56 Feeds and Feeding. 



began. In this case 1 iicre was a greater decomposition of protein 

 into ui-ea and fat, with a smaller absorption of oxygen, and con- 

 sequently a decreased oxidation of the fat, both processes com- 

 bining to produce fat in the body. The muscles of the poisoned 

 dog contained 42.4 per cent, of fat, and the liver 30 i)cr cent., or 

 three times more than was present in the normal nutrition of the 

 dog, and at least ten times more than would have been found after 

 twenty days of starvation, if phosphorus had not been administoied. 

 According to Henneberg, ^ 100 pounds of protein will form 

 33.45 pounds of urea on decomposition; the remainder, 66.55 

 pounds, after uniting with 12.3 parts of water, may form 51.4 

 pounds of fat and 27.4 pounds of carbonic acid. The maximum 

 quantity of fat which protein can form under the most favorable 

 conditions is, therefore, 51.4 per cent. 



ni. Formation of Fat in (he Body. 



79. Concerning fat. — Having ascertained the sources of fat in 

 the animal body, we next consider the principles governing its 

 formation and consumption. The formation of fat in the body 

 will take place when the supply of nutrients in the food exceeds 

 the immediate demands of the system. To study the effect of 

 single nutrients on fat formation and consumption, we follow the 

 plan employed in the study of protein consumption, and investi- 

 gate the conditions which are most favorable to the formation of 

 fat in the animal body and least favorable to its consumption. 



80. reeding with fat alone. — While exclusive protein feeding 

 induces only protein consumption in the body, and does not con- 

 tribute to the formation of flesh, an exclusive fat diet has no 

 influence on the decomposition of fat in the body, the same amount 

 being decomposed whether much or little fat is fed. A dog ex- 

 perimented with by Pettenkofer and Voit lost 96 grams of fat daily 

 during hunger. When 100 grams of fat were fed daily, an average 

 of 97 grams of fat was oxidized, showing that the loss of fat in the 

 body was barely covered by the feeding of fat. ^ A relatively 

 larger decomposition of fat takes place in the bodies of very fat 



» Landw. Versuchs-Stationen, XX, p. 394. 

 » Voit, Physiologie, p. 128. 



