CHILDREN'S GROWTH IN WEIGHT AND HEIGHT of the most interesting tasks of anthropology is to investigate the growth of children from the time of birth to the completion of the period of development. The physician and hygienist must possess a knowledge of the processes of growth. This knowledge enables him to judge whether and how far the growth of a given individual deviates front the normal, and furnishes him the indication for his therapeutics. The hygienist has for his field the prevention of disease, and he must be well informed about the processes of growth in order to recognize and combat intelligently the many dangers to which the growing organism is exposed and the injuries which it so frequently sustains. This is particularly true for the school hygienist. There is a close relation be growth and the schools. We may here call attention to the in fluence which the length of the children has on the shape and construction of the school benches, and also on the condition of the school room, the division of the school hours during the day, the duration and timing of the recesses (particularly of the noon-day recess), the interpolation of physical exercises between the school hours proper, and the duration and the season of vacations.
Growth in its more restricted sense means those processes in the healthy youthful body which, following the laws of evolution, lead to an increase in size., weight, and mass of the total body and its individual parts.
Investigations with regard to the growth of single organs, as for instance the brain, or of single systems, as the muscles, are extremely difficult, and our knowledge is rather incomplete in this regard. It is more simple to study the growth of the body in regard to its weight and length. For instance, the opinion is frequently voiced that it is possi ble to obtain satisfactory information of the growth of an infant if it is weighed at certain intervals and its length is determined, the comparison of the data thus gained furnishing the desired information. It can be easily shown that such a procedure may lead to great mistakes. For, while the growth forms the most important cause of the increase in weight and length of an infant, it is by no means the only one. Numerous other factors may change the weight, and to a less degree the length, either increasing or diminishing it. The variations of the weight in the
414 course of 21- hours are quite considerable. The lowest weight is regis tered in the morning before breakfast, the highest in the evening after supper. The difference bet \vcen the morning and the evening weight is about 200 Cm. in the case of an infant four months old, about 700 Gin. in a child ten years old, and about MOO (lin. in the adult. This increase in weight is due to the fact that the intake exceeds the excretions during the day. The loss of weight front evening to morning is chiefly caused by the elimination of water through the kidneys, skin, and lungs during the night (Fig. 60). This loss of weight is, on an average, equal to the gain in the case of the adult. In the growing child it is somewhat less than the gain during the day (Fig. 61). The increase of weight from morning to evening does not progress at a regular rate, but is subject to great oscillations, corresponding to the continuous change of the ex ternal conditions—ingestion of food, excretions, humidity of the air, occupation. The decrease of weight during the night pro ceeds more regularly. This may best be seen on the curves of Figs. 60 and 61 (observations of the elder Camerer). In order to explain Curve 1, the following may be added: An infant 16 weeks of age receiving mother's milk weighs 5200 Gm., and this weight is registered in the fig ure as 0. From 7 to 7.30 A.M. it took 107 Gm. mother's milk (represented by the ascending line) and the weight increased 107 Gin. Between 7 and 10 it lost 2S Gin. in the form of gaseous excretion (represented by the second more horizontal line) and secreted 64 Gm. urine (repre sented by the vertically descending line). In consequence of these pro cesses the weight at 10 o'clock exceeds that of 7 o'clock before nursing by only 15 Gm. The nursing at 10 o'clock increased the weight 122 Gm. above the initial weight, etc. The figures of Curve II were obtained in a youth seventeen years of age. The body weight of 52800 Gm. is regis tered as 0. The increase in weight is due to the intake of food; the decrease, to excretions through the intestines, kidneys, skin and lungs. The broad line placed in Fig. 60 at 7 o'clock A.AL and in Fig. 61 at 12 noon designates defecation.