THE FORMATION OF FAT IN THE ANIMAL BODY. 189 



geese tliey observed that more oxygen was combined with carbon tban 

 was necessary for the formation of fat, and therefore concluded that 

 not fat but glycogen was formed. It was necessary to take carbo- 

 hydrates into account in considering the formation of glycogen and 

 eventually of 27 gm. of fat per day. One goose produced 22 gm. of fat 

 and another 16 gm. of fat pei- day from carbohydrates. On an average 

 17 per cent of fat was produced from the starch assimilated. Indeed, 

 by applying Henneberg's principle of the cleavage of protein without 

 the action of air a maximum of 41 gm. of fat could be formed from 

 100 gm. of starch, together with 18 per cent of carbon dioxid and 11 

 per : ent of water. Voit believed that it was true that if much starch 

 and little fat and protein were supplied fat would be formed from the 

 starch. The carbohydrates must be far in excess of the amount actu- 

 ally required if fat is to be formed from them. If much fat or protein 

 and little carbohydrates are assimilated from the food, then the, tirst 

 two will account for the fat formed and the carbohydrates will be 

 burned in the organism. Voit therefore held to the idea that the pro- 

 tein and fat of the food were the ordinary sources from which fat was 

 formed in the animal body. 



The experiments which have been cited up to this time as proofs of 

 the formation of fat from carbohydrates have been made with Omnivora 

 and Herbivora. Munk and liubner made experiments with Carnivora — 

 that is, dogs. Munk ' fed a dog, which had fasted for 31 days and 

 become very poor, 200 gm. of meat daily with starch, gradually increas- 

 ing the amount of the latter from 2.30 to 500 gm. li^ order to protect 

 the protein more fully, for 10 days 100 gm. of gelatin per day was also 

 fed. The dog remained in good health for 23 days, but on the 21:th 

 day suffered fi'om diarrhea and the experiment was discontinued. The 

 dog's body yielded 1,070 gm. of fat. Of tliis at least nine-tenths, or 

 900 gm., must have been formed during the experiment. The food con- 

 sumed could have furnished 172 gm. of fat, assuming that 12 per cent 

 of fat can be formed from protein, this being the highest value found 

 by Voit; or it could furnish 490.3 gm. of fat, assuming that Henne- 

 berg's figure — 51.4 per cent — represents the amount of fat formed from 

 protein. On the last assumption 470 gm. of fat, or 49 per cent, must 

 have been formed from carbohydrates; and even assuming that fat 

 can be formed from gelatin, with Volt's figure 203 gm. and with Hen- 

 neberg's 102 gm. of fat still remain which must have been formed from 

 carbohydrates. 



Rubner^ fed a dog for 2 days 100 gm. of cane sugar and 85 gm. of dry 

 starch daily, after a preliminary period of 13 days on a meat diet and 

 2 days of fasting. During the 2 days 89.5 gm. of the carbon consumed 

 was not excreted ; of this amount 13 gm. were derived from the fat in 

 the food consumed and the cleavage of the protein; carbohydrates 



1 Virchow's Arch. path. Anat. und Physiol., 101 (1885), p. 91. 

 ^Ztschr. Biol., 22 (1886), p. 272. 



