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

Appendix II
[pages 215 - 243]

MEMORANDUM ON THE ANATOMICAL AND PHYSIOLOGICAL CHARACTERISTICS AND DEVELOPMENT OF CHILDREN BETWEEN THE AGES OF TWO AND SEVEN BY HA HARRIS, MD, BS, DSC, MRCP, PROFESSOR OF CLINICAL ANATOMY, UNIVERSITY COLLEGE AND UNIVERSITY COLLEGE HOSPITAL, LONDON.

Contents

Growth
The growth curve
Slowness of growth in man
The experimental aspects of retardation and arrest of growth
Resumption of growth
Amount of food consumed in relation to growth
The master tissues of the body
Muscular activity in starvation
The diet of the growing child
The shortage of animal fats
The powers of recuperation in the child
Sleep and wakefulness
Exercise and movement
The skin
Structure of the skin
The skin as a nervous organ
The hair
Vision
Short sight or myopia
Hearing
Disease of the middle ear
The brain
Dentition
The teeth in young children

In my memorandum on the anatomical and physiological characteristics and development of children between the ages of seven and eleven, which was printed as Appendix II to the Consultative Committee's Report on The Primary School (1931), (1) I attempted to give a brief outline of the salient features of growth in children during those years. In the present memorandum I have tried to trace briefly the physical development of the child up to the age of seven plus, with special reference to the period between the ages of two and seven. An effort has been made to avoid mere repetition of what appeared in the earlier publication, but it has been felt desirable to make the present memorandum self-contained so far as possible for the use of readers of this Report who may not have the time or opportunity to refer to the report on The Primary School.

An outline of this size and character is necessarily restricted in its scope, but I have attempted to give a general survey of the somewhat complex process of growth in young children up to the age of seven, together with a more detailed account of the development and functioning of some organs, e.g. the skin and the teeth, which were only discussed briefly in the earlier memorandum.

GROWTH

Growth in the true sense of the word implies more than mere change in size and form. It includes that gradual development from the ovum 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 studied by the older anatomists is inadequate and room must be found for concepts which are on the one hand frankly physical, chemical or biological, and on the other psychological. Our real interest in children is not determined by their anatomy, but by their changing activity and behaviour as they pass from one developmental stage to another. Still more stimulating than the change is the rate of change and the variation in the rate of change from child to child.

It is necessary to consider the manner in which a growing organism, whether animal or plant, reacts to the conditions of its surroundings. Growth is at its maximum in the earliest stages of development. The human ovum two weeks after conception doubles its weight in 6 days. The human embryo of the third month doubles its weight in the next month, the new-born child takes 6 months to double its weight, and one year to treble its birth weight. There is a considerable body of experimental proof, ranging from the experiments of Vernon (2) in animal life to those of De Vries (3) in vegetable life, that external conditions do not act equally powerfully at all periods in the growth of a developing organism, but that the effect of the environment is the more noticeable as growth is the 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 impregnation onwards.

In addition to the increased susceptibility to environmental conditions in periods of rapid growth, there is the well-established fact that the variability of response is greater during the earlier periods of growth. Babies vary more amongst themselves than do children or adults. Embryos vary more than babies. This is the scientific basis for the belief of the special influence of the condition of the mother at the time of conception upon the subsequently developing offspring.

The extent to which a retardation or acceleration of growth produced at any particular period of development may persist throughout childhood is difficult to assess in many cases. Such an effect, produced in the earliest stages, may be entirely compensated by a subsequent variation of the rate of growth in the reverse direction. The fact that variability in height and weight decreases with growth indicates that there is a definite tendency for previous irregularities to be eliminated.

The health of the mother during pregnancy, and of the offspring during their early years, is of paramount importance in its permanent effects on the physique, constitution and health of later years. Notwithstanding the checks and spurts of growth in childhood there is, as Lorrain Smith (4) states, a Law of Uniform Stature to which the organism tends to conform. Few are the adults who differ by more than 5 per cent from the average stature of the race, or by more than 5 per cent from the average for the circumference of the head.

THE GROWTH CURVE

The foetus in the month before birth grows more rapidly than at any other period. During this month the infant increases his weight by 1 per cent each and every day. If he continued to grow at this rate after birth, he would weigh 200 Ib. at the end of the first year and at the end of 20 years would be as big as the earth. During the first year of postnatal life the babe grows rapidly and this period may be called the first springing-up period (Fig. 1). From one to five years he grows more slowly and more steadily. This is the first filling-out period. From five to seven years there is a second springing-up period. It is at this stage that the child increases rapidly in height, loses his milk dentition, and begins to cut his second or permanent teeth, becomes thin and long in the leg and exchanges the chubbiness of babyhood for the characteristic family countenance. At seven years of age his head is almost as large as it ever will be. Between seven and eleven or twelve, according to sex, occurs the second filling-out period with steady growth as its characteristic, to be followed by the third springing up period associated with puberty. The startling changes associated with the rapid growth of puberty give place to the third and last filling-out period, as puberty is succeeded by the period of adolescence.

Thus each 'springing-up' period is followed by a 'filling-out' period. Each 'springing-up' period has its own peculiar problems and to lesser extent each 'filling-out' period has its peculiarities. All these periods are apt to be upset by oscillations of growth, and may be modified by diet, environmental conditions and disease. The first 'springing-up' period presents the dangers of certain nutritional diseases such as rickets, scurvy, infantile diarrhoea and digestive disturbances, The second 'springing-up' period from five to seven years and the first 'filling-out' period immediately preceding it are peculiarly associated with the acute infections and fevers of childhood such as whooping-cough, measles, chicken-pox, and diphtheria. The second 'filling-out' period from seven to eleven or twelve is the period during which the child presents in varying degree the sequelae of these acute infections. The problems presented during this interval concern themselves predominantly with the heritage of the diseases and deficiencies of the preceding years. Notably, defects of dentition and vision, enlarged tonsils and adenoids, middle-ear disease, and disease of the lymphatic glands in the chest, neck and abdomen call for urgent attention. This period of consolidation from the age of seven to that of eleven may be regarded at one and the same time as the opportunity for retrieving past errors of development and for preparing for the heavy demands necessitated by rapid growth during the third 'springing-up' period of puberty.

The type of growth registered by this curve is far from being an adequate representation of the profound changes taking place in any given child, and deals wholly with changes in height and weight. Practically every external lineal dimension of the body, with the exception of the head and neck, follows this type of growth. The growth of the skeleton, of the limbs, of the thoracic cage and respiratory organs and of the muscular system as a whole conforms to this general type of skeletal growth.

The growth of the brain, the eyeball and the skull is peculiar. From birth to the age of eighteen months, these organs grow with extreme rapidity; by the age of two years they have reached 60 per cent of their adult size, and by the age of seven almost adult size. This type of growth may be regarded as neural, and applies to the brain, spinal cord, eyeball, ear and skull, exclusive of the face.

The lymphoid tissue of the body, as illustrated by the lymphatic glands, tonsils and thymus, grows rapidly in childhood and continues to grow at a somewhat slower rate until puberty. During adolescence and adult life there is both an absolute and a relative decrease in the amount of lymphoid tissue. In view of the extent to which the lymphatic glands are involved in children at all ages as a result of acute disease and of chronic infections, this third type of lymphoid growth must be of deep significance.

The fourth type of growth is that presented by the genital organs. These organs grow but slowly in infancy, remain almost stationary from two to ten, and grow rapidly in the two years before puberty, during puberty and during adolescence.

Scammon (5) lays emphasis on the fact that these four types of growth, general or skeletal, nervous, lymphoid and genital are but crude representations of the complexity of the process involved. Dentition is not completed until about the 21st year when the 'wisdom' teeth erupt. Growth in the face and neck continues to the same age. The suprarenal glands, the paired organs which lie in relation to the kidneys, lose one half of their weight in the first two weeks of postnatal life, increase slowly up to the fifth year, and do not reach birth weight until puberty. The uterus, which grows rapidly in the last month of antenatal life. loses 50 per cent of its weight in the first two weeks of postnatal life and does not begin to grow appreciably until two or three years before the onset of menstruation.

The ductless glands, or glands of the endocrine system, which have provided material for so many remarkable experimental observations and for so much doubtful theorising, present a picture which so far defies analysis. The thyroid gland displays steady growth from birth to maturity, with the tendency to enlargement in relation to puberty and pregnancy as a characteristic. The thymus follows the lymphoid type of growth. The pineal gland follows the nervous type, and the pituitary follows the thyroid. There is thus no trace of correlation in the growth pattern of the ductless glands.

It should be mentioned that the second 'springing-up' period of growth between five and seven years is not so clearly indicated on some of the growth curves of height and weight as it in fact appears to the careful observer of young children. The cutting of the second dentition, often accompanied by nervous disturbances as significant as those of the first dentition, the marked lengthening of the face, the rapid development of the air sinuses in the face, and even the rapid lengthening of the foot in the sixth year, necessitating a larger size in footwear, the anxiety of the parents because the child is 'going thin', the loss of subcutaneous fat - these are more evident to the careful observer of children than to the statistician.

It cannot be too strongly emphasised that there is no growth curve by which an individual child can be assessed. Even though both plant and animals tend to remain in adult life in that group into which they fall in the early stages of growth there is no quantitative estimation of the genetic factors which result in the small babe growing to be a small man or in the big babe growing to be a big man. The differences between both animals and plants cannot be explained solely on the grounds of heterogeneity of environment. Neither the efficiency of the mother as extolled by Paton and Findlay (6) nor the health of the mother as emphasised by Elderton (7) can be regarded as the all-determining factor in the growth of the offspring.

SLOWNESS OF GROWTH IN MAN

In my memorandum, printed as Appendix II to the Consultative Committee's report on The Primary School, the slowness of growth was emphasised as the main feature of the child. This slowness of growth deserves further attention. The growth curve in most domestic animals presents a gradual decrease in the growth factor from birth to maturity with no periods of relative retardation or acceleration. The neonatal loss of weight which is so common in the human baby, amounting from 5 to even 10 per cent of the birth weight, is not a feature of the domestic animals. The growth curves in these animals display a rapid development from babyhood through childhood to puberty. The animal continues to grow for a considerable time after puberty. Most domestic animals arrive at puberty at a time when the body weight is roughly one third of the mature weight. On the other hand, man alone has a long drawn out period of childhood, with eight to nine years intervening between the period of commencement of the second dentition and the onset of puberty. At puberty the boy or girl is roughly two thirds of the adult weight. Further, the boy or girl takes a proportionally much longer time to increase the weight from puberty to adult life than does the domestic animal. In sheep, the adult weight is reached about six to seven months after puberty, i.e. the percentage decrease in the growth rate is about 15 per cent. In man, the adult weight is reached in nine to twelve years after puberty and the percentage decrease in the growth rate is about 3 per cent.

The absence of a period of rapid increase of growth at puberty in the domestic animals, in combination with a frank sexual behaviour pattern is well known. The presence of a period of rapid increase of growth at puberty, slightly earlier in girls than in boys, in combination with a prepubertal shyness, a pubertal reticence and a subsequent complex behaviour pattern indicates the danger of transferring data from animals to man.

Except in so far as it may resemble the growth curves of anthropoids (about which we have but meagre information), the growth curve in man is entirely distinct from that in all other animals. The latter afford but slight differences amongst themselves.

THE EXPERIMENTAL ASPECTS OF RETARDATION AND ARREST OF GROWTH

The lines of arrested growth due to acute infections or metabolic diseases such as diabetes were illustrated in the previous report. It was emphasised that our knowledge of the arrest of growth in organs other than the skeletal tissues was but imperfectly understood. A considerable body of data relating to arrest and retardation of growth has been derived from animal experiment. The position was postulated by Darwin (8) when he stated that 'of all the causes which induce variability, excess of food, whether or not changed in nature, is probably the most powerful'. The potency of food has been recognised more clearly in animal husbandry than in the home or the school. Growth can only take place at the expense of food material, and unless this is always more than sufficient for the needs of the organism, the rate of growth must be dependent upon it. There are innumerable experiments which prove that excess of food and heavy feeding is more advantageous and profitable in the youngest stages of animal husbandry. The statistical returns on this fact are incontrovertible, both as regards the experiments upon young plants performed by Gilbert and Lawes (9) at Rothampsted in 1895 and innumerable experiments upon animals since that date.

The recent animal experiments upon the retardation of growth have been directed mainly towards maintaining the growing animal at a constant weight over a period of time. The obvious methods, following the classification of AH Smith (10), involved:

(i) Limitation of total diet.
(ii) Limitation of total diet to minimal calorific value, but with the addition of the essential salts and vitamins.
(iii) Limitation of ingested water.
(iv) Restriction of protein.
(v) Restriction of salts.
(vi) Vitamin deprivation.
(vii) Increase of the concentration of waste products in the body, as by removal of one kidney.

This is the scientific reason for advising the use of cereals, such as wheat and barley, in their cheaper forms, e.g. bread or dry toast, rather than in the form of various patent preparations, especially in cases where economy is a consideration. Fresh cow's milk, eggs, butter, cheese, meat and fish are a better investment both as regards essential proteins and fat.

Of all the methods of rapidly arresting growth, salt starvation and the withdrawal of fluids are the most potent. Even today, when the significance of salt balance in the diet is well recognised, the provision of adequate fluid either as milk, skim-milk, oatmeal-water, barley-water or plain drinking water does not hold as important a place in the school and home as it does in animal husbandry.

RESUMPTION OF GROWTH

The question as to the extent to which an animal whose growth has been arrested can recover on the restoration of good or optimal conditions is of great interest. Aron (12) subjected dogs to a period of restricted diet whereby growth was decreased. Even when the dogs were restored to vigorous feeding normal weight was not regained. Aron (13) repeated the experiment with rats which had been relatively starved on a diet poor in protein. Restoration to a full diet did not result in normal growth. Jackson and Stewart (14) showed that young rats which were underfed for some weeks failed to regain normal weight. Yet, on the other hand, Osborne and Mendel (15) showed that the albino rat retains over a considerable period the ability to resume growth after retarded development.

Obviously, from the nature of the experiment, data on children are few and far between and the toll of intercurrent disease vitiates those mass experiments in starvation which occurred during the war. It is surprising to what an extent the young actively growing animal is upset by an injurious agent, but it is in some ways more surprising to what extent growth may be arrested in the young animal without transcending the limit of possibility of resumption in growth.

Of all the experimental observations which prove the futility of estimating growth and physical efficiency in terms of height and weight, probably there are no observations more fundamental than those of CM Jackson (16) based on a group of experiments in which the diet of the growing animal has been curtailed so as to keep the animal, during considerable periods, at constant weight. In none of these cases has there been total suppression of growth if the weight has been maintained at constant level. Total suppression of growth has usually occurred only in association with loss of weight and active disease. Wherever the graduated dietetic deficiency has maintained the animal at constant weight, there has been actual growth of the skeleton in linear dimension. This has only been accomplished by the animal consuming its own reserve of fat and muscle and using some of this for growth. This mobilisation and actual consumption of the fat and protein depots leads to a marked alteration of physique so that the outward bodily proportions are decidedly altered. The animal has been living on himself. It is this weedy type of growth which exposes the animal to such dangers from infectious diseases by reason of the loss of the fatty protective thermostatic layer, the loss of the muscle so necessary to active movement and digestion, and the depletion of that reserve which we call 'resistance'. This type of child, who grows in height without gaining weight, who has a low degree of resistance, high fatiguability and general listlessness is not unknown in some of our schools. It is evident from what has been said about the adequacy of diet that such a child may present marked anorexia and loss of appetite. The condition has all the characteristics of a vicious circle. The more inadequate the diet in certain respects, the greater the anorexia. This condition is seen in the aetiolated seedling or 'weed' of our city population.

It is necessary to emphasise how varied are the factors which lead to relative arrest of growth. Quite apart from the adequacy or sufficiency of diet, there is an important distinction between acute arrests of growth and chronic arrests of growth. Acute arrest of growth is most frequently seen in the acute infections of childhood, such as measles and whooping cough complicated by a severe broncho-pneumonia; in scarlet fever, diphtheria or typhoid. Chronic arrest of growth is seen in the longstanding infections such as syphilis, tuberculosis, empyema and otorrhoea. In tuberculosis there may be even active growth, for a mild degree of tuberculosis may act as a stimulus to growth. Humphry (17) described cases 50 years ago in which the tuberculous limb was longer than its normal fellow.

In metabolic diseases such as diabetes, the arrests of growth may be proportional to the severity of the disease and may only occur during acute exacerbations. In rickets, the disease only occurs during a period of active growth. The non-growing child automatically loses his rickets. In scurvy rickets, renal rickets and coeliac rickets the pattern of growth is most complex, but the onset of the disease coincides with a period of active growth even though the end of the disease may present arrest of growth and deformity.

AMOUNT OF FOOD CONSUMED IN RELATION TO GROWTH

The commonest error in dietetics is a belief in the infallibility of human appetite. There is no more amazing example of credulity than that involved in the supposition that the hungry child or badly fed child will consume more food if he wants it.

It is twenty years since Hopkins (18) proved conclusively that in animals reared on an inadequate diet, the failure in appetite follows the failure in growth. The animal stops eating because he has ceased to grow. He does not stop growing because he has ceased to eat. This fundamental fact is lost sight of repeatedly by parents, school teachers, school matrons and medical officers when reporting on the general nutrition of children. Hopkins says: 'If then a factor or factors essential to growth be missing from or deficient in a dietary, the consequent 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 dictum should be in mind whenever one is faced by the problem of the stunted starveling whose diet is automatically reduced in quantity of intake because it is deficient in quality. It is in these stunted starvelings, reared on a diet of bread, margarine, jam, sugar, tea, with occasional yet extravagant supplements of biscuits, chocolate and various beef 'essences', that such phenomenal increases in food intake are seen once the processes of growth are set in motion by the addition of the necessary dietetic factors through the medium of fresh animal and vegetable food, with or without that wonderfully potent adjuvant, cod liver oil. (19)

The position may be stated in another form. The growing child requires the exhibition of adequate foods in surplus quantities, so that no failure of growth or failure of appetite may ensue. This is the pith of the plea for variety and freshness in food. The need for the 'little extra' is more marked in young children than in older ones, and a special effort should be made to provide it. There is such a tendency in many educated households to reserve the variety of dishes for the adults whilst the youngest are condemned to the dull routine of baby food. It is a well known fact in animal husbandry that anything approaching extravagance in feeding should be reserved for the youngest animals, as they profit most by it.

THE MASTER TISSUES OF THE BODY

Throughout all the vicissitudes of growth, arrest and resumption, certain tissues of the body stand out by their unique power to withstand the implications of starvation or disease. The brain, first and foremost, maintains its growth and activity to an inordinate degree. The heart and 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 the main excretory organ of the body approach the brain, heart and diaphragm in resistance to the unfavourable conditions. For this reason they are justly termed 'master tissues' and are the last to be influenced or sacrificed. The blood also may be regarded as a master tissue in that it makes valiant efforts to retain a constant composition during starvation. If there is any shortage of minerals or salts, the resistance of the blood is rapidly broken down and profound anaemia results. The skeleton is not a master tissue especially when the diet is inadequate in minerals and salts or vitamins. It is true that the animal will make an effort to grow 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. (See Table 1 above). The wasting of the muscles tends to be selective and the first muscles to be involved are usually the deltoid muscle of the shoulder, the glutaeus maximus 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 muscle and fat the skin becomes loose, wrinkled and unhealthy, so that when a portion of the skin is taken up between the fingers and then released, a wrinkled appearance is maintained. Wasting of the fat inside the abdomen gives undue mobility to the viscera, both the hollow viscera and the solid kidney, and may lead to prolapse of the anal mucous membrane.

Inasmuch as the wastage of the facial subcutaneous fat and muscles of mastication is so variable it is not possible to assess the degree of bodily wastage by the facial appearance only. The pinched face with pointed nose and ears and large eyes is an index of dehydration rather than starvation. Furthermore, in many forms of starvation the actual degree of wasting is masked by the swollen, water-logged subcutaneous tissues which may be so oedematous as to simulate dropsy.

The behavioural characteristics of starved animals are as variable and as difficult to assess as those of starved children. In both animals and children the response to starvation in the earliest stages may be increased activity, either muscular or mental. In the later stages inactivity, mental apathy, leading on to muscular inertia and lethargy is seen. The difficulty in maintaining sustained effort is emphasised and this was probably the main feature of the children in areas where war hunger was rife in 1918 - 1920.

Muscular activity in starvation. The existence of increased muscular activity as a response to the early stages of starvation in certain animals and children is well known. It is essentially a response to the subjective sensation of cold which so frequently accompanies hunger. It is a common sight on a cold day to see children with hands in pockets jumping on and off the curb with rapidity in order to keep warm. The very attitude of the child displays in the posture of the hands and chest an attempt at 'curling up' to keep warm; the motor activity of the lower limbs is an attempt to keep warm by increasing the heat production as a result of muscular effort. The furtive appearance in combination with increased muscular activity is seen in children no less than in animals. In the later stages of starvation animals curl up so as to avoid loss of heat; hunger and appetite not infrequently decrease so that the animal presents the picture of listlessness.

THE DIET OF THE GROWING CHILD

At a time when the field of dietetics tends to be obscured by the phenomenal increase in our knowledge of the vitamins and the significance of the balance of calcium and phosphorus, it is wise to consider certain other potent essentials in the diet of the growing child. There are four cardinal facts with regard to diet. The first is that man, in common with other mammals, lives and grows most rapidly from birth to the cutting of the first teeth on mother's milk. The second is that the more the composition of the food differs from the composition of the adult tissues the longer must that food take to be digested and absorbed into the tissues. For this reason the placid cow takes the whole day to eat and chew the cud, whereas the dog, cat and man find time for other activities. The third is that there is no such thing as a single natural food for man. The fourth is the surprising range of 'uneconomic' adaptability to abnormal diets which can be displayed by the growing animal.*

*Spallanzani (20), about one hundred and fifty years ago, showed that with patience a pigeon could be gradually accustomed to a meat diet, and an eagle to a diet of bread. Such an experiment is a valuable index of the range of adaptability in animal life, but is not a safe index for rearing pigeons or eagles.

There are many and obvious reasons why milk cannot be continued as the sole food of the growing child and adult. In order to provide the energy for a day's work and play, quite apart from the energy necessary for growth, the child would require an unwieldy volume of milk. However the problem of diet is approached the significance of the composition of milk as a mixture of fat, protein and carbohydrate is paramount. All the foods of man, ancient and modern, illustrate the search for a mixture of foods which would approximate to milk as regards the mixture of fat, protein and carbohydrate. Man has been mixing his foods and his drinks for countless years, blindly searching for a mixture which would not depart too far from the fluid that had stood the test of time since the first milk-giving animals appeared on earth. Notwithstanding all the sound writing about the art of cooking, good feeding, gastronomy and dietetics, the main object of man's labour in this direction has been to imitate in a less bulky form the mixture provided in milk. Milk has two great disadvantages. It will not keep fresh for any length of time; it is extremely poor in iron. Laboriously man learnt to make fermented milk, butter and cheese, and to add these to the carbohydrate cereals which agriculture was providing in increasing quantities. The same yearning for a mixed diet led him to fatten the domestic animals and birds so that he could obtain both protein and fat in one morsel.

In these days when so much of our food comes from abroad it is essential that the housewife should understand what is meant by the term 'fresh food'. Fresh food is food which is fresh from the animal or the plant. Foods which have been transported huge distances in refrigerators may be reasonably fresh. This applies to butter and meat. Cheese, a valuable and somewhat neglected article of food, even when transported from New Zealand is relatively fresh, since it is a food which undergoes natural ripening with the aid of bacteria which are friendly to man. On the other hand, cereals which are cooked abroad and then imported as ideal breakfast dishes for children are but stale food.

If a varied supply of fresh food is available, there is no need to worry to any extent about vitamins or a balanced diet. Man is not exclusively a vegetarian or a meat eater. He requires a mixed diet. No amount of sunshine or fad-feeding will make up for a diet of white bread, margarine, jam, tea and tinned milk. It is unfortunate that milk, butter and eggs, together with home-produced meat cost so much. There are, however, certain cheap sources of animal fat which the housewife should use more extensively. In the first place marrowbones yield in addition to the blood-forming red marrow and the gelatine, about one fifth of their weight of pure animal fat. Marrowbones should be the basis of all broths and soups. Secondly, the fresh herring gives a high yield of fat for energy and protein for flesh forming, A working class family can ill afford to neglect the marrowbones and the herring.

THE SHORTAGE OF ANIMAL FATS

The results of animal experiments by Mellanby (21), Cramer (22) and others have proved the importance of an adequate ration of animal fat. The investigations of Corry Mann (23) on the effect of an additional ration of cow's milk to growing schoolboys proved that gain of weight and height was accompanied by improved health and 'spirit'. When in infant is weaned it is consuming almost a quart [1.14l] of milk a day, containing about 1½ oz. [42g] of actual fat. As the child is weaned, in order to guarantee the fat intake, a pint [0.57l] of milk and one ounce [28g] of butter per day are necessary. The total consumption of milk fat in fresh milk and butter for the whole population is decidedly below this desired quantity and is nearer to ½ oz. [14g] of butter and ¼ pint [0.14l] of milk per head per day. Thus the consumption of milk fat and butter in children is probably less than one half the requirement. Allowing for the fact that the poorer classes cannot afford fresh milk and butter, but rely on margarine and condensed milk, the average consumption in the growing child is probably about one quarter of the optimum.

With a small family budget, fresh food is difficult to supply in adequate quantities for the growing child, especially if there is no garden supply of fresh vegetables and salads. For the growing child there is one cheap method of remedying the deficiency of fresh food, and one alone. This is the supply of a daily ration of one teaspoonful of cod liver oil during the winter months. In relation to the certainty of action of butter and cod liver oil in the case of children, a mass experiment in Denmark, as reported by Bloch (24), may be quoted. From 1914 to 1917 many of the Danish babies suffered from malnutrition with sore eyes, owing to the difficulty of obtaining fresh milk, butter and eggs. In December 1917 the Danish Government took over the whole supply of butter and rationed it. Half a pound [226g] was allowed for everyone, weekly, at a low price. From that date everyone ate butter instead of butter substitutes and this particular form of malnutrition in association with sore eyes disappeared. The Danish doctors had also found that all such cases in hospital during the war could be rapidly cured by cod liver oil. This is of considerable historical interest as an Edinburgh physician, John Hughes Bennet (25), had cured similar cases in Edinburgh nearly a century ago.

A valuable adjunct to milk and butter is cheese, for it contains not only butter fat, but also protein and valuable calcium and phosphorus in addition to other salts.

THE POWERS OF RECUPERATION IN THE CHILD

The powers of repair after injury or disease in childhood are striking. We constantly hear the expression 'he will probably grow out of it' in reference to skeletal disease such as rickets, failure of control such as bed-wetting, or disabilities such as stammering. Underneath this idea of outgrowing disease there is a modicum of truth, though all too frequently the phrase has become the last refuge of the incompetent physician and the last hope of the harassed mother.

It is of interest to examine the extent to which children 'grow out of it' in relation to disease in the organs involved in the four types of growth which were surveyed earlier.

In the skeletal organs the power of repair is comparatively great.* The slight degrees of bow legs, knock knees, and flat feet which are so common in children from 2 to 4 years almost invariably disappear by 10 years of age. The pigeon breast and other deformities associated with emphysema (loss of elasticity) of the lungs, and bronchiolectasis (dilatation of the bronchioles) after severe whooping cough and pneumonia often disappear. The child tends to grow clean of limb and straight of trunk after severe deformities. In no case is this seen to greater advantage than in the bony deformities of rickets which disappear to a large extent, irrespective of treatment, because of the innate tendency towards symmetrical and harmonious growth. (See Fig. 2 below).

*For detailed clinical accounts of repair in bone see Bone Growth in Health and Disease, HA Harris, Oxford University Press, 1933.

In the organs involved in the lymphoid type of growth, the extent to which the phenomenon of 'growing out of it' is exhibited is less marked. Yet even now there is a pronounced tendency to hesitate for a time before recommending the wholesale removal of tonsils and adenoids. Similarly with enlarged tuberculous glands in the neck, the tendency today is against operative treatment. We have learned the extent to which the enlarged tuberculous glands will heal under suitable conditions, of which rest to the diseased part is the most important.

The organs involved in the urogenital type of growth display varying degrees of damage and repair in illness. The kidney is frequently injured in the acute fevers of childhood. Yet the nephritis following scarlet fever and diphtheria usually clears up with or without medical treatment. It is probable that carefully guarded convalescence with competent medical supervision of the diet would lead to a decrease in the number of cases of chronic nephritis. As regards the genital organs it is well known that mumps is frequently complicated by a severe orchitis in the male, or a severe mastitis in the female, with permanent damage to either organ according to sex. This is not an uncommon occurrence in puberty or adolescence. It is very rare indeed to find any definite injury to the testicle or breast in the child.

In the organs involved in the nervous type of growth, the brain and the organs of special sense, the potentiality to grow out of the disability is minimal as the process involved calls not only for repair to the damaged tissue but also for re-education, unless, as is sometimes the case, the lesion is so extensive as to lead to complete loss of function.

The nervous system as a whole is insulated from the rest of the body in a peculiar manner. It has an astounding precocity of growth, not only centrally in the brain, but also in the special sense organs, such as the eye and ear. The rate of growth of the brain, which reaches 83 per cent of adult weight at 7 years of age, has already been emphasised. The diagram (Fig. 3 below) shows how the size of the cranium increases in accord with the growth of the brain, whereas growth in the face (and concomitant dentition) continues until adolescence.

In the case of the eye as a whole the growth is more precocious than that of the brain. The conjunctival sac is almost adult in size at the end of the second year. The eyeball grows with extreme rapidity in the first two years and by 7 years has completed its growth. The eyes are so prominent a feature of the face by reason of their relative overgrowth in babyhood.

The tympanic membrane or drum of the ear, the ossicles of the ear, the actual cochlea of the internal ear and the semicircular canals are more precocious than the eye. The radiograph of the human foetal skull of twenty-two weeks of foetal life shows the early ossification in the tympanic ring around the drum and in the semicircular canals. After the sixth month of foetal life there is no appreciable growth in the actual drum of the ear, in the semicircular canals (the organs of equilibration), in the internal ear (the organ of hearing). It is at this time that the human foetus presents rapid growth of the muscular system, myelinisation of the vestibulospinal tract in the spinal cord and that active muscular movement which gives to the mother the subjective symptom of 'quickening' in the child.

The eye and the ear differ considerably as regards the effects of age. Whereas the organ of hearing has reached its definitive adult size before birth, the eye is an optical instrument of geometric exactness which has to adapt itself to certain definite changes in the growth of the brain and skull throughout childhood. The eyeball itself alters in shape with age. Shortsightedness, ranging through normal vision to longsightedness is an age change, susceptible to arrest or rapid changes with growth. The irregular rates of growth in the complexity of parts lead to certain failures of adaptation which are common in young children. The degree of muscular coordination involved in the movements of the eyeball by the ocular muscles is high. Failure of coordination results in one form of squint or strabismus. The child in many cases tends to grow out of this but by far the greater number of cases of squint require correction by glasses, special exercises and even operation.

It thus becomes apparent that the varied anatomical and physiological features which characterise certain organs are paralleled by differences in the growth pattern which can be crudely classified as skeletal, neural, lymphoid and urogenital. These various organs, once injured by acute or chronic disease, display a power of repair which is maximal in the skeletal organs and minimal in the nervous system. The period of convalescence after illness presents difficult problems of treatment and prognosis, according to the particular organs involved in the disease.

SLEEP AND WAKEFULNESS

Sleep is essential to refresh the wearied body and exhausted mind. In children sleep is essential not only to exercise a restorative effect over the functions of life but also to grant respite from the exhaustion produced by enforced standing - and enforced stationary posture. Standing motionless and sitting still in one position are tasks which involve considerable effort and inordinate fatigue in the young. In order that sleep should be adequate it is necessary that it should take place at a stated hour, continue for a definite time in a comfortable restful position without any disturbance of the natural functions by overheating, faulty digestion or congested atmosphere. In children with a poor circulation, cold feet frequently prevent the onset of sleep.

The amount of sleep necessary varies greatly with the state of the body, the temperament and the habits of the individual. Infants pass most of their time in sleep: children under two may sleep 12 to 14 hours; children from two to seven may sleep 10 to 12 hours. It is quite usual for them to take up to 30 minutes to fall asleep. Disease or uneasiness of any kind often produces unsound sleep. The diseases which are most frequently associated with wakefulness are the acute fevers, inflammatory disorders and cerebral diseases. Disturbed sleep is seen most frequently in those children subjected to some form of peripheral irritation such as a skin irritation, worms, phimosis, or a foreign body of any kind in proximity to any one of the orifices of the body, either cranially or caudally. The troubles of dentition and earache are also an incubus.

In disease of bone and joints such as rheumatism, disturbed sleep and 'night cries' are common. In disease of bone and cerebral disease pain itself may awaken the child. Epilepsy and other cerebral conditions are potent disturbers of sleep. In the relatively healthy child, indigestion and intestinal disturbance due to the heavy meal before retiring or overheating are common causes. Children are commonly disturbed in their sleep by bouts of coughing. The parents are frequently more disturbed thereby than the children.

When sleeplessness arises from over-activity of the mind, an endeavour must be made to change the mode of behaviour and the train of thought in the hour before retiring to rest. The bath and absence of supper are to be commended. In certain children self-reproach, blighted hope, or carking [anxious] care will disturb that composure which is so essential to sleep. Wounded vanity or a promise imprudently unfulfilled are also of some significance.

EXERCISE AND MOVEMENT

There is a tendency to forget that animal life, as distinct from static vegetable life, is essentially dynamic. Animal life subsists through a series of movements and all these movements should be sustained in regular and adequate exercise. Respiration, digestion and the circulation of the blood involve movement. All the excretory operations involve movement. If any become suspended, or decline in activity, the organs shrink and more or less deleterious effects on the general health ensue, according to the importance of the parts consigned to stultifying quiescence. If the organ undergoes prolonged suspension of movement, its anatomical structure degenerates. Muscular fibres, consigned to inactivity, waste progressively with corresponding loss of power. The laws of muscular action, whether in the voluntary muscles of the body, or in the involuntary muscles of the blood vessels and alimentary canal, require that the muscle, in order to maintain structure and function, must be guaranteed both adequate exercise and rest. Otherwise the muscle declines in volume and power, and all the functions to which its actions are subservient become impeded.

THE SKIN

The skin or integument is a continuous organ, covering the whole body. It consists of a superficial part called the epidermis or cuticle and a deep part called the dermis or corium. At the orifices of the body the skin is replaced by the pinkish mucous membrane as at the lip and eyelid. The mucous membrane is an integument of greater delicacy, in which the superficial layer or epithelium is very transparent and the deep layer highly vascular. The deeper layers of the skin contain much connective tissue which yields gelatine on boiling. Deep to the whole integument is a subcutaneous layer of fat, the panniculus adiposus.

The epidermis in the new-born babe is about 0.2 mm thick and the dermis 0.8 mm. In adults the epidermis varies considerably in thickness, ranging from 0.1 mm on the cheek to 0.8 mm on the palms and finger tips. The dermis amounts to 2 mm or even 3 mm on the sole of the foot.

Structure of the skin. The epidermis consists of flat cells, several layers deep, of which the deepest layer is actively proliferating, whereas the more superficial layers consist of virtually dying and dead cells which are shed naturally or removed by washing. The number of layers of cells varies in different parts of the body with age and with constitution. Some children naturally have a thick skin, others, such as red-haired children, naturally 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. The dermis also differs considerably with age, site and diathesis. Further, the amount of pigment in the skin varies with race, age and environment. As a general rule all pigment, even in the coloured races, appears at or after birth. It may be wise to emphasise that certain children fail to develop a natural tan to sunshine and outdoor exposure. These must be treated carefully as they are apt to suffer from sunburn.

The vessels of the skin exhibit considerable variation in richness of distribution and the relative depth at which they lie. In some children a flush is easily seen because the vessels are relatively superficial. In others the converse holds. It should be noted that the cutaneous veins lie superficially, as on the back of the hand. They enable large volumes of blood to be brought rapidly to the surface to be cooled in order to reduce bodily temperature during or after violent effort, and react to a cold environment by contraction. The vessels of the skin are under the control of the sympathetic autonomic nervous system.

The skin is characterised in most areas of the body by the presence of hair in association with sebaceous glands and sweat glands. In the unborn babe the relatively unpigmented fine hair is called lanugo or 'down'. It often persists with undue prominence on the face, neck and back of children who are definitely below the average in physical and nutritional development.

The fatty subcutaneous layer is well developed in the new-born child, except in the eyelids, scrotum and penis. In the adult the subcutaneous fat varies considerably with habit, diet, sex and climate. The period of life at which the subcutaneous fat is reduced to a minimum corresponds to the second 'springing-up' period (5-7 years) and again, in certain cases, old age. The reduction of subcutaneous fat at the commencement of the second dentition, when the child exchanges the chubbiness of infancy for the familial physiognomy at a time of rapid growth, is of great import.

This is the time when so many children are either undergoing an attack of the various infections of childhood or suffering from some of the common sequelae thereof. It is sufficient to say that this fatty subcutaneous layer, like that which lines the interior of the abdominal cavity, exercises a valuable function as a thermostatic layer tending to keep the body temperature constant. Any considerable reduction thereof is associated with increased susceptibility to extremes of changes in external temperature.

Since the new-born babe has a much larger surface area in relation to body weight than the adult, the cooling of the body tends to be very rapid in the former. In the case of the new-born infant for each pound [454g] of body weight there is a surface area of roughly 45 square inches [290cm²]: at 2 years of age to each pound of body weight 36 square inches [232cm²]: at 7 years of age 30 square inches [193cm²] and in adult life 16 square inches [103cm²]. Thus heat loss in the child is much greater than in the adult. This is the reason for the extreme degrees of motor activity which children display to cold. They not only shiver but they run and jump to keep warm. If they are underfed or overdisciplined they suffer under such conditions. The underfed child has too much surface area in proportion to weight. He 'catches' cold easily. This is more so in the case of the underfed lanky child above average height than in the case of the underfed starveling who is under average height.

The skin, in addition to providing a protective function, also serves as an excretory organ, an organ for regulating the temperature of the blood and a peripheral nervous organ. The skin serves as an excretory organ by ridding the body of carbon dioxide, urea and sweat. The amount of carbon dioxide excreted by the skin is about one seven-hundredth of that excreted by the lungs in the expiratory air. Yet this amounts to 5g in 24 hours. There is sound evidence that in the infant the excretion of carbon dioxide through the skin is double that in the adult.

The excretion of sweat by sweat glands is considerable. The new-born babe pours out in the form of insensible perspiration about ½ oz. [14g] per pound [454g] of body weight in 24 hours. This rises to nearly 1 oz. [28g] per pound of body weight at one year of age, and is roughly ¼ oz. [7g] per pound of body weight in the adult. The adult sweats 40 ozs. [1.12kg] per day. During physical effort the quantity may be increased ninefold, as in the tinplate worker or coal miner. Thirst is an expression of a natural demand for replacement of body fluids lost in sweating, micturition and defecation.

The sweat glands begin to develop in the fifth month of embryonic life as down-growths from the epidermis. The degree of development at birth and in early childhood shows marked individual variation. Visible perspiration, as distinct from insensible perspiration, is rarely seen in the babe under 5 months. Quite distinct from the ordinary sweat glands are those specialised sweat glands, associated with a characteristic odour of the secretion, which develop in the axilla and genital region, and the glands which secrete wax, as those of the earhole.

The sebaceous glands develop in relation to the hair follicles. They are well-developed in the new-born child. They persist as 'free' sebaceous glands in areas, such as the chest and neck, where the hair does not persist, and frequently give rise to sebaceous cysts. In relation to the hair follicles are special involuntary muscles buried in the skin, the arrectores pilorum, which can cause the hairs to stand up - as seen in 'goose-flesh'. It is important to note that the erection of the hairs as seen in goose-flesh is an involuntary reflex response to cold or, more rarely, to fright. Goose-flesh is not usually seen in the child under 2 years. Like the sweat glands and the blood vessels of the skin, the arrectores pilorum are under the control of the sympathetic autonomic system. The absence of goose-flesh under 2 years of age serves as a useful reminder that temperature control is not acquired until the end of the second year.

The persistence of lanugo or 'down' in children of poor constitution has already been mentioned. In such children the eyelashes are often dark, long and unusually curled. Even in the normal child the eyelashes reach their adult length before 5 years of age, so that they present that precocity of growth which has already been emphasised in the case of the eyeball. This fact also explains the aesthetic appeal of the eyes in children.

The nails often give valuable evidence of the nutritional condition as well as of the habits of children. The longitudinally fluted, brittle nails of malnutrition are familiar. After severe illnesses transverse ridges are often seen in the nails and they register the periods of acutely arrested growth previously described in the long bones. The growth of the nail is about 1mm per week, or roughly one half the rate of growth of the hair. The hair like the nails often affords evidence of the nutritional condition, no less than of the habits of personal cleanliness.

At the time when the loss of subcutaneous fat in combination with rapid increase of stature and eruption of the second dentition is most marked, from 5 to 7 years of age, the furrows, lines and dimples of the skin tend to become fixed for life.

The pattern rarely changes after this age, though the furrows, lines and wrinkles may become deeper. On the face in particular the increase in wrinkling of the forehead and in the 'crow's feet' under the eyes should call attention to possible errors of refraction in the eyes. Children who are hard of hearing frequently acquire either a countenance lined by anxiety or a blank, expressionless stare. The facies is worthy of careful study in relation to certain mental characteristics. In malnutrition the skin often becomes lax and wrinkled, loses its native elasticity and gives a senile appearance to the child.

The colour of the skin depends largely on the thickness and transparency of the epidermis, the extent to which the blood capillaries transmit their colour through it and the development of pigment in its deep layers. For this reason it is very difficult to assess in different children pallor or cyanosis, anaemia or plethora, even cleanliness or dirtiness, by vision alone. The rosy freshness of the child's skin has not only particular beauty but also definite sources of weakness. The thin epidermis is only slightly protected against mechanical injury through over-vigorous washing and rubbing. The epidermis is as easily destroyed by the over-application of alkaline soaps which remove the natural fat, faulty drying, and exposure to cold dry winds or too much sunshine, as by dirt and parasites. Foreign bodies and bacteria effect an entry easily. Children are susceptible to staphylococcal infections (pimples and boils) and to sireptococcic infections (impetigo contagiosa). Certain children, particularly those of the asthmatic diathesis, are peculiarly liable to rashes, such as prickly heat or nettle rash, as a result of undue exposure or dietetic idiosyncrasy.

The skin as a nervous organ. The skin is richly supplied with nerves, and in the child the concentration of nerve endings per square inch of skin is obviously 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 functions of the special nerve endings are brought into action for the registration of pain, heat, cold, coarse touch (protopathic) and light touch (epicritic). The sensory nerves subserving these functions are associated with definite nerve endings for each function. The nerves controlling the vasoconstriction of the blood vessels of the skin, and those controlling the arrectores pilorum (for goose-flesh) and the sweat glands are not under the control of the voluntary nervous system, but are subject to the autonomic sympathetic nervous system.

It cannot be too strongly emphasised that stimulation of the nerve endings, varied and frequent, by touch, exposure, sunshine and fresh air is a valuable part of the education of the peripheral nervous system and gives the child that sense of aliveness and awareness which is essential to purposive activity in later life.

The hair. The general conditions of nutrition are often reflected in the condition of the hair. This fact is keenly appreciated by the exhibitors of animals in agricultural shows. It is definitely known that the hair is also influenced by the endocrine glands. In deficient secretion of the thyroid gland the hair becomes brittle, poorly pigmented, even to the degree which is described as 'mouse-coloured'. In certain disturbances of the suprarenal gland excessive hair growth is often seen. The changes in distribution, quantity and quality of the hair at puberty in the two sexes is related to the secondary sexual changes. At present our knowledge of the hair in terms of nutritional, endocrine, and diathetic factors is such that one is dependent on a somewhat rough and ready appreciation of the condition of the skin, subcutaneous tissue and hair in general rather than in particular.

The powers of observation which are necessary for appreciation of the physical and mental condition of a child are not easily acquired and the observations are frequently qualitative rather than quantitative. The posture and gait of the child are suggestive. The movements of the head and neck, the disposition of the hands, the shuffling of the feet, involuntary movements or spasms of certain muscles strike the onlooker. The coloration of the skin and mucous membranes, the condition of the subcutaneous fat, the character of the hair, the facial expression and the brightness of eye yield information. The tonus of the muscles, the recent loss of weight and the alertness or apathy are registered. There is no single feature which may be regarded as a safe index to the condition of the child. The summation of the features noted by the most careful observer is not infallible.

VISION

The one fact which emerges from the study of the comparative anatomy of the eye is the close association between vision, tactile discrimination and motor skill. As Elliot Smith (26) has repeatedly emphasised, the distinctive power of the human brain confers upon man the ability to see the world and what is happening in it with an appreciation of visual experience denied to all other living creatures. It is important to realise that vision, tactile discrimination and motor skill have to be acquired slowly after birth. At the time of entering school most children are markedly immature in respect of these three qualities. The acquirement of all three is a slow process which emerges in a more or less constant pattern, but at varying times and to a varying degree in individual children.

The immaturity of children must be borne in mind when designing any programme of formal education which makes a call on vision, tactile discrimination and manual dexterity. The child gradually builds up types of response which are individual and distinctive, and not necessarily conformable to any general laws of pedagogy. At birth the infant is not only virtually deaf, but to all intents and purposes olfaction, taste and vision are but poorly developed. Such movements as occur in response to the stimulus of touch, cold, light and sound are little more than those which are exhibited by the new-born pup or kitten. The infant does not respond to light for some weeks. The following average times of appearance of certain responses are given by Mary Cover Jones (27):

The orderly progression of stages of convergence, accommodation and appreciation of distance in the development of vision precedes the various stages which lead up to orderly locomotion. The stages of walking have been analysed by Gesell (28) as follows:

Crawling occurs at 4 months in 90 per cent of cases.
Creeping occurs at 6 months in 10 per cent of cases.
Creeping occurs at 9 months in 75 per cent of cases.
Creeping occurs at 12 months in 85 per cent of cases.

Standing with help occurs at 9 months in 35 per cent of cases.
Standing with help occurs at 12 months in 90 per cent of cases.

Standing alone occurs at 12 months in 35 per cent of cases.
Standing alone occurs at 18 months in 90 per cent of cases.

Walking occurs at 12 months in 35 per cent of cases.
Walking occurs at 18 months in 90 per cent of cases.

It is well known that in feeble-minded children vision, tactile discrimination and muscular control are retarded to varying degrees. Whereas the majority of normal children walk at about 14 months, feeble-minded children walk at about 2 years. As determined by Mead (29), the age of walking seems to be related to general mental development.

The ages given above are approximate and it is well known that girls on the average are precocious as compared with boys. It cannot be too strongly emphasised that walking on two legs involves a much higher degree of tactile discrimination and a much higher degree of visual perception and appreciation of distance than that exhibited by animals which walk on four legs.

Even at the risk of appearing vicariously anxious about vision in children it may be said that it is quite possible that the eyes may be as sensitive to errors of diet, to undue strain, to unfavourable environment and to acute illnesses as the bones of the skeleton. Eye-strain, squint, shortsightedness and even mental disturbances may result from severe illness or dietetic deficiency. The infant at first sees 'as in a glass, darkly'. Gradually he appreciates varying degrees of brightness in objects, learns to focus on near or distant objects by the effort of 'accommodation', ceases 'to reach for the moon', acquires binocular stereoscopic vision and judges distance and colour. Whereas most muscular efforts such as the orderly ones of respiration or walking involve the alternate use of antagonistic sets of muscles, accommodation for near vision is peculiar in that it involves sustained muscular effort over a considerable period of time. The muscular effort involved in reading should be compared in many respects to that required in maintaining the arm aloft for a considerable period.

The increase in size of the eyeball in postnatal life is confined to infancy and early childhood. The growth is most rapid in the first 2 years of life and by 5 years of age the eyeball has almost reached its mature dimensions. A considerable amount of this increase of growth is due to increase in the thickness of the coats of the eye so that the lens and the cornea show the least postnatal increase. It is estimated that the increase between birth and maturity in the diameter of the cornea is only 2mm or about 20 per cent. This occurs almost entirely during the first two years. It is evident that the precocity of growth displayed by the eyeball is more marked than that of the brain. Moreover, growth of the eyeball ceases before that of the brain. It is not surprising that the rapid growth of the conjunctival sac, the cornea and the eyeball should thus lead to a peculiar susceptibility to injurious agencies during early childhood. Furthermore, although the lachrymal (tear forming) gland effectively washes the conjunctival sac with secretion (tears) of considerable bactericidal power, the actual lymphatic drainage of the eyeball proper is subject to many obstacles especially during sustained visual effort.

The eyelashes are special hairs, associated with which are distinctive sebaceous glands called Meibomian glands, which are peculiarly liable to infection and inflammation in childhood. The lids become red and heavy, the eyelashes fall out and frequently styes appear. The sore eyes are largely attributable to dirt, but the condition is aggravated by eye-strain. Styes occur frequently during malnutrition or in convalescence after an acute illness. Inflammation of the margins of the eyelids is called 'blepharitis'. Not infrequently children present another form of sore eyes called 'pink eye' or 'conjunctivitis' in which the delicate lining of the front of the eyeball and of the back of the eyelids - the conjunctiva - is inflamed. Conjunctivitis often occurs in epidemic forms and calls for strict routine in cleanliness not only of the eyes but also of the hands, nails and towels. In cases of malnutrition and tuberculosis small white patches progressing to ulcers appear on the rim of the anterior layer of the eyeball - the cornea. This is called phlyctenular conjunctivitis. The condition is chronic and is rarely cured except by good feeding, a change of air and improvement in the general health.

Eye-strain is a term loosely used for a condition which is common in young children. Frowning, blinking and even twitching of the face and rubbing of the eyes occur with or without subjective symptoms of headache. In short the eyes are easily fatigued. The treatment for fatigue is rest. As lying down is the treatment for the undue bodily fatigue of long standing, so resting and sleeping in a dark room is the only treatment for fatigue of the eyes. Bright light, whether of the sun or the cinema, exhausts the visual purple which sensitises the rods of the retina. The visual purple is only restored in darkness. Children should sleep in the dark. Children with blue eyes are not able to withstand bright glares as well as those with deeply pigmented brown eyes; at birth all children have blue eyes and the development of the brown pigment is a gradual process. The eyes of young children should therefore be protected from blinding sunshine.

Amongst the conditions which require immediate and urgent medical attention in children are squint and shortsightedness. Squint or strabismus since it prevents both eyes being used simultaneously on the same objective point results in a failure of binocular and stereoscopic vision. The child uses one eye to the gradual exclusion of the other. The latter eventually undergoes disuse atrophy and becomes blind. The child is reduced to an appreciation of his surroundings little better than that possessed by a rabbit or a babe. Squint involves a serious handicap on man's acquired cortical ability to interpret the meaning of experience by comparison with memories of the binocular stereoscopic feelings and sensations previously enjoyed. Squint involves a definite check in that continuity of experience which is so fundamental in education. Practically all cases of squint in children are amenable to rapid, early and painstaking medical treatment. Squint is one of the most potent causes of a progressive inferiority complex.

Short sight or Myopia. In the shortsighted eye either the anteroposterior axis of the eye is too long or, more rarely, the refractive index of the lens is too high. In children under two years of age myopia is rare. The condition usually appears during school age and tends to be progressive during the period of growth. The number of cases increases with the school age, so that both the frequency of cases of myopia and the degree of the myopia increase. The mild cases of myopia respond readily to correction by concave lenses which should be habitually worn, as good distant vision cannot be obtained without them. The severe cases require careful training with avoidance of all excess in close work, such as reading, writing and sewing.

HEARING

The organ of hearing consists essentially of an external ear (auricle and earhole), middle ear (drum and ossicles) and internal ear (cochlea). These three parts are essentially sound collecting, sound conducting and sound perceiving. In man the auricle is not as specially developed as that in the lower animals where the cocking of the ears in relation to localisation of sound is well marked. The middle ear is bounded on the outer side by the drum (tympanum) and on the inner side it connects with the nasopharynx by a narrow canal lined by mucous membrane. This narrow canal is the Eustachian tube and it is the path whereby infection spreads from the nose or pharynx to the middle ear. The internal ear or labyrinth consists of an acoustic part concerned with the perception of hearing; this part, the cochlea, conveys auditory stimuli to the parts of the brain which interpret the stimuli. 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 causes vertigo (giddiness) and nystagmus (jerky movements of the eyeball).

The growth of the drum, middle ear and internal ear in antenatal life is extremely precocious so that at the sixth month of foetal life these organs are within 10 per cent of their adult size. This precocity of the apparatus of hearing is accompanied by a relatively late development from the functional point of view of those parts of the cortex of the brain which are peculiarly associated with hearing and speech. The apparatus is laid down early in the development of the individual but the complete functioning of the apparatus is a late feature.

Hearing varies more than vision in children, Most children can hear sound waves extending over 7 octaves (40-4,700 vibrations per second). Some children, like dogs, can appreciate lower notes, others can appreciate higher notes such as those emitted by the flight of a bat. One of the main features of development in the child is the manner in which he learns to become insensitive to sound stimuli, ranging from the tick of the clock to the 'don't do that' of the parent; in short, the child may become cortically deaf to spoken words as to other sounds. Auditory memory probably displays a greater range of variation in different children than visual memory. It is possible that the recent tendency in the school in favour of 'silent' work which is essentially visual is not as efficient in certain cases as the recitation aloud which was formerly practised.

Disease of the middle ear. 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 the common cold or an acute infectious fever, involves by extension inflammation of the Eustachian tube and middle ear. In the baby both on account of the shortness of the neck, the reclining position and the weakness of expiratory effort, as in coughing and sneezing, the back of the nose is not easily cleared of an accumulation of mucus. Furthermore, if an infant is fed in the horizontal position food and drink easily regurgitate above the palate into the nose and may even reach the middle ear by way of the Eustachian tube. Thus inflammatory conditions of the middle ear are most frequent in the youngest, in whom the control of head movements, expiratory effort and spitting are not well developed. They are peculiarly dangerous in children because the excruciating pain of earache does not always appear in the very young when there is severe inflammation in the middle ear, as the various parts of the temporal bone do not become consolidated to form a compact whole until early childhood. 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 meninges of the brain or appear under the skin above, behind, below or even in front of the ear. Disease of the middle ear is a killing disease and inflammation of the middle ear is present in 80 per cent of the infants under 2 years of age who reach autopsy.

Acute inflammation of the middle ear is a common condition as an accompaniment of the ordinary cold. It frequently accompanies acute infections such as measles, scarlet fever, diphtheria and even severe chicken pox. Chronic inflammation of the middle ear with its discharge (otorrhoea) is too frequently a sequel of the acute fevers mentioned above. In the first place the chronic infection saps the vitality of the body and the progress of the child mentally and physically is handicapped. In the second place the scar tissue formed in the middle ear as a result of the inflammation and the permanent destruction of the drum leads to deafness which is a second handicap. The progress of the child in school, his reaction to his environment at home, and his potential disability in that so many avenues of play, sport and employment are closed to him, are of grave significance. The behaviour of the child and his emotional responses are considerably disturbed. Middle ear disease cannot always be prevented in its acute forms, but there is no justification for the existence of chronic middle ear disease in the presence of active medical treatment. Treatment of chronic middle ear disease not infrequently calls for treatment of associated enlargement of the lymphoid tissue in the mouth (tonsils) and nasopharynx (adenoids).

THE BRAIN

The precocity of growth of the nervous system as compared with the skeletal system is well established. The actual rate of growth and differentiation of the various parts of the cerebral cortex still awaits intensive research. The child of seven years of age presents an arrangement of layers of cells and fibres in the cortex which cannot be distinguished from that of an adult.

It has been widely accepted that the actual number of nerve cells in the cortex of the brain undergoes no increase after birth. This has become a tenet of many neurologists and psychologists. Aldama (30), among others, has focused attention on the fact that up to five years of age the various layers of the cortex possess a reserve of agranular cells, some of which may be able to differentiate in order to remedy deficiencies due to disease or injury in cells, which had been differentiated during late embryonic life or early childhood. Those areas of the brain peculiarly associated with late myelinisation, prolonged differentiation and functions which even now are not clearly defined, are also the identical areas which display an orderly progress in development from the anthropoid brain to that of ancient and modern man. These areas tend to be related to those overlying sutures of the skull which display late union. (Harris) (31). These areas, comprising portions of the frontal, parietal and temporal lobes, were previously referred to as associational or 'silent' areas. They are the very areas which Aldama depicts in his studies as areas which at 5½ years of age are further removed from their definitive adult form. than the remaining parts of the cortex. (See report on The Primary School).

DENTITION

Most of those animals which present differences in size, shape and number of roots of the teeth according to differences in situation in the mouth also develop two sets of teeth. The primary deciduous dentition or 'milk' set is replaced by a secondary dentition or 'permanent' set. Animals differ widely both in the number of teeth in either set and in the time of cutting of the teeth. In some animals, such as the seal, the milk teeth are cut and shed in utero: in others, such as the pup, milk teeth are cut and rapidly replaced by the permanent set. In certain ruminants, such as the horse, milk teeth are retained until the animal is almost of adult size. In man the milk teeth are destined to function until at least 7 years of age and there is a close correlation between the condition of the milk teeth and that of the permanent teeth. On the whole the child who has sound milk teeth will tend to have sound permanent teeth. The child with carious milk teeth requires careful nutrition and dental care to acquire even a moderately well-formed permanent set.

Even during the fourth month of embryonic life the milk teeth of man have commenced to undergo calcification. At birth all twenty unerupted milk teeth are heavily calcified with dense enamel in their crowns. The first permanent molar tooth, which is often referred to as the 'six year old' molar, even though it will not erupt until the sixth or seventh year, already possesses before birth a distinctly calcified crown. Hence it follows that the care of the teeth must be undertaken before the child is born.

The radiograph (Fig. 4 above) of a child of five years shows the manner in which the permanent teeth are housed in the bony jaws before displacement of the deciduous teeth. It is the eruption of the permanent teeth in the sixth and seventh year which leads to that elongation of the face, excavation of pneumatic sinuses such as the maxillary antrum, and the change in physiognomy which characterises the second 'springing-up' stage of growth from 5 to 7 years of age.

The following tables of dentition are given as a rough guide to the average date at which the various teeth of the milk and permanent set are cut.

In comparison with the precocity of growth of the brain, it should be noted that the growth of the face and the eruption of the third permanent molar or 'wisdom' tooth are not complete until approximately 21 years of age. Any faulty development of the permanent dentition is apt to be associated with irregularities in the development of the jaws, palate and pneumatic sinuses in relation to the respiratory pathway in the nose and pharynx.

The teeth in young children. In this country no organ or tissue of the human body is so frequently affected by disease as are the teeth. A child of school age without some evidence of dental caries, past or present, is unfortunately almost a curiosity.

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 bacteria found in the mouth, which have the power to attack and produce disintegration of 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 calcined tooth was believed to be little more susceptible to caries than one which was well formed. Mainly for this reason, therefore, comparatively little research was directed towards elucidating the factors responsible for determining the structure of the teeth. Investigators of the problem of caries concentrated largely on what might be called the environment of the teeth, and their work was directed towards such questions as the physical and chemical characters of a satisfactory diet, the composition and functions of saliva, and so on. 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. It is agreed by most dentists that the systematic use of a toothbrush, useful though it may be in helping to remove these fermentable substances, cannot be relied upon to prevent caries entirely, and that its effect is inferior to that produced by a diet such as Dr Sim Wallace (32) advocates.

There is no doubt whatever that our modern methods of cooking and preparation of food result in our teeth and jaws having much 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 results.

It has already been noted that for many years the structure of the teeth received comparatively little attention, but this is not true of the post-war years. The development of this recent research is of interest. In the later stages of, and immediately after, the Great War, it was observed that rickets was remarkably prevalent in some European countries, and investigations eventually proved that this condition was due to the comparative lack of vitamin D in the food of the children affected. In this work Professor Mellanby (33) of Sheffield was a pioneer.

The principal natural source of vitamin D is animal fats, for example, butter and cod liver oil. As fats are a relatively expensive form of food, the children in countries such as Austria were, in many cases, unable to obtain these foods in anything like adequate quantities. This essential vitamin is also formed in the body under the influence of the ultra-violet rays of sunlight - whether derived from natural or artificial sources.

The disease known as rickets or rachitis is characterised by defective calcification of the bones. 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 taken up by Mrs Mellanby (34), who has worked on the various aspects of the subject for the past decade or so. 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 to produce at will well-formed teeth or the reverse, according to whether or not an adequate supply of vitamin D in the diet is secured. More recently she has shown that cereals tend to have the opposite effect in puppies, that is, that they have anti-calcifying properties. Her work, however, would probably not have aroused widespread interest in the absence of evidence that the variations in structure thus produced had some effect on the susceptibility of the teeth to caries.

The view held formerly that there was little relationship between the two conditions 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 positive correlation between defective structure and caries in human teeth. (Owing to the fact that dental caries is not a canine disease, such a correlation could not be observed in dogs).

It then remained to be seen whether the controlled administration of vitamin D to children would have the effect of reducing the incidence either of defective structure or of caries. Such work as has already been done by Mrs Mellanby and her collaborators on this subject has yielded suggestive results. In her experiments there was observed a notable reduction in the incidence of caries amongst children receiving a regular supply of vitamin D as compared with that found in the children acting 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.

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