SOME PHYSIOLOGICAL ERRORS.
One of the notable examples of popular delusions regarding bodily structure and functions, is exemplified by the belief that the third finger was selected as the bearer of the wedding-ring because a particular nerve placed this member in direct communication with the heart. Over and over again has this belief been expressed, and in the belief is found an apparently satisfactory reason why the third finger is thus honoured. The slightest acquaintance with physiological science shews that the supposition referred to has not even a germ of probability to shew on its behalf. The ring-finger is supplied with nerves according to the rule of nervous supply in the body generally, and, it need hardly be said, without the slightest reference to the heart; the nerves of which in turn are supplied from an independent source and one quite dissociated from that which supplies the nerves of the hand.
Equally curious and erroneous beliefs intrude themselves into the domain of medicine and surgery. Thus for instance it is a matter of ordinary belief that a cut in the space which separates the thumb from the forefinger is of necessity a most dangerous injury. The popular notion regarding this region is that an injury inflicted thereupon is singularly liable to be followed by tetanus or lock-jaw. There exist not the slightest grounds for this supposition. Lock-jaw it is true might follow an injury to this part of the hand, as it might supervene after a wound of any of the fingers. But physiology and medicine alike emphatically dispel the idea that any peculiarity of structure which might predispose to the affection just named, exists chiefly in the region of the thumb. It may be that the difficulty experienced in securing the healing of wounds in this portion of the hand—owing to the amount of loose tissue and to the free movements of the part which it is almost impossible to prevent—might favour or predispose to an attack of tetanus. But as the same remark may be made of many other portions of the body, it follows that the thumb-region possesses no peculiarity whatever in this respect over any other part of the frame.
One of the points which has been most hotly contested in technical as well as in popular physiology is the use and functions of the spleen. This organ, as most readers are aware, is a gland, of somewhat oval shape, lying close to the left side or extremity of the stomach. It is one of the so-called ‘ductless’ glands of the body—that is, it possesses no duct or outlet, as do the liver, sweetbread, and other glands concerned with the formation of special fluids used in digestion and other functions. In olden times philosophers puzzled themselves over this mysterious organ; nor was its nature rendered any clearer by the discovery of the fact that it may be removed from the bodies of the higher animals without causing any great or subsequent inconvenience, and without affecting in any perceptible degree the health of the subject operated upon. One classical authority went so far as to allege that he could find no use whatever for the organ; whilst another maintained that possibly it was intended to serve as a kind of packing for the other organs around it, and that it kept them from getting out of their places in the movements of the body. The idea, however, which obtained most credence was that which regarded the spleen as the fountain and origin of all the vile ‘humours’ which rankled the blood and soured the disposition of man. We can still trace in the metaphorical expressions of our literature this ancient belief; so that what at first were regarded as literal and true ideas of the spleen and its use, have come in modern days to do duty simply as metaphors.
Modern science, in dispelling those antiquated notions, has now assigned to the spleen a very important part in our internal mechanism. The part it plays may be thus described. The blood, as every one who has looked at a thin film of that substance through a microscope will know, is in reality a fluid as clear as water, and derives its colour from the immense number of little red bodies the ‘corpuscles,’ which float in it. These red corpuscles of human blood do not attain a greater size than the 1/3500th part of an inch—that is, three thousand five hundred of these little bodies placed in a line would make up an inch in length. In addition to the red bodies, there exist in the blood a much smaller number of ‘white corpuscles,’ each containing a little central particle which the red ones want. From the results of the most recent researches it would appear that the red corpuscles are produced by the partial destruction of the white ones; and that the little central particles of the white globules, when coloured, appear before us as the red corpuscles of the blood. Now the spleen is to be regarded as the great manufactory or depôt in which the red corpuscles are thus produced from the white ones, and in which also many of the white corpuscles are themselves developed. And it would also appear highly probable, that when the red globules of the blood have served their turn in the economy of the body they are broken down in the spleen; their material being doubtless used for some wise purpose in the maintenance of our complicated frame.
A very common idea, but one founded on no certain or feasible grounds, is that which maintains that our bodies undergo a complete change and renewal of all their parts every seven years. The ‘mystical’ nature of the number seven, has had an unquestionable effect in originating this opinion; and although the age of fourteen and again that of twenty-one may be regarded as marking the attainment of youth and manhood or womanhood respectively, yet physiology gives no countenance to the popular opinion that of necessity these periods are those of sweeping bodily change. On the contrary, it might be shewn that the periods at which full growth of body is attained vary with climate, race, and constitution—that is, with the personal nature, and with the physical surroundings of individuals, communities, and nations. The true state of matters as disclosed by physiology, leads us to contemplate actions and changes which are of infinitely more wondrous kind than those involved in the idea of septennial change. For if there is one axiom which physiology maintains more constantly than another, it is that which teaches that constant and never-ceasing change is the lot of life from its beginning to its end.
No part of the body of a living being is free from these changes of substance, through which indeed every act of life is carried on. Every movement of a muscle—the winking of an eyelid or the lifting of a finger—implies waste of the organs and parts which move. The thinking of a thought implies wear and tear of the organ which thinks—the brain itself. Were it possible to spend existence even in a perfectly still and rigid condition, there are still actions to be performed which are necessary for the maintenance of life, and which necessitate continual waste and wear of the tissues. Thus the beating of the heart, the movements of our chest in breathing, and the very act of receiving and digesting food—actions which are in themselves concerned with the repair of the frame—can only be performed through the intervention of processes of work, and waste of body. So that a living being is to be regarded as passing its existence in a constant state of change. Its particles are being continually wasted, and as incessantly renewed; and although the growth of our bodies may be said to culminate at various periods of our life, yet it is anything but correct to say that there are marked epochs of change in human existence. The truth is that change and alteration are our continual heritage; and it is strange indeed to think that not an organ or part of our bodies exists which has not repeatedly in its history been insensibly and gradually, but none the less perfectly, renewed in all its parts. Our particles and substance are being dissipated in very many ways and fashions. Chemically and physically, we are in a state of continual break-down; whilst on the other hand, it may be shewn that the forces of life are enlisted powerfully on the side of renewal and repair.
In connection with the exercise of our senses there are not a few points on which popular ideas stand in need of correction. When we speak of ‘seeing’ or ‘hearing,’ the exercise of these or any other of our senses indeed, is usually referred to the organ concerned—eye, ear, nose, or tongue, as the case may be. A little consideration, however, will shew us that we make a very grievous mistake in referring the act of sensation or perception to the organ itself. Let us consider for a moment what happens when we acquire ideas regarding the form of an object through the sense of touch. We may in the first place ‘will’ to touch the object in question; the act of ‘volition’ as it is termed, originating in the brain, being transformed into nerve-force, and being further directed along the particular nerves which supply the muscles of one finger or along those which supply all the fingers. The muscles are thus stimulated to action, and through their agency the fingers are brought into contact with the desired object. Leaving the sense of sight out of consideration for a moment, we know that we can through the sense of touch gain ideas regarding the form, size, hardness, and other qualities of the object. Our nervous system is thus bringing us into relation with the outer world and specially with that portion of it represented by the object we have touched. But how have we gained our knowledge? The reply to this question leads us at once to perceive that the tips of the fingers do not represent the seat of knowledge. And a further consideration makes it equally clear that the brain must be credited not only with the task of perceiving, but also with that of appreciating what has been perceived. Hence we are forced to conclude that just as the first nervous impulse shot through the nerves to the fingers, so a second impulse has passed from the fingers to the brain. Our sense of touch has given origin to a subtle force which has passed upwards to the brain, and has there become transformed, through a mechanism—of the working of which we know as yet absolutely nothing—into perception and thought. Similarly with the work of the eye, of the ear, and of other senses.
When we talk of seeing or hearing, we are in reality speaking of the act of the brain, not of the eye or ear, which are merely the ‘gateways’ through which the brain obtains its knowledge. And that the brain is the true seat of the senses, may be proved to us from the side of pathology—the science which makes us acquainted with the causes and nature of disease. Cases are well known in which injury of the brain as the seat of sense has given origin to depraved sensations. Post-mortem examinations of persons who were continually conscious of a disagreeable odour have proved that these persons had laboured under brain-disease; whilst one case is on record in which, after a fall from a horse, and for several years before his death, a person believed that he smelt a bad odour. So also the sense of sight may be altered from internal causes, and on this ground may be explained the real nature of many cases of so-called ghost-seeing and spectral illusions. One well-known case, in illustration of this latter point, was that of Nicolai, a Berlin bookseller, who, neglecting to be bled in accordance with his usual custom, began to see strange persons in his room, and faithfully described the appearance of the figures. The figures disappeared when he had been bled once more. Thus in all such cases we must believe that those parts of the eye or ear which would have been concerned in seeing the supposititious objects or hearing the supposititious sounds—had either existed—were irritated from the brain and produced the delusive sensations. Thus the common phrase that ‘seeing is believing’ is in one sense literally true; for the act of sight apparently exercised in the person who suffers from optical illusions is in reality performed by the brain and is thus an act of belief, even if it be one of unconscious kind. The entire subject of physiological errors teems with valuable applications, but with none more practical or worthy of remark than that which would insist on the advantages, in the ruling wisely of our lives, to be derived from even an elementary acquaintance—such as should be included in the curriculum of every school—with the science of life.