SOURCE OF THE BODY FAT 



415 



body fat is sharply increased in the second period, due to the stimulating 

 influence of the proteid. 



This is demonstrated by the following determination of Rubner: 



The fat of the ordinary daily diet is absorbed into the blood and no doubt 

 contributes directly to oxidation processes. Just the steps in this oxidation 

 process cannot at present be given. If the fat food is insufficient, then the 

 body store is drawn upon ; if in excess, then it is stored in the body. 



Source of the Body Fat. Excess of fat in the food can be stored 

 as fat in the body. This fact is demonstrated by Voit, Hoffmann, Rubner, 

 and others. Rubner states that 82 to 92 per cent of the fat excess can be 

 stored. The fat stored is of the same kind given in the food, even though 

 the usual fat of the animal is different. The melting point of dog's fat is 

 about 20 C., but by feeding an excess of mutton fat the melting point has been 

 raised to 40 C. The subcutaneous fat of pigs subjected to this experi- 

 ment is more or less fluid according to the melting point of the fat fed. 



The body fat can also be derived from carbohydrate food, a fact which 

 the practices of the stock feeder and dairyman constantly verify. Two ex- 

 periments will present the matter more vividly than pages of description. 



GAIN IN FAT OF A PIG FED ON RICE. (MEISSL AND STROHMER.) 



It is obvious that the 5.3 grams of fat and the 66 grams of proteid cannot 

 account for the carbon retained, and one must look to the carbohydrate as 

 the source of the fat. 



Jordan placed a Jersey cow on a feed of hay and grain from which the 

 fat was extracted. The cow in 95 days assimilated 5.7 pounds of fat, in- 

 creased 47 pounds in weight, and produced 62.9 pounds of fat in the milk. 

 The nitrogen excreted was the equivalent of 33.3 pounds of proteid. The 

 non-nitrogenous moiety of the proteid, if its carbon had all gone into fat, 

 could not have produced over 17 pounds. Summarized, this experiment 



