THE FORMATION OF FAT IN THE ANIMAL BODY. 183 



and cooked albumen were clianged into fat when introduced into the 

 abdominal cavity of living animals. The substances were inclosed in 

 collodium, gutta-percha, organic membrane, or even in glass tubes to 

 prevent the infiltration of fat. Toit very justly observed that the sub- 

 stance inclosed in a glass tube might just as well be kept in a water 

 bath at about 40°, since in this case the body temperature was the only 

 factor which could have any influence. He kept glass tubes containing 

 pieces of meat and cooked albumen for 3i months in a water bath at 

 40°. At the end of this time he found an increase in the fat content of 

 the substance, but the amount was very small. 



The fact of a fatty metamorphosis and the accumulation of fat in ani- 

 mal organs which was observed and investigated by Fick, Rokitansky, 

 Eeinhard, and Yirchow; further observations regarding fatty degen- 

 eration by Wittich, Forster, Wundt, and others; and the fatty meta- 

 morj)hosis of the entire body of new-born children (Buhl), lambs, colts 

 calves (Fiirsteuberg), and pigs (Roloff), were all regarded by Voit as 

 proofs of a very general process which changed protein into fat. Fur- 

 ther, there was the increase in fat observed by Blondeau in the ripening 

 of cheese. This was disputed by Brassier, but confirmed by Kemmerich. 



All these observations led Voit to make experiments, the purpose of 

 which was to investigate the question of fat formation. The respira- 

 tion experiments made by him and Pettenkofer' in 1861 and 1863 had 

 already convinced him that the carbon which was not recovered in the 

 excretory products was retained in the organism as fat. Some of the 

 experiments on which Voit founded his theory will be discussed in 

 detail. 



From February 16 to March 14, 1863, a dog was fed daily 1,500 gm. 

 of meat; 3.8 gm. of the carbon contained in the food was, on an aver- 

 age, not recovered in the excretory products. This small deficit was 

 not regarded as due to experimental errors. Voit believed that the 

 3.8 gm. of carbon was used in the formation of 5 gm. of fat. 



At the meeting of agricultural chemists in Munich in 1865 a paper 

 entitled "The formation of fat in the animal body, and fattening,"- was 

 read by Voit, in which he described his experiments with dogs on the 

 formation of fat from protein, and also those on carbohydrates. At 

 this meeting it was decided that independent investigations should be 

 carried on by Voit and G. Kiihn with milch cows in order that the 

 formation of fat from protein by Herbivora might be studied. 



Voit made 2 experiments in which he fed the cows a ration for 

 increase. He comments on the results of the experiments in these 

 words: " It is very probable that the fat from the food and that from 

 the metabolized protein would account for the fat of the milk, and also 

 a large part of the milk sugar besides." ^ 



'Ann. Cheni. uud Pharm., 2 Snppl., 1862-1863, p. 361. 

 2Landw. Vers. Stat., 8 (1866), p. 23. 

 3 Ztschr. Biol., 5 (1869), p. 79. 



