Popular Science Monthly/Volume 13/August 1878/Voluntary Motion

From Wikisource
Jump to: navigation, search

VOLUNTARY MOTION.
By Professor PAYTON SPENCE, M. D.
"The primitive elements of the will have been stated to be—1. The spontaneity of movement; and, 2. The link between action and feeling, grounded on self-conservation. In the maturing or growth of the will, there is an extensive series of acquisitions, under the law of retentiveness or contiguity" (Bain, "Mental Science," p. 318).

"The elements of voluntary power being assumed as—1. Spontaneity; and, 2. Self-conservation, we have to exemplify the connection of these into the matured will, by a process of education" (Bain, "Mental Science," p. 325).

TO what extent we differ from the above propositions, and especially from those parts of them which we have italicized, will more fully appear in the following article. To the superficial observer, a human being, during the interval between birth and adult life, seems to learn a great deal; but, if he did really learn all that he seems to learn, it would be marvelous in a degree wholly beyond the power of the human mind to conceive of, and far beyond the power of human language to express. Omitting, at present, that immense domain of the mind which is embraced under the terms sensation, emotion, and intellection, we will endeavor to make a comparative estimate as to how much we seem to learn, but do not learn, and how much we do really learn, in that limited department of the will which is covered by the term voluntary motion.

We will begin by endeavoring to ascertain how much a child would have to acquire in simply learning to pronounce the letter A, at will, supposing that none of the movements, or combinations of movements, which are made in the utterance of that one sound, are organic and inherited, but that they all have to be acquired or learned by practice and experience.

Between the states of the greatest and the least contraction of any muscle of the body, there are, of course, an infinite number of degrees of contraction. In order, however, that we may not seem to exaggerate the difficulties of the child's task, we will suppose that a muscle is susceptible of only three degrees of contraction, and that, therefore, three experiments, at most, would ultimate in the production of the sound of A, supposing it to depend upon the proper contraction of only one muscle. But how many muscles are engaged in the production of that one sound? A great many, namely, the muscles of the vocal chords, the muscles of the back part of the mouth, of the tongue, the cheeks, the lips, and the muscles that expand and contract the chest. We will largely understate their number, and suppose that there are only 20 involved in the pronunciation of A, each one of which, as we have already supposed, is susceptible of only 3 distinct degrees of contraction. Now, 2 muscles, each one of which is susceptible of 3 degrees of contraction, can be made to contract together in 9 different combinations, consisting of one degree of the contraction of each muscle to each combination; 3 muscles will give 27 possible combinations, 4 muscles 81 possible combinations, and so on, in a geometrical ratio of increase, up to the supposed 20 muscles, with which there would be 3,113,884,401 possible combinations of muscular contractions. Now, in all this wilderness of possibilities, there is but one combination which can produce the sound of the letter A, and that one the child must find, although, according to the supposition, he knows nothing about it, and has no organic tendencies in the direction toward it. He can find it only by experiment. Each possible combination must be successively tried and rejected, until he comes to the right one. Assuming that his chances of hitting upon the right combination are equal to his chances of missing it, the number of experiments which he would have to make, before he would hit upon the right one, would be just one-half of 3,113,884,401, which is 1,556,942,200. Supposing, therefore, that the child makes 100 experiments in a minute, it would take him within a fraction of thirty years to attain the first successful utterance of the letter A.

But the child's task is not yet accomplished when he has succeeded in pronouncing the letter once. He must pronounce it again and again, before it is so completely within the reach of his will that he can pronounce it immediately, making automatically all the required muscular contractions of the combination the instant the volition calls for the letter. It is evident that, in the absence of all knowledge of those 20 muscles, and of all organic tendencies in the right direction (which could only be acquired by repeated successful experiments), it would be almost as difficult for the child to hit upon the right combination the second and the third time as the first; and, therefore, only after many successes would the required combination become automatic, and the utterance of the letter A really be so completely brought under the dominion of the will as to be classed among the voluntary movements. If, therefore, we again under-estimate the difficulties of the case, as we have done all along, and suppose that only 10 successful experiments would be necessary to accomplish the result—that is, to agglutinate into a unitary movement the required group or combination of muscular contractions, so that the group should be instantaneously and automatically adjusted the moment a volition is made for the letter A—we find that the child's lesson, the learning to pronounce a single letter at will, is a task which would require for its accomplishment 300 years of steady work, night and day, at the rate of 100 experiments every minute!

How insignificant, however, is the successful pronunciation at will of one letter, when we reflect that the child ultimately attains the voluntary control of, not merely one of the billions of possible combinations of 20 muscles, but that he attains the absolute voluntary command of all the 450 voluntary muscles of his body, individually and collectively, in all their possible combined, as well as isolated, contractions! In some of the combinations of muscular contractions which the child ultimately becomes capable of executing, nearly every one of the 450 voluntary muscles of the body participates; as, for example, in the throwing of a stone; and yet the wonderful combination is made and the movement executed with as much precision and promptness as the crooking of his finger. We have no hesitation in saying that, if all this had to be learned by the child, it would require a lifetime of many millions of years; and, as we know that the requisite knowledge or capacity is not a miraculous donation to the child, but must be the accumulated acquisitions of a slow process of experience of some kind, and at some time or other, we should be appalled by the magnitude of our own figures, did we not know that man is not the creature of to-day, but the child of the ages, incubated in the primitive submarine protoplasm, born as the simple monad, creeping for aeons of time as the blind-worm upon its belly, swimming for untold ages as the fish of the sea, flying as a bird in the air for hundreds of thousands of years, and, for centuries without number, roaming the earth as a mammal, and walking the globe erect as a man. But, all this time, immense and inconceivable as it is, would be too insignificant to enable one individual, unaided and alone, to learn (were it accomplished by learning) to execute all those infinite muscular contractions, and combinations of contractions, of which we have spoken; and we are only helped out of the difficulty by a knowledge of the fact that, in the evolution of the power of voluntary motion and of the will, in the animal kingdom, during all the immensity of the past ages, the organized experiences and acquisitions of all the millions of individuals of each species of animal life were, by the process of reproduction and the law of heredity, so completely interchanged and shuffled up with each other that the organized experiences and acquisitions of each individual became the organized experiences and acquisitions of the species, and the organized experiences and acquisitions of the species became the organized experiences and acquisitions of each individual.

We are now prepared to make an approximate estimate as to how much of our command over our voluntary muscles is acquired by education and experience, and how much is the result of the simple maturation of an inheritance, which evolution had prepared and stored up for us. If, as we have already shown, many millions of years would be required to enable one individual to acquire as perfect a control of all the voluntary muscles of the body as we know that each adult human being has, how much of that could be acquired by the individual himself after birth? Supposing him to reach the height of his muscular capabilities at thirty years, and that only 3,000,000 years, instead of many millions, are, as we have shown, necessary to enable him to obtain that complete mastery over his voluntary muscles which he actually possesses in. adult life, then his own individual acquirements would bear the same ratio to his inherited acquirements that 30 bears to 3,000,000, or that 1 bears to 100,000. Therefore, he inherits 99,999 parts, and learns but 1—a quantity so small as to dwindle into almost nothingness in the comparison.

An apparent objection to our conclusions is met with in the fact that the child does not use his 450 muscles, at birth, with the same ease, precision, and freedom, that he does in after-years; but, from the helplessness of the babe, which can scarcely be said to make a single voluntary movement, there is a gradual advance in the variety and extent of his control over his voluntary muscles, until we may say that, by the time he reaches adult life, he is completely master of his voluntary muscular system. If, then, it is true that we acquire by education and experience nothing, or almost nothing, of that vast department of mental acquisitions which is embraced under the term voluntary motion, yet it must be admitted that we seem to learn how to use our muscles, and it seems as if all our voluntary control over them were acquired by education and experience. It is but seeming, however; and, instead of our learning how to use our muscles, we simply learn that we can use them, in all the endless varieties of isolated and combined contractions of which they are capable. The how of their use is our vast organized inheritance; and it is this which gives even the child, as he matures, that sure, unerring tendency to the right movement to attain any desired end, and soon teaches him that he can do what he wills to do, thus obviating a resort to that infinitude of experiments which, as we have shown, would otherwise be absolutely necessary. It is the organized inheritance which takes the lead, and teaches the child that he can make the required voluntary movements, and not the child which teaches the organization how to make them. The newly-born babe is helpless and capable of making only a few instinctive or automatic movements, not for want of education and experience, but for want of organic maturity; and, hence, we see that some animals which are more matured at birth, or when hatched, than the human infant, walk, run, swim, or fly, as soon as they are born, or as soon as they escape from the egg; and the butterfly and those insects which emerge from the chrysalis fully matured need no experience or education whatever to enable them to command at will all their voluntary muscles; their organic maturity alone giving them at once full control over that department of their nature.

In the case of the child, it is impossible, either by observation or experiment, to separate the results of the maturation of the organization from the results of education and experience, for the obvious reason that the maturing of the child's nervous and muscular system proceeds, at a very rapid rate, simultaneous with its education and experience; and, therefore, were the point not already settled by the estimate which we have just made, it would be impossible to form even an approximate estimate as to how much of the child's progress is dependent upon his own acquisitions, and how much upon the ripening of an inherited organization. It is not possible, experimentally or otherwise, to isolate these two factors and their results from each other so as to ascertain, in that way, which factor is the largest and most important. The child's muscular education, the progress which he makes in his voluntary control over his muscles, and the maturing of his organization, all proceed simultaneously and inseparably together. Nevertheless, facts do occasionally crop out, here and there, confirmatory of the calculations already made, and the inferences drawn from them, if they needed confirmation. If our voluntary control over our muscles is not an educational acquirement, but is the result of the ripening of our organic inheritance, we would naturally expect an occasional exhibition of muscular agility, precision, and dexterity, and of complicated grouping and combinations of many muscles, far beyond any educated capacity which the individual is known to have acquired. This expectation is frequently realized in individuals when under the dominion of exalted emotions, in insane persons, and in persons when in mesmeric, somnambulic, trance, and other abnormal conditions, who often perform feats of agility, dexterity, and wonderful freedom and precision in the combined contractions of a great many muscles of the body, equaling the nimbleness and mobility of the ballet-dancer, the surefootedness of the rope-walker, and the consummate skill of the trained acrobat, although they had no special training calculated to qualify them for the performance of such feats. In fact, in their normal states, they did not believe themselves capable of performing such feats, because they had not yet learned that the feats, marvelous as they seemed to themselves and others, were already accomplished facts, packed away in their organizations, awaiting the magic word, the real "open sesame" to command them to come forth. The records are loaded with such unused facts, that are simply labeled "abnormal," and then abandoned. It will generally be found, however, that the abnormal, simply from the fact that it is abnormal—an outlaw to all that is now considered fixed and established in science—is the key to a higher law and a broader generalization. A few illustrations will suffice:

Dr. Rush relates the case of a young man named Wilkison, in whom the habit of stammering was suspended during his mental derangement, but returned as soon as he began to mend.[1] It is evident that, in stammering, the groupings of muscular contractions which produce articulate sounds are very different from those which produce the sounds without stammering. From some cause, not yet understood, there is in stammering an interference with the correct muscular groupings which, we claim, are organic and inherited, and a series of random, confused, and semi-spasmodic muscular movements become mixed up with the correct groupings. In this instance, the mixture had continued from childhood up to manhood, a period long enough surely to have agglutinated them indissolubly together, if practice, habit, or education, ever caused such agglutinations, as some believe. It is evident, therefore, that this man not only had not learned or acquired by education the correct use of his muscles of articulation, but had seemingly acquired an incorrect use of them; yet, the moment he became insane, the impediment was removed, the habits of a lifetime vanished, and his organically inherited command over those muscles asserted itself, and enabled him to do what he had never done before, and what, unless the views which we have presented are correct, must be acquired after birth, and can only be acquired after birth by long-continued practice.

The following case is related by Dr. Abercrombie: A lady laboring under some disease of the nervous system, not disclosed by an autopsy, as she recovered, exhibited, among other things, the following remarkable powers:

"After lying for a considerable time quiet, she would in an instant throw her whole body into a kind of convulsive spring, by which she was thrown entirely out of bed; and in the same manner, while sitting or lying on the floor, she would throw herself into bed, or leap on the top of a wardrobe fully five feet high. During the whole of these symptoms her mind continued entire, and the only account she could give of her extravagance was, a secret impulse which she could not resist."[2]

This case cannot be disposed of by saying that the movements were convulsive, because it is evident that they were definitely combined and adjusted to the production of a well-defined result—the landing of the patient's body either upon the floor, the bed, or the wardrobe—so that a certain amount of mentality or volition accompanied the result; this she herself was aware of, and called it a "secret impulse." It is also evident that the movements were very complex, and required a special and peculiar coördination of a great many muscles; in-fact, nearly every voluntary muscle of the body. The only conclusion at which we can arrive is, that the patient, in the abnormal state into which disease had thrown her, was able to draw upon an inheritance of muscular capacity to which she had matured, but which she had not been called upon to use before.

Dr. Abercrombie also relates the following case: A young lady, fifteen years of age, was subject to attacks of catalepsy, in consequence of a fall from a horse.

"On one occasion, she was playing from a book a piece of music which was new to her, and had played a part of it, when she was seized with a cataleptic attack. During the paroxysm she continued to play this part, and repeated it five or six times in the most correct manner; but, when she recovered from the attack, she could not play it without the book."[3]

In this case the young lady was able to execute, in the cataleptic state, what she apparently had not learned and could not execute when out of that state. From this and similar cases it would seem that much of our inherited voluntary command over our muscles is ordinarily disguised or marked, as it were—held in abeyance—how or why we know not, and we are enabled to get glimpses of it during those states of mental and organic spontaneity and mobility which, for want of a better name, we call abnormal, and which often seem temporarily to put the individual en rapport with the secret chambers of his own boundless wealth—the countless treasures of ages of accumulation.

The following case, taken from the Globe-Democrat, of St. Louis, Missouri, is as remarkable, perhaps, as any of a similar character on record:

"James H. Prior, of St. Louis, has an adopted daughter, of thirteen years, who performs wonderful gymnastic feats in her sleep. Finding her room vacant one night, Mr. Prior began a search, which resulted in discovering her walking along a narrow iron railing which protected a gallery running the entire width of the house. When she reached the end of the railing she deliberately turned and walked back. This she performed with grace and apparent carelessness. In the mean time Mr. Prior, fearing that if he moved it would startle the girl, and she would fall to the paved yard below, remained quiet while she continued her perilous walk. In a few moments she seemed to be satisfied, and, carefully stepping to a chair, reached the floor, and glided slowly by Mr. Prior, down the hallway into her apartment and bed, where she was soon sleeping sweetly. At another time, Mr. and Mrs. Prior found the girl had crawled through the skylight, and was promenading the length of the roof-ridge. She was walking with her hands hanging listlessly by her side, and her head inclined forward as if she were looking immediately in front of her feet. The moon was shining brightly, and the white, lithe form of the sleeping girl could have been seen a block distant. There was a chimney half-way to the ridge, and sometimes she made détours to the right or to the left, going completely around the obstruction, regaining the ridge and traversing its entire length. Once she leaned on a chimney, and seemed absorbed in meditation. Each time she reached the end of the roof it appeared to be her deliberate purpose to walk off, but she always checked herself when within a foot of the edge, and, slowly turning, carefully retraced her steps. Twice she descended on the incline of the roof, each time returning to the ridge very rapidly, as if she had met with something that excited her fears. Several times she looked up, as if gazing at the stars or listening to some distant sounds. Suddenly, while at the point of the ridge, which she had first reached, she began to descend in the direction of the skylight, taking each step with great caution and making slow progress. When she had nearly reached the opening Mr. Prior quietly withdrew. In a moment Laura followed, proceeding at once to the garret-stairs, and disappearing down the dark passage. Mr. and Mrs. Prior followed, keeping behind her as close as possible, but, before they could reach her, she was in her own room, and composing herself in bed."

Whatever voluntary muscular movements we may make, therefore—be they ever so new and wonderful to ourselves or to others—we make because we can; because they are already accomplished facts packed up in our inherited organization. The truth of this proposition makes its converse also true, and the proposition itself receives additional confirmation from the truth of the converse, namely, whatever muscular movements are beyond our voluntary control are so because they are not accomplished facts in our inherited organization. Take, for example, the familiar, schoolboy, muscular puzzle, which seems to be a very simple movement, and very easy of execution; yet we doubt whether it has ever been really mastered, even after the most protracted efforts, so that it could be executed with the automatic ease and dexterity with which we execute our voluntary movements. It is easy enough to extend the forefinger of the right hand, and revolve it rapidly so as to describe a cylinder as it moves; it is also easy to do the same thing with the forefinger of the left hand; and it is equally easy to revolve them both at once in the same direction; but the puzzle is to revolve them both at the same time, but in opposite directions, the points of the fingers facing each other. Much practice may enable one to execute it slowly, defectively, and awkwardly; never, however, with the same ease, freedom, and dexterity, with which we revolve either finger alone, or the two fingers together in the same direction. Again, it is not only difficult, but impossible, simply by a voluntary effort, or by any amount of practice, to roll one eye up and one down at the same time, or to turn both outward at the same time, beyond the parallelism of their axes. The muscular combination or coördination required in such movements is not organically possible, and no amount of education can make it so; otherwise, education would be a substitute for evolution and maturation.

The current ideas of the growth of voluntary motion and the will are based upon an ill-defined notion that the muscular and nervous systems were first developed, like a piece of complex machinery, and then the mind somehow came into rapport with it, or happened to be there, just at the right time, and commenced to learn how to work a certain part of it—for it is admitted that the rest can get along without the mind. But the truth is, the importance of the mind as a factor in the movements of the body is vastly overrated. It never really learns how to work even the limited portion of the organization which the current theories assign to it. When a child or even a man makes a certain voluntary movement for the first time, and practises it until he can execute it with ease and rapidity, has he learned how to do it? If so, he can tell how it is done. But, the fact is, he has learned nothing at all about the mechanism which he seems to handle so dexterously, and can give no account whatever as to how he does it—that is something which has staggered the most capable and profound students of voluntary motion and the will. Look at it. A child reaches out after a bright object and misses it. Does it know how or why it happened to miss it? It keeps reaching, fumbling, and trying, and now it grasps it. Does it know how or why? Does it know that now it opens an outlet or a valve of nervous discharge which then was closed; or, that it shuts one which it had left open; or, that it opens three instead of two or one; or, that it opens them one-half, one-third, or one-fourth, instead of full flood? Does it learn any of these things, and then treasure them up in the memory consciously or intentionally, so as to be able to do it again, next time, without balk or failure? The growth of a voluntary movement is an organic procedure, not such a mechanical process as that. That would, indeed, make the organization a machine for the mind to manipulate, instead of the mind being (as we think we can easily show) but a symbolical representation in consciousness of the workings of certain parts of the organization—the brain. Then, when we have mastered a voluntary movement, all that we have really learned is that we can make it.

But, again, a bright object is presented to a child. Its desire for it ultimates in a movement that misses it, and then in one that grasps it. In what respect do the mental accompaniments of the movement differ in the two cases? In nothing whatever. The mental phenomena which accompany both the failure and the success are a desire for the object and a volition for the movement. Next week or month, you hold the bright object before the child again, and he succeeds in grasping it every time; and still the mental accompaniments of the movement are the same—the same desire for the object, and the same volition for the movement—not for the wrong movement, even when the failure was made. Then, if the desire and the volition are precisely the same in both cases, why should one movement be a success and the other a failure? It is evident that the fact that the child has learned that he can make the movement does not contribute to the success, for the first success was made before he had learned that he could; and the knowledge that he can does not contribute to a future success, because it does not contribute in the least to a knowledge of how to do it. Then, where are we driven to? The mental accompaniments or phenomena do not (with a qualification which it is not important to explain here) contribute to the success of our voluntary movements. Therefore, we must look for the reason why one voluntary movement is a success and another a failure, in the phenomena of organization, and not in those of mind.

If the final conclusion above reached is true, there should be no difference, physiologically, between a voluntary and a reflex movement. And such we find to be the case. The essential physiological phenomena of a voluntary movement are, an impression upon a peripheral surface, conducted thence along certain nerves to a nervous centre which is thereby excited to a peculiar kind of molecular action, and that action generates what is called a nervous force, which is discharged through another set of nerves upon certain muscles, causing them to contract. The essential physiological phenomena of a reflex movement are precisely the same. The point of present interest in both, cases is that peculiar molecular action of the nervous centres (which, as we have stated, is essentially the same in both cases) which generates the nervous force that is discharged upon the muscles, causing their contraction. Now, if there is no essential difference, physiologically, between a voluntary and a reflex movement, in what do they differ? Of course, the former is the latter with volition superadded, or the latter is the former with volition deducted. And what is volition? Volition is simply a peculiar molecular action of a nervous centre of motion reflected upon consciousness—translated into a state of consciousness—symbolized in consciousness. The mental part of the phenomena—the volition—being simply a state of consciousness—a consciousness of the molecular action—then, the molecular action is a condition precedent to that state of consciousness which is a symbolical representation of it. The molecular action, being precedent to the symbol of itself, cannot be determined or controlled by that symbol—that state of consciousness—that mental part of the phenomena which we call volition. Therefore, if from a voluntary movement we strike out the only mental part—the volition—which, as we have seen, is not a factor, what is left is as purely organic, and hence as purely reflex or automatic, as the movements of a decapitated frog upon the application of an external irritant. Of the truth of this we may satisfy ourselves by simply looking at the nature of a voluntary movement from another point of view. Thus, I will to move my arm, and it moves. The only voluntary part of that very complex operation is the volition itself. I do not intentionally and knowingly direct the nervous discharge along one set of nerves rather than another, or upon one set of muscles rather than another; nor do I knowingly and intentionally cause one set to contract and another to relax, or one to contract much, and another little, and another less. All these things, which are so numerous and complicated in that one movement, and which constitute the whole of the mechanism, are purely automatic, being not in the least dependent upon the mental part—the volition—although wholly dependent upon that organic activity of which the volition is a symbol in consciousness. It is easy to understand, therefore, that if the molecular action which generates the nervous force that causes a reflex movement could be symbolized in consciousness, that symbol could not be called anything but a volition—a mandate for the movement. As many reflex movements are movements which were once voluntary, and have become reflex by a withdrawal of them from the sphere of consciousness, to relate them again to consciousness would be to make them again voluntary. While it is very easy to understand how a reflex movement might thus be converted into, or restored back to, a voluntary movement, it is an actual fact that by dislocating consciousness from its connections with voluntary movements we at once make them reflex or automatic, as is the case, for example, in many habitual or oft-repeated movements, such as the fingering of the keys of a piano when the music is known by heart. The following singular case is also in point: Many years ago, a medical gentleman related to me a case which came under his own observation, namely, that of a lawyer, who, without any other perceptible physical or mental disorder, would, in the course of ordinary conversation, let slip one or another legal term between words and in sentences with which it had no connection whatever. They seemed to utter themselves without any volition on his part, and in fact he did not know that one was coming until it was pronounced. The muscular movements in such cases are wholly automatic, which means wholly organic, without any associated mental phenomena.

From the foregoing considerations it is evident that a scientific solution of the problem of voluntary motion (and that of the will which is based upon it) requires a full and separate consideration and explanation of four distinct branches of the subject, namely:

1. The genesis of the power of voluntary motion, or its differentiation from some mental power which preceded it; and how it was differentiated.

2. The evolution of the power of voluntary motion considered as an organic procedure in the entire animal kingdom, by which it was developed from its earliest genesis up to its highest capabilities in man, as the result of such changes in the faculty, from any cause whatever, as were transmissible and transmitted by inheritance.

3. The maturation of the power of voluntary motion considered as an organic procedure in the individual (man, for instance), by which it develops or ripens through the gradations of evolution independently of the operation of any external cause, such as education and experience.

4. The acquisitions of the power of voluntary motion, or whatever is added to the maturing or matured faculty, by which it is enabled to do with greater ease, freedom, force, or dexterity, what, without evolution and maturation, it could not do at all, and could never be educated to do.

In view of these obvious facts, were we to venture a criticism of Bain's celebrated treatise on the will, we should say that his method is defective, inasmuch as he has disregarded those natural and important divisions of the subject which we have pointed out, each of which requires a separate treatment. The careful reader will be able to discover not a little confusion in that treatise, and will be able to trace it to the fact that the distinguished author has treated as a unit things which are so dissimilar; and especially is this true of his method of dealing with maturation and acquisitions, by which the reader is led to believe that acquisition is maturation, and maturation is acquisition.

 
Rule Segment - Span - 40px.svg Rule Segment - Span - 40px.svg Rule Segment - Flare Left - 12px.svg Rule Segment - Span - 5px.svg Rule Segment - Circle - 6px.svg Rule Segment - Span - 5px.svg Rule Segment - Flare Right - 12px.svg Rule Segment - Span - 40px.svg Rule Segment - Span - 40px.svg
  1. Rush, "Medical Inquiries and Observations on Diseases of the Mind, p. 254.
  2. Abercrombie, "Diseasse of the Brain and Spinal Cord," p. 292.
  3. Ibid., pp. 293-295.