444 ORIGIN OF THE FAT IN THE BODY, 



addition to the starch, contained in the food, the more readily is an excess of 

 starch to be attained without the necessity of supplying too much starch. If 

 this condition of such an excess is not fulfilled, fat does not result even with 

 generous administration of carbohydrates. The newly formed fat possesses the 

 same potential energy as the nutritive excess resulting from the carbohydrates 

 administered. 



Deposition of fat in the body does not take place, however large the excess 

 of proteid food, if carbohydrates or fat be not supplied at the same time. On 

 feeding with meat and starch, or in general with a mixed diet, the amount of 

 newly formed fat depends in no wise upon the amount of proteid decomposed, 

 but only upon the amount of nutritive excess due to carbohydrates. Deposition 

 of fat from carbohydrates takes place even when no proteid at all is supplied 

 and the metabolism, therefore, must be maintained in part at the expense of a 

 portion of the body-proteid. 



While for the maintenance of the metabolic equilibrium on a pure meat-diet 

 an enormous consumption (from 2 V to ^ of the body-weight in the dog) is required, 

 a third of the amount of meat suffices with an adequate addition of fat or carbo- 

 hydrate. For 100 parts of fat, added to the meat, 245 parts of dry meat or 227 

 of syntonin can be conserved. If carbohydrates are selected instead of additional 

 fat, 100 parts of fat correspond to from 230 to 250 parts of carbohydrate. It 

 should, however, be borne in mind that, at least for a short time, the carbohy- 

 drates are superior to fat as a proteid-sparer, as the fat is less completely 

 utilized in the process of metabolism than the carbohydrates. 



It appears that, instead of fat, a corresponding amount of fatty acids has the 

 same effect in the process of metabolism. 



Glycerin is not capable of lessening the destruction of bodily proteid, although 

 recently I. Munk has stated that moderate amounts of glycerin introduced into 

 the circulation are consumed in the body and through their oxidation protect a 

 portion of the bodily fat against oxidation. According to Lebedeff, v. Voit and 

 Arnschink, glycerin, however, diminishes the decomposition of bodily fat and is 

 therefore a food-material. 



ORIGIN OF THE FAT IN THE BODY. 



A portion of the bodily fat is derived directly from the food, being simply 

 deposited in the tissues after absorption. In favor of this view is the observation 

 that with a scanty proteid diet a generous addition of meat causes the deposition 

 of large amounts of fat in the body. The administration of fatty acids alone may 

 also contribute to the formation of fat, inasmuch as glycerin, formed by the 

 body, must combine with them in the process of metabolism. 



As a result of fattening experiments with different warm-blooded animals 

 (pig, goose, dog), in which, in addition to a large excess of starch, only a small 

 amount of fat and proteid is supplied, the conclusion has been reached that a 

 direct transformation of the absorbed carbohydrates, rich in oxygen, into fatty 

 tissue, poor in oxygen, takes place. Pfluger found that the sugar-molecule of the 

 food, given in excess of the requirements for the development of fat in the animal, 

 is in part oxidized and in part reduced, so that, on the one hand, carbon dioxid, 

 and, on the other hand, the group of atoms concerned in the formation of fat, 

 result, inasmuch as the molecular groups CH OH are reduced to CH 3 . The carbon 

 dioxid that is exhaled when fat-formation takes place in consequence of the 

 administration of starch is thus derived from two sources, namely, in part from 

 the process of decomposition described, and in part from the total combustion 

 of starch. The excessive elimination of carbon dioxid in this process of fat- 

 formation in consequence of an excessive starchy diet must naturally cause an 

 increase in the respiratory quotient, even above 1.2. 



If the carbohydrates be considered as decomposing into fat, carbon dioxid 

 and water, 100 grams of starch or in.i grams of sugar will yield at most 41.1 

 grams of fat, 47.5 grams of carbon dioxid and 11.4 grams of water. Also the 

 circumstance that bees utilize the sugar of honey in the formation of wax is in 

 favor of the production of fat from carbohydrates. According to Pasteur and 

 E. Voigt, glycerin can be formed from carbohydrates. 



Does fat result from proteid metabolism ? v. Pettenkofer and v. Voit reached 

 the conclusion, as a result of their experiments, that fat can be formed in the ani- 

 mal body from proteids. They fed a dog with large amounts of meat, and although 

 all of the nitrogen thereof was excreted in the urine and the feces, a portion of 



