408 FORMATION OF FAT FROM PROTEIN 



metabolism, believes that really the formation of fat from 

 protein does not occur to any important amount, although 

 the possibility of such process must be maintained. Nor is it 

 absolutely essential that the route should be through a fully 

 formed sugar; for if we may presume that groups of six 

 carbon atoms, combined from the "building stones " of the 

 protein molecule, unite to the formation of the sugar mole- 

 cule, we have as much right to fancy that eight or nine such 

 groups, if need be, can enter into the construction of the long 

 fatty acid chains. When, however, would this be needed? 

 "When carbohydrates and fat are available in metabolism 

 there is no occasion for further production from protein. 

 Whenever, in case of deficiency of carbohydrate, important 

 amounts of sugar are formed from protein, it seems to be 

 required for the immediate needs of the body, unless, as in 

 diabetics, it is excreted. As we cannot recognize in animal 

 experiments that in case of exclusive protein diet any exten- 

 sive formation of fat takes place, so there is no reason for 

 holding that the process plays any important part under 

 natural conditions of life in the carnivorous individual. ' ' 24 

 On the contrary, only recently E. A. Bogdanow has con- 

 cluded from his studies on the fattening of pigs that fat for- 

 mation from protein is at least probable. 25 



Tangl and Farkas 26 have found an increase in fat con- 

 tent of trout-eggs in the course of development which was 

 held to be due to transformation of protein into fat because 

 the undeveloped egg does not contain any important supply 

 of either glycogen or sugar ; although the possibility of gly- 

 coproteid with its carbohydrate group in combination in pro- 

 tein, should be considered. 



It is the same old story : the great conflict over the for- 

 mation of fat from protein in metabolism has, if the expres- 



84 A. Magnus-Levy and L. F. Meyer, 1. c., p. 453. 



15 E. A. Bogdanow (Moscow, 1909), cited from the Russian in Jahresber. 

 f. Tierchem., 39, 585, 1909. 



*F. Tangl and Farkas (Budapesth), Pfluger's Arch., 104, 624, 1904. 



