REPLACEMENT OF NUTRIENTS. 



17 



body fat, but it is most natural to suppose that the resorbed fat of the feed, 

 being already in circulation in the body, is more easily accessible to the active 

 cells than the stored-up fat of the adipose tissue and is therefore metabolized 

 in preference to the latter. 



CABBOHYDBATES AND BODY FAT. 



Experiments precisely similar to those on fat just described show 

 that carbohydrates may also diminish or suspend the loss of body fat. 

 This may be illustrated by the results of three experiments upon a dog 

 by Rubner. 



Replacement of body fat by carbohydrates — Rubner. 



Food. 



None 



76.12 grams cane sugar. 

 104.97 grams cane sugar 



None 



42.96 grams starch 



None 



57.38 grams starch 



Total nitro- 

 gen of ex- 

 creta. 



Grams. 

 1.94 

 1. 45 

 1.07 

 1.42 

 1.53 

 2.00 

 1.52 



Total car- 

 bon of ex- 

 creta. 



Grams. 

 38. 18 

 43. 19 

 47. 78 

 26. 47 

 33. 28 

 31.53 

 39. 67 



CABBOHYDBATES AND FEED FAT. 



Rubner substituted dextrose for fat in the diet of a dog receiving 

 also a fixed amount of lean meat. The results of this substitution 

 are given in the following table, and show that with the larger 

 amount of dextrose in place of the fat previously fed the loss of body 

 fat was prevented : 



Replacement of feed fat by carbohydrates — Rubner. 



Ration. 



Feed per day. 



Gain or loss by- 

 animal. 



Meat. 



Fat. 



Dextrose. 



Nitrogen. 



Carbon. 



Meat and fat 



Grams. 

 300 

 300 

 300 

 300 

 300 



Grams. 

 42 

 50 



Grams. 



Grams. 

 +1.81 

 + .10 

 +1.78 

 +2.28 

 +1.98 



Grams. 

 +1.27 

 +9.31 

 -7.44 

 -8. 15 

 +6. 21 



Do 





Meat and dextrose 



63.7 

 79.7 

 115.5 



Do 





Do 









FEED PBOTE1N AND BODY FAT. 



It has already been shown that body protein may replace body fat 

 in the katabolism of the fasting animal. A similar substitution of 

 feed protein for body fat may take place. When protein is given 

 to a previously fasting animal it is a well-known fact that the 

 nitrogen of the protein is rapidly split off and excreted, while the 

 nonnitrogenous portion of the molecule serves as a source of energy 

 8489°— Bull. 143—12 2 



