I.
Such, as far as it can be compressed into four short essays, is the nature of protoplasm. We have sketched out its powers; described how it exists only in the form of a cell; and shown how cells, by forming a community and sharing the work, simplify the business of living, and secure great advantages for themselves individually. But now we have something fresh—the body.
The body is an organic whole, like the cell. It is composed of cells, but these cells only develop one of their many powers to its utmost that they may justify their existence in the community; they do not acquire fresh properties. So really the body is merely a mass of protoplasm in which—though in a greater quantity—the same changes are going on that we find in a single cell. Yet how utterly different is the body from the cell! what a wide gulf yawns between a man and an amœba!
The body has powers of its own, distinct from those of protoplasm; and the protoplasm may still be alive when the body it helped to compose is dead. A few thousand pounds of protoplasm could not have built Westminster Abbey, but a few hundred men did; for just as out of protoplasm arises the body, so the body gives rise to the mind, a thing as much above it as it is above the cell.
So far we have taken the cellular units as our starting-point in discussing life; but a bird’s-eye view of physiology would be incomplete which contained no mention of the major tactics of protoplasm—the life of the body. We must consider the needs of a man as such.
A man requires, as we have described before, air and food. The air must contain the proper amount of oxygen, and the food must consist of liquids and solids.
The important liquid is water. More than half by weight of the whole body is water, and we are always losing it: through the skin, through the lungs, and through the kidneys. People may drink alcohol with water, but not instead of it. Indeed, the more alcohol they take, the more water they require, for if they take their spirits in an undiluted form, they take water out of the body. If you dip a piece of wet cloth into alcohol for a minute, it dries with remarkable rapidity, because the water has been absorbed out of it. In the same way, if you drink neat spirits, they pass into the blood and stimulate the nervous system, ultimately being excreted by the kidneys; but on their way through the tissues they absorb a great deal of water, which must be replaced.
Milk is often spoken of as the ideal food, and so it may be for very young animals; but it lacks one important constituent—iron. A young animal is born with enough iron in its body to do without any in its food until it can take something better than milk. If it is weaned late it becomes anæmic. An adult animal requires iron and also a certain amount of solid food. Its alimentary canal is provided with a good deal of muscle; and this muscle, to be kept healthy, must have something to work upon—in fact, be exercised.
A man’s food should contain a certain amount of coarse material—cellulose, for instance, which forms the envelope of vegetable cells. And here we see a distinctive feature of the body. Protoplasm can make no use of cellulose, there is no digestive juice which will act upon it; but its presence in the alimentary canal in the form of husk and small seeds stimulates the walls by contact, and produces peristaltic movements.
In [Essay II.], which dealt with the chemistry of the body, we said that if we were only to live upon meat we should tax our digestive apparatus severely by having to eat more proteid than we required in order to get enough carbon. The converse, however, is equally true: if we fed only upon vegetables, we should again have to over-eat. Plants most of them contain large stores of carbohydrate; potatoes and rice are rich in starch, onions in sugar; but an exclusively vegetarian diet would necessitate our consuming huge quantities, as its proteid-supply is bad. It is defective not only in amount—for sometimes, as in beans, the proportion is fairly large—but in being so indigestible that a good deal of it passes through the body unabsorbed.
Both science and experience teach that we live most economically upon the carbohydrates of vegetables and the proteid of animals, and that our food is the better for being cooked. In cooking, parasitic animals which are strong enough to survive the ordeal by acid in the stomach are killed, and the food itself is made more accessible, the indigestible cellulose envelopes of the vegetable cells being burst open, and the collagen of the connective tissues converted into gelatin.
No less important than the quality of our food is the quantity; and here, again, we get a good illustration of the necessity for regarding the body as a whole. A healthy man’s appetite is his best guide, and if he follows it he cannot go far wrong. People who arrogate to themselves a wisdom superior to that of Nature little know the harm they do when they force food down an unwilling throat. The cells of the alimentary canal digest and absorb what is sent to them, minding their own business, which is not to criticise the appetite.
‘Theirs not to question why;
Theirs but to do and die.’
So the digestive and excretory systems embark on hard and profitless labour, and the whole body suffers.
Passing on to another subject, we find that the body eats that it may work, and works that it may eat. This cycle comes naturally enough to animals which have to go and find their food, but men with a sedentary occupation have, in view of the artificial conditions under which they live, to take constitutional exercise.
There are many reasons why the numerous and bulky muscles with which the body is endowed must be constantly used. In [the third essay] in this volume we saw that the flow of the lymph and the blood in the veins is largely dependent upon the movements of the limbs. Muscular exercise, therefore, must be taken to prevent the circulating streams from growing sluggish. Obviously, many evils must arise if they do so. Not only would the muscles be starved by the slowness with which they received their food, but they would also be poisoned by the slowness with which the products of their own metabolism were removed. The blood-stream would become tainted, and the brain, which requires pure blood, would suffer.
In other ways, however, than by their action on the vessels themselves do the muscles help the circulation. Exercise has secondary effects upon the circulatory and respiratory centres in the base of the brain, and makes the heart beat more strongly and the diaphragm contract more forcibly. The influence of the latter upon the circulation we have already described; but its vigorous action is required not only to aid the circulation through the liver and viscera, but to inflate the lungs to their fullest extent. In the breathing of a man who takes no exercise only a small part of the air which the lungs hold is pumped out at each breath, the greater part remaining stagnant in chambers which are practically unused. Thus, not only is the revenue of oxygen diminished, but there are numerous little crannies in the body filled with still, warm air which are ideal nurseries for bacteria. The devil of consumption does not allow such dwellings to long remain swept and garnished.
Without exercise the sweat glands of the skin will not act, and its pores get closed up. The muscular coats of the alimentary canal, too, reflect in their state of health the condition of the voluntary muscles; laziness is followed by constipation, for if the voluntary muscles rust, so do the involuntary.
The muscles, moreover, must be well developed and kept in a healthy condition for their own sake. They form a large part of the whole bulk, and no healthy man can have unhealthy muscles. Ignorant people sneeringly say that they have no ambition to lift weights or bend pokers; but they should remember that they are dependent upon their muscles for their bodily warmth, and also to save their internal organs from being oppressed by their own weight.
The bones of the skeleton do not rest one upon another; they are jointed, and kept slung in position by springing bands of muscle attached to their levers. If these muscles are not properly developed, they tire under the strain of holding the frame up, and a disastrous rearrangement of the organs is made to save labour. The chest is drawn in, the hips and knees thrust forward, and the man stands with cramped chest, compressed viscera, and his diaphragm under dire constraint. The result of the redistribution of weight is that his bones tend to rest upon one another like a column of bricks, and his whole weight is upon his heels. Such an individual cannot walk; he stumps along, jarring his whole body at every step.
A pleasant contrast is the athlete. The athlete is a man who endeavours to develop the latent powers of his body to the utmost; and in the achievement of this desirable object the physiologist takes great interest. Physiology has revolutionized our ideas of training, as well as many other things, during the last half-century. We now recognise two kinds of training—the preparation which a healthy man makes for an occasion on which unusual exertions will be expected of him, and the slower and permanent strengthening of the whole body, now usually called physical culture. The former is a comparatively short process now that athletes no longer think it de rigueur to live in bestial intemperance when they have no contest in immediate prospect. A little extra exercise, to stimulate excretion and clear away any waste products that may have accumulated in the tissues; a little extra proteid in the diet, since there is at first a slight inclination to growth; a good deal of extra carbohydrate, since the muscles want extra fuel; rest—and the man is ready. Many athletes live continually in training, and are ready at any moment to ‘fight for their lives.’
The second kind of training is for those who are weakly or those who wish to excel. Its object is not only to improve the health, but to increase the absolute strength and size of the body, and its effects are permanent. It necessitates careful diet and constant exercise for a long period, and proves equally beneficial to both sexes. This book has been written in vain if the reader has not grasped by now that the activity of the muscles implies the activity of all the organs in the body. Accordingly, the whole muscular system is by appropriate methods given frequent exercise: gentle at first; never exhausting; but constantly increasing as the strength grows. The result is a general development of the organs throughout the body, which will in time work a complete metamorphosis in the individual’s physique.
Yet by strength alone no athlete can excel; success depends upon skill. He must have the strength to work with, but he must have the knowledge to apply it without wasting energy, and the ability to do this with precision. He must practise well the sport he intends to adopt—in other words, train his central nervous system.
Here, again, we must hark back to the main idea—the unity of the body. We have already dealt in this essay with the bodily needs in the way of food and exercise, and we must now consider the needs of its nervous components. The chief of these is education; but education of the nervous system means, of course, education of the whole body. There are still people who cling to the old fallacy that the mind can be developed at the expense of the body, but a visit to a hospital or a lunatic asylum will afford many opportunities of seeing how Nature avenges ill-treatment of ‘those delicate tissues wherein the soul transacts its earthly business.’ Physical culture must come before mental: Mens sana in corpore sano—hackneyed, but true.
I do not, of course, say that a man must develop equally both his body and mind; only, that the former must be functionally competent. The absurdity of supposing that the brain can benefit by forming part of an unhealthy body is, surely, obvious to all. Determined invalids may produce splendid work, as Darwin did, in spite of ill-health, but not because of it, and men of great mental energy will sometimes wear themselves out prematurely by their restlessness; but starvation and maltreatment of the body will not create intellect, however morbidly it may stimulate the imagination.
Granting the tenement of a healthy body, the education of the central nervous system must proceed along four distinct lines. A child must learn useful reflex actions, such as walking; have its association centres trained, that it may reason quickly and correctly; be endued, if it is not to live upon a desert island, with a sense of moral responsibility and ethical principles; and have its head stored with useful facts, from the meaning of words and the A B C to the value of the coinage.
Few people seem to realize how much a child has to learn before it gets to the A B C. It begins life with very little beyond a capacity for learning, and even its sense organs tell it little until it has had practice in using them. If baby is so unfortunate as to get a scratch from a pin, he wriggles, and makes the whole house aware of it; but he does not seem to have a clear idea at all as to where he is hurt. He has to learn the way about his own body. He passes his hand over his face, and learns that he has features with a definite position and magnitude; he then waves his arms in the air, and learns that there is such a thing as empty space; finally, he knocks his knuckles against the edge of his cradle, and learns that there are other things in existence besides himself. Of course, his eyes help him considerably to form his ideas of things, but his eyes tell him nothing until he has learnt how far to believe them by correcting their impressions by touch. He learns the properties of matter by experiment, not intuition.
Very interesting experiments have been made upon people who have been born blind, and to whom sight has been given late in life by an operation. They generally take some time to appreciate their good fortune. Things, they say, are all pressed up against their eyes, and they are afraid to move. Objects with which they have carefully been made familiar before the operation—wooden spheres, cubes, cones and prisms—they have been absolutely unable to recognise by sight until they have handled them. They have mistaken sparrows for tea-cups, and it is sometimes only after weeks that they have suddenly discovered that pictures are something more than a mixture of irregular splashes of colour on a flat surface.
Babies have to learn to interpret what they see in much the same way, and take longer about it. The child who cries for the moon is probably not so unreasonable as people think. He focuses his eyes upon the little, bright, sharply-defined disc, and it appears to him, if not actually within arm’s length, at any rate near enough to be caught with a butterfly-net. It is only after he has seen it sink behind a large tree on the distant horizon that he gathers a vague idea of its real size and remoteness.
The term ‘physical culture,’ as usually applied, is supposed only to mean the development of the muscles and viscera; really it only begins there. After the organs of nutrition have been got into a healthy state the motor organs are developed. Finally the nervous system should be trained. Mere muscle will not make even a good runner. He must practise carefully till he can take his full stride, and do so without wasting energy by any needless movements. Then he must make the action which his brain has decided is the most effective for his build the property of his spinal cord, that in a race he may use his strength economically, with his thoughts free to deal with the tactics of his opponents and the peculiarities of the course, or he will not make his supreme effort at the most advantageous moment. This is only one instance. Many men having a normal body develop organs of perception, not motion: the musician and the wine-taster, as well as the juggler and the athlete, are products of physical culture. Even the philosopher must foster the physical basis of intellect.
The education of the nervous system goes on all through life; and just as oft-repeated actions become automatic, so are habits of thought formed which are almost as regular; in fact, we might almost call them cerebral reflexes. Without constant exercise, men lose their flexibility of mind as well as of body.
But we have already passed the boundaries of our subject, and it is time for us to pull up, lest we trench further upon another science; for the study of the mind is the province, not of the physiologist, but of the psychologist.