244 FORMATION OF SUGAR FROM FAT 



most simple and direct means of settling the question of the 

 production of sugar from the higher fatty acids would be by 

 determining whether on introduction of a large quantity of 

 such substances into a diabetic the excretion of sugar would 

 be increased. In the great majority of observations with 

 this point in view, not only has such increase been missed 

 as a matter of fact, but in addition in a number of cases there 

 has been a noted lowering of the sugar excretion after ad- 

 ministration of fatty acids (interpreted on the supposition 

 that the combustion of the latter serves to protect the protein 

 from undergoing destruction and in this way reduces the 

 formation of sugar from the protein) , 62 It would, however, 

 be another mistake to regard such negative results as a satis- 

 factory proof that formation of sugar from the higher fatty 

 acids is impossible. Eeference may be made here to the 

 interpretation of A. Magnus -Levy, 63 whose perspicaciously 

 conducted investigations have distinctly advanced the 

 physiology of metabolism in so many ways, upon these 

 points: "In contrast to the conditions prevailing with 

 varying introduction of protein, where as a matter of fact 

 every addition of protein occasions a corresponding increase 

 in protein exchange, the most marked addition of fat in- 

 creases but little the fat exchange. Fat does not in any 

 sense displace other food from metabolism. In the starving 

 dog it replaces the previously consumed body fat; is con- 

 sumed in its place. An excess is deposited almost in its 

 total amount without essentially increasing metabolism. 

 . . . We can also subscribe to the statement here outlined 

 in this, that fat as the most passive of all the foodstuffs 

 always takes part in the combustion process after all the 

 other foods, after protein, the carbohydrates and alcohol, 

 and takes part only as far as an existing demand is not 



63 L. Mohr (F. Kraus's Clinic, Berlin), Zeitschr. f. exper. Pathol., 2, 463, 

 481, 1906; E. Pfliiger, Pfltiger's Arch., 108, 115, 1905; S. Bondi and E. Rud- 

 inger, Wiener klin. Wochenschr., 19, 1029, 1906; F. Maignon, Jour, de Physiol., 

 10, 866, 1908; cf. therein the older literature. 



88 A. Magnus-Levy, Handb. d. Biochem., 4' 343-344, 1909. 



