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stamped upon the ganglion-globules of the brain, is retained by some faculty of the intellect which is independent of physical change, although some physical changes may temporarily affect it.

Dr. Maudsley holds that there is something in the brainvesicles, over and above the part which is unceasingly changed, which constitutes a kind of enduring framework, upon which the new globules are moulded, and that the permanence of ideas and the endurance of memories are due to these undecomposable and unchangeable portions of the structure. In some recent microscopic examinations of the brains of aged men, it was noticed that at the points where the angular corners, or horns, of the ganglion-corpuscles should be in free communication with the pulp-core of nerve-threads, the proper connexion had been destroyed by the drying and withering away of the nervethreads at those points. Such impairment of structure would very amply account for the failure of memory in advanced years, since whatever the residual contents of the globules might be, they would in such circumstances of necessity be quite inaccessible for any purpose of renewed mental work. In reference to the physical state which is concerned in the production of memory, Dr. Maudsley says:

'That which has existed with any completeness in consciousness leaves behind it, after its disappearance therefrom, in the mind or brain, a functional disposition to its reproduction or reappearance in consciousness at some future time. Of no mental act can we say that it is "writ in water." Something remains from it whereby its recurrence is facilitated. Every impression of sense upon the brain, every current of molecular activity from one to another part of the brain, every cerebral reaction which passes into movement, leaves behind it some modification of the nerve-elements concerned in its function, some after-effect, or, so to speak, memory of itself in them, which renders its reproduction an easier matter, the more easy the more often it has been repeated, and makes it impossible to say that, however trivial, it shall not in some circumstances recur. Let the excitation take place in one of two nerve-cells lying side by side, and between which there was not any original specific difference, there will be ever afterwards a difference between them. This physiological process, whatever be its nature, is the physical basis of memory, and it is the foundation of the development of our mental functions."

The difficulty of apportioning out the cerebral ganglia into parts charged with the performance of particular operations of the mind has been one that has pressed heavily upon physiologists. That the brain is subdivided into subordinate organs which are distinct from each other both in structure and function, is probable in the highest degree. In some recent experiments, performed upon the lower animals whilst under the

influence of anesthetics, Dr. Ferrier was able to produce particular actions at will by passing gentle currents of electricity through different parts of the cerebral ganglia. Thus, for instance, when one definite spot in the brain-convolution of a dog was acted upon, the animal wagged its tail, and when another part of the brain-mass was stimulated, it twitched its left ear, held up its head, opened its eyes, and assumed the familiar expression of fawning. In a similar way a cat was made to start up, throw back its head, open its eyes, and lash angrily with its tail. There can be no doubt that in these experiments ideas were excited in the brains of the insensible animals by the physical agency of electrical currents. The brain convolutions in reality consist of a number of distinct mind-centres, spread out in a kind of vault over the subordinate centres of nerve-action which have the charge of consciousness, and are arranged in layer above layer. Dr. Lockhart Clarke, as a first step towards the mapping out of the brain-substance into distinguishable parts, has shown that there are at least seven concentric layers of nerve-substance in the convolutions, which are alternately of darker and lighter tints; and Dr. Maudsley suggests in reference to these observations of Lockhart Clarke's that, in all probability, the superimposed strata correspond with operations of increasing complexity, the lowest layer being mainly concerned with the simpler acts of perception and memory, while the higher layers are employed in the more complicated task of converting those first rude impressions into more abstract ideas and the more finished conceptions of intellectual activity. The structure of the brain is, however, of such surpassing delicacy and such exquisite minuteness, that very little progress has yet been made in the direction of this branch of investigation, even by the highest skill of the observer and the utmost perfection of microscopes. A fragment of the grey substance of the brain, not larger than the head of a very small pin, contains parts of many thousands of commingled globules and fibres. Of ganglion-globules alone, according to the estimate of the physiologist Meynert, there cannot be less than six hundred millions in the convolutions of a human brain. They are, indeed, in such infinite numbers that possibly only a small portion of the globules provided are ever turned to account in even the most energetic brains. In one particular passage of his book Dr. Maudsley finds occasion to contrast the 15,000 words which Shakespeare employs for the expression of his ideas with the hundreds of millions of brain-globules that must have been concerned in the production of this intellectual harvest.

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Since both impressions of sense and impressions of memory are brought up to the bar of the sensorium to be dealt with upon their merits, it may very well happen that sometimes the great centre of consciousness gets sorely puzzled to discriminate between the two different classes of ideas. Many of the operations of the mind are so essentially the reproductions of impressions of sense, that in some circumstances it must be very easy to mistake them for the things which they represent. In the general work of life the power of discriminating between fancies and facts implies a complex mental act, which is only matured and perfected by long-continued training. There must consequently at all times be many people with whom this training is not complete, and who do not efficiently distinguish between sensory impressions and ideas. Such persons, accordingly, are prone to accept ideas as facts, and so receive as real whatever their imaginations suggest. They reflect their own inner life upon the outside world. Many of the motives under which people ordinarily act are, undoubtedly, of this mistaken and illusory character. In such circumstances the actions are what the physiologist terms ideo-motor-actions involuntarily performed under the direction of ideas. They are, indeed, essentially reflex actions of the brain '-movements as involuntarily performed under the stimulation of ideas, as sneezing is involuntarily performed under a special sense-impression applied through the nose. Dr. Carpenter ascribes many of the extraordinary phenomena that are met with amongst mesmerists, electro-biologists, table-turners, table-talkers, and spiritualists, to this class of involuntary cerebral actions; and the passages in which he has developed his views upon this matter are amongst the most interesting and able portions of his book. In very many instances effects of this character are produced in persons who are intellectually weak, and who have not enough strength of character and force of purpose to retain the full command of their own mental operations. But these results are not exclusively found amongst weak people. Nothing is of more frequent occurrence in life than to meet men of highly cultivated and powerful intellects, who are misled as much as the weakest victims of mental fatuity-men who dwell in the retirement of their studies, amidst their own reveries and thoughts, and who only come out from such retirement into the world, to see there the images which have been fabricated in their own brains. With such people the unbiassed investigation of facts becomes almost an impossible process. They can see nothing but what they have already determined is to be seen.

The involuntary reflex action of the brain, and the consequent tyranny of ideas, is a very real and prominent feature in the mental and intellectual existence of man. It goes, indeed, very much further in its operation than is generally conceived. It sufficiently accounts for the vast number of individuals who claim superior and infallible insight for themselves in a sphere of existence where, nevertheless, no two are altogether agreed in their views and opinions. It is the secret of the wide sway of dogmatism. Each man, with entire conscientiousness, believes in the strength of his own position, and is as honest as he is uncompromising in his faith. He is none the less the thrall of his own ideas, and the victim of a cerebral tyranny from which there is no escape. The same influence can be traced, with scarcely less force, into the region of mental pathology. Its application to the phenomena of insanity is obvious to everyone. But it is not so generally understood that much of what is familiarly termed temper' is really to be referred to the same instrumentality. Few persons, who have intelligently observed this form of mental aberration, can have failed to notice how terribly real the illusory fancies of bad-tempered people are. They honestly believe that they are the most ill-used persons on the earth, when they are surrounded only by kindly regard and forbearing indulgence. The true explanation of this pitiable state simply is that such people are the victims of the involuntary ideomotor operations of their own too active brains.

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There is another side, however, of this question of reflex cerebral action, which it is more pleasant to contemplate, and in which material amends are made for the unamiable phase of its agency. It is that which is now very expressively recognised as unconscious cerebration.' This designation refers to a remarkable faculty of the mind, which was recognised by German physiologists more promptly and readily than it was by Englishmen, although it had been in some measure noticed by Sir William Hamilton. Dr. Carpenter appears to have arrived at a knowledge of this matter by an independent line of thought, and as a consequence of the perception that the sensorium was the effective centre of consciousness for the internal senses, or ideas, as well as for the external impressions of sense. His views on the subject were distinctly expressed in the fourth edition of his book on Human Physiology' as long back as 1852, and it certainly must be admitted that he has done more than any other English physiologist to make this particular region of mental physiology his own, and to render its doctrines intelligible to the multitude.

The unconscious cerebration of Dr. Carpenter means simply that the human brain is capable of carrying on long trains of mental operations on its own account, when it is once fairly started on the track, and of finally arriving at conclusions which can be received as conscious ideas, although there has been no conscioussness whatever of the process by which the operation has been conducted. The physiological explanation of this curious power is that the convoluted ganglion-masses of the brain continue their activity in working upon ideas when the functions of the sensorium, which is the seat of consciousness, are entirely suspended and in abeyance, as they are in profound sleep; or when they are exclusively occupied with other trains of impressions, and, on that account, incapable of taking sensorial note of what is passing in the brain. Dr. Carpenter's own statement of his views upon this point is contained in the following brief sentence: Mental changes, of 'whose results we subsequently become conscious, may go on below the plane of consciousness, either during profound sleep or while the attention is wholly engrossed by some entirely • different train of thought.'

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Dr. Maudsley remarks in reference to the same matter:-'Whatever the organic process in the brain, it takes place, like the action of other elements of the body, quite out of the reach of consciousness. We are not aware how our general and abstract ideas are formed; the due material is consciously supplied, and there is an unconscious elaboration of the result. Mental development thus represents a sort of nutrition and organisation; or, as Milton aptly says of the opinions of good men, that they are truth in the making, so we may truly say of the formation of our general and complex ideas that it is mind in the making. When the individual brain is a well-constituted one and has been duly cultivated, the results of its latent activity, rising into consciousness suddenly, sometimes seem like intuitions; they are strange and startling as the products of a dream ofttimes are, to the person who has actually produced them. Hence it was no extravagant fancy in Plato to look upon them as reminiscences of a previous higher existence. His brain was a brain of the highest order, and the results of its unconscious activity, as they flashed into consciousness, would show like revelations, and might well seem intuitions of a higher life quite beyond the reach of present will.'

Whilst alluding to this remarkable power of independent and unconscious action of the brain, it should, perhaps, be observed that in reality there is no culture more rare than the one which gives men absolute control of the operations of their own minds, and the power not only of directing their trains of thought to a definite end, but also of estimating correctly the value of the conclusions that are ultimately arrived at. It

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