THE FASTING KATABOLISM. 9 

 Consumption of oxygen in fasting man weighmg 70 kilograms — Zuntz. 



Cubic 

 centimeters 

 per minute. 



Percentage. 



Circulation and respiration 



Voluntary muscles 



30.0 

 112.0 



12. 45 

 46.49 



Glands and other organs: 



Liver 



Small intestine 



Kidneys 



Pancreas 



Large intestine 



Salivary glands 



45.0 

 25.1 

 10.5 

 9.3 

 7.0 

 2.0 



9S. 



9 



18.68 

 10. 42 

 4. 36 

 3. 86 

 2. 91 

 .83 



41.06 



Total 



240.9 



100. 00 



According to the foregoing table nearly 60 per cent of the metab- 

 olism of a fasting man is due to the work of the muscles, including 

 that of respiration and circulation as well as the limited activity of 

 the voluntary muscles, while somewhat over 40 per cent is due to the 

 internal organs. No equally complete data are available for farm 

 animals, but the supposition seems justified that their metabolism 

 in its main features is not greatly unlike that of man. It may be 

 noted that Zuntz and Hagemann found the energy expended in 

 respiration and circulation by the horse in a state of rest to be, re- 

 spectively, 4.7 and 5.01 per cent of the total metabolism. The sum 

 of these — 9.71 per cent — is approximately comparable with the cor- 

 responding figure for man. 



The animal body is primarily a transformer of energy. From the 

 biochemical standpoint the essential phenomenon of physical life 

 is the transformation of chemical into kinetic energy which accom- 

 panies the breaking down of more or less complex molecules into 

 simpler ones, and all vital activities are essentially manifestations of 

 energy. In the fasting state this energy is derived from the store 

 of chemical energy contained in the materials of the body itself. 

 The very act of living, in the foregoing view of it, is synonymous 

 with the expenditure by the organism of its stored-up capital of 

 energy. The prime and dominating purpose of the fasting katab- 

 olism, therefore, is to supply energy for the life actions. 



But since the necessary activities of the fasting organism are car- 

 ried on by means of energy derived from the katabolism of materials 

 contained in the tissues, the body's store of matter and of energy is' 

 being constantly depleted. To prevent or replace this loss will re-' 

 quire a corresponding supply of available material and energy in the 

 feed. A knowledge of the kind and quantity of material katabolized 

 during fasting and of the amount of energy liberated, therefore, is 

 obviously the first step toward ascertaining the supply necessar3 T in 

 the feed. 



PURPOSE OF THE FASTING KATABOLISM. 



