316 LECTURE XIV. 



sugar during diabetes, by the behavior of fat materials in the general 

 metabolism. In the first place, it is brought forward that the animal 

 organism does not regulate its consumption of energy according to the 

 quantity of food administered; that is, the combustion in the organism can- 

 not be increased beyond certain limits by the amount eaten. The amount 

 of energy utilized is dependent on the work that the organs have to do. 

 This regulates the amount of material consumed. If more food is eaten 

 than is utilized, the excess can be stored up. If all food is withheld from 

 an animal, it will live largely upon its store of fat. An appreciable fall- 

 ing off in metabolism immediately follows, which cannot be entirely 

 recovered simply by a diet of fat. This may, however, be accomplished 

 if a little albumin is added. Voit has also shown that fat metabolism 

 ceases when a sufficient amount of albumin is fed to an animal. It 

 will then live solely at the expense of albumin. This observation applies, 

 strictly speaking, only to the carnivora. The omnivora and herbivora are 

 unable to handle as much albumin as the metabolism requires. They con- 

 sume carbohydrate and fat in proportion as the albumin alone is insuffi- 

 cient to fulfill all of the requirements. The quantities of carbohydrate and 

 fat changed over are regulated by the supply of albumin at hand. " The 

 extent of albumin metabolism is dependent on the amount of albumin 

 presented; while fat metabolism is independent of the fat supply." 1 Fat 

 changes are regulated chiefly by the supply of albumin, and, secondarily, 

 the amount of carbohydrates. Every excess of fat is deposited. The 

 reason that a diet of fat does not cause any increased elimination of sugar 

 in a diabetic patient, is due to the fact that the fat consumed cannot go 

 beyond prescribed limits. By feeding fats we only produce an accumula- 

 tion thereof. The formation of sugar from fat is regulated exclusively 

 by the amount of work performed by the cells which oxidize fat to sugar. 

 In order to trace the influence of fat upon the elimination of sugar, there 

 remains the method proposed by E. Pfliiger. 2 A dog, with extirpated 

 pancreas, is fed exclusively on albumin. If the eliminated sugar is derived 

 from the body fat, we would expect, as soon as the animal had been freed 

 of its fat, that the elimination of sugar would cease. Pfl tiger's experi- 

 ments in this direction led to no definite conclusions, for his animals all 

 died at a time when the fat supplies were about exhausted. 



Now what is the origin of the sugar which the animals in the experi- 

 ments of Pfltiger and others always eliminated, even when all carbo- 

 hydrates were withheld from them? Ltithje, to whom much credit is due 

 for his extensive investigations regarding the production of sugar during 

 diabetes, is of the opinion that the albumins in the food are the source of 

 the sugar in such experiments. This brings us to the relations of the albu- 



1 E. Pfliiger: Glycogen, loc. cit. p. 329. 



2 E. Pfliiger: Pfliiger's Arch. 108, 115 (1905). 



