What was said of hereditary transmission in the second chapter of this work applies here with increased force. It is of the highest possible importance that this subject should receive the especial attention of every parent, and of all who may hereafter sustain the parental relation; for posterity, to the latest generations, will be affected by the laws of hereditary transmission, whether those laws are understood and obeyed or not. The importance of this subject, already inconceivably vast, becomes infinitely momentous in view of the probability that the evils under consideration are not confined to this life, but must, from the nature of the case, continue to be felt while mind endures.
Unfortunately, it is not merely as a cause of disease that hereditary predisposition is to be dreaded. The obstacles which it throws in the way of permanent recovery are even more formidable, and can never be entirely removed. Safety is to be found only in avoiding the perpetuation of the mischief. When, therefore, two persons, each naturally of an excitable and delicate nervous temperament, choose to unite for life, they have themselves to blame for the concentrated influence of similar tendencies in destroying the health of their offspring, and subjecting them to all the miseries of nervous disease, melancholy, or madness.
There is another consideration that should be noticed here: it is this. Even where no hereditary defect exists, the state of the mother during pregnancy has an influence on the mental character and health of the offspring, of which even few parents have any adequate conception. "It is often in the maternal womb that we are to look for the true cause not only of imbecility, but of the different kinds of mania. During the agitated periods of the French Revolution, many ladies then pregnant, and whose minds were kept constantly on the stretch by the anxiety and alarm inseparable from the epoch in which they lived, and whose nervous systems were thereby rendered irritable in the highest degree compatible with sanity, were afterward delivered of infants whose brains and nervous systems had been affected to such a degree by the state of their parent, that, in future life, as children they were subject to spasms, convulsions, and other nervous affections, and in youth to imbecility or madness, almost without any exciting cause."[22]
Dr. Caldwell, too, an able and philanthropic advocate of an improved system of physical, intellectual, and moral education in this country, is very urgent in enforcing rational care, during the period of gestation, on the part of every mother who values the future health and happiness of her offspring. Among other things, he insists on mothers taking more active exercise in the open air than they usually do. He also cautions them against allowing a feeling of false delicacy to keep them confined in their rooms for weeks and months together. At such times especially the mind ought to be kept free from gloom or anxiety, and in that state of cheerful activity which results from the proper exercise of the intellect, and especially of the moral and social feelings.
But if seclusion and depression be hurtful to the unborn progeny, surely thoughtless dissipation and late hours, dancing and waltzing, together with irritability of temper and peevishness of disposition, can not be less injurious. Every female that is about to become a mother should treasure up the remark of that sensible lady, the Margravine of Anspach, who says, "when a female is likely to become a mother, she ought to be doubly careful of her temper, and, in particular, to indulge no ideas that are not cheerful and no sentiments that are not kind. Such is the connection between the mind and the body, that the features of the face are moulded commonly into an expression of the internal disposition; and is it not natural to think that an infant, before it is born, may be affected by the temper of its mother?" If these things are true—and they are as well authenticated as any physiological facts are or can be—then not only mothers, but all with whom they associate, and especially fathers, are interested in knowing these important physiological laws; and they should aim, from the very beginning, so to observe them as to secure to posterity, physically and mentally, the full benefits that are connected with cheerful obedience.
A due supply of properly oxygenated blood is another condition upon which the healthy action of the brain depends. Although it may not be easy to perceive the effects of slight differences in the quality of the blood, still, when these differences exist in a considerable degree, the effects are too obvious to be overlooked. Withdraw entirely the stimulus of arterial blood, and the brain ceases to act, and sensibility and consciousness become extinct. When carbonic acid gas is inhaled, the blood circulating through the lungs does not undergo that process of oxygenation which is essential to life, as has been explained in a preceding chapter. As the venous blood in this unchanged state is unfit to excite or sustain the action of the brain, the mental functions become impaired, and death speedily ensues, as in the case of a number of persons breathing a portion of confined air, or inhaling the fumes of charcoal. On the other hand, if oxygen gas be inhaled instead of common air, the blood becomes too much oxygenated, and, as a consequence, the brain is unduly stimulated, and an intensity of action bordering on inflammation takes place, which also soon terminates in death.
These are extreme cases, I admit; but their consequences are equally remarkable and fatal. The slighter variations in the state of the blood produce equally sure, though less palpable effects. Whenever its vitality is impaired by breathing an atmosphere so vitiated as not to produce the proper degree of oxygenation, the blood can only afford an imperfect stimulus to the brain. As a necessary consequence, languor and inactivity of the mental and nervous functions ensue, and a tendency to headache, fainting, or hysteria makes its appearance. This is seen every day in the listlessness and apathy prevalent in crowded and ill-ventilated school-rooms, and in the headaches and liability to fainting which are so sure to attack persons of a delicate habit, in the contaminated atmospheres of crowded theaters, churches, and assemblies of whatever kind. The same effects, although less strikingly apparent, are perhaps more permanently felt by the inmates of cotton manufactories and public hospitals, who are noted for being irritable and sensitive. The languor and nervous debility consequent on confinement in ill-ventilated apartments, or in air vitiated by the breath of many people, are neither more nor less than minor degrees of the process of poisoning, which was particularly explained in the preceding chapter, while treating upon the philosophy of respiration.
That it is not real debility which produces these effects, is apparent from the fact, that egress to the open air almost instantly restores activity and vigor to both mind and body, unless the exposure has been very long. There is an interesting but fearful illustration of the truth of this statement at the 96th page of this work, to which I beg leave to refer. Where the exposure has been very long continued, more time is of course required to re-establish the exhausted powers of the brain. Indeed, we may not, in such cases, hope for complete recovery; for when persons remain several hours a day in a vitiated atmosphere, for weeks and months together, both mind and body become permanently diseased. It is well known to every person who has given attention to the subject, that hitherto this has been the condition of public schools, generally, in every part of the United States, and throughout the civilized world. This has, perhaps, tended more than all other causes combined, to render the profession of teaching disreputable, and to constitute the very name of schoolmaster, or pedagogue, a hissing and a by-word. And why is this? I can account for it in but one way. The school teacher is subject to the same organic laws as other men; and, either on account of the ignorance or parsimony of his employers, he has been shut up with their children several hours a day, in narrow and ill-ventilated apartments, where, whatever else they may have done, their principal business has of necessity been to poison one another to death. And, as if not satisfied with this, when the teacher has ruined his health in our employment, and become a mere wreck, physically and mentally, we despise him. This is a double injustice, and is adding insult to injury. And the consequences are hardly less fatal to the children. The situation of the majority of our schools, when viewed in connection with the physiological laws already explained, sufficiently accounts for that irritability, listlessness, and languor which have been so often observed in both teachers and pupils. Both irritability of the nervous system and dullness of the intellect are unquestionably the direct and necessary result of a want of pure air. The vital energies of the pupils are thus prostrated, and they become not only restless and indisposed to study, but absolutely incapable of studying. Their minds hence wander, and they unavoidably seek relief in mischievous and disorderly conduct. This doubly provokes the already exasperated teacher, who can hardly look with complaisance upon good behavior, and who, from a like cause, is in the same irritable condition of both body and mind with themselves. He, too, must needs give vent to his irascible feelings some how. And what way is more natural, under such circumstances, than to resort to the use of the ferule, the rod, and the strap! We have already referred to a case, in which formerly fever constantly prevailed, but where disease disappeared altogether upon the introduction of pure air. Let the same prudential course be adopted in our schools, in connection with other appropriate means, and we shall readily see the superiority of the natural stimulus of oxygen over the artificial sedative of the rod.
The regular and systematic exercise of the functions of the brain is another condition upon which its healthy action depends. The brain is an organized part, and is subject to precisely the same laws of exercise that the other bodily organs are. If it is doomed to inactivity, its health decays, and the mental operations and feelings, as a necessary consequence, become dull, feeble, and slow. But let it be duly exercised after regular intervals of repose, and the mind acquires activity and strength. Too severe or too protracted exercise of the brain is as great a violation of the organic law just stated as inactivity is, and is sometimes productive of the most fearful consequences. By over-tasking this organ, either in the force or duration of its activity, its functions become impaired, and irritability and disease take the place of health and vigor.
So important is the law under consideration, and so essential to the health of the brain and to the welfare of man, that I deem it advisable to explain more particularly the consequences of both inadequate and excessive exercise.