184 MANUAL OF CATTLE-FEEDIKG. 



kofer & Voit, tlio fat deposited in tlie l)ody was a]\\ajs 

 lully accounted for by that wliicli could be formed from 

 the amount of albuminoids decomposed in the body, and 

 wafe proportional not to the carbhydrates but to the albu- 

 minoids of the food. "With the same (pantity of albtmd- 

 noids in the food, an increase of the carbhydrates caused no 

 increase in the amount of fat formed, but only an in- 

 creased excretion of carbonic acid, showing that the carb- 

 hydrates were rapidly oxidized in the blood.* On the 

 other hand, an increase in the albuminoids of the food — 

 the quantity of carbhydrates remaining the same — caused 

 a very considerable increase in the amount of fat pro- 

 duced, thus showing an intimate connection between the 

 supply of protein in the food and the formation of fat in 

 the body. 



Sources of Uncertainty. — Having considered the ex- 

 perimental evidence bearing on the question of the souu-es 

 of animal fat, it now becomes necesbary to consider briefly 

 how much weight attaches to this evidence. 



It must be admitted at once that the data now at our 

 command are not sufficient to enable us to solve the prob- 

 lem. No thorough and accurate scientific study of the 

 subject has yet been made, if we except Pettenkofer & 

 Voit's experiments on dogs. The conclusions drawn in 

 the preceding paragraphs from experiments on farm ani- 



*It should be said that, according' to Zuntz {Landuo, Ja?irbucher, 

 VIII. , 94), carbhydrates cause no increase m the excretion of carl^onic 

 acid when introduced directly into the bloody but only when taken into 

 the alimentary canal. According to him, the increased excretion of 

 carbonic acid is caused by the excitation of the nerves of the stomach 

 and intestines In a practical point of view, however, the result is 

 much the same, since the carbhydrates of the food must be taken mto 

 the alimentary canal, and it makes little diffeience whether the car- 

 bonic acid is produced from them oi fiom the tissues ol the body. 



