708 REPRODUCTION AND GROWTH 



The growth of the body in length during the later years of childhood will 

 be evident from the following table : 



Obviously it is much more difficult to get an extensive series of observations 

 on the growth of the child during the first five or six years of life than it is 

 later. Within the years of seven and nineteen the material is much more 

 accessible and the total number of observations on the rate of growth in length 

 and body weight, made on children of school age by Bowditch in Boston, Key 

 in Sweden, Kotelmann in Hamburg, Pagliani in Turin, Roberts in England 

 and Porter in St. Louis, foots up a total of more than 125,000 individuals. 



But we should not be warranted in drawing an average from all of this 

 material taken together. There are certain racial characteristics which would 

 need to be taken into account in so doing, and our purpose here will be better 

 served if the material chosen be as homogeneous as possible. The observations 

 of Key in Sweden probably fulfill this requirement as well as any. 1 It may 

 be remarked however that the conclusions drawn from this material have 

 been fully confirmed in the gross by observations in other countries. Certain 

 age differences only are to be noted. 



Fig. 304 represents, according to Key, the mean height and mean weight 

 of male and female pupils in the higher schools of Sweden between the years 

 of seven and twenty-one. 



Up to and including the eleventh year boys are both taller and heavier 

 than girls. From the twelfth year to the sixteenth this relationship changes : 

 girls are then both taller and heavier on the average than boys. With the 

 seventeenth year the relationship once more changes and the curve of devel- 

 opment for boys rises above that for girls and the difference becomes greater 

 and greater thereafter until complete maturity. 



The yearly increase in height and weight in boys for the seventh year is 



5 cm. and 2.3 kg., and for the eighth year, 5 cm. and 3.4 kg. For the ninth 



to the thirteenth year the growth in height by years is 4, 2, 3, 4, 4 cm., and 



the growth in weight by years is 1.7, 1.0, 1.9, 2.3, 3.1 kg. The growth in 



boys is at its feeblest during the twelfth and thirteenth years. With the 



fourteenth year the period of puberty is reached and the growth both in 



height and weight becomes much more rapid, the increase in the former 



the fourteenth, fifteenth, sixteenth and seventeenth years being 5, 7, 6, 



5 cm., and the increase in the latter being 4.7, 4.5, 5.5, 5.3 kg. respectively. 



: rapid growth in height takes place earlier (fifteenth and sixteenth 



'Certainly much better than would observations made in any of the larger cities of 

 the United States. ED. 



