Ml T\l:u|.i>\i 





THE MATERIAL BALANCE OF THE EODY 



We musl distinguish between the balai i tic and the in- 



organic foodstuffs. Prom a studj of the former we Bhall gain informal 



arding the Bources of the energy production whose behavior under 

 various conditions we have just studied. Prom a stud] nic 



balance, although we Bhall learn nothing regarding ene (change — 



for Buch substances can yield no energy we shall become acquainl 



with Beveral facts of extreme importance in the maintenam f nutrition 



and growth. 



To draw up a balanct sheet of organic intafo and output requires an 

 accurate chemical analysis of the food and of the excreta urine and 

 pired air). 



Methods for Measuring- Output 



The principle by which the output is measured will be understood by 

 referring to Pig. lTii. from which if will be seen thai the calorimeter 

 is connected with a closed system of tubes provided with an air-tighl 



< Q * - water to absorb heat/ 



d Chamber for animal 

 window 



Fig. 17i Dia( 

 the to 

 amoui 



1. lh< 



tary blower or pump to maintain a constant cum ted by 



the arrows. Following the air stream .-is it leaves the chamber, v. 

 a side tube connecting with a meter to indicate changes in volume 



