IOO 



ELEMENTARY BIOLOGY 



The food required " per man per day " being taken as one 

 hundred, the food requirements of children under sixteen years 

 of age have been given as in this table : 



The nutritive ratio is left the same for children as it is for 

 adults, although we should expect children who are growing 

 to require relatively more protein. The balance is probably 

 brought about by the fact that children are relatively more 

 active than adults, so that they use up comparatively more 

 fats and carbohydrates. 



The amount and character of work done by a person are 

 important factors in determining his food requirements. Ex- 

 periments made to show the quantity of energy used up by a 

 man under varying conditions gave the results summarized in 

 the following table : 



CALORIES 

 CONDITION OF THE BODY PER HOUR 



At rest, sleeping . ' . . . ; 65 



At rest, awake, sitting up 100 



At rest, standing 117 



Engaged in light muscular exercise . .... 170 



Engaged in moderately active muscular exercise . 290 



Engaged in severe muscular exercise ..... 450 



Engaged in very severe muscular exercise . . . 650-675 



Since people do not ordinarily sleep all the time or work all the 

 time, the amount of energy used up per day will depend upon one's 

 daily program ; that is, on the distribution of sleep and rest and 

 various degrees of activity. Thus, a person working in the steel mills 

 twelve hours a day, seven days in the week, expends more energy 



