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CRITICAL NOTICES OF NEW PUBLICATIONS.

The Principles of Physiology applied to the Preservation of Health, and

to the Improvement of Physical and Mental Education ; by Andrew Combe, M.D. Second edition, enlarged and improved ; 8vo, pp.

385, Edinburgh and London, 1834. Dr. Combe undertakes, in this beautiful and instructive volume, to lay before the public a plain and intelligible description of the structure and uses of some of the more important organs of the human body, and to shew how information of this kind may be usefully applied both to the preservation of health and to the improvement of physical and mental education. Among other important prefatory observations, he introduces the remark—that, in the case of the lower animals, the necessity of modifying the method of cultivation according to the peculiarities of constitution which they present, has long been perceived and consistently acted on, and with such success as to afford us good reason for applying the same rule to our own species, and for considering every mode of education as erroneous and inefficient, which is not in harmony with the higher nature of man: indeed, there can scarcely be a doubt that were the same principle followed in the cultivation of his physical, moral, and intellectual powers, and were no role received which is not in accordance with the laws of his constitution, a much higher degree of success would reward our exertions, than has ever yet been experienced.

Dr. C. farther observes, at p. 6, it has been objected, that to teach any one how to take care of his own health, is sure to do harm by making him constantly think of precautions, to the utter sacrifice of every noble and generous feeling, and to the certain production of hypochondriacal peevishness and discontent. The result, however, is exactly the reverse ; and it would be a singular anomaly in the constitution of the moral world, were it otherwise. He, who is acquainted with the fabric of the human body, and with the laws which regulate its action, sees at once his true position when exposed to the causes of disease, decides what ought to be done, and thereafter feels himself at liberty to devote his undivided attention to the calls of higher duties. It is ignorance, and not knowledge, that renders an individual full of fancies and apprehensions, and robs him of his usefulness; it would be a stigma on the Creator's wisdom, if true knowledge weakened the understanding, and led to injurious results. Those who have had the most extensive opportunities of forming an opinion on this subject from experience, bear unequivocal testimony to the advantages which knowledge confers in saving health and life, time and anxiety. Nevertheless, he concludes, p. 11, I must express my belief, that the study of diseases and their modes of cure by unprofessional persons, is not only unprofitable, but often deeply injurious; because such persons cannot possibly possess the collateral knowledge required to form a correct judgment of all the attending circumstances, and are therefore extremely liable to fall into error, where every error is attended with risk, often of the most dangerous kind.

Dr. Combe's “ Principles of Physiology” are consecutively expounded in ten elaborate chapters, comprising introductory remarks ; observations on the structure and functions of the skin; on the preservation of the health of the skin ; on the nature of the muscular system; on the effects of, and rules for, muscular exercise ; on the

bones, their structure, uses, and health ; on respiration, and its uses; on the nervous system and mental faculties ; the application of the preceding principles; and, on the application of the principles of physiology to the amelioration of the condition of the insane—all which most interesting topics, whether as premises or inductions, are discussed in a style and method of illustration singularly adapted to the comprehension of popular readers.

This volume of Dr. C.'s is so remarkably comprehensive, with its diction so concise, expressive, and perspicuous, that we should utterly fail, were we to engage in any attempt to exhibit an analytical condensation of its pages; for this reason, and for the present, we propose confining our own and the reader's attention to the valuable practical doctrines unfolded in the eighth chapter, on the nervous system and the mental faculties.

Dr. C. opens this section of his work with stating--that, in man and the higher order of animals, the nervous system is composed of the brain, the spinal marrow, and the nerves; and that he confines his remarks chiefly to the brain, and to such points regarding it, as all are agreed upon, and the general reader can easily comprehend. The brain is that large organized mass which, along with its enveloping membranes, completely fills the cavity of the skull. It is the seat of thought, of feeling, and of consciousness, and the centre towards which all impressions made on the nerves distributed throughout the body are conveyed, and from which the commands of the will are transmitted to put the various parts in motion. Its structure is so complicated, that less is known of its true nature than of that of almost any other organ. Dr. C. limits his observations to a general statement of its principal divisions—the cerebrum or brain proper, the cerebellum or little brain, and the cerebral membranes-and, at p. 257, he adds that, on examining the convolutions in different brains, they are found to vary a good deal in size, depth, and general appearance: in the various regions of the same brain, they are also different, but preserve the same general aspect: thus, they are always small and numerous in the anterior lobe, larger and deeper in the middle, and still larger in the posterior lobe. It receives an unusually large supply of blood, in comparison with the rest of the body.

Most physiologists are agreed that the different parts of the brain perform distinct functions, and that these functions are the highest and most important in the animal economy; but, there is a great discrepancy of opinion as to what the function of each part is, and as to the best mode of removing the obsurity in which the subject is involved. This much, however, is certain that all physiologists and philosophers regard the brain as the organ of the mind; that most of them consider it as an aggregate of parts, each charged with a specific function; and, that a large majority regard the anterior lobe as more immediately the seat of the intellectual faculties. Farther, says Dr. C. by nearly universal consent, the brain is held to be also the seat of the passions and moral feelings of our nature, as well as of consciousness and every other mental act, and to be the chief source of that nervous influence which is indispensable to the vitality and action of every organ of the body. Many animals possess individual senses or instincts in greater perfection than man, but there is not one which can be compared with him in the number and range of its faculties ; and, as a necessary consequence, there is not one which approaches him in the development and perfection of its nervous system. No organ can execute more than one single function; and, accordingly, in precise proportion as we ascend in the scale of creation, and the

animal acquires a sense, a power, or an instinct, do its nerves multiply and its brain improve in structure and augment in volume, each addition being marked by some addition or amplification of the powers of the animal, until in man we behold it possessing some parts of which animals are destitute, and wanting none which they possess, so that we are enabled to associate every faculty which gives superiority, with some addition to the nervous mass, even from the smallest indications of sensation and will, up to the highest degree of sensibility, judgment, and expression. It is extremely important to bear in mind this constant relation between mental power and development of brain; because it not only explains why capacities and dispositions are so different, but shews incontrovertibly that the cultivation of the moral and intellectual faculties can be successfully carried on by acting in obedience to the laws of organization, and associating together those faculties the organs of which are simultaneously progressive in their growth. For instance, it is a law that alternate periods of activity and repose conduce to the strength and development of every organ, and to the easy performance of its function, and that excess in either is alike hurtful in its consequences. When the brain is not exercised in conformity with the organic laws, we shall look in vain for the same amount of improvement which would have followed their fulfilment; and yet, so far is the physiology of the brain from being considered as the only sound basis on which the science of education can rest, that very few teachers or moralists are aware that the organic laws have any connexion with the operations of mind, and still fewer have ever thought of adapting their practice to the dictates of these laws; although, than this, no truth in education or philosophy can be more clearly proved, or more beneficially applied. It has been said, in answer to this proposition, that a month's vacation and idleness in the country, after ten or eleven months spent at schools in town, are beneficial to the scholar by increasing his aptitude for mental exertion. Now, this is true; but, it is in reality no exception to the rule previously stated: this result follows simply because the boy's health, which had been impaired by confinement and overtasking, becomes restored by country air, idleness and exercise; and his brain has regained its lost tone and is able to manifest the mental faculties with greater vigour. But it does not follow, from this circumstance—that, if the brain and mind be always duly exercised according to their strength and the laws of nature, a month or two of idleness will then be advantageous. On the contrary, it would be not less hurtful than irksome to the individual; and, if a healthy young person were so situated, idleness would be so unpleasant to him, that he would desire mental occupation in some shape, for himself. Parents, guardians, and instructors of the young, ought never to lose sight of this essential distinction.

In thus treating of the brain as the indispensable instrument or organ of the mental faculties, Dr. C. must not be understood as representing mind and brain to be one and the same thing: he means only that the brain is necessarily engaged in every intellectual and moral operation, exactly as the eye is in every act of vision; and that, as the mind cannot see without the intervention of the eye, so neither can it think or feel, during life, except through the instrumentality of the brain : consequently, it would be as reasonable and logical to infer, from the former proposition, that the eye is the mind, or the mind the eye, as to infer from the latter, that the brain is the mind, or the mind the brain. He adds, p. 262, it requires however to be distinctly understood, that activity of mind and activity of

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brain are inseparable, and that every change of the one is attended by a corresponding change in the condition of the other. If, by the excessive use of stimulants, the brain be highly excited, the mind will be disturbed in an equal degree, as is exemplified every day in cases of intoxication ; and if, on the other hand, the mind be suddenly roused by violent passions, the vessels of the brain will instantly take an increased action, redness will suffuse the face, and excitement of the brain will shew itself in characters as legible as if produced by a physical cause. The mind and brain being thus inseparably associated, during life, it becomes an object of primary importance to discover the laws by which their healthy action is regulated, that we may yield them willing obedience, and escape the numerous evils consequent on their violation.

Regarding the brain as a most important part of the animal system, and subject to the same general laws as every other organ, Dr. C. proceeds to state the conditions of its healthy action; and the first of these he believes to be a sound original constitution. If the brain possess, from birth, a freedom from all hereditary taints and imperfections, and have acquired no unusual susceptibility from injudicious treatment in infancy, it will withstand a great deal, in after life, before its health gives way; but if, either it inherit deficiencies, or if early mismanagement have entailed upon it an unusual proneness to morbid action, it will give way under circumstances which would otherwise have been perfectly innocuous; and, accordingly, the most powerful of all the causes which predispose to nervous and mental disease, is the transmission of an hereditary tendency from parents to children, producing an increased liability to the same maladies with which the parents had been afflicted. Even the doctor adds p. 263, when the defect in the parents is merely some peculiarity of disposition or temper, amounting

perhaps to eccentricity, its influence on some of the progeny may be traced, as well as its interferences with a man's happiness or success in life. When such original eccentricity is on the mother's side, and she gifted with much force of character, the evil extends more widely among the children, than when it is on the father's side: when both parents are descended from tainted families, their offspring is more affected than when one of them is from a pure stock; and, seemingly for this reason, hereditary predisposition is a more common cause of nervous disease in the higher classes, who intermarry much with each other, than in the lower who have a wider choice. Unhappily, hereditary predisposition is to be dreaded, not merely as a cause of disease, but for the obstacles it throws in the way of permanent recovery: these are most formidable, and can never be entirely removed. Safety is to be found only in avoiding the perpetration of the mischief; and, therefore, if two persons, each naturally of an excitable and delicate nervous constitution, choose to unite for life, they have themselves to blame for the concentrated influence of similar tendencies in destroying the health of their children, and subjecting them to all the miseries of nervous disease, madness, or melancholy. Even when no hereditary defect exists, continued excitement of the nervous functions in the mother, from anxiety, grief, or other causes, during pregnancy, has often a striking effect on the future mental health and constitution of her offspring: many authors testify to the truth of this fact, and it has not escaped the penetration of some mothers.

According to our author p. 264, the second condition required for the health of the brain, is a due supply of properly oxygenated blood. The effects of slight differences in the quality of the blood, are not easily

recognized; but, when extreme, they are too obvious to be overlooked. If the stimulus of arterial blood be altogether withdrawn, the brain ceases to act, and sensibility and consciousness become extinct : thus, when fixed air is inhaled, the blood circulating through the lungs does not undergo that process of oxygenation which is essential to life; and, as in this state, it is unfit to excite or support the action of the brain, the mental functions become paired and death speedily ensues; but, if the blood be too highly oxygenated, as by breathing oxygen gas instead of common air, the brain is too much stimulated, and an intensity of action, bordering on inflammation, takes place and soon terminates in death. Slighter variations in the state of the blood have equally sure, although less palpable, effects; if its vitality be impaired by breathing an atmosphere so much vitiated as to be insufficient to produce the proper degree of oxygenation, the blood then affords an imperfect stimulus to the brain; and, as a necessary consequence, languor and inactivity of the mental and nervous functions ensue, and a tendency to head-ach, syncopé, or hysteria, makes its appearance. This is seen, every day, in the listlessness and apathy prevalent in crowded and ill-ventilated sc ols; and in the head-achs and liability to fainting which attack persons of a delicate habit, in the contaminated atmosphere of crowded theatres, churches, and assemblies: it appears less strikingly, but more permanently in the irritable and sensitive condition of the inmates of manufactories and public hospitals. In these instances, the languor and 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 same process of poisoning: it is not real debility which produces them; for egress to the open air almost instantly restores activity and vigour to both mind and body, unless the exposure has been very long, in which case more time is required to re-establish the exhausted powers of the brain. The transmission of imperfectly oxygenated blood to the cerebral organs is greatly more infinential in the production of nervous disease and delicacy of constitution, than is commonly imagined. Starvation often affects the brain so much as to produce ferocious delirium, and there is a species of insanity arising from defective nourishment, which is easily cured by nourishing diet. The mental functions are sometimes weakened, and the brain disordered, by the same cause, at the period of rapid growth : but, this defective nutrition does not always depend on want of proper food ; among the higher classes, it is frequently the result of too much or too stimulating food over-exciting and ultimately impairing the digestive powers. The proneness to morbid excitement in the brain, induced by insufficient food, Dr. C. represents as one cause why, in times of public distress, the lower orders are so apt to resort to violence to remove the sources of their discontent.

At p. 267, the third condition of health in the brain and nervous system, is shewn to be the regular exercise of their respective functions. So far as regards its exercise, the brain is subject to the same laws as the other organs of the body: if it be doomed to inactivity, its functions languish and its health decays: if it be duly exercised, after regular intervals of repose, its functions acquire readiness and strength: and, if it be over-tasked either in the force or duration of its activity, it functions become impaired, and irritability and disease take place of health and vigour.

Permanent inactivity impairs the tone of the brain, and renders it less fit to manifest the mental powers with promptitude and energy. Withdrawal of the stimulus necessary for the healthy exercise of the

March, 1835.-VOL. II. NO. VIII.

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