Hadow (1933)

Notes on the text
Preliminary pages Membership, Analysis, Preface, Introduction
Chapter 1 History of the development of infant education
Chapter 2 Physical development of children up to 7
Chapter 3 Mental development of children up to 7
Chapter 4 Age limits and organisation of the infant stage
Chapter 5 Medical supervision, education and training of under 5s
Chapter 6 Training and teaching of children in infant and nursery schools
Chapter 7 Staffing of infant and nursery schools, training of teachers
Chapter 8 Premises and equipment of infant and nursery schools
Chapter 9 Summary of principal conclusions and recommendations
Appendix I List of witnesses
Appendix II Anatomical and physiological characteristics of 2-7 year olds (Harris)
Appendix III Emotional development of children up to seven plus (Burt and Isaacs)
Appendix IV Notes on typical nursery schools and classes
Appendix V Manchester's student nurse scheme for 'helpers'
Appendix VI Practice in Europe and US
Index

London: HM Stationery Office

Chapter 2 The physical development of children up to the age of seven
[pages 47 - 68]

25. There is a large body of traditional opinion about the physical and mental development of infants and young children up to the age of seven. These views represent the garnered experience and observations of successive generations of parents, nurses, teachers, inspectors and administrators. Of late years, however, there has been much systematic study of children in the earliest years of life, and in consequence the accuracy of many of the older notions about the growth, habits and capabilities of young children has been called in question by scientific investigators - both physiologists and psychologists. We accordingly regard it as important for the purpose of our present inquiry to summarise such knowledge as is available regarding the anatomy and physiology of growth, and the general mental development of young children.

Teachers, parents and nurses will appreciate the significance of the inferences that may reasonably be drawn from the summary of the basic facts of bodily and mental development which is attempted in this and the following chapter, and we believe that the necessity of recognising adequately the general characteristics of young children during this early stage of their development will justify a close study of such physiological and psychological evidence as is available.

THE GENERAL CHARACTERISTICS OF EARLY CHILDHOOD

26. Childhood is the period of life most abounding in problems for the parent, the physician, and the teacher. Too often at present parents are overwhelmed by the responsibilities of their problems, confused by the experience of other parents, and unable to appreciate the extent to which their children are influenced by the example of other children, rather than by the precepts of parents. The physician or surgeon is often at a loss since he is asked to treat abnormalities or disorders of growth before he is thoroughly versed in its normal features. (1) The school teacher often knows little of the interaction between physical growth, health, and intellectual and emotional performance. In Section 33 on the growth curve, an attempt is made to give a brief sketch of the salient characteristics of growth in children, but as is pointed out in that section, the representation of the process of growth by a mathematical curve is only partially accurate, and for this reason an attempt must be made to indicate in greater detail the complexity of the process of growth in young children, and to emphasise the extensive gaps in our present knowledge.

The results of aberrations in growth in young children are at least as manifest as the results of errors in social adjustment. The causes of such aberrations are more easily ascertainable, and steps can more easily be taken to obviate them.

The processes of growth which operate in the human organism are more numerous, more delicately balanced, and more rapid during early childhood than at any other period of life.

GROWTH

27. Growth in the true sense of the term implies far more than mere change in form and size. It includes that gradual development from the embryo to old age which involves the acquisition of new functions and fresh responses to the environment by the unfolding of new patterns of behaviour. The mere morphogenetic aspect of growth which was so carefully studied by the older anatomists is inadequate, and in order more completely to understand growth a place must be found for concepts which are on the one hand frankly physical, chemical or biological, and on the other hand psychological. Our real interest in young children is not determined by their anatomical structure, but by their changing activity and behaviour as they pass from one stage of development to another. The rate of change, and the variation in the rate of change from child to child must also be carefully observed and studied. A process so vast and yet so self-contained as growth in the young child cannot be adequately analysed by mere studies, however carefully made, of form, height and weight. It is exceedingly difficult to make a quantitative estimate of the changing form of a child, and an appreciation of the general characteristics of an individual child is probably of more use than the record of a large number of indices such as those presented in the mass statistics of anthropometrical reports. It must, however, be pointed out that the capacity for remembering and presenting the general characteristics of individual children is poorly developed in the average parent, teacher and doctor. Few parents or teachers can give a coherent account of the particular growth and characteristics of behaviour of any given child in earlier years, say from the age of two to that of seven. Both the anatomist and anthropologist have failed to explain the essential phenomena of growth. Biochemistry has added considerably to our knowledge; genetics may add much; further study of the effect of environment on physical aspects of growth may prove fertile of results.

THE INFLUENCE OF ENVIRONMENT ON GROWTH

28. It is necessary to consider briefly the manner in which growing organisms, whether animals or plants, react to the conditions of their surroundings. The rate of growth is most intense and most rapid in the earliest stages of development. For instance, the human embryo (ovum) two weeks after fertilisation doubles its weight within the third week; the embryo three months after the beginning of gestation doubles its weight within the fourth month. The new born child takes six months to double and a year to treble its birth weight.

External conditions do not act with equal intensity at all stages in the growth of a developing organism, but the effect of environment is more noticeable at the period when growth is more active. It would appear to be a law of general application that the permanent effect of environment on the growth of a developing organism diminishes rapidly and regularly from the time of fertilisation onwards.

The extent to which a retardation or acceleration of growth induced at any particular stage of development may persist throughout childhood is difficult to assess. Such an effect, produced in the earliest stages, may be wholly rectified by a subsequent variation in the rate of growth. The fact that variability in height and weight decreases with growth, indicates that there is a definite tendency for earlier irregularities to be eliminated. The health of the mother during pregnancy and of the child during its early years are reflected in the physique, constitution and health of the child in later years.

SLOWNESS OF GROWTH IN MAN

29. The growth curve in most domestic animals shows a gradual decrease in the rate of growth from birth to maturity with no stages of relative retardation or acceleration. The loss of weight in the human baby shortly after birth, ranging from 5 to even 10 per cent of its weight at birth, does not occur in the domestic animals. The curves for domestic animals exhibit a process of growth with a rapid passage from babyhood through childhood to puberty. Most domestic animals reach puberty at a time when their bodily weight is roughly one third of their weight at maturity. Man, on the other hand, has a long drawn out period of childhood, with seven or eight years intervening between the stages of commencement of the second dentition and the onset of puberty. At puberty the boy or girl has attained roughly two thirds of the adult weight. Except so far as the growth curve in man may resemble the growth curves of anthropoids, about which the available information is very meagre, it is wholly distinct from the growth curve in all other animals. It would, therefore, seem that arguments about growth in children based on analogies drawn from the lower animals are apt to be fallacious.

THE FOUR MAIN ASPECTS OR TYPES OF GROWTH (2)

30. There are at least four clearly defined aspects or types of growth in the human organism, the skeletal, the neural, the lymphoid, and the genital. On the other hand it must be emphasised that these four types, aspects or systems of growth are at best only imperfect representations of the complexity of the processes actually involved.

The skeletal type. Skeletal development, which may be represented graphically as a growth curve, related only to modifications in height and weight, cannot be regarded as an adequate representation of the profound changes that take place at successive stages in the development of any given child. Almost every external linear dimension of the body, except the head and neck, falls under this type of growth. The skeleton as a whole, the length of the limbs, the development of the thoracic cage, of the respiratory apparatus and of the muscular system, present this general type of skeletal growth.

The neural type. The brain, the spinal cord, the eyeball and the skull display a peculiar type of growth that may be described as neural. During the first eighteen months of postnatal life these organs develop with great rapidity. When the infant has reached the age of two, his brain has attained 60 per cent of its adult size, and by the age of seven it has almost reached adult size.

The lymphoid type. The lymphoid tissue of the body, as illustrated by the lymphoid glands, tonsils, and thymus, develops rapidly in childhood, and continues to grow at a somewhat slower rate up to puberty. Professor HA Harris pointed out that this type of growth must be of profound significance in young children, since one of the most important functions of the lymphoid glands is to act as a defensive mechanism against both acute and chronic infections.

The genital type. The genital organs present a distinct type of development. These organs grow but slowly in infancy, are almost stationary from the age of two to that of ten, and develop rapidly in the two years before puberty, during puberty and later adolescence.

THE EXPERIMENTAL ASPECTS OF RETARDED OR ARRESTED GROWTH

31. In Section 30 of Chapter 2 of our report on The Primary School (1931) we gave a description, based on Appendix II to that Report, of the evidence for arrested skeletal growth in children due to illness and malnutrition. We there stressed the fact that our knowledge of arrestation of growth in organs other than the skeletal tissues was at present imperfect.

A considerable body of data bearing on the arrestation and retardation of growth has been derived from experiments in the dieting of animals. The importance of appropriate food arid the nature of its constituents has been more clearly recognised in the keeping of farm animals than in the home or the school. Growth can only take place by the assimilation of food material, and the rate of growth must be adversely affected unless there is a surplus of food over and above what is required for the other needs of the living organism. There are many experiments which prove that abundance of food is more advantageous and profitable in the earliest stages of animal husbandry.

In the course of recent experiments, it has been found that the problem of retarded growth in animals is extraordinarily complex. For example, an animal on a diet without salt dies before an animal on absolute starvation diet. It would seem that of all the methods that may be employed for the rapid arrestation of growth, salt starvation and the withdrawal of fluids are the most potent. Even at the present time when the importance of the various mineral constituents, such as calcium, in the diet is more or less adequately recognised for children, suitable fluids such as milk, skimmed milk, oatmeal water, barley water, or ordinary drinking water are often not provided in sufficient quantity.

RESUMPTION OF GROWTH

32. The question regarding the extent to which an animal, whose growth has been arrested, can recover strength and make up for lost ground on the restoration of favourable conditions is of great interest. The available evidence obtained from recent experiments is briefly described in Appendix II to our report on The Primary School. Here it will suffice to emphasise how varied are the factors which lead to the arrest of growth. Apart from the adequacy or sufficiency of diet, there is an important distinction between acute and chronic arrestations of growth. The former is most frequently observed in the acute affections of childhood, such as measles and whooping cough (if complicated by severe bronchial pneumonia), scarlet fever, diphtheria, typhoid; the latter in long-standing affections, such as tuberculosis and empyema. In metabolic diseases, such as diabetes, the arrest of growth may be proportional to the severity of the disease, and may only occur during acute exacerbations. In rickets, the bony abnormalities are produced only during the period of growth.

THE SUCCESSIVE STAGES OF GENERAL (SKELETAL) GROWTH IN YOUNG CHILDREN UP TO THE STAGE OF ADOLESCENCE (3)

33. During the month before birth the infant grows at a more rapid rate than at any other period. During this month the child increases in weight by one per cent every day. During the first year of postnatal life the baby grows rapidly and this stage may be described as the first 'springing-up' period. Between the ages of one and five years the normal infant grows more slowly and more steadily; this stage may be described as the first 'filling-out' period. From the age of about five to that of seven there is a second 'springing-up' period. At this stage of the development the child increases rapidly in height, begins to lose his milk teeth and cut his second or permanent teeth; he becomes thin and long in the limbs and exchanges the chubbiness of babyhood for the characteristic family countenance. At the age of about seven the head of the ordinary child is almost as large as it ever will be. Between the ages of seven and eleven or twelve, according to sex, there is a second 'filling-out' period, with steady growth. After the age of eleven or twelve there is a third 'springing-up' period associated with puberty, and after the age of fifteen or sixteen there is a third and final 'filling-out' period lasting up to the age of nineteen or twenty as puberty gives place to the stage of adolescence.

It will be seen on comparing this brief statement, with the diagram illustrating the growth curves (4), that each of the three 'springing-up' periods is in its turn followed by a 'filling-out' period. Each of these stages has its peculiar characteristics. The normal development at each of these several stages is liable to be disturbed by oscillations of growth and may be appreciably modified by diet, environmental conditions and diseases. It should be mentioned that several physiologists have recently described the human growth curve as exhibiting only two outstanding periods, of accelerated growth, that immediately before and after birth, and that of adolescence. These two stages of rapid growth are, according to this view, superimposed upon a process of steady development, out of which the accelerations arise. This process of regular and steady growth leads, in healthy children, to an annual increase in weight of about 4Ib (2 kilograms) between the ages of two and twelve. In the present brief statement, however, the older view of three 'springing-up' periods has been retained on clinical grounds which, in the present state of research, appear to be more trustworthy. The graphical representation of the second 'springing-up' period between the ages of five and seven is obscured to a great extent in statistical curves of height and weight. It is found, however, that when children are examined as individuals the changes in body build at the time of the onset of the second dentition are noticeable and significant. The rapid increase in height and foot length, the modifications in the proportion of the limbs and the peculiar liability to certain diseases, justify the retention of the older conception of three 'springing-up' periods. It is impossible to overemphasise the fact that curves of height and weight give a very imperfect picture of the interrelated patterns of growth in the various systems of the human body. At any one particular moment in the child's life one or more organs show a rapidity of growth which may or may not be reflected in the development of other organs. Furthermore, the ages selected in discussing the six stages of growth should be regarded as rough land marks only and not as strict lines of biological demarcation.

THE COMPARATIVE INCIDENCE OF CERTAIN DISEASES AT SUCCESSIVE PERIODS IN THE CHILD'S DEVELOPMENT

34. The available evidence indicates that the three 'springing-up' periods are peculiarly associated with certain diseases, and that illness tends to leave more severe sequelae if it comes within one of these periods, when the child's organism is already taxed to the utmost in providing the energy required for growth. During the first 'springing-up' period to the end of the first year of postnatal life, the infant is specially liable to certain nutritional diseases, such as infantile diarrhoea, rickets, and digestive disturbances. During the first 'filling-out' stage, between the ages of one and five, and during the second 'springing-up' stage, between the ages of five and seven, the incidence of acute infections and fevers, such as measles, scarlet fever, chicken pox, whooping cough, and diphtheria, is heavier than at other periods. Some of these epidemic diseases tend to leave serious after effects; for instance, measles and whooping cough, which involve the respiratory tract, may be followed by tuberculosis in the glands of the chest, and scarlet fever in children between the ages of five and seven is not infrequently followed by running ears and inflammation of the kidneys. Moreover, the milk teeth of many children frequently become carious. Oral sepsis ensues in many cases, and causes much ill-health from septic products being either swallowed or absorbed from the gums. Furthermore, the tender teeth and inflamed gums lead to digestive disturbances as a result of faulty mastication.

During the second 'filling-out' period between the ages of seven and eleven, the incidence of acute infectious diseases is less heavy, but the chronic sequelae of preceding infections may be observed in many children. It will thus be seen that children are on the whole more liable to infectious illness during the lower stage of primary education. It has been found that the risk of the spread of infectious diseases among young children at school is largely reduced when the school buildings are designed on open-air lines and when there is an adequate allowance of cubic space for each child. The most important single factor in reducing the incidence of infectious disease is that the school should be of open-air design. (5)

THE MASTER TISSUES OF THE BODY AND THE EFFECT OF STARVATION ON THEM IN GROWING CHILDREN

35. Throughout all the vicissitudes of growth, certain tissues of the human body are distinguished by their capacity to resist the effects of starvation or disease. For instance, the brain maintains its growth and activity in a remarkable degree; the heart and the diaphragm resist wasting so that the circulatory and respiratory systems may continue to function; the liver as the laboratory of the body, and the kidney as its main excretory organ, approach the brain, heart and diaphragm in resisting unfavourable conditions. For this reason they are justly described as 'master tissues' and are the last to be influenced by starvation. The blood also may be regarded as a master tissue, since it makes efforts to retain a constant composition during starvation. If there is, however, any shortage of minerals or salts the resistance of the blood rapidly collapses and anaemia results.

The skeleton has not the resistance of a master tissue, particularly when the diet is inadequate in mineral salts or vitamins. The growing organism of a young child will indeed make an effort in such circumstances to increase in length, but the quality of the bone laid down is poor. The tissues which waste most rapidly in starvation are the subcutaneous fat, the fat in the abdominal cavity, the voluntary muscles of the limbs, and the involuntary muscle of the gut. The wastage of the muscles tends to be selective, and among the first to be involved are usually the deltoid muscle of the shoulder, the muscles of the buttock, and the vastus internus above the knee. Later the flexor muscles of the forearm and the muscles of the calf begin to atrophy. As a result of the wastage of fat and muscle, the skin becomes loose, wrinkled and unhealthy. Inasmuch as the wastage of the subcutaneous fat and muscles of mastication is so variable, it is not possible to gauge the degree of bodily wastage by the facial appearance only. The characteristics of behaviour in underfed children are also variable and difficult to assess. As in starved animals, the response to starvation or malnutrition in children in the earliest stages may be increased activity, either muscular or mental, to be followed in the later stages by comparative inactivity and mental apathy, leading to muscular inertia and lethargy. In particular, the difficulty in maintaining sustained effort of any sort is very noticeable. Inactivity and mental apathy in a child should call for an investigation of his dietary, both in its quantitative and qualitative aspects.

THE AMOUNT OF FOOD CONSUMED IN RELATION TO GROWTH

36. One of the commonest errors in dietetics is a belief in the infallibility of the human appetite. It is a complete fallacy to suppose that an undernourished or badly fed child will eat more food if he needs it. Experiments with animals reared on an inadequate diet have proved conclusively that failure in appetite follows failure in growth. This fundamental fact is frequently ignored by parents and nurses, by teachers, and even sometimes by physicians. Sir Frederick Gowland Hopkins in an article in the Journal of Physiology for 1912 writes, 'If then a factor or factors essential to growth be missing from, or deficient in, a dietary, the constant arrest of, or diminution in, growth energy may diminish the instinctive consumption of food, while the supply of such factors may increase consumption as an indirect result of a direct effect upon growth.' This consideration should be borne in mind by teachers and doctors when confronted with the problem of the stunted, undernourished child. The child may seem not to desire more food because it is deficient in quality, owing to his being fed on a diet consisting almost wholly of bread, margarine, jam, sugar, tea, with occasional biscuits, chocolate and beef essences. In such children a remarkable increase in the intake of food may usually be observed almost at once when the processes of growth have been set in motion by adding the dietetic factors that are lacking, viz, fresh animal and vegetable food and cod liver oil. This important truth may be stated in another form. A growing child should have variety of suitable foods placed before him in considerable quantities, so that no loss of appetite may ensue through the omission of some essential factor with a consequent failure of growth. The food should be varied and above all fresh.

THE IMPORTANCE OF AN ADEQUATE SUPPLY OF ANIMAL FATS AND FRESH VEGETABLES FOR YOUNG CHILDREN

37. The results of recent experiments on human beings and lower animals have proved conclusively the importance of an adequate ration of animal fat. When an infant is weaned it is consuming almost a quart of milk a day, containing about one and a half ounces of fat. The weaned child, therefore, in order to obtain the necessary fat, should have a pint of cow's milk and one ounce of butter per day. In view of the fact that many families cannot afford this quantity of milk and butter, but have to feed their children largely on margarine and condensed milk, the average consumption of fresh milk and butter by growing children is frequently only about a quarter of what is really necessary. Sufficient fresh food for growing children is especially difficult to get when there is no garden supply of fresh vegetables and salads, and where fruit is not available. Experiments have shown that the best and most inexpensive way of remedying any deficiency of fresh food is to give a daily ration of about one teaspoonful of cod liver oil to each child during winter months, and an adequate supply of cheaper fruits and vegetables such as oranges, tomatoes, greens and carrots. Where school meals are provided, these considerations should be borne in mind.

THE CAPACITY OF YOUNG CHILDREN TO GROW OUT OF VARIOUS DEFECTS AND AILMENTS

38. The recuperative powers of the organism in childhood are very great, and there is a measure of truth underlying the common expression often used in reference to childish ailments and defects, such as rickets, stammering, failure of control, etc, that the child will probably 'grow out of it'. For the present purpose, it is of interest to examine briefly the extent to which children do in fact grow out of various diseases in the organs involved in the four types of growth described above, viz, skeletal, neural, lymphoid and genital.

(i) In the skeletal organs the power of repair is very considerable. For instance, the slight degrees of bow legs, knock knees and flat feet, which are common in children between the ages of two and four years, often disappear by the age of ten. The pigeon breast and other deformities resulting from emphysema (loss of elasticity) of the lungs, and bronchiolectasis (dilatation of the small tubes) after severe whooping cough and pneumonia largely disappear. Owing partly to their response to exercise, the muscles exert a valuable corrective influence in cases of skeletal defect and aid that innate tendency towards symmetrical growth which is possessed in greater or lesser degree by all the skeletal structures. (6)

(ii) In the organs involved in the lymphoid type of growth, the recuperative power is less noticeable. Nevertheless, careful observation has revealed the extent to which tuberculous glands will heal, provided the diseased part be given adequate rest. The importance of rest, diet and fresh air is so great that many doctors hesitate to recommend operative treatment. Like considerations apply to enlarged tonsils and adenoids. It is now being realised that abnormal conditions of these structures tend, in a considerable number of cases, to subside spontaneously. If the children affected are kept under observation for a period, it is found that the apparent need for operation no longer exists in all cases.

(iii) The organs involved in the urogenital type of growth (e.g. the kidneys) are for the most part exceedingly complex. The kidney is often injured in the acute fevers of childhood. Nevertheless, the nephritis following scarlet fever and diphtheria usually disappears with or without medical treatment, if the child is put on a suitable diet.

(iv) In the brain and the organs of special sense, displaying the neural type of growth, the capacity to grow out of inherent disability seems to be very slight, since the process demands not only repair to the damaged structure, but functional re-education of the tissues involved. In some instances the lesion is so extensive as to result in complete loss of function. In fact, the nervous system as a whole seems to be isolated from the rest of the organism to a remarkable degree. It possesses an amazing precocity of growth, not only in its centre, the brain, but also in the special sense organs. For instance, the brain attains 83 per cent of adult weight in children of the age of seven years, the growth of the eye as a whole is even more precocious than that of the brain: the conjunctival sac which keeps the eye moist, attains adult size at the end of the second year; the eyeball grows with great rapidity in the first two years of postnatal life, and has completed its development by the age of seven. Similarly, the most important stage in the growth of the ear is completed in the sixth month of prenatal life.

The eye and the ear (7) differ appreciably in respect of the effects of age. The eye has to adapt itself to certain definite changes in the growth of the brain, in the eye itself, and in the skull at successive ages. The eyeball itself alters in shape with age, as does also the actual structure of the lens. Defective vision in childhood is usually due to abnormalities in the shape of the eyeball, and the visual acuity in these cases does not always remain constant. Such variations may be regarded as an age change, susceptible to arrestation and to rapid alterations with growth. The irregular rates of growth in different parts of the eye lead to temporary failures of adaptation that are common in young children. The degree of muscular coordination involved in the movements of the eyeball by means of the ocular muscles is high. Imperfect coordination in this respect produces squint (strabismus). In some instances children tend to grow out of this defect, but by far the greater number of cases of squint require correction by glasses, by special exercises, and even by an operation.

EXERCISE AND MOVEMENT IN CHILDREN

39. Animal life, being essentially dynamic, as distinct from static vegetable life, subsists through a series of movements, and all these movements should be sustained in regular and adequate exercises. Respiration, digestion, the circulation of the blood, and all the excretory operations involve movement. If any mobile organ undergoes suspension of movement, its anatomical structure degenerates. Muscular fibres which are not exercised waste progressively with corresponding loss of power. The laws of muscular action, alike in the voluntary muscles of the body, in the involuntary muscles of the blood vessels and in the alimentary canal, require that the muscle, in order to maintain its structure and function, must have adequate exercise.

SLEEP AND WAKEFULNESS IN CHILDREN

40. Sleep is essential for young children, not only to produce a restorative effect on the functions of life, but also to grant respite from the exhaustion produced by enforced standing, and by stationary postures, e.g. sitting. Standing and sitting still alike involve considerable effort for children. In order that sleep may be adequate, it is necessary that it should take place at a stated hour and continue for a definite time in a recumbent posture without any disturbance of the natural functions by overheating, faulty digestion, or vitiated air. In children with a poor circulation, cold feet frequently prevent or delay the onset of sleep. The amount of sleep required varies greatly according to the state of the organism and the temperament and habits of the individual child. Infants pass most of their time in sleep; children under the age of two sleep for twelve or fourteen hours of the day; children between the ages of two and seven may sleep from ten to twelve hours of the day. It is quite common for healthy children to take a considerable time, say half an hour, to fall asleep. Disease or uneasiness of any kind often produces unsound sleep. The diseases most associated with wakefulness are the acute fevers, inflammatory disorders, and brain diseases. Disturbed sleep is frequently observed in children subjected to some form of irritation on the surface of the body, such as an affection of the skin, worms, or phimosis. Earache and the cutting of teeth produce uneasy sleep, and in diseases of the bones and joints, such as rickets, disturbed sleep and night cries are common. In diseases of the bone and in brain disease the actual pain may awaken the child. In relatively healthy children overheating or indigestion due to a heavy meal before retiring frequently interferes with regular sleep. Many children are disturbed in their sleep by bouts of coughing, which are frequently due either to bronchitis or to enlarged tonsils and adenoids. In cases where sleeplessness is due to over activity of the mind, an effort should be made to change the child's train of thought and mode of behaviour in the hour before retiring to rest.

It is most desirable that adequate facilities for sleep should be provided for children below the age of five in nursery schools and classes. Facilities for sleep should also be provided for some children above the age of five in infant schools. (8)

VISION IN YOUNG CHILDREN

41. For some weeks after birth the infant does not respond to light. Gradually he appreciates varying degrees of brightness, learns to focus on near or distant objects by the effort of 'accommodation', acquires binocular stereoscopic vision, and judges distance and colour. The development of these processes is slow and conforms, with due allowance for differences in individual children, to a more or less definite pattern.

The growth of the eyeball is most rapid in the first two years of life, and by the age of five it has almost attained its maximum size. A considerable amount of this growth is due to increase in the thickness of the coats of the eye, though the increase in the diameter of the cornea between birth and maturity is only 2 millimetres, or approximately 20 per cent. This increase occurs almost wholly during the first two years after birth. The rapidity of growth displayed by the eyeball is even more noticeable than that of the brain, and it is not surprising that the eye should be peculiarly susceptible to injurious influences during early childhood.

The process of adaptation which enables the eye to focus rays of light from near as well as from distant sources is known technically as 'accommodation'. Most orderly muscular efforts, such as those involved in respiration and walking, involve the alternate use of antagonistic sets of muscles. 'Accommodation' for near vision is however peculiar, since it frequently involves sustained muscular effort extending over a considerable period of time. The muscular effort entailed in continued reading is of a type comparable with that required to hold the arm aloft for a long time, and symptoms of ocular fatigue may therefore be frequently observed in school children. The only rational treatment for any form of fatigue is rest, and rest for the tired eye can best be secured in darkness, since bright light exhausts the visual purple which sensitises the rods of the retina. Restoration of this visual purple takes place in darkness. The normal eye, if overworked, may suffer from fatigue, and such fatigue is likely to occur even more readily in children who have an error of refraction; they are working under a visual handicap. Among the ordinary symptoms of eyestrain are headache, frowning, blinking, twitching, and rubbing of the eyes. (9) There may be, in addition, some external inflammation, as of the margins of the eyelids (blepharitis) or of the delicate lining of the front of the eyeball (conjunctivitis). These inflammatory conditions are by no means invariably due to eyestrain; they may be produced by external infections, by malnutrition, or by uncleanliness. Since however, the lymphatic drainage of the eyeball is hampered by sustained ocular effort, such conditions will always tend to be aggravated when any eyestrain is already present.

Squint (strabismus) in children is a condition which usually yields to early treatment. If, on the other hand, it be neglected, a failure of binocular and stereoscopic vision results. The child uses one eye to the gradual exclusion of the other, the function of which eventually undergoes atrophy through disuse.

Myopia, or short sight, is not common in children under the age of two. This condition usually appears during school age, and has a tendency to be progressive in greater or less degree during the period of growth. Many cases of myopia are readily corrected by concave lenses, but severe cases require careful treatment with rigid limitation of close work, such as that involved in reading, writing and sewing.

Hypermetropia, often inaccurately described as long sight, is a normal condition in the early stages of childhood and causes trouble only in extreme cases, which are comparatively uncommon.

THE SENSE OF HEARING IN YOUNG CHILDREN

42. The organ of hearing consists essentially of an external ear (auricle and ear hole) middle ear (drum and ossicles) and internal ear (cochlea). These three parts are respectively sound collecting, sound conducting, and sound receiving. In man the auricle is not so specially developed as the auricle in many lower animals which cock their ears in order to localise sound. The middle ear is bounded on the outer side by the drum and on the inner side it connects with the nasopharynx by a narrow canal lined by mucous membrane. This narrow canal, known as the Eustachian tube, is the path whereby infection spreads from the nose to the middle ear. The internal ear (labyrinth) consists of an acoustic portion called the cochlea, which conveys auditory stimuli to those parts of the brain which interpret them. In addition to the cochlea the internal ear also contains the three semicircular canals arranged in three axes at right angles to one another, which give to the brain the sense of orientation or position in space. Disease of the cochlea causes deafness. Disease of the semicircular canals produces giddiness (vertigo) and jerky movements of the eyeball (nystagmus). The growth of the drum, middle ear and internal ear in antenatal life is extremely rapid so that by the sixth month of foetal life these organs are within 10 per cent of their adult size. This early development of the apparatus of hearing is accompanied by a comparatively late development from the functional point of view of those parts in the cortex of the brain that are peculiarly associated with hearing and speech. The apparatus is laid down early in the growth of the individual, but the complete functioning of the apparatus is of late development.

Hearing, like vision, varies considerably in children. Most children can hear sound waves extending over seven octaves (40-4,700 vibrations per second). Some children, like dogs, can appreciate still lower notes, others can distinguish higher notes such as those emitted by a bat during its flight. One of the main features in the development of the child is the manner in which he learns to become insensitive to particular sound stimuli. Auditory memory probably displays a greater range of variation in different children than visual memory.

The delicate mucous membrane of the deep surface of the drum, of the middle ear and of the Eustachian tube is continuous with that of the respiratory tract. Any inflammation of the latter, whether it be due to irritating gases, or to an infection such as an ordinary cold, or an acute infectious fever, may extend to the Eustachian tube and middle ear. Inflammatory conditions of the middle ear are most frequent in the youngest children. They are peculiarly dangerous in children because the acute pain of earache does not always appear in the very young when there is severe inflammation in the middle ear, as the several parts of the temporal bone have not then become consolidated to form a compact whole. Thus instead of pus bursting the drum and so leading to a discharge from the ear as usually happens, pus may make its way to the membranes of the brain, or appear under the skin above, behind, below or even in front of the ear. Acute inflammation of the middle ear is a condition commonly associated with an ordinary cold. It frequently accompanies acute infections such as measles, scarlet fever, and diphtheria. Chronic inflammation of the middle ear with its discharge (otorrhoea) frequently occurs as an after effect of these acute fevers. This chronic infection lowers the vitality of the body, and retards the physical and mental development of the child. Furthermore, the scar tissue formed in the middle ear as a result of the inflammation and destruction of the drum leads to deafness, and the behaviour of the child and his emotional responses are considerably disturbed. Acute middle ear disease cannot be wholly prevented, but there is no justification for the continued existence of chronic middle ear disease in the presence of active medical treatment.

The treatment of chronic middle ear disease in children may be unsuccessful if attention be directed to the aural condition alone. In a number of cases it is necessary first to render the throat and nasopharynx healthy by dealing with chronic infection of the lymphoid tissue (tonsils and adenoids) in this region. It is important that parents and teachers should not assume that a condition of deafness and middle ear disease may not exist merely because there is an absence of earache. Teachers in infant schools should be on the alert to detect even slight defects of vision or hearing, or any nervous peculiarities, and should bring them to the notice of the school doctor, as such defects are responsible for much that is mistakenly regarded as 'backwardness'.

THE RESPIRATORY AND EXCRETORY FUNCTIONS OF THE SKIN

43. The skin consists of two layers, the outer layer called the epidermis and the inner layer called the dermis. At the orifices of the body the structure of the skin is somewhat modified, as may be seen for example at the lips. This latter type of skin structure is known as the mucous membrane; its superficial layer is very transparent, while the deep layer is highly vascular. The epidermis consists of flat cells, several layers deep, of which the deep layer is actively growing, whereas the superficial layer consists of virtually dead cells, which are shed naturally or are removed by washing. Some children have a thick skin; others, such as red haired children, have a thin skin. Pallor or flushing at the onset of illness or under emotional stress has not the same significance in the two types of child. Furthermore, the amount of pigment in the skin varies with race, age and environment. It is important to note that the skin of some children does not react normally to sunshine and outdoor exposure. Production of pigment is the normal response to sunshine, and children who do not develop this tan must be watched to ensure that they do not suffer from sunburn.

The vessels of the skin exhibit considerable variation in richness of distribution, and in the relative depth at which they lie. In some children a flush is easily seen, because the vessels are superficial. The veins which lie superficially, as on the back of the hand, enable large volumes of blood to be brought rapidly to the surface to be cooled in order to reduce the temperature of the body during or after strenuous exercise. A cold environment causes them to contract. The skin is characterised in most areas of the body by the presence of hair. In the new born babe the relatively unpigmented fine hair is called 'down'. It often persists with undue prominence in children who are definitely below the average in physical and nutritional development; in these children the eyelashes are often dark, long and unusually curled. The nails often afford valuable evidence of nutritional condition. The longitudinally fluted brittle nails of children suffering from malnutrition are easily recognisable. After severe illnesses, transverse ridges are often seen in the nails, and they register the periods of acutely arrested growth, which have already been described in the section dealing with the skeletal system. The skin is not merely a protective organ; it has definite excretory functions, ridding the body of carbon dioxide, urea and sweat. The amount of carbon dioxide excreted by the skin is only about 1/700th of that expired by the lungs, but the excretion of sweat by the skin is very considerable. In addition to the sweat glands, there are other glands in the skin, developing in relation to the hair follicles, and known as sebaceous glands. Closely related to the hair follicles are special involuntary muscles which can cause the hairs to stand up, producing the condition seen in 'goose flesh'. The erection of the hairs is an involuntary reflex response to cold or, more rarely, to fright. 'Goose flesh' is not usually seen in children under two years of age. (10) The question of response to changes in temperature merits further consideration. Underneath the dermis is a fatty layer. The principal period of life at which there is a reduction of subcutaneous fat is the second 'springing up' period between the ages of about five and seven. This reduction at the beginning of the second dentition is of considerable importance. The fatty layer exercises a valuable function in tending to keep the temperature of the body constant, and any considerable alteration in the thickness of this layer is associated with increased susceptibility to changes in external temperature. The child has a much larger surface area in relation to his body weight than the adult. There are 30 square inches of surface area for each pound of body weight in a child of the age of seven, as compared with 16 square inches in an adult. The heat loss in the normal child is greater than in the adult, and the difference is still greater when children are suffering from malnutrition.

Between the ages of five and seven when the loss of subcutaneous fat in combination with rapid increase in height is most marked, the furrows, lines and dimples of the skin tend to become fixed and may become deeper, though any increase in wrinkling of the forehead should direct attention to possible errors of refraction in the eyes. Children who are hard of hearing frequently acquire either a countenance lined with anxiety or a blank expressionless stare. In cases of malnutrition the skin often becomes lax and wrinkled.

The thin outer layer or epidermis in young children may be injured by too vigorous washing and rubbing, by too free use of alkaline fat-solvent soaps, by faulty drying, by exposure to cold dry winds, by too much sunshine, as well as by dirt and parasites. Children are apt to be susceptible to bacterial infections, such as impetigo, while some children with a tendency to asthma are peculiarly liable to certain rashes usually associated with dietetic idiosyncrasy.

The health of the skin is of importance not only to the various functions already described, but also because it is richly supplied with nerves. In the child the concentration of nerve endings per square inch of skin is greater than in the adult, since no new nerves are formed after birth. On the other hand, the nerves of the skin do not function properly at birth, and it is only gradually that the special nerve endings are brought into action for the registration of sensations. It cannot be too strongly emphasised that the stimulation of the nerve endings by exposure to sunshine and fresh air forms a valuable part of the general education of the nervous system, and gives the child that sense of aliveness and awareness which is so essential to purposive activity in later life.

THE TEETH IN YOUNG CHILDREN

44. In this country no organ or tissue of the human body is so frequently affected by disease as are the teeth. It is rare to find a child of school age without some evidence of dental caries, past or present.

There is general agreement that dental caries is produced by the acid fermentation of carbohydrate food in the mouth. The acid thus formed acts as a solvent on the enamel of the tooth, and when this has been penetrated, further solvent action is reinforced by the action of certain germs (bacteria) found in the flora of the mouth, which have the power to disintegrate the organic content of the dentine.

For many years the view was generally held that liability to caries and the rate at which the carious process progressed were comparatively uninfluenced by variations in the structure of the teeth. In other words, a poorly calcified tooth was believed to be little more susceptible to decay than one that was well formed. Comparatively little research was accordingly directed towards elucidating the factors responsible for determining the structure of the teeth. Investigators of the problem of caries concentrated their attention largely on what might be called the environment of the teeth, and their researches were directed towards such questions as the physical and chemical constituents of a satisfactory diet, the composition and functions of the saliva, and so forth. (11)

There is no doubt whatever that modern methods of cooking and preparing food result in the teeth and jaws having less work to do than nature intended. It is common experience that any organ of the body which is not given a proper amount of work to do tends to degenerate or atrophy. While the structure of the teeth is such that they cannot be subject to the same kind of atrophy or wasting as that which affects, say, an unused muscle, still nature penalises those who do not use their teeth as they were intended to be used, and if, partly through inefficient mastication, fermentable foodstuffs are left adhering to the teeth after meals, it is not surprising that caries so often appears. Most dentists agree that the systematic use of a toothbrush, useful though it may be in helping to remove these fermentable substances, cannot wholly prevent caries, and that its effect is inferior to that produced by a suitable diet.

The structure of the teeth has received much attention in recent years. The disease known as rickets is characterised by defective calcification of the bones. (12) It appears that, without an adequate supply of vitamin D, the body cannot properly utilise the calcium which is ingested in food, and the structure of the growing bones is therefore seriously affected

The fact that bones and teeth, while differing in many respects, are both calcified structures, suggested that bone calcification and tooth calcification might be subject to the same influences, and this point was discussed in a memorandum prepared for this Committee by Mrs Mellanby, who has worked on the various aspects of the subject for the past decade. By feeding experiments on puppies, she showed that vitamin D has a remarkable effect on the structure of the developing teeth in these animals, and that it is possible at will to produce well formed or poorly formed teeth, according to the adequacy of the supply of this vitamin in the diet. More recently she has shown that cereals tend to have the opposite effect, that is, that they have anti-calcifying properties.

The view held formerly that there was little causal connection between dental caries and defective structure was based to some extent on the belief that whereas dental caries in human beings in this country was widespread, defective dental structure was somewhat exceptional. Mrs Mellanby, however, showed that defective structure is much more common than had been supposed, and that there is a close connection between defective structure and caries in human teeth.

It then remained to be seen whether the controlled administration of vitamin D to children would have the effect of reducing the incidence of caries or of retarding its progress. Such work as has already been done by Mrs Mellanby and her collaborators on this subject has yielded suggestive results. In her experiments she observed a notable reduction in the incidence of caries among children receiving a regular supply of vitamin D as compared with that found in those children who acted as controls. Caries, however, was not abolished, and it is therefore impossible to say more at present than that there is evidence that the administration of vitamin D appears to increase the resistance of human teeth to dental caries.

Footnotes

(1) e.g. the development in radiology was so rapid that acquaintance with abnormalities in the skeletal system was often acquired by young doctors in the hospital before its normal development could be adequately studied.

(2) A more detailed treatment of these aspects of growth will be found in Chapter 2 and Appendix II of our report on The Primary School (1931).

(3) This aspect of growth is more fully discussed in Section 27 of our report on The Primary School (1931).

(4) Appendix II, The growth curve.

(5) See also Chapter 8, Section 116.

(6) See also Section 39.

(7) See also Sections 41 and 42.

(8) See also Chapter 6, Section 96.

(9) See Handbook of Suggestions on Health Education (1933), page 31, issued by the Board of Education.

(10) This fact is an important reminder that temperature control is of somewhat slow development.

(11) The work of Dr Sim Wallace in this connection is well known, and his advocacy of a diet which would tend to secure that fermentable carbohydrates do not remain in the mouth at the end of a meal has been of great value.

(12) Prof. E Mellanby, FRS, Secretary to the Medical Research Council, has done much pioneer work on this subject.