Hadow (1931)

Notes on the text
Preliminary pages Membership, Analysis, Preface, Introduction
Chapter 1 The history of the development of the conception of primary education
Chapter 2 The physical development of children between the ages of 7 and 11
Chapter 3 The mental development of children between the ages of 7 and 11
Chapter 4 The age limits for the upper stage of primary education
Chapter 5 The internal organisation of primary schools
Chapter 6 Retarded children in the primary school
Chapter 7 The curriculum of the primary school
Chapter 8 The staffing of primary schools and the training of teachers
Chapter 9 The premises and equipment of primary schools
Chapter 10 Examinations in primary schools
Chapter 11 Summary of principal conclusions and recommendations
Chapter 12 Suggestions on the curriculum of primary schools
Appendix I List of witnesses
Appendix II Physical development of 7-11 year olds (Harris)
Appendix III Mental development of 7-11 year olds (Burt)
Index

London: HM Stationery Office

APPENDIX II
[pages 222 - 254]

MEMORANDUM ON THE ANATOMICAL AND PHYSIOLOGICAL CHARACTERISTICS AND DEVELOPMENT OF CHILDREN BETWEEN THE AGES OF 7+ AND 11+ BY MR HA HARRIS, MB, BS, DSc, ASSISTANT PROFESSOR OF ANATOMY, UNIVERSITY COLLEGE, AND ASSISTANT TO THE MEDICAL UNIT, UNIVERSITY COLLEGE HOSPITAL, LONDON.

Contents
Introduction
The growth curve
Slowness of growth in the child
Evidence of arrested growth in children
Diseases in relation to the curve of skeletal growth
Growth in animals and plants
The growth of the nervous system in the child
Histology (microscopic anatomy) of the brain
Diathesis, bodily habitus and physical types
The growth of the muscular system
Fatiguability, mental and physical
Bibliography

It is a healthy sign of the times that the terms of inquiry for this report refer to children from 7+ to 11+, ages which bear no relation to the quinquennial and decennial periods which obscure the significance of anatomical and physiological facts in the mass of our statistics. When Francis Bacon sketched his vision of the future development of science, he included among the major problems of physical science the analysis of the growth of the human body. (Of the Advancement of Learning (1605) Works (Ed. Ellis and Spedding) III, 374; Catalogus historiarum particularium (1620), Works, I. 407-408.) We are as yet, however, not within measurable approach of that science of embryology, the ultimate aim of which, according to William His, is the mathematical derivation of the adult from the distribution of growth in the germ.

Scammon (1) has surveyed the work of the last three hundred years so as to indicate the extent to which the world has become a stage for children rather than adults. The total number of publications dealing with the growth of the child shows the increasing extent to which the child absorbs the working hours of the scientist. In the 16th century there was one publication, in the 17th century thirty publications, in the 18th century two hundred, in the 19th century two thousand five hundred, and in the first quarter of the 20th century, notwithstanding the Great War, three thousand five hundred. Of these publications 50 per cent were in German, 20 per cent in French and only 18 per cent in the English language.

The valuable analysis of Scammon shows that the medical sciences have accounted for more than two thirds, and journals dealing with psychology and education for less than one thirtieth of the total number of publications. Further, if one considers publications dealing with the nervous system, three quarters of the total publications have appeared in journals of medical science and but 0.5 per cent in journals devoted to psychology and education. This statistical distribution is of interest as an indication of the continued interest of the medical scientist in the growth and development of the body and mind of the child as compared with the relatively recent interest of the workers in the limited fields of education and psychology.

The fundamental phenomenon of a healthy young animal is growth coupled with facility in the performance of work. The growing animal is able to absorb living or non-living organic matter, with a certain amount of inorganic matter, and to convert it into matter like unto itself, endowed with life. Growth is essentially a biochemical process of conversion. Health is a state of facile ability to perform work. All records of growth, whether they be obtained by the collective method of mass statistics with a view to ascertaining the norm, or by the individual and clinical method designed to give a particular child a chance in life, valuable as they may be, fail to yield an insight into the essential physico-chemical processes involved. The autonomous nature of the process is its chief virtue. The number of variables involved in the process of growth is at once the despair of and the stimulus to the biologist.

Growth in the animal is not synonymous with increase in bodily dimensions and weight, but involves an actual difference in the chemical composition of the tissues of the animal and in its behaviour. The animal grows into a larger animal, but simultaneously yet asynchronously develops into a different animal with a view to reproduction, senescence and finally, death.

The earlier studies of growth in children, based largely on measurements of height and weight at different ages, yielded in the hands of Quetelet (2) and Vierordt (3), a crude norm. Vierordt not only published weights of the body as a whole, but recorded the weights of the various organs, a procedure which was largely extended by Oppenheimer (4). In recent years there have been numerous publications dealing with measurements of height and weight in children of various races. The value of the work is not commensurate with the number of measurements. The statistical evidence that can be wrung out of such measurements may have very little meaning because the quantities measured depend on such a multiplicity of causes. Statistical treatment may indicate that certain results are significant, but what they signify, is still unknown.

The simple study of the course of growth by the pictorial representation. of certain 'stages' was first employed by Fabricius of Acquapendente (5) (1621) and Blasius (6) (1692) for the 'stages' of development in the chick. Albinus (7) and Soemmerring (8) illustrated stages of growth in the human foetus, Astley Cooper (9) of Guy's Hospital in the breast, and His (10) in human embryos. A notable advance in this pictorial method was made by Poland (11), a much neglected English surgeon, who first depicted the growth changes in the bones of the hands by a series of radiograms. The radiographic method has the advantage of preserving a set of records which can be submitted to measurement and statistical analysis.

Modern methods of mathematical analysis of growth date from the time of Francis Galton (12), who introduced the conception of percentile notation and of correlation factors. This method of analysis in the hands of Pearson, Jackson, Pearl, Brownlee, Greenwood, Scammon and Dunn has produced a group of analytical expressions for growth which have the advantage of brevity and avoid the presentation of extensive tables and elaborate graphs.

From all the factors influencing growth, either hereditary on the one hand, or environmental on the other, as emphasised by Galton, the one significant factor which has emerged in recent times, is nutrition. The extent to which growth can be controlled by nutrition - a commonplace of the farmyard - has as yet been but poorly reflected in the diet of the growing child. Hopkins and Mellanby (13) in this country, Hess (14) and McCollum (15) and their co-workers in the United states of America by reason of their studies in the biochemistry of the vitamins, Corry Mann (16), Paton and Findlay (17) by reason of their study of environment and diet, have created a public conscience with regard to dietetics. This conscience is sadly abused by the interested manufacturer of patent foods.

The state of knowledge of the growth of the brain in relation to the growth of the body has been admirably summarised by Donaldson (18). Since that time (1895) the anatomical work of Brodmann(19), Flechsig (20), Bolton (21) and Elliot Smith (22), and the physiological discoveries of Sherrington(23) and Pavlov (24) have led to a conception of growth and function in the brain far removed from that expressed by mere ponderal relationships.

Galton was the first to suggest the possibility of measuring human ability quantitatively. From this starting point have emerged tests of juvenile intelligence, such as the Binet-Simon tests, and of greater importance, that study of the gradual growth and emergence of behavioural patterns in the child which can be so closely related to definite stages in the growth of the skeleton and nervous system. The growing child, as emphasised by Coghill (25), is more than the sum of his reflexes, instincts and immediate reactions, since he also has his creative potential for the future. Lastly Spearman (26) and his co-workers have shown the innate character of mental powers and the comparative insignificance of that formal education which the state is able to impress upon the growing child.

The views expressed in the following sections are based on a close acquaintance with the growing child in the hospital, the home and the school. It is a pleasure to admit my indebtedness to Professor Donaldson of the Wistar Institute, Philadelphia, and to Professor Scammon of the University of Minnesota. To my colleagues at University College and University College Hospital my thanks are due, especially Professor Elliot Smith, FRS, Professor TR Elliott, FRS, and Dr Barton, to whom the subject of 'growth' is 'anatomy writ large'. For valuable assistance with clinical material, illustrations and radiograms I am indebted to Dr Audrey Russell, Mr AK Maxwell and Mr F Melville respectively.

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 200Ib. 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 gives place to 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 a 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. In particular, dentition, defective 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 7 to that of 11 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 purely 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 (27) 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 processes 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 so many astounding experimental observations and so much feeble theorising, present a picture which 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 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 shown on some of the growth curves of height and weight as it is made manifest 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.

Of all the potentialities of the newborn infant, growth, maturity, reproduction and decay, none is so marvellous as the phenomenon called growth. Growth in the babe is more complex than in the young of any other animal. The baby is of all animals the one which grows most slowly. An Airedale puppy doubles his weight in the first week of life. A newborn babe, whether born in the palace or the cottage, takes six months to accomplish this. The kitten and the baby rabbit almost cease to grow at the end of the first year, but the human babe continues to grow until the age of twenty-one or later. The kitten and pup, born blind and helpless as they are, can be removed from the atmosphere of maternal care at thirty days. The human babe is of all young creatures the most helpless. He grows extremely slowly, but continues to grow over a long period by fits and starts. He is dependent for many years on his mother, on the family, the school, the state.

The educability of the child is closely associated with this slow rate of growth. Animals such as the lamb, calf and colt, which run about as soon as they are born, cannot learn new methods of thinking with the same facility as the helpless pup, kitten or bear cub. They have scampered through their childhood at too great a pace. The newborn guinea pig presents the same degree of ossification in the bones of the hind limb and the same relative ponderal development of the brain as the child of eight years. The guinea pig has, so to speak, wasted eight years of life in utero in an environment limited by such stimuli as could penetrate the amniotic fluid. He has lost those eight years of education in an outside world with new stimuli, new experiences, new responses which are given to the human child. Both the guinea pig and the pig are able to walk, to run and to fend for themselves to a considerable extent at birth. But such development is bought at a price and is reflected in the low degree of educability which they present, and in their limited range of what might be called intellectual impulse. On the other hand, the kitten, pup and rat are born in a distinctly immature condition. The rat at birth presents the same degree of ossification in the hind limb and the same degree of ponderal development of the brain as the human foetus of the fourth month of pregnancy. The kitten and the pup are born at a time when the ossification pattern of the hind limb and the ponderal development of the brain correspond to that of a human foetus of the seventh month. They, blind and helpless, unlike the pig, calf, colt and guinea pig, may look forward to a comparatively long period of childhood and educability, during which new behaviour patterns can be acquired. Yet, in such forms as the kitten, and pup, the period of effective childhood is relatively short, since they pass from the stage of the suckling through the stages of primary and secondary dentition to adolescence and sexual maturity within one year. The characteristic of man is the slowness of growth and the postponement of sexual maturity. The race is not to the swift, but to the simple. This has been emphasised by Bolk (28) and Elliot Smith (29) as the anatomical persistence of foetal and childish characters. Precocity of development and specialisation is bought only at the price of diminished final attainment.

The comparative state of development of the skeleton and brain at birth in different species is paralleled in mild degree by those differences observed in man and woman. Centres of ossification in relation to developing bone appear earlier in the girl baby than in the boy. Moreover, epiphysial union, and that knitting of the bones which heralds cessation of growth in length at the end of adolescence, occur earlier in the female. Energetic champions of the anatomical virtues of women have repeatedly pointed out that the female brain, as well as the skeletal development, is remarkably precocious. The brain weight in a girl of ten is four times that of the brain weight at birth, but in the boy the brain weight is not quadrupled until the age of 14. On the other hand growth of the brain persists in man for a longer period than in woman. It would appear that the precocity of the female, both as regards brain growth and ossification, is an indication of the earlier acquisition of a common behaviour pattern and of a more readily exhausted intellectual impulse. This problem has its repercussion on the problem of coeducation, since the differences between the sexes which are so often regarded as commencing at puberty are far more profound and are at work from the early stages of embryonic life. The girl of twelve is taller and heavier than the boy of the same age. Her skeleton is nearer maturity, her brain is nearer maturity. The sexual differences are as complicated at ten years of age as at fourteen, except for the absence of such a dramatic event as the onset of menstruation in the girl.

Growth even in the period between this ages of 7 and 11 has to be interpreted in the boy and girl, as everywhere else in the biological world, in terms of the antagonistic factors of vegetative reproduction or proliferative growth proper, and differentiation for specialised function, sexual or otherwise. The significance of slowness of growth in the child is admirably expressed in the adage: apples which ripen most slowly, last longest.

The one thing which has emerged from my own observations (30) at University College Hospital has been the inordinate extent to which the growth of the skeleton is sensitive to relatively slight and transient illnesses and periods of malnutrition. Every acute illness, whether it be due to an acute fever of to disease of the respiratory system such as broncho-pneumonia, upsets the normal metabolism and growth of the child. Such illnesses are recorded on the bone as 'lines of arrested growth'. (Fig. 2). The radiological and histological structure of these lines of arrested growth shows that they are due to a defensive mechanism in the bone. When the child is ill or starved, the epiphysial growth cartilage at the end of the shaft of the long bones ceases to proliferate, and becomes heavily calcined. When growth is resumed, after the removal of the nociceptive stimulus, this line of arrested growth appears as a veritable scar on the bone. Such lines of arrested growth differ in extent, but not in genesis from the lines of complete cessation of growth which appear as a result of the final calcification of the epiphysial growth cartilage on the completion of adolescence. These lines of arrested growth in bone following acute illness or starvation may be compared with the permanent transverse ridges in the enamel of the permanent teeth, with the transient ridges running transversely across the nails, with the annual rings on the scales of fish, or the seasonal rings in deciduous trees.

These lines of arrested growth have not only been studied in the acute fevers of childhood but also in metabolic diseases such as diabetes. (Fig. 3). The young victim of this pernicious disease displays a series of lines of arrested growth indicative of the extent to which growth is controlled by the administration of insulin, and acute exacerbations of the condition are faithfully recorded.

This indication of the extent to which illness is registered as a veritable scar in bone, is emphasised in order that we may realise how sensitive the growing child is to illness or starvation. We know but little of the extent to which illness involves the growth organs which display the neural, lymphoid or genital type of growth. The involvement of the skeletal system, as demonstrated by the lines of arrested growth, is far greater than was anticipated. The muscular system and fat deposits of the body, it is true, had always been associated with rapid wasting in illness and starvation. When we realise the extent to which the various organs of the body, especially the blood-forming organs in the marrow and spleen, may be involved in illness or malnutrition, it becomes apparent how grave is the responsibility assumed by those who wish 'to make the children work' or to curtail the period of convalescence. There is little doubt that an equally intensive study of the organs and tissues other than bone would indicate the extent to which acute illness and starvation are registered upon them.

I have been interested for some years in plotting the incidence of various acute and chronic diseases on the growth curve. There is evidence that the three 'springing-up' periods are peculiarly associated with certain diseases. Moreover, any disease which might appear at any year of school age shows a tendency to leave more severe sequelae if it occurs during one of the 'springing-up' periods when the child is already taxed to the utmost in providing the necessary energy for growth.

Two of the most studied chronic infections illustrate this. Congenital syphilis, if it fails to manifest itself in the first year of life, tends to appear during the second dentition or during puberty, the stress falling essentially on the teeth, the joints or the eyes. Tuberculosis is invariably fatal in the first year and assumes the widely disseminated miliary form, with or without tubercular meningitis. During the second 'springing-up' period, the acute fevers involving the respiratory tract, especially measles and whooping cough, are often followed by tubercular involvement of the glands of the chest. Running ears and nephritis as sequelae of scarlet fever at this age are well known. One might say that the age from 7+ to 11+ is of peculiar interest in the hospital clinic by reason of the relative rarity of acute disease, and the relative frequency of the chronic sequelae of the preceding acute infections. The burden tends to fall most heavily on the lymphatic system in the neck, chest and abdomen. In those districts where the milk supply is inadequately guarded, tuberculosis of the bones and joints is also common.

The third 'springing-up' period of puberty presents the familiar picture of the boy or girl outgrowing his or her strength, with a tendency to the reappearance of severe sequelae, to acute infections, and a predisposition to disabling manifestations of the chronic infections. The peak incidence of enteric fever occurs in this period, and critical complications tend to be seen at an earlier age in girls than in boys in accord with the earlier onset of puberty.

As long as the school leaving age stands at 14 or 15 years of age, the state has to regard the period from 7+ to 11+ as the last opportunity for retrieving the errors of the past and consolidating young children for the strain of puberty. With a school leaving age of eighteen there would be a final opportunity at the end of puberty and during adolescence of retrieving to no mean extent the errors and scars of childhood and of providing for a healthy period of adult life. After the completion of adolescence there is but scant opportunity to convert a C3 population into an A1 population. It thus becomes all the more imperative in view of the existing school leaving age that the years from 7 to 11 should be recognised as the last available opportunity for raising the norm of physical efficiency, for eradicating the errors of early childhood and for preparing for the severe burdens of puberty.

The statistics of the incidence of disease and death which are now rendered in quinquennial and decennial periods, should be plotted as yearly returns on the growth curve so that the distribution of disease may be related to the underlying anatomical facts of growth and development. If the perversions of growth such as rickets, coeliac rickets, renal rickets and adolescent rickets be plotted on the growth curve in terms of age distribution, the trimodal curve corresponds very closely to the three 'springing-up' periods. Measles, whooping cough, scarlet fever, diphtheria, chicken pox and infantile palsy are acute infections which characterise early childhood. Further, the complications of these diseases tend to be more marked, if the onset of the disease falls within the first or second 'springing-up' periods. The troublesome sequelae are more severe, if the disease falls upon the child when he is faced with a period of rapid growth. The peak of incidence in scarlet fever falls in the sixth year. The mean incidence of the septic form is in the seventh year. The severe complications, other than otitis, such as adenitis, nephritis and endocarditis also fall in the second 'springing-up' period. In the case of diphtheria the peak of incidence is in the fifth year. The age incidence of the complications shows that apart from otitis, which is always most severe in young babies who can make no vigorous expiratory effort, the albuminuria reaches a maximum in the seventh year. Diphtheritic palsy is usually somewhat later, in the ninth year. Of all cases of scarlet fever and diphtheria occurring from birth to sixteen years of age, approximately 70 per cent of the cases of scarlet fever and 80 per cent of those of diphtheria fall within the age group of 0-8. In cases of acute fevers occurring after eight years of age the incidence of complications decreases rapidly. This is a strong argument in favour of seven (7+) or even eight years as the age of transference from the infants' department to the upper section of the primary school. The recent report by Goodall, Greenwood and Russell (31) confirms this point of view.

The differences between growth in animals and plants have been discussed since the time of Aristotle and Theophrastus (Aristotle, De Generatione Animalium, I.1., p. 715b, 21 foll, Berlin Ed. 1831. Theophrastus, Historia Plantarum, I.1., Sections 1-5) and since some educationists have clearer views upon growth in plants than upon growth in children, it may be wise to consider some of these differences. The plant continues throughout life to form new organs, whereas the animal concentrates or telescopes the process of organogeny into the first part of embryonic life. All the essential organs in man are laid down before the end of the fourth month and the primordia are clearly demarcated by the seventh week of embryonic life. The plant regulates its growth by its leaf area, the photosynthesis being a function of leaf surface. The animal does not grow in response to so simple a factor as increase in surface area. The plant always retains at the growing point embryonic tissue, rapidly growing and peculiarly susceptible to injurious stimuli such as cold winds or frost. This persistence of embryonic tissue allows the plant to grow new organs throughout life. There is nothing strictly comparable to the growing point of the plant in the animal, in which powers of regeneration and repair are so strictly limited in accord with the position of the animal in the evolutionary scale. No new nerve cells can be grown and nerve cells once destroyed are never replaced after birth. Lastly the plant is largely the plaything of its environment, whereas the animal, particularly the warm-blooded animal, can rise, within limits, superior to its environment.

Almost all our knowledge of growth in plants has been expressed in terms of size; almost all our knowledge of growth in animals has been expressed in terms of weight. Plants can be measured with ease, but can only be weighed with difficulty. Animals can be weighed with ease, but measured with difficulty. Changes in the chemical composition of plants have been studied in detail, but studies in the chemical composition of animals have been comparatively few. There has been no satisfactory analysis - organ by organ and tissue by tissue - of the changes in composition of the animal. Moulton (32) is the sole pioneer in this field.

The graphic method of tabulating weights and heights so dear to the physical anthropologist is apt to lead to the assumption that the growth rates of the different organs and tissues do not differ greatly among themselves. There is no reason for regarding the growth curve as the resultant of a series of components that differ but slightly from one another. Growth in the animal is not uniformly distributed through all the tissues at a given time, nor is it accomplished by cell multiplication as distinct from increase in size of the cell.

The skin, muscles, skeleton and viscera grow at different rates at different ages. The rapid growth of the muscular system in the last month of antenatal life and again in puberty illustrates this fact. Actual muscle forms but 25 per cent of the body weight in the newborn, whereas in the young adult it forms 43 per cent. Different tissues and different organs cease growing at different ages, and relatively inert tissues such as fat undergo great variation in response to changes in diet and exercise. The important characteristic in the growth of the animal is the substitution of mere proliferative growth in the cell by special function in the cell. The nerve cell does not proliferate in postnatal life and is designed to carry out its special function for three score years and ten. Similarly the cells of the sweat and salivary glands function as working cells without any appreciable degree of proliferation. A scar in the skin never grows hair follicles or sweat glands and so is never completely regenerated skin. The athlete in training does not grow new muscle cells; he simply increases the size of the cells. This point of view must be grasped both because curves of height and weight yield but meagre information and because growth involves two wholly distinct and mutually exclusive processes: (1) mere proliferation of pre-existing cells and (2) differentiation of the cell, involving the surrender of proliferation, for special function. Richard Owen, Curator of the Royal College of Surgeons, said, as far back as 1843:

'Organic form results from the antagonistic working of two principles, of which one brings about a vegetative repetition of structure, while the other, a teleological principle, shapes the living thing to its functions ... In every species these two forces are at work, and the extent to which the general polarising or 'vegetative repetition' force is subdued by the teleological, is an index of the grade of the species'.

The inherent complexity of growth and development, far greater than that indicated by Scammon's four types of growth described in an earlier section as skeletal, nervous, lymphoid and genital, must be borne in mind when the data of the physical anthropologist are presented. All efforts to subject the growth curve to mathematical analysis have failed. All attempts to give the growth curve a chemical interpretation in terms of autocatalytic reactions have failed. Our knowledge of growth, proliferation, differentiation, decay and death in the cell is inadequate. The limitations of the physical anthropologist, no less than the limitations of the vocational psychologist, are apt to be submerged. Each child in himself is a new biological experiment, and is after all essentially but a potential producer of a progeny of new experiments in biology.

Plants have no work to do besides nutrition, growth and reproduction. All animals possess, in addition, sensation and the sensitive or perceptive soul. Aristotle (34) wrote:

'Plants, again, in as much as they are without locomotion, present no great variety in their heterogeneous parts. For, where the functions are but few, few also are the organs required to effect them. Animals, however, that not only live but feel, present a greater multiformity of parts, and this diversity is greater in some animals than in others, being most varied in those to whose share has fallen not mere life, but life of high degree. Now such an animal is man.'

It was also Aristotle who said of animals:

'Their manner of life differs in their having pleasure in sexual intercourse, in their mode of parturition and rearing their young.'

This presents baldly a fact which we cannot afford to dismiss from our scheme of education.

The first attempt to interpret the course of human growth on a chemical basis was made in the same year by W Ostwald and that brilliant Australian, the late T Brailsford Robertson (35). Robertson concluded that there are three maxima in the curve of growth, and constructed his so-called 'autocatalytic curve'. Davenport (36), who has contributed numerous important papers on the subject of human growth, insists that there are but two periods of accelerated growth, the one circumnatal and the other adolescent. Davenport's curve of growth shows but two growth accelerations superimposed on a residual curve of growth out of which the accelerations arrive. The residual curve is characterised by a low velocity, averaging about 4½Ib. [2.04kg] per year from two to twelve years. No period of acceleration between the fourth and seventh years is recognised.

In the discussion of the growth curve in the child we have adhered to the curve which presents three 'springing-up' periods, mainly because of its clinical value in the study of the individual child, partly by reason of its emphasis in the curves given by Pfuhl (37) and because of its general acceptance by Brownlee (38). Moreover the growth curve based on mass statistics tends to be smoothed out by mutual cancelling of the growth of children above and below the norm.

Donaldson (39) and Scammon have insisted on the different types of growth in various organs and tissues at different periods of the life cycle. The growth rate at a given instant in a child as a whole is the resultant of a considerable number of different growth rates. Each one of these rates is probably susceptible in a varying degree to injurious stimuli such as disease and malnutrition. Each one of these rates of growth probably presents a different rate of re-establishment on the removal of the injurious stimuli. Thus little remains of the conception that growth as a whole, as indicated by van de Sande-Bakhuyzen and Alsberg (40), is controlled by a single master reaction.

Numerous attempts have been made to express in the form of an index the relative proportions of brain and body in various animals during the different stages of growth. Cuvier (41) more than a hundred years ago published a comparative table of the ratio of brain weight to body weight. This ratio alone is obviously an inadequate expression of psychological differences. The fact that the body weight of the mouse is thirty times that of the brain weight, whereas the body weight of man is forty times that of the brain weight is enough to indicate this. Brandt (42) emphasised the significance of surface area rather than body weight in small mammals. But even if the brain weight of small animals be assessed in terms of their relatively large surface area, it still remains relatively great because it is associated with a high metabolic rate and great muscular activity. Manouvrier (43) suggested that brain weight could be analysed into two factors, one of which represented the weight of brain substance (i) devoted to the exercise of intelligence, and the other the weight (m) subserving the functions of the body. Thus the brain weight = i + m. Lapicque (44) indicated that the latter factor (m) is really concerned in particular with the actively innervated part of the body as distinct from inert deposits of tissues such as fat; and he accordingly modified the formula so that the brain weight equals i + km where k is a constant for the species.

Keith (45) designated that part of the brain which is present by virtue of the mass of the body as the 'corporeal concomitant', and indicated that it decreases with increase in body weight of the animal, so that for the whale or the elephant the corporeal concomitant reaches a minimum. Broca (46) had sought a similar expression for man when he stated that each addition of 10cm to the stature yielded a corresponding addition of 5g to the weight of the brain. Marshall, (47) basing his results on the data of Boyd, calculated that 10cm of stature accounted for an increase in brain weight of 2.4g.

Richet (48), in order to avoid the errors due to the relatively inert portions of the body, compared brain weight with the weight of the liver. This method is open to objection, as the relative weight of the liver varies markedly with age and the deposit of fat therein is remarkably inconstant. Manouvrier accordingly compared brain weight with the weight of the fresh femur, and found a closer degree of constancy within any given species. Dubois (49), working with closely related species, postulated an empirical formula E/E1 = (S/S1)p where E and E1 are brain weights and S and S1 are body weights and p is an index to be determined. Dubois found that p ranged from 0.54 to 0.58 with a mean value of 0.56. This leads to the formula of Dubois:

where p = 0.56 is the exposant de relation and K is the coefficient de cephalisation.

Scammon and Dunn (50), dealing exclusively with postnatal brains in a series of 3,000 autopsies, obtained a formula of the general type:

where 100Y = brain weight in grammes, x = age in years, and a, b and c are empirical constants.

Recently Anthony and Coupin (51), instead of regarding brain weight as a function of the approximate square root of the body weight as found by Dubois, or of the approximate cube of a function of length as found by Scammon and Dunn, have envisaged brain weight as a function of the fourth root of the body weight and have established a new formula:

where

PE1 = calculated brain weight,
PS = body weight,
p = 0.25 = coefficient,

K = constant for the species.

Thus in the case of a boy of seven years of age, with a body weight of about one third of his father's, the calculated brain weight if he were a reduced image of his father would be 1,000g. Actually the brain weight of the body is 1,250g. Thus the Index of Cerebral Value for the boy is 1.25, and the weight of the brain is one quarter more than the brain weight of the reduced image of the father. Anthony and Coupin claim that the Index of Cerebral Value gives a definite picture of the urge (la poussee) of brain growth. In the human embryo the index increases from 0.13 at the fifth month to 0.60 at birth. The index reaches 1.0 at the age of one year, and increases to a maximum of about 1.27 at seven years of age. A progressively slower decrease is seen from seven and the index returns to unity at about 30 years of age.

This index of Anthony and Coupin is useful as it indicates the ages at which the child has a brain which is relatively large. The index is at a maximum about the seventh year. The sixth and seventh year corresponding to the second 'springing-up' period of skeletal growth are thus seen to be very important years from the point of view of brain growth. Many educationists, particularly those working in intimate contact with abnormal children, have described marked transitions in mental growth at 5½ or 6 years of age. Froebel and Montessori have emphasised this marked change in mental activity at this age.

In searching for some relationship between the rapid brain growth of the sixth and seventh years and the rapid skeletal growth of the same period I have stumbled upon a relationship which may be of some significance in comparative psychology and in education (52). I have taken X-ray pictures of a large number of newborn animals and from the weight of the body and the brain have calculated the Index of Cerebral Value. There is a definite relationship between the ossification pattern and development of the hind limb on the one hand and the growth of the brain on the other. The newborn rat has a ponderal brain development and an ossification pattern in the hind limb comparable to that of the human embryo of the fourth month. This rat, born blind, helpless and hairless is, both as regards brain growth and skeletal growth, at the stage of the nonviable human embryo of the fourth month. The newborn pup, presenting many features in common with a prematurely born human foetus, has both a brain development and a skeletal development comparable to that of the human foetus of 26 weeks gestation, i.e. a premature babe of the seventh month. The newborn pig and guinea-pig on the other hand, born in a state of great activity, running about and able to fend for themselves to a considerable extent, are born with a hind limb presenting the same stage of ossification as that of a boy of seven or eight years of age, and also the ponderal brain development of a boy of seven or eight. Thus the young of these forms whilst they are still in the mother's womb are already relatively grown up and have hurried through those phases of development which occupy early childhood in the human babe.

The precocity of the animals such as the pig, guinea-pig, lamb, calf and colt, which are able in large manner to fend for themselves at birth is bought at the price of diminished final attainment. The newborn pig has spent the equivalent of seven years on the human scale in a sphere of amniotic fluid where new experiences are rare. The newborn babe in the first seven years of postnatal life is subjected to a change of environment, to a variety of stimuli, to an excessive maternal care: and this results in a corresponding variety of responses. The brain of the pig ceases to grow, like that of the calf, at the end of six months. The brain of the cat and dog ceases to grow at one year, when the animals reach sexual maturity. The continued susceptibility of such forms as the dog and the pig to formal education is widely different. The latter is too old at birth to learn much: the former can look forward to a period of educability. The marked difference in the behaviour patterns of animals, the extent to which they can learn new methods of thinking and the limits of formal education are thus seen to be related not only to the ponderal development of the brain but also to the state of skeletal development at birth.

According to the differences enumerated above for various species it might be argued that the rat, kitten and pup should by reason of their immaturity at birth look forward to a further final attainment than the human babe. The sexual development of these forms compared to the human is early. Thus the rat ovulates at seventy days, and the dog and cat are sexually mature at one year. In man alone has the skeletal growth curve been broken up into a succession of 'springing-up' periods and 'filling-out' periods. In man alone has sexual development been postponed to a relatively late age. The important years for education are the years preceding sexual maturity.

The differences in skeletal and brain development between the species may be studied also within the species. Skeletal development varies markedly with sex and race. The study of essential differences in the brain of man and woman have led to no important sexual distinctions. As Havelock Ellis (53) says: 'The history of opinion regarding cerebral sexual difference forms a painful page in scientific annals. If is full of prejudices, assumptions, fallacies, overhasty generalisations. The unscientific have had a predilection for this subject: and men of science seem to have lost the scientific spirit when they approached the study of its seat. Many a reputation has been lost in these soft and sinuous convolutions.' The development of the skeleton in the girl as compared with the boy is precocious. The centres of ossification of the bones appear days earlier in foetal life, weeks earlier in babyhood and from one to two years earlier in childhood and puberty. (Figs. 4 and 5.) The bones of the skeleton are knitted together earlier in the girl, in conformity with the earlier onset of puberty and the earlier appearance of cessation of growth. The growth of the brain in the girl is also precocious as compared with that of the boy, so that in the girl the brain weight is quadrupled before ten years of age, whereas in the boy the brain weight at birth is not quadrupled until fourteen years of age. Thus quite apart from the usual conception of secondary sexual characters, there is a close relationship between the skeletal characters as demonstrated radiographically and the development of the brain.

In the same manner as boys and girls of a given race show these differences in rate of skeletal development and brain growth, so different races display wide differences. Certain races mature early both from the point of view of brain growth and from the point of view of skeletal growth. Long before the dramatic appearance of menstruation these processes of maturity have been progressing in these two systems within the organism, and the rate of progress is a racial feature. The diminished final attainment and the limit of educability in the primitive races is thus more than a matter of sex. There are evidences that even amongst a relatively unmixed population of one social class the differences in growth of the skeletal and nervous systems, quite apart from sex, are sufficiently marked to indicate a true familial or diathetic character. The revolutionary experimental work of Smith and Engle (54) must be mentioned in this connection. By injecting extract of the anterior lobe of the pituitary gland into various laboratory animals they have been able to hasten the process of sexual maturity to a marked degree, so that the time necessary to reach puberty has been reduced by one third. The converse experiment whereby puberty from the sex point of view is delayed by a corresponding margin of time is not yet possible. The results of this artificially induced sexual maturity on the educability of the animal opens up a new experimental approach to the problem of behaviour, and to the genesis of those mental characters which have always been associated with the races in which sexual maturity is relatively late.

Our conceptions of the age of 7+ to 11+ as a neutral age, a conception formed by some educational administrators, has thus to be surrendered. The boy is a boy from the earliest weeks of embryonic life and the girl is essentially feminine from the same time. Throughout childhood the development of the skeletal system, the nervous system and the endocrine system in the two sexes is distinct, and the development of the behaviour pattern is distinct. Coeducation during these early ages may be justified if it is advocated on account of the benefits accruing to both sexes from close association. There is no basis for coeducation on the ground that the differences between the sexes are small or minimal during the period of so-called neutral childhood. As is shown by the radiograms of two children of ten years of age (Fig. 6), the pelvis of the boy and girl are as distinct in their sex features at ten years of age as at any later period of life. This is in accord with the appearance of the emotional and morose characteristics some years before puberty. This fact yields yet another argument for bringing the age of transfer from the primary school to the secondary school down to the age of eleven years.

The architecture of the brain in the child from 7+ to 11+ still awaits intensive study and we are acquainted only with the gross differences between the newborn and the adult. Certain facts which have emerged from the comparison of the foetus, newborn babe and adult have an important bearing on the problems of education. In any given area of the cortex of the brain, the single layer of nerve cells in the foetus of four months undergoes differentiation into three layers of cells. These layers are called from within outwards the polymorphic or inner cell lamina, the granular or middle cell lamina, and the pyramidal or outer cell lamina. The three laminae are distinct at birth, and it is the outer cell lamina, which is the last to appear, which grows most markedly during childhood. In any form of amentia it is the outer cell lamina which fails to develop, and the middle cell lamina to a slighter extent. Further, in any form of dementia this outer cell lamina, which is the last to develop, is the first to undergo dissolution.

The fact that the order of appearance in normal growth is known, that the susceptibility of the various laminae to maldevelopment and decay is known, that the last layer to develop is the first to suffer, combined with the fact that this layer increases in thickness in the normal child from birth to maturity by more than 50 per cent, indicates the need for detailed knowledge of these processes in children of school age. It is possible that the processes of development and differentiation of the laminae of the cortex are susceptible to malnutrition and disease to a far greater extent than may at present be hazarded.

This process of differentiation of the cerebral cortex into three layers does not take place at the same time in all regions of the brain. It takes place in the visual cortex later than in the motor cortex, but before it occurs in the frontal cortex. In fact that portion of the brain which is regarded as peculiarly subserving the functions of the higher associations is characterised by a late appearance of differentiation. The child kicks in the womb, sees when he is born, thinks later. Since the area of the brain concerned with thinking is the last to undergo differentiation, this area is brought more and more clearly into the age period when malnutrition and acute disease are most liable to register their effects.

It is imperative that the age changes in the cortex from birth to seven years should be much more intensively studied. It is almost true to state that between the ages of two and eighteen years the changes are unknown. It is equally true that anatomical facts are wanting to suggest many of the precepts of the educationist and psychologist. Excluding the gross changes found in aments and dements, it must be noted that, as there are wide individual variations in the degree of apparently normal cortical development, so there are wide variations in the degree of mental development in apparently normal infants and young children. At present we do not know to what degree, if at all these normal anatomical and mental variations are related. This should not deter research, but rather stimulate it. Bolton (55) indicates the likelihood of a structural origin for individual differences in mental endowment.

In the varied growth patterns of the individual systems of organs in the child it is indeed fortunate that the nervous system enjoys a certain priority. Wilfred Trotter (56) has emphasised the extent to which the nervous system is insulated from the remainder of the organism, and endowed with a special degree of resistance and durability. It is this special measure of protection which gives to the brain a preferential status and endows behavioural patterns with such significance in the study of growth. For instance, on the average, babies smile at 58 days. blink at 76 days, show coordination of the eye muscles in all directions at 78 days, oppose the thumb at 148 days, reach for objects at 152 days and sit at 217 days. The appearance of these reflexes is not a haphazard pattern involving only time and relationship, but is an orderly and progressive pattern involving intrinsic internal relationship. The extent to which the order of emergence and the time of emergence of these patterns may be altered by diseases or malnutrition still awaits careful examination. Zuehl (57) has shown that events in health history have a higher correlation with variations in hearing ability than the the latter have with chronological age. Ewing (58), in his recent work on aphasia in children, concludes that in cases of linguistic retardation, the aetiological factor, in the absence of hereditary tendencies, is in some cases a period of lowered vitality retarding or arresting speech and language at a specific stage.

The attempts to classify children and adults into particular types of body build have always interested the physician. Such a subject allows of much loose theorising, much play on physical measurements and much bias in terms of one's own clinical experience in disease. Recent work in this direction has received a stimulus by reason of the ease with which the form, size and site of the viscera can be related to the skeletal outline with the aid of radiography of the chest and abdomen. Variation in physical form and in visceral topography has shown that there is a real correlation between the skeleton and the viscera. Stout children of stocky build tend to have hypertonic stomachs in a relatively high position. Slender frail children tend to have atonic stomachs placed at a low level. In heavily built children the thorax is short longitudinally and the abdomen long. In slender children the thorax is long and the abdomen short. The degree of strength and tonus of the skeletal muscle exerts an influence on visceral topography. The abdominal muscles determine to some extent the shape of the abdominal cavity and the position of the contained viscera. The general tonus of the skeletal muscles influence the static poise or carriage of the child and so influence the shape of the abdomen. Any generally faulty attitude is reflected in the visceral topography.

Mills (59) has classified the various types of body habitus as hypersthenic, sthenic, hyposthenic and asthenic. (Fig. 8.) The metabolic needs of a hypersthenic individual of the 'John Bull' type require that the alimentary tract should be adapted to the accommodation and digestion of a large amount of food commensurate with the activity of the individual. This requires a digestive system of great motility and rapid contraction; it is accomplished by a high position of the viscera and a high degree of tonus in the muscles of the gut. The asthenic individual has relatively small metabolic needs, the viscera are low in position and motility and tonus are small.

When it is remembered that man and the domestic animals, as a result of artificial selection, exhibit among themselves respectively a wider range of variation than is presented by neighbouring species of wild animals, it is seen to what extent man is a creature of fixed physical characteristics. Although man never by reason of illness or starvation undergoes considerable changes of bodily habitus and cannot be converted from the hypersthenic type to the asthenic type, yet by feeding and exercise be can be moved up the scale to some extent from the asthenic region. The hypersthenic type tends to show certain dominant characteristics and the asthenic or hyposthenic type tends to be recessive. Thus the four main types of bodily habitus admit of a further classification in terms of subtypes and a given child might advance from one subtype to a neighbouring one.

It cannot be too strongly urged that one type of bodily habitus and one type of visceral topography cannot be acquired. We cannot all become John Bulls. There is a definite limit to the amount of change in physique which can be impressed upon the growing child. No amount of propaganda by the advocates of multiple chewing, vegetarianism and frequent defaecation will be of avail. The evidence of multiple types, each consistent with good health and efficiency, each sexually potent, each with different requirements as regards food intake and yield of excreta, each with a tendency to react badly to certain diseases or even to be predisposed to certain diseases, is a fundamental fact in biology. This basic fact always threatens the value of all anthropological mass statistics and threatens the results of all mass feeding experiments. There is no room for the fixed conceptions of the old type of sergeant major or drill instructor in our schools. The school medical officer, acquainted with the significance of the bodily habitus of the child, alive to that peculiar susceptibility to disease which is involved in the conception of diathesis, can do more to guarantee to a particular child that measure of growth and physical efficiency which is the norm for his type. The extent to which the norm can be raised is at present problematical. The extent to which the various types of bodily habit can be associated with varying rates of growth and development in the skeletal and nervous system is yet to be ascertained. Lastly, the extent to which bodily habitus may figure in the determination and measurement of the mental characters of the child is one of the main attractions of fundamental psychology in the future. The problems of rigid behaviour as demonstrated by reflexes and habits and the problems of modifiable behaviour as demonstrated by learning and conditioning of reflexes must have an anatomical basis. Cell growth and proliferation on the one hand and cell differentiation for special function on the other will probably be found to be the ultimate basis of a rational psychology, whether it be labelled 'Gestalt' or not.

The most remarkable study of constitutional types and characteristics is that of Walther Jaensch (60) of Berlin, who has made a daring attempt to correlate and synthesise data from many fields. Jaensch has examined in children the physique, physiognomy, expressive features, pulse, circulation, dermal and anatomical stigmata, galvanic and mechanical irritability in sensory and motor fields. To these he has added various eidetic phenomena, such as the nature, colour, duration and definition of images, reaction to psychic influence, level of calcium metabolism and the pattern of the blood capillary network at the base of the nail. The work has been widely criticised as an attempt to affiliate and hyphenate various scientific disciplines in anatomy, physiology and psychology. On the other hand, the work in general, and that portion which deals with the capillaries of the nail bed in particular, serves to concentrate attention on the converging problems of growth in the normal and abnormal child.

To the layman the weight curve and the degree of development of the muscular system yield the readiest means of assessing the growth and physical efficiency of the cliild. Stance or poise in itself is a valuable index, and a profile view of the naked child gives much information to the careful observer. In the newborn babe actual muscle accounts for less than 25 per cent of the body weight. In the young adult muscle accounts for about 43 per cent of the body weight. Since the muscular system grows most rapidly during the last two months of antenatal life and during the latter part of puberty and adolescence, it is a particularly sensitive recorder of the changes in health and disease at those ages. At all ages the muscular system wastes very rapidly in acute illness and starvation; at all ages it responds to feeding and exercise. During the periods of rapid growth the muscular system is a particularly sensitive recorder of nociceptive stimuli which are always apt to fall heavily on the fast growing tissues. This is equally true of both animals and plants. The most rapid growth of the muscular system in postnatal life occurs in the latter half of puberty and is carried forward into adolescence until that age at which the bones of the skeleton are knitted together at the time of cessation of growth.

The coracoid and scapula bones (Fig. 8) are not united together to form a one-piece shoulder blade until puberty. The ilium, ischium and pubis (Fig. 9) are not united together to form a one-piece hip bone until slightly later, the union taking place at about the fifteenth year in girls and the sixteenth or seventeenth in boys. The formation of the definitive shoulder blade and hip bone are of fundamental significance in all animal forms. The former corresponds to the last stage of development in the muscular system and the latter to the completion of the sexual changes involved in puberty and to the ability of the female to bear young. Thus the skeletal growth gives a very precise and purposive indication by means of bony union as to the age at which it is safe to subject a given individual to heavy muscular work. No boy or girl with ununited parts of the shoulder blade or hip bone should be subjected to such heavy muscular strain as is involved in the carrying of the bricklayer's hod, the delivery of heavy parcels or standing for long hours in domestic service or behind the counter. Further, no boy or girl should be submitted to the sustained muscular effort involved by playing 45 minutes 'each way' in a hockey or football match. These anatomical landmarks in the growing child are definite and precise: they are disregarded only at peril.

Man is a biped and the erect attitude in itself is a severe muscular feat. To have transferred the weight shared equally between four limbs in the quadruped to two limbs in man has been a perilous task. The erect attitude is very fatiguing to children and is a most unsuitable position both because of the small size of the base covered by the feet and because of the high position of the centre of gravity due to the relatively large head and liver. To resist a push we stand with feet apart and knees bent. We must not expect children to stand like soldiers at attention. The economic position for a child is that which he adopts when playing. He stands with feet apart and knees bent, and he delights in squatting.

The perfect growth of the human machine requires a sound and well trained muscular system. The picture of a weak muscular system is all too common and in its milder degree is shown by the majority of our boys and girls. The children in secondary schools by reason of excessive homework and inadequate sleep, the children in boarding schools by reason of a faulty diet, and the children of the slums by reason of a summation of factors, present the picture of a weak muscular system. The curved back is accompanied by a poor respiratory system. The protuberant abdomen and weak abdominal muscle go hand in hand with imperfect absorption of food and inefficient pumping of blood from the liver. The weak musculature of the lower limbs leads to knock-knee and flat foot. The general insufficiency of the circulation produces cold, blue, sweaty hands and feet. The muscular system is an integral part of a perfect piece of machinery must beautifully and most delicately constructed for sustaining the weight of the body and for allowing rapid, easy and elastic movements. The muscular system, by reason of its rapid growth, suffers severely in disease, malnutrition, inadequate sleep and unfavourable environment. On the other hand, as every farmer knows, no system responds so rapidly to good feeding, healthy surroundings, fresh air and exercise. The nation's reserves of sound womanhood and manhood demand that special care of the muscular system which cannot be guaranteed today because of the fact that the school leaving age of the majority of the children precedes the period of active growth of the muscular system.

A word of warning is necessary to the most vigorous advocates of the equality of the sexes. Not only are the stages of skeletal and nervous growth different in the two sexes, but the development of the muscular system is different. The bones of the female skeleton are on the average smaller and less heavily built within a given family. The bones are slender and the muscular and ligamentous markings are less distinct than in the male. In early childhood the boy has greater muscular power than the girl; at puberty the boy's strength is nearly 50 per cent greater and at adult age nearly 100 per cent greater. Games involving vigorous throwing and jumping are less suitable for girls.

The commonest symptom complained of by adults presenting themselves for medical treatment is 'fatigue'. It is the first and most significant symptom of innumerable diseases. Fatigue is an important signpost in the child. The rate of onset of mental fatigue may be very different from the rate of onset of physical fatigue. The phase of growth in the child, nutrition and sleep may influence the onset of either to a considerable extent. The limit of physical fatigue can be extended by well-devised physical exercises and training. It is still doubtful to what extent the limit of mental fatigue may be so extended. It is more difficult to obtain and sustain in relation to mental fatigue the equivalent of that spirit of 'team' work which is so invaluable in postponing physical fatigue both at work and play.

We are not justified in assuming that a child who has been away from school for six weeks is in a fit state to return to school and take up his studies where he left off. The scars of illness in bone suggest that, quite apart from the familiar changes in temperament such as whimpering and fretfulness, illness may produce an arrest in the processes of 'facilitation' which are so characteristic of most processes of learning. Mental setbacks of this kind have to be considered, and no attempt should be made to force the young convalescent. Moreover, the reactions of individual children after a prolonged illness are most complex. The fact that one child responds actively and visibly by an expression of grief (dolor pectoris), increases the danger of ignoring the other and more important case of the undemonstrative child who suffers in silence much mental anguish (angor animi).

In particular it must be emphasised that the child who is above the average in weight and height, is often more susceptible to fatigue and more severely handicapped by illness than the normal or even the subnormal child. Lack of interest in his surroundings, retardation in reaction time and low grade of mental retentivity are often seen in this type of child who tends to become the 'loutish' lad of the higher classes of the school. The child who has 'overgrown his strength' also affords a difficult problem in this respect. Until the characteristics of mental and physical fatigue are better understood, 'forcing' children in school, and out of school by 'homework', is a grave danger. The child who is forced beyond his efficient rate of mental activity can only attain the standard of progress set for him with the expenditure of his maximum effort. The fatigue induced by the prolonged exertion of his maximum effort tends to diminish his efficient rate of mental activity, which in turn reduces the peak of the maximum effort of which he is capable. This constitutes a vicious cycle. The onset of mental fatigue is occasionally accelerated in some children by the practice of well-meant 'nagging' on the part of the parent or teacher.

Mental fatiguability displays marked differences in a given child according to the nature of the task, whether it involves smell, sight, hearing or other senses. It varies widely from child to child. That valuable mental endowment connoted by the term equanimity may to a considerable extent consist of an obtuseness to certain external stimuli such as cold, noise and interruption, as well as an ability to disregard internal stimuli such as those of digestion on the one hand, those of the joints, muscle and skin on the other, and even those now often grouped under the term 'phantasy'.

Sleep is as indispensable as good food to the child. Sleep and food must be guaranteed in sufficient quantity at regular hours. The requirements of both vary with age, build, temperament and rate of growth. It is most difficult to dissociate the effects of malnutrition from the effects of inadequate sleep. The child of thin, anaemic langourous type who arrives at school tired, aetiolated and incapable of concentrating on mental work, is often suffering mainly from loss of sleep. Home work, social duties, compulsory sports, the loud speaker of the wireless broadcast and attendance at cinemas present an accumulation of physical and intellectual exigencies which children are unable to bear without serious inroads on that nocturnal repose which is one of their main needs during the period of growth. Neither artificial sunlight nor vitamin preparations afford a substitute for sleep.

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