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These centres are fully developed only in the brain of human beings; and when their nervous substance is destroyed, the power of expressing his thoughts in intelligent language which man under ordinary conditions possesses is abolished.
In addition to the evidence already given of the part played by the cerebral cortex in the transformation of the contents of ideas into thoughts, the following considerations are of importance. From the dawn of their independent life young infants display instinctive acts and emotional feelings, the nervous structures of their basal systems being fully developed ; but it is not until later in life that the nervous structures of the psychical areas of their brains are matured; pari passu with this development their psychical powers come into operation. Individuals born with imperfectly developed cerebral hemispheres possess intelligence of a no higher order than that displayed by an ape. 17
In the lower animals destruction of the cerebral hemispheres is attended with the loss of intelligence and of everything they may have learnt previously during their lives.
From the earliest stages of the well-recognised form of disease known as ' general paralysis of the insane,' degenerative changes are found in the living substance of the nerve-cells of the cortex of the psychical areas of the brain. One of the earliest symptoms presented by persons suffering from this disease is a peculiar hesitating and irregular movement of the lips and other muscles concerned in the production of articulate speech, indicating faulty action of the nerve-cells constituting the motor-centres of speech. At the same time the individual unconsciously drops syllables in forming sentences or in writing. When attempting to think, he finds his memory for certain words is defective, and thus he loses the power of continuous thought : so much is this the case that persons affected by this disease, even in its early stages, are often unfit to manage their own affairs. The progressive degeneration of the living substance of the nerve-cells of the psychical areas of the cerebral cortex is marked by corresponding deterioration of the memory for words, and the power to think or form correct judgments. The various sense-organs may continue for a time to perform their respective functions and ideas may be formed of external objects and of movements made by our bodies, but with the progressive degeneration of the living matter of the psychical elements of the cerebral cortex its work becomes impaired, it fails to associate and co-ordinate the contents of the ideas which reach it, and thus leads to faults in the mental processes of the individual,
17 International Scientific Series, vol. xcvii. p. 135.
and to the loss of the control which, under ordinary conditions, they exercise over the motor-centres of the vocal apparatus.
The potential powers possessed by the living substance of the cortical or neo-pallial areas of the brain, unlike that of the basal system, can only be developed by use or education through the instrumentality of energy derived from the various senseorgans. As the cases of Laura Bridgeman and H. Kellner show, if the principal sense-organs are destroyed in childhood, the intellectual powers of such a person remain dormant until brought into action by careful training of the tactile sense-organs. Knowledge acquired during an individual's lifetime cannot be passed on to descendants through the germ-cell. It is even questionable how far a special aptitude for any kind of knowledge is hereditary, i.e. whether parents who for several generations have shown more than ordinary powers of observation, of thought, etc., pass on such qualities to their children. This subject, however, has been ably discussed in a recent article in this Review ; 18 we shall not attempt therefore to offer any further comments on it, but only emphatically reiterate the fact, that we know and learn from what we see, feel, hear, taste and smell.
The histories of the deaf and dumb children referred to above show that so long as their psychical powers remained undeveloped their emotional feelings ran rampant, but as soon as their intellectual powers had been brought into play they were, to a considerable extent, able to control their hereditary instinctive and emotional actions. The automatic movements
. of young infants predominate until their psychical nervous system has become fully matured, and brought into healthy action by proper training. These facts lead us to consider the effect of the reciprocal action constantly at work throughout every part of a well-organised brain." Although, for convenience of description, we have referred to the basal, sensory, psychical, and motor-cerebral areas, it is obvious that these and other portions of the brain are so many parts of one system, and that any action taking place in one part of the brain implies compensating action in some other part, in order that the two may arrive at a state of equilibrium. In this way we can form an idea of the reciprocal action of psychical and emotional nervous forces, and the influence, therefore, which the large psychical areas
18 ' Eminence and Heredity,' by W. C. D. Whetham, F.R.S., and Mrs. Whetham, Nineteenth Century and After, May 1911.
19 If the intensity factors of any particular form of energy in a system are not equal, the system will be in a state of unstable equilibrium. Such a condition will not be permanent, and energy will flow, so to speak, from one part to another until the different intensity factors become equal.
of the brain, if properly developed, may exercise upon the basal nervous system.
The reciprocal action of one or more cerebral centres on other parts of the brain may probably be best realised by referring to an example such as the following :
While driving along a country lane, my horse fell down and I was thrown on to the road and rather severely bruised. Some three weeks after the accident, when driving along this same lane, I experienced an unpleasant emotional feeling on reaching the place where the accident had occurred. This tone of feeling may be explained as follows: On the first occasion as I drove along the lane the hedges on either side of the road were of no particular interest, and consequently made no marked impression on my visual nervous centres ; but my sudden fall out of the dogcart was accompanied by a painful sensation, with its corresponding mental latent image. Although at the moment the accident happened my visual sensation and ideas of surrounding objects were of an indifferent character, they had been established in my cerebral cortex simultaneously with the painful impression caused by my fall, so that these visual and tactile impressions were closely associated ; if they differ in their intensities, they modify each other so that an equilibrium may be established between the differing factors. In this way part of the painful (negative) tactual tone of feeling, excited in my emotional centres by my fall, passed on to my less intense visual nervous centres, which latter, on my returning to the spot where the accident had happened, were re-excited by visual impressions, which had been primarily indifferent, but had become charged with a stream of negative tone of feeling from my emotional centres. A process of this kind is technically described as a nervous irradiation' or overflow-of an emotional tone in the instance referred to-to a psychical area of the brain, a process akin to radiation or diffusion in physics. We can thus realise the processes by means of which the transference of tone of one to another idea takes place, and how energy derived from the cerebral cortex of the human brain comes to influence primitive emotional feelings elaborated by the basal and its associated system, or vice versa. For instance, we may thus comprehend how, having heard a certain musical combination produced frequently in conjunction with a set of mournful words, while the succession of tone in the chord itself does not partake of a mournful character, the words that are sung to this series of tones produce mournful ideas. The negative emotional tone of the latter is thus gradually imparted to both the musical sensation and its correlative mental image; finally, the chord is sufficient to produce a negative change in the tone of feeling quite inde
pendently of mournful words. Again, the memory of a flower having a disagreeable odour is as a whole disagreeable; the component idea of its odour transmits its emotional tone to the entire conception. Professor Ziehen states, when discussing this subject, 'our entire emotional and psychical life is ruled by these irradiations, our antipathies and sympathies, prejudices and prepossessions flow chiefly from this source. The numberless movements constantly performed for the satisfaction of some desire are emotional.'
We have thus endeavoured to show that human beings possess in their hereditary basal nervous systems a form of matter which transmutes energy derived from the sense-organs into instinctive action and emotional feelings. They have inherited this form of matter from the lower animals, a fact which must be reckoned with in any rational system of education. Human beings, how
. ever, differ from the lower animals in that large masses of nervous matter have been developed in their brains, whose function it is to elaborate a higher order of nerve-force than that which any of the lower animals possess : further, the human brain has evolved a specific form of cortical substance whose function it is to control the muscles of the vocal apparatus, to enable men to think in words, and to express their thoughts in intelligent speech.
We have further come to recognise the fact that the quality of our intellectual processes mainly depends on the kind of training which the psychical elements of the brain receive during the early years of an individual's life. We have shown that the
. force which drives the psychical mechanism takes its rise from energy received from the outside world, and from muscular movements acting through the sense-organs on sensory-cortical centres; impressions thus received are transformed by the living substances of these centres into sensations and latent ideas. Doubtless the inherited structural arrangement of the elements forming the cerebral cortex, and its proper nourishment and use, have much to do with the efficiency of its working powers.
Energy derived from the contents of ideas extends to the cortical-psychical elements, and through their instrumentality is correlated and transmuted into thoughts and other intellectual processes. Consequently the main effort of primary education should be directed to an endeavour to awaken related ideas in a child simultaneously, i.e. to combine them by means of external associations. Training of the kind we have referred to must be commenced and carried on systematically from childhood, in order to bring all parts of the living nervous matter of the cere
20_Introduction to the Study of Physiological Psychology, p. 176. By Prof. Dr. J. Ziehen.
brum into co-ordinate action, and thus form well-established paths of communication between its various parts. By developing the innate properties possessed by cortical elements at an early period of life, we have good reason to hope that the nerve-force derived from this source may be brought by practice to bear with good effect upon the basal system, by processes such as those to which we have referred, and so to control its undesirable, and augment its desirable, qualities; especially if the trend of these qualities in an individual has been seriously taken into consideration, so that those responsible for his education may possess definite ideas as to what they have to deal with. In not a few cases, especially among our city-bred children, this nerve-material has been derived from parents who, in common with their progenitors, have existed from childhood under terribly defective hygienic and other conditions. The psychical elements of their brains have been subjected to little but vicious treatment. Judged by the ordinary standards of civilised human beings, such people are mentally defective : their conduct is not their own fault. In too many instances they fall into the criminal classes, because they have no power of control over their animal propensities, and possess only human intelligence of a low order. By the time these individuals have reached the adult period of life but faint hopes can be entertained of any improvement in their personal or intellectual qualities ; we can then only treat them, as we do persons of acknowledged unsound mind, by separating them from the rest of the community. At the same time we are bound to secure the control of their young children, and by careful management to rear them up to become selfreliant, useful members of society. 21
In the existing system of compulsory education, carried on in our publicly-supported infant schools, the Froebel system of teaching is extensively in use, and is well adapted to mould the living cerebral matter of young children into a form capable of further development in primary schools; especially if the head of the school into which the child passes is made acquainted, through information received from the infant-school teacher, with the character of his pupil, and when possible, those of the child's parents. With knowledge of this kind at his command, the head of the primary school knows where to place, and how to treat, his pupil. The object to be kept in view in the child's further education is, first and foremost, the building up of a self-reliant, loyal, and true personal character; mentally the aim should be, not so much to increase the stock of what boys or girls know, as of what they can do, so that they may carry out with satisfaction to themselves and their employers the duties
» The Education of Neglected Children in Germany. Special Reports on Educational Subjects, vol. ix. p. 605.