CHAPTEE YIL 



THE FORMATIOlSr OF FAT. 

 § 1. Sources of Fat. 



The Fat of the Food, wlien digested and resorbed, 

 may remain nndestroyed nnder suitable conditions, and be 

 stored np in tlie body ; this is now as certain as that a for- 

 mation of fat from other constituents of the food may also 

 take place. We will, on this point, only refer to the re- 

 sults of some of the later experiments, which, like many on 

 the laws of flesh formation, we owe to the activity of the 

 Physiological Institute at Munich. 



Carnivorous animals which, by a previous feeding with 

 meat exclusively, have become rich in flesh and compara- 

 tively poor in fat, can be easily made quite fat-free by 

 long fasting ; the time when the mininmm of fat remains 

 is easily recognized from the fact that the excretion of 

 urea, which during hunger is very constant, at last in- 

 creases quite suddenly, because with the entire disappear- 

 ance of the fat more protein is eonsximed in the body. 

 Such an animal, a dog weighing about 20 kilogrammes, 

 after thirty days of fasting, was fed for five days with the 

 greatest possible quantities of pure fat, of which, on an 

 average, 3T0.8 grammes daily were digested. This is such 

 a large quantity that it is impo^sihle to suppose it to liave 

 been completely oxidized in the body, for then 1,040 

 grammes of carbonic acid should have been excreted 



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