334 Trans. Acad. Sci. of St. Louis. 
mechanical motion and other forms of dissipation of energy 
making up the ordinary output of life, and, in addition, with 
the extraordinary function of storing energy in the increase 
of tissue which constitutes growth. 
In view of these facts, Plate XLV cannot fail to be instruct- 
ive. It shows the ratio of span of arms, height sitting, chest- 
girth, weight, strength of squeeze with right hand, and five head 
and face measurements to height standing. Height standing 
is here expressed by an abscissa, and the percentage relation 
of weight and the other dimensions are displayed in curves. 
Of all these, span of arms most closely approximates the 
height, the difference being less than one per cent. of the 
latter from age 6 to 11 and scarcely more than 2 per cent. 
in subsequent ages. Span of arms in both sexes is therefore 
nearly the same as height standing throughout the period of 
observation, becoming very slightly greater than the height as 
growth progresses. The height sitting and the girth of chest 
run a parallel course and are, moreover, nearly equal, the 
girth of chest being about 2 per cent. less than the height 
sitting. They increase a little less rapidly than the height, 
showing a decline of about 4 per cent. in thirteen years. 
Height sitting and chest-girth are not far from half the height 
standing. 
Far different is the development of weight and strength of 
squeeze. These increase much more rapidly than height, for 
at age 6 the height stands to weight in the ratio of 100 to 18 
and to strength of squeeze as 100 to 6, while at age 16 these 
ratios are 100 to 34 and 100 to about 16, respectively. The 
parallelism in the development of weight and strength of 
Squeeze is of much interest. The dimensions of head and 
face increase somewhat less rapidly than the height. The 
length of head, for example, falls from ,th of the height, at 
age 6, to about th at age 18. 
