144 



BIOLOGY AND HUMAN LIFE 



to a daily consumption of about three ounces of protein as being 

 safe from a health point of view, and at the same time abundant 

 to meet the needs of metabolism and growth. 



122. Age and diet. If we take the food required by a man of 

 about 150 pounds weight, doing moderately hard work, such as 

 a weaver or a bookbinder, as one hundred, the amounts needed 

 by children at different ages are about as follows : 



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

 adults, although growing children need more proteins. The bal- 

 ance is brought about by the fact that the children are more ac- 

 tive than adults and use up comparatively more fuel. Indeed, 

 some students of the problem would give boys and girls of high- 

 school age more food than hard-working adults. This agrees 

 with the fact that at this period many of us seem to be always 

 eating, or at any rate always hungry. The basic metabolism is 

 known to be greater at this period, so it is likely that we shall 

 have to correct our figures upward. 



123. Work and other conditions. Experiments made to show 

 the quantity of energy used up by a man under varying condi- 

 tions gave the results summarized in this table : 



r. T^ Calories 



Condition of the Body 



PER Hour 



At rest, sleeping (corresponds probably with basic metabolism) 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 



