I 



450 REPRODUCTION AND DEVELOPMENT 



lates little nourishing food for the first day or so, its weight falls in two or 

 four days 175 gm. and often more. In babies fed from vigorous breasts 

 however, this loss is often much less or even none. At ten days old the 

 child weighs 100 gm. more than at birth. For the first six months, 

 speaking roundly, the infant gains 25 gm. daily, and for the next six 

 months 15 gm. The birth- weight is about doubled at five months and 

 trebled at fifteen months. When a year old the child weighs 9000 or 

 9800 gm. (20 to 21 Ibs.), and this weight is doubled at seven years and 

 quadrupled at fourteen. Breast-fed babies gain in weight much more 

 regularly and certainly during the first half-year, but later the difference 

 between these and those fed from the bottle with modified cows' milk is 

 not so marked. As before remarked, the liability to death is very much 

 greater in bottle-fed infants, especially if the milk be improperly modified 

 and cared for. 



The proportions of the various organs differ not a little in childhood 

 and adulthood, Of these the relative weights of brain and spinal cord 

 to the body are most conspicuous. According to Bischoff, the brain at 

 birth weighs one-eighth as much as does the whole body, at the end of 

 one year one-sixteenth as much, and at fourteen one-twentieth as much. 

 In the adult the brain is only about one forty-third of the body by 

 weight Similarly with the spinal cord : at birth it is one five-hundredth 

 as heavy as the body, but in the adult only one fifteen-hundredth as 

 heavy. This relative preponderance of the nervous system is clearly 

 seen in the conduct of the child. The actuating aspects of the nervous 

 system are especially conspicuous, while its inhibitory functions are 

 relatively little developed 



The liver and adrenals are relatively large in childhood, the spleen 

 relatively small, while the heart bears about the same proportion to the 

 body-weight at all ages. 



Height. The average length of babies when born is 49 or 50 cm. 

 In a year this has increased to about 70 cm., in two years to 79 cm., 

 in three years to 86.5 cm., in four years to 93 cm., and at the end 

 of five years the average height is almost a meter. After this period 

 the child grows not far from 6 cm. yearly, so that when he or she is 

 fifteen the height is just about treble that at birth, or 150 cm., its doub- 

 ling having occurred at the beginning of the seventh year. Rotch notes 

 that growth in height is fastest in the spring. 



Nutrition in children is in general more normal and vigorous in all 

 directions than it is in adults, excepting in the first few months. The full 

 powers of the digestive enzymes do not develop all at once, but more or 

 less gradually in the first third or half of the first year. This is particu- 

 larly true of the amylolytic juices, and starch is particularly ill-digested 

 in the first months. Normally, that is in woman's milk, the only carbo- 

 hydrate ingested is lactose or milk-sugar. In general, however, the 

 child from three years onward digests more vigorously than the adult 

 does, for the supply of digestive juices is proportionally greater and the 

 alimentary movements more active. It is by this means that the child's 



