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better, perhaps, in a moral point of view. The difference consists, in their opinion, solely in the fact that, whereas Herbert Spencer has a good tool to work with, the idiot has a bad one, and hence the product of his labor is of an inferior quality.
The essential fault of these philosophers is that they confound the mind with the soul. Science has nothing to do with the latter. Its existence is altogether a matter of faith -not of proof—which people believe in or not, according to the education they have received and the subsequent reflection they have bestowed upon the subject. But the mind is found wherever there is gray nerve-matter in action, from the lowest invertebrate animal up to the highest and most intellectual man who walks the earth. With it science may properly concern itself, and with it theologians, as such, have nothing to do.
The several categories of facts which go to establish the connection between the mind and the brain have been well set forth by Mr. Bain,' and are in general character similar to those which exist between any other viscus and the product of its action. They are as follows:
1. The action of an organ, even within the limits of health, frequently gives rise to sensations of various kinds, and slight functional derangements are very distinctly felt. Thus the pain of indigestion is referred to the stomach or bowels, as the case may be; disorders of the urinary excretion are manifested by uneasiness in the kidneys ; derangements of the secretion of the bile cause pain in the liver; loud noises produce unpleasant feelings in the ears; and excessive or improper use of the eyes causes pain and other abnormalities of these organs. So it is with the brain, and often to a very marked degree. Though ordinarily we are not conscious by any particular sensation that we are using it when we think (and the same is true, mutatis mutandis, of the other organs mentioned), yet inordinate mental exertion, or continual disturbance, gives rise to headache, vertigo, and other derangements of sensibility referable to the brain. If the disturbing factor be continued in action, not only are these indications of disorder increased, but the mind shows evidences of derangement, and the organs of the body whose functions are controlled by the brain are likewise affected. As a consequence, insanity and paralysis result, and, upon post-mortem examination, the brain is found to be the seat of organic disease. There are many persons in whom only very slight mental action invariably produces pain in the head, and others again who are similarly affected by particular kinds of mental exertion, while other kinds, even in excess of proper limits, cause no sensations. Thus some individuals cannot attempt the solution of mathematical problems without suffering from pain in the head, and some experience a like disturbance from the very slight mental effort necessary in adding up a column of figures.
1 " The Senses and the Intellect," second edition, London, 1864, p. 11.
2. Injury or disease of the brain impairs in some way or other the capacity or endurance of the mind. A blow on the head causes confusion of ideas, and, if hard enough, may abolish consciousness or the power of thought altogether. A piece of fractured bone, or a bullet pressing on the brain, likewise destroys the ability to think ; and the same result, or some other indication of mental disturbance, accompanies brain tumors, extravasations of blood within the cranial cavity, congestion, embolism or thrombosis of the cerebral blood-vessels, inflammation, or other disease of the brain. The fact that occasionally, on post-mortem examination, severe organic disease of the brain is found to have existed during life without the production of notable symptoms, is no argument against the view here taken. All parts of the brain are not equally concerned in the production of mind, and by far the larger portion-the white substance-is only a medium for the transmission of the nerve-force which has been generated by the gray matter. I think, however, that it may be laid down as a law, admitting of no exception, that injury or disease of the convolutions, or any other portion of the gray tissue, is invariably accompanied by a disturbance of the functions of the brain of a character and extent commensurate with the seat and severity of the lesion. Cases are on record in which the consciousness of the individual has been suspended for sev. eral months, from the fact of pressure exerted by depressed bone upon some portion of the cortex, and in which, on the instant that the pressure was removed by surgical interference, consciousness was restored.
3. The action of the brain, like that of any other of the animal organs, results in the disintegration of its substance, and this destruction is in direct proportion to the amount of mental work done. We find, therefore, that the alkaline phosphates, which are mainly derived from the destructive metamorphosis of the nervous tissue, and which are excreted by the kidneys, are increased in quantity after severe intellectual labor, and are diminished by mental quietude. In a memoir published several years ago, I gave the results of a series of experiments performed upon myself, which show conclusively that increased use of the brain causes increased decay of its tissue, as demonstrated by the largely augmented quantity of phosphates excreted by the urine.' As the chemist, by weighing the ashes on the hearth, determines how much wood has been burnt, so the physiologist, by weighing the ashes of the brain—the phosphates—measures the amount of thought which has resulted from the combustion of the encephalon.
4. The size of the brain is well known to bear a direct relation to the intelligence of the individual ; and, when all other conditions are alike, it may be said that the largest brain will produce the greatest amount of mental energy. This deduction is based upon the fact that, as a rule, the larger the brain as a whole, the greater is the quantity of gray matter upon which its activity depends. Occasionally there are apparent exceptions to this statement, but there is reason for thinking that they are not so real as they seem. It is entirely consonant with the results of experience to meet with individuals of moderate-sized brains and great intellectual activity in whom the cortical substance is of unusual thickness, and the convolutions of more than ordinary complexity.
At the same time it is a well-known fact that, when the brain is markedly below the average in weight, mental weakness is a necessary concomitant. Thus Dr. Thurnam has shown that the average weight of the brain of Europeans is 49 ounces, while in ten men remarkable for their intellectual development it was 54.7 ounces. Of these, the brain of Cuvier, the celebrated naturalist, weighed 64.5 ounces, Spurzheim's 55-6, and Daniel Webster's 53-5. On the other hand, the brain is small in idiots. In three individuals of very feeble intelligence, whose ages were sixteen, forty, and fifty years, respectively, Tiedemann found the weights of their brains to be 194,
1 " Urological Contributions,” American Journal of the Medical Sciences, April, 1856, p. 330; also, “Physiological Memoirs,” Philadelphia, 1863, p.
• Journal of Mental Science, April, 1866.
254, and 22 ounces. Mr. Gore' has reported the case of a woman, forty-two years of age, whose intellect was infantine, who could scarcely say a few words, whose gait was unsteady, and whose chief occupation was carrying and nursing a doll. After death, the weight of her brain was found to be but 10 ounces and 5 grains.
Mr. Marshall' has also reported a case of microcephaly existing in the person of a boy twelve years of age, whose brain weighed but 84 ounces. The convolutions were strongly marked, though few in number and narrow. In a remarkable case which came under my own observation, the individual, a woman twenty-two years of age, was unable to talk, though she could utter a few inarticulate sounds expressive of the more imperious of her wants. The cranium had a circumference of only 14 inches at its largest measurement, and the brain was found to weigh but 23} ounces. The thickness of the gray matter at no part of the surface exceeded of an inch, and generally was below this point, whereas in the brain of a person of ordinary intelligence it is often more than twice this depth. The convolutions were of very simple structure, and the fissuration comparatively slightly marked. In no adult not an idiot is the cranium less than 17 inches in circumference.
Gratiolet' fixes the lowest weight of the human brain in a person of ordinary intelligence at about 314 ounces. When the weight is below this, the individual is necessarily an idiot.
Thurnam · states that, as the result of his observations, the weight of the female brain is about ten per cent. less than that of the male, and this is about the difference as determined by other observers. Of course this is an average result, for there are many women with larger brains than many men, and of consequently higher mental capacity.
5. Experiments performed upon the nerves and nerve-centres show that from the brain proceeds the force by which muscles are moved ; that it is the chief organ by which sensations are perceived-all the special senses, with the possible
1 “Notes of a Case of Microcephaly," Anthropological Reciev, No. 1, May, 1863, p. 168.
2 "Brain and Calvarium of a Microcephale, Anthropological Review, No. 2, August, 1863, p. 8.
3 " Anatomie comparée du système nerveux," Paris, 1857, t. ii, p. 318. • Op. cit.
exception of touch, having their centres of perception in the brain alone—and that certain portions of the brain are in direct relation with certain faculties of the mind, sensorial operations and muscular actions. Thus, division of a nerve supplying any particular muscle cuts off the connection between the brain and that muscle, and hence the will can no longer act upon it. Division of any nerve of special sense prevents the perception of sensorial impressions. If, for instance, the optic nerve be cut, though the whole optical apparatus of the eye remain unimpaired, the sight is destroyed, for the reason that the communication with the organ of perception is severed. Again, by destroying certain portions of the brain, the power to exercise those sensorial organs which are under the control of the injured regions is lost, faculties of the mind are abolished or impaired, and the ability to move the muscles which derive their innervation from those parts is abolished or diminished. From all of which considerations the connection between the brain and the mind is as clearly made out as any other fact in physiology.'
DIVISIONS OF MIND.
The mind, like some other forces, is compound—that is, is made up of several sub-forces. These are: perception, intellect, emotions, and will. All the mental manifestations of which the brain is capable are embraced in one or more of these parts. Either one may be exercised independently of the other, though they are very intimately connected, and in all continuous mental processes are brought more or less into relative and consecutive action. To the consideration of some of the primary facts associated with each of these divisions a brief space may be given.
1. Perception.-By perception is to be understood that part
* That the spinal cord is likewise the seat of certain elements of mind, or rather is capable of evolving them, can be satisfactorily shown by a parity of reasoning. For the illustrations and arguments relative to this subject, the reader is referred to the author's inaugural address as President of the New York Neurological Society, entitled “The Brain not the Sole Organ of the Mind," Journal of Nerdous and Mental Disease, January, 1876.