Our Wonderful Bodies
Living Machinery. By A. V. Hill. (Bell. Is. 6d.)
PROFESSOR HELL'S book consists of lectures delivered before
" a juvenile auditory " at the Royal Institution during the Christmas of 1925. If children can understand the Professor's explanation of how a nerve works, then we adults have unquestionably much to learn. We can immerse an iron wire in nitric acid and make it carry a wave of electro-chemical energy similar to that carried by the nerves. Still, it is not a living thing, How our nerves conduct messages in the body is not yet clear, but " there is nothing essentially mysterious in it : with the help of physics and chemistry we ought to be able to understand it, and when we do, we shall find (as people have found with X-rays and wireless and countless other things) that there are all kinds of ways in which we shall be able to use the knowledge which we have gained."
The marvellous, and until lately, unknown nervous pro- cesses of the body could never have been discovered except for the very delicate instruments which have been made available by the popular use of wireless. There is an electric " potential for instance, Professor Hill tells us, coursing through the nerves of the human body which is different in degree although not probably in kind from the emanations of a strange Japanese fish which is equipped with an electric battery in its head. From this battery it can liberate a dis- charge of thirty volts, which in sea water would give a man a nasty shock, thereby paralyzing or stunning his prey. Is it unreasonable to assume that the phenomena of telepathy in human subjects are dependent on some force similar to that possessed by this fish ?
Our heart, of course, is the most important organ in the body, and although William Harvey discovered the circulation of the blood about three hundred years ago, Professor Hill very rightly says that in a sense we are only at the beginning of our knowledge of the subject. We remain in ignorance of the fundamental nature of the mechanism of the cardiac muscle cells, of their rhythm, and of the electric charges which can be detected when a heart beats. Our pulse is not a flow of blood but a wave of pressure varying at different ages. In a child it runs four or five yards a second. The voice of the heart tells much to the ear of a doctor.
When the muscle contracts there is a low-pitched-whirr which generations of medical students have heard described as LUVV. When the muscle relaxes the blood rushes back and would fill the heart again were it not for the valves, which promptly close with a sharp and high-pitched DUP. " This luvv, dup, pause ; luvv, dup, pause, can be picked up by a microphone and amplified till the sound of a man's heart can be heard all round a hall. It can even be broadcast so that physicians all over the country can diagnose its condition."
Imagine fifty years ago a prize offered to anyone who could do this, or could photograph the inside of the body of a living child. Yet now such things are perfectly possible, and Professor Hill shows us an X-ray snapshot of the chest of his daughter : we can see her lungs, heart, and diaphragm ; it would have been just as easy to show the beating of her heart or the breathing of her lungs on a cinematograph screen.
Finally, we must consider Professor Hill's charming dis- quisition (illustrated) on why a cat falls on its feet. If a cat, asleep or awake, is held upside down a few feet off the floor and suddenly released, it can always right itself. How does she manage this ? With no support in space she turns herself round in a great deal less than a fifth of a second, lands right way up, puts her ears back, whisks her tail, and walks away rather annoyed and certainly not realizing how clever she has been. " All this skilful movement, executed largely unconsciously by means of the beautiful mechanism of incoming and outgoing impulses, can be studied by means of the slow-motion cinematograph." Such slow-motion study is of importance for skill in" games, for our success in sport depends largely on the employment of a jerk. In throwing a cricket ball, for instance, the body and arms are rapidly moved, but it would be impossible to develop the energy required to project it from the hand at eighty miles an hour without a jerk. At the appropriate moment a check is introduced which causes a wave of energy to pass along the arm, centring it at the psychological moment in the fingers in which the ball is held. Everything must be exactly right, every adjustment made of momentum created, of check introduced, of jerk propagated along a
partly rigid body. The process is not thought out, yet if the timing of the muscles were a few thousandths of a second wrong, the throw would be a failure. Living Machinery makes us understand what a long and fascinating road we have to travel before we can say (if we shall do so) that we really know ourselves and are captains of our fate.
Healthy Growth is the life-work of a man who could have followed the most lucrative paths of Medicine, but chose instead to devote his youthful abilities to the children of the poor and the prime of his manhood to laying the foundation of modem educational physiology. As Sir Arthur Keith well says : " This is a book which may make medical men- proud of their profession, for it is written by an acute observer who is not only a Medical Officer but an educationalist and a philanthropist." All of us should read it who are interested in education or even in our own health, for it is packed with interesting information.
The days when teachers gathered into schools large numbers of ill-fed and even ailing children for an examination by school inspectors is mercifully a thing of the past. Yet we are only at the beginning of the scientific study of matters such as the buoyancy index of adolescents, routine medical examination of the skin, study of sleep and over-fatigue and diet and stamina and growth, and output of work. These experiments, which have been carried out over a number of years at the Manchester Grammar School, should be studied by parents, head-masters, and educational authorities. For many years to eome they will form the standard by which doctors and teachers together will base the researches that are necessary before we may understand the wonderful and delicate pro- cesses that go on in the brains and hodies of the young.
Since Dr. Berriran wrote his classic, The Glands Regulating Personality, a great many fantastic things have been said about those curious repositories of essential bodily juices, the endocrine glands. Dr. Cobb does not appear to have any- thing which is new to tell us in his latest volume, but his work is frankly popular and is to be welcomed as such, foi the subject is one on which the public should have the guidance of qualified men, rather than essayists or " quacks."
The time may soon come when instead of speaking of the sanguine, the phlegmatic, or the bilious temperament, we shall allude to individuals as adrenal-centred, thyroid-dominant, or thymo-centric. A man who knows what he wants and gets it will -be found to possess in a very active condition those two little glands above his kidneys which secrete adrenaline into his blood-stream. And he who is deficient in the essence of that ounce of mystery in his throat, known as the thyroid, is irritable, unreasonable, unduly emotional, and may develop goitre and become a cretin. At the base of the brain, again, in a cavity shaped like a Turkish saddle lies the -pituitary, which is apparently concerned with a restraining influence on sex and growth. It also has some as yet unexplained influence on sleep. Then there is the pineal, which may be a vestigial eye and may have functions in the future still unknown to us. Some mystics assert that it is the organ of second-sight. From infancy to age our destiny is largely shaped by our internal secretions. Many riddles are still to be solved, but bit by bit the puzzle is falling into place.
Perhaps the most interesting chapter in a book abounding with interest is that dealing with civilization and warfare. From savagery to civilization man has had to play many parts. " As the centuries passed the human being developed his frontal lobes at the expense of his biceps and learnt how to cook, while his tail atrophied." We are becoming brainier but less muscular. In the recent War, the most terrible of all history, the human machine was severely tested in its glandular functions : the adrenal glands of the soldiers were overworked, with the consequence that afterwards " a post- War neurosis stretched across the world." What are we to dci now with these glands of fighting ? How are we to sub- limate their activities ? It will be an age-long business, but specialization is no new thing to mad, and there is no doUbt that • all our glands are capable of reorganization and re- adjustment : the processes of our bodies may be modified in accordance with our wishes, and will be so modified as humanity evolves. Temperament, in short, is largely an affair of the balance of various glands of internal secretion, and although in saying this we are no nearer to a solution of the mysteries of life and character, yet in acquiring a knowledge of these mechanisms our feet would seem to be definitely on a path which will lead to greater self-control and therefore to greater happiness. F. Y.-B.
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