Energy Loss in Work of Digestion 165 



Between the time when it is taken into the mouth and 

 when it passes into the circulation, it must have work 

 expended on it in the way of mastication, solution and 

 moving it along the digestive tract, and it appears 

 highly probable that the amount of this work per 

 pound of food must vary greatly in different cases. 

 In fact, we know this is so from the result of some 

 masterly investigations conducted by Zuntz in Ger- 

 many. By means of various devices and methods, a 

 description of which would be out of place here, he 

 measured the oxygen consumption necessary to sustain 

 the mechanical energy of mastication and digestion, 

 and he calculates from his determinations that the fol- 

 lowing heat units represented the energy used in 

 chewing certain feeding stuffs: 



cal. cal. 



1 pound hay 76 1 pound corn 6/3 



1 pound oats 21 Green fodder equal to 1 



pound of hay 47 



The differences revealed by these figures are inter- 

 esting and important. Chewing green food cost in 

 labor only about 62 per cent of the effort required to 

 masticate its equivalent of dry hay, the proportions of 

 labor for hay, oats and corn being in the ratio of 

 100, 27 and 8%. 



This author goer: further and calculates that the 

 work of mastication and digestion combined is 48 

 per cent of the energy value of the digested mate- 

 rial from hay and 19.7 per cent of that from oats. 

 He also makes the statement that in general the coarse 

 foods have 20 per cent less net energy value than the 



