50 GRAHAM Ll'SK 



approximately how much one must eat in order to maintain the body tempera- 

 ture at a given level of metabolism during a given time: 



Table of Isodynamic Values 



Liebig Rubner 



in 1846 in 1885 



Fat 100 100 



Starch 242 232 



Cane-sugar 249 234 



Dried meat 300 243 



This, surely, is a divination of Rubner's subsequently enunciated isody- 

 namic law. 



As regards the oxygen requirement for the combustion of different 

 foods, comparisons may be made between the findings of Liebig in 1846 

 and those of Loewy in 1911 : 



To oxidize requires O 2 in c.c. 



Liebig Loewy 



Fat, 1 gm 2050 2019 



Starch, 1 gm 832 828 



It is evident that Liebig clearly understood that it was protein, car- 

 bohydrate and fat which were oxidized in the -body and that they were 

 the source of energy and not carbon and hydrogen supposed to be pro- 

 duced from them. 



Liebig divides the foodstuffs of man into two classes, the nitrogenous 

 and the non-nitrogenous. The first class can be converted into blood ; the 

 other cannot be. The constituents of organs of the body are built up 

 from those foods which are convertible into blood. In the state of normal 

 health the other foodstuffs are used merely for maintaining the respira- 

 tion process. He calls the nitrogen-containing foods the plastic food- 

 stuffs and the non-nitrogenous, the respiratory foodstuffs. They are as 

 follows : 



Plastic Foods Respiratory Foods 



Plant fibrin Fat 



Vegetable albumin Starch 



Vegetable casein Gum 



Meat and blood of animals Sugars 



Pectin 



Bassorin, 



Beer 



Wine 



Brandy 



