MAN FROM THE FARTHEST PAST 
Compared to the adult, the length of a newly-born in- 
fant may be taken as thirty per cent, and the weight as 
five per cent. But if the total weight is thus to increase 
twentyfold between infancy and adult life, the different 
organs of the body show great differences in this respect. 
Thus, in average terms, if we take the infant weights in 
each case as unity, the adult weights of corresponding 
organs are as follows: 
Stomach 
Eye | Brain| Skin | Heart and Lungs | Skeleton | Muscles 
Intestine 
Ty. RIB RTD 15 20 20 26 48 
It is thus apparent that the eyes and brains of newly-born 
infants are greatly developed compared to other organs, 
a fact which is of high importance to a creature whose 
command over nature rests so much more upon sight 
and thought than upon size and strength. 
The rate of growth of the child decreases very rapidly 
during the first two or three years, then remains nearly 
stationary until about the seventh or eighth year, when it 
again rises rapidly, so that the youth from twelve to fifteen 
years of age 1s fairly racing toward adult growth and his 
food demands are correspondingly increased. From this 
maximum of growth rate there is a gradual decline, and 
growth practically ceases at about the twenty-fifth year. 
In later life the weight, however, often has a marked in- 
crease after about the fiftieth year. 
The heart-beat of the babe is very rapid, and ap- 
proximates 135 per minute, falling to 110 in the second 
year, about ninety in the tenth, and seventy-five in adult 
life. Considering the very much smaller volume of the 
infant body, this relatively great rapidity of heart action 
causes an exceedingly more rapid renewal of the blood 
in the tissues than occurs in adult life. 
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