative faculty and the memory. Of these, reading and music—the lightest of all—should precede; dictation and geography may follow. When the programme includes an afternoon recess, history may follow with advantage. The most appropriate time for writing and drawing is from half-past three to four. The muscles of the hand are steady, the pupils are fatigued mentally, and the imitative faculty—the lowest in the scale—is the only one called into play.
Two o'clock may be set down as the most judicious time for the opening of the afternoon session. Half-past one is not quite so good, but will answer very well. To begin at one is a positive detriment. The pupils hurry home, snatch a hasty dinner, and as hurriedly return. Those who dwell at some distance are often late. Some are obliged to attend to household duties, and this also occasions tardiness. Sunlight is cheap and plenty, and the half-hour gained would be more useful if taken at the end of the session. Indeed, two hours' steady work will exhaust the majority of children, and will leave all seriously disinclined to exertion. When school assembles at two, and is dismissed at four, no recess is necessary, if the plan here indicated is followed, for the work is much lighter than during the morning session.
Of late certain spasmodic efforts have been made to abolish recess, and hold but one long session per day from nine to one or half-past one; but this is a mistaken notion, founded on lack of knowledge of the effects of long-continued study and the physical needs of the young. It is true that in some of the largest cities this plan is followed in the high-schools, but the cause is local, for the pupils come from long distances—in New York city, for instance, as far as five miles. Besides, in many of these schools the pupils do much of their studying at their homes, and the majority are in the neighborhood of twenty years of age, so that they are in a better condition to stand the additional strain without injury.
Anything that distracts the pupil's attention from his studies retards his progress, by making less vivid the impressions received by the nerve-cells; for, by concentrating the mental vision upon one point, to the exclusion of others, we see that point more distinctly. All peripheral irritation, therefore, should be removed as far as possible. The distraction of discomfort, particularly of the cutaneous surface, is a serious drawback; comfortable seats—preferably single—high enough to support the lower limbs, and desks of the proper height to rest the arms, are in this way valuable indirect aids to study. But of all peripheral irritation, that produced by cold is perhaps the most distracting. When the temperature of the room falls below 50° Fahr., the next exercise should be dismissal. Between 50° and 70° the temperature may range; but from 60° to 65° is the safest and most comfortable; safest, because the cutaneous surface does not become overheated and congested—liable to be chilled by the lower temperature of the open air—and most comfortable, because neither heat nor cold is perceptible. It is needless to add that every school-room should have a thermometer, which the teacher should frequently consult, and govern himself according to its indications.
For the reasons noted above, children at home should not be allowed to prepare their lessons immediately after supper, or late into the night; for study congests the brain, and, as sleep is produced by the opposite condition, they lie awake and restless until the amount and pressure of blood within the cranium are greatly diminished.
Strange as the assertion may seem, a pupil's diet has much to do with his progress. A liberal supply of non-stimulating food—in other words, bread, milk, vegetables, fruits, and a farinaceous diet principally—is far superior for the healthy growth of bone and nerve and muscle than a regimen into which nitrogenized materials—flesh-meat, eggs, etc.—enter largely. These latter unduly stimulate the nervous system, cause a premature development of the body, and load the blood with impurities, that tax the liver and the excretory organs sorely. In a warm climate, such as ours, the liver, choked with albuminoids, will fail in its function periodically, through sheer fatigue; the bilious matters then circulate throughout the system and stain the complexion; torpor, malaise, and headache, will result. In this condition study is a task instead of a pleasure; the mind is weak, and the memory can not retain imparted knowledge for any great length of time.
In general terms, it may be laid down as a rule, that much effective study must not be expected from a pupil who is overfed, especially if on rich and stimulating food. Let it not be understood that flesh-meat should be excluded from the diet of the young. By no means; it is only its excess that is objected to. An overfed pupil is indolent, intellectually, not because he may be so inclined willfully, but for the reason that his digestive organs rob his brain, and his blood is charged with effete matter; in figurative phrase, the fire is slow because the stove is filled with coal and choked with ashes.
To recapitulate: The more abstruse studies—mathematics, science, rhetoric—should be taken up during the morning session. The proper time for the forenoon recess is at half-past ten. The lighter or concrete subjects—reading, history, geography, writing, drawing, music—should occupy the afternoon session, commencing preferably at two o'clock. When it begins at half-past one, a recess of ten or fifteen minutes is necessary, preferably the quarter-hour preceding three o'clock. No out-door recess when the weather is inclement. For the younger pupils, short lessons frequently repeated, exercising chiefly the imitative faculty and the memory, should be the rule.