198 ORGANIC AGRICULTURAL CHEMISTRY 



mean only one thing, that is, that, as the carbon dioxide ex- 

 haled is greater in volume than the oxygen used, some oxygen 

 must have been supplied from some other source than the 

 inhaled air. If now we try to convert carbohydrates into fats, 

 we find that in doing so some of the oxygen of the carbohydrate 

 must be given off as free oxygen. 



19 CeHisOs -> 2 C57H110O6 + 4 H2O + 49 O2 



Glucose Glyceryl tri-stearate 



This free oxygen obtained from the conversion of carbohydrates 

 into fats would then be used to oxidize other carbohydrate and 

 thus diminish the oxygen required by inhalation, so that the 

 ratio of carbon dioxide exhaled to oxygen inhaled would be 

 greater than i.e. 



Thus the experimental fact that with excess of carbohydrate 

 food the respiratory quotient becomes greater than i.o can mean 

 only one thing, viz. carbohydrate is being converted into fat. 



We have then not only results of feeding experiments but 

 also results of the respiratory quotient proving that in the 

 animal body carbohydrate food is metabolized into body fat 

 or into milk fat. The body fat so formed is, in part at least, 

 simply a more lasting reserve form of storing the excess of car- 

 bohydrate food. On fasting, this body fat is drawn upon for 

 producing energy as is shown by loss in body fat in fasting, or 

 in the case of hibernating animals. 



METABOLISM OF FATS 



The digestive action upon the fat constituents of food results 

 in the hydrolysis of the fats into fatty acids and glycerol. The 

 products of digestion are absorbed through the intestinal wall 

 and enter the capillaries, not of the blood circulatory system, 

 as do the products of carbohydrate digestion, but of the lym- 

 phatic system, from which they pass to the thoracic duct and 

 thence to the general venous system, where they are present 

 in the blood plasma or liquid constituent of the blood. The 

 fatty acids are rendered soluble and diffusible by means 



