Diets can be planned to meet daily needs by using the "share" technique. 

 A share of any food-essential is that quantity which supplies one thirtieth 

 of the daily needs for an adult using 3000 Calories per day. Thus a share of 

 energy is equivalent to 100 Calories. 



EXPLORATIONS AND PROJECTS 



1 To measure the rate at which a person spends energy, find out how much 

 oxygen he uses in a given time. Where a basal-metabolism apparatus is not acces- 

 sible, it is possible to construct one patterned after Benedict's Student Respiration 

 Apparatus/ The subject (sitting or lying quietly) holds the mouthpiece in mouth 

 while breathing through the nose. Attach oxygen tank to air inlet and fill inside of 

 apparatus with oxygen. Remove hose from oxygen tank and connect pump." 



When everything is in readiness have the subject start breathing through his 

 mouth. Place nose-clip on his nose. Count the time from the first exhalation that 

 fails to make the rubber cap touch the stop wire. The starting time can be has- 

 tened by adjusting the amount of air inside the apparatus with the pump, im- 

 mediately after the subject starts breathing from it. As the test proceeds, keep the 

 volume of gas constant within the apparatus by pumping in air to replace oxygen 

 used by the subject. Oxygen used by the subject is measured by the quantity of air 

 pumped in to replace the oxygen consumed. The carbon dioxide breathed out by 

 the subject is absorbed by the soda-lime. Tests should be run from five to ten 

 minutes. 



From the number of cubic centimeters of oxygen used and the duration of the 

 test, calculate the amount of energy the subject would spend in a day if he used 

 energy continuously at the same rate.^ Record the observations and make the 

 calculations in table form.* (Do not write in this book.) 



2 To calculate your own basal expenditure of energy per day, use the table 

 on page 121. 



'See illustration, p. 120. The material, with the exception of the rubber gas-mask valves, 

 rubber bathing cap, and the soda-lime, can be picked up locally. This apparatus is just as satisfac- 

 tory for classroom measurements as the more expensi\e purchased ones. (Respiradon apparatus 

 and accessories may be obtained from Warren E. Collins, 555 Huntington A\ e., Boston, Mass.) 



"The pump can be calibrated by measuring the volume of vv'ater that each pumpful of air 

 displaces from a graduated cylinder inverted over a water bath. 



^Assume .004825 Calorie for each cubic centimeter of oxygen used. 



^Figures for column IV are obtained by muldplving the number of pumpfuls (III) bv 

 the volume of the pump in cubic centimeters. Figures for column VI are obtained by multi- 

 plying cubic cendmeters per minute (column V) by 1440, the number of minutes per day. 



135 



