DIET OF MIXTURE OF FLESH AND FAT. 487 



excreted, than a quantity of fat, which requires the same amount of 

 to oxidise it, as is required by the amount of carbohydrates con- 

 sumed. When the amount of flesh is insufficient, the addition of fat 

 or carbohydrates to the food always limits the decomposition of the 

 animal's own substance. Lastly, when too much flesh is given along 

 with these substances, the weight of the body increases more with 

 them than without them. Under these circumstances, the animal's 

 body puts on more fat than flesh. 



The consumption of in the body is regulated by the mixture 

 of flesh and non-nitrogenous substances, rising and falling Avith the 

 amount of flesh consumed. It is remarkable that more is con- 

 sumed when a given amount of flesh is taken, than when the same 

 amount of flesh is taken with the addition of fat (v. Pettenkofer 

 and v. Voit). 



It seems that instead of fat, the corresponding amount of fatty acids has the 

 same effect on the metabolism. They are absorbed as an emulsion just like the 

 fats. When so absorbed, they seem to be reconverted into fats in their passage 

 from the intestine to the thoracic duct (J. Munk, Will). Glycerin does not 

 diminish the decomposition of albumin within the body (Lewin, Tschirwinsky, 

 J. Munk). According to Lebedeff and v. Voit, it diminishes the decomposition of 

 the fats, and is therefore a food. 



241. Origin of Fat in the Body. 



I. Part of the fat of the body is derived directly from the food, i.e., 

 it is absorbed and deposited in the tissues. This is shown by the fact 

 that, with a diet containing a small amount of albumin, the addition of 

 more fat causes the deposition of a larger amount of fat in the body 

 (v. Voit, Hofmann). 



Lebedeff found that dogs, which were starved for a month, so as to get rid of 

 all their own fat, on being fed with linseed oil or mutton suet and flesh, had these 

 fats restored to their tissues. These fats, therefore, must have been absorbed 

 and deposited. 



II. A second source of the fats is their formation from albuminous 

 bodies (Liebig and others). 



In the case of the formation of fat from proteids, which may yield 

 11 per cent, of fat, these proteids split up into a non-nitrogenous and a 

 nitrogenous atomic compound. The former, during a diet containing 

 much albumin, when it is not completely oxidised into C0 , and H 0, is 

 the substance from which the fat is formed the latter leaves the body 

 oxidised chiefly to the stage of urea (Hoppe-Seyler, Fiirstenberg, v. 

 Voit, v. Pettenkofer). 



Examples. That/cite are formed from proteids is shown by the following : 1. 

 A cow which produces 1 Ib. of butter daily, does not take nearly this amount of 



