NUTRITIVE VALUE OF GELATIN. 853 



after food rich in proteins, as observed by NENCKI and ZALESKI/ seems to- 

 speak in favor of this view. 



It has been stated above that other foods may decrease the catab- 

 olism of proteins. Gelatin is such a food. Gelatin and the gelatin-formers 

 do not seem to be converted into protein in the body, and this last cannot 

 be entirely replaced by gelatin in the food. For example, if a dog is fed 

 on gelatin and fat, its body sustains a loss of proteins even when the 

 quantity of gelatin is great enough so that the animal with an amount ot 

 fat and meat containing just the same quantity of nitrogen as the gelatin 

 in question, remains in nitrogenous equilibrium. On the other hand, 

 gelatin, as VOIT, PAN UM, and OERUM 2 have shown, has great value as 

 a means of sparing the proteins, and it may decrease the catabolism of 

 proteins to a still greater extent than fats and carbohydrates. This is 

 apparent from the following summary of VOIT'S experiments upon a dog: 



Food per Day. Flesh. 



.Meat Gelatin. Fat. Sugar. Catabolized. On the Body. 



400 200 450 -50 



400 250 43Q -39 



400 200 356 +44 



I. MUNK 3 has later arrived at similar results by means of more deci- 

 sive experiments. He found that in dogs on a mixed diet which con- 

 tained 3.7 grams protein per kilo of body, of which hardly 3.6 grams were 

 catabolized, nearly five-sixths could be replaced by gelatin. The same dog 

 catabolized on the second day of starvation three times as much protein 

 as with the gelatin feeding. MUNK also states that gelatin has a much 

 greater sparing action on proteins than the fats or the carbohydrates. 



This ability of gelatin to spare the proteins is explained by VOIT by 

 the fact that the gelatin is decomposed instead of a part of the circulat- 

 ing proteins, whereby a part of this last may be organized. 



The recent investigations of KRUMMACHER and KIRCHMANN show the 

 extent of the sparing action of gelatin upon proteins. The extent of 

 protein destruction during gelatin feeding was compared with the extent 

 of protein catabolism in starvation, and it was found that 35-37.5 per 

 cent of the quantity of protein decomposed in starvation could be spared 

 by gelatin. The physiological availability of gelatin was found by 

 KR.UMMACHER to be equal to 3.88 calories for 1 gram, which corresponds 

 to about 72.4 per cent of the energy-content of the gelatin. KAUFMANN, 

 who experimented upon dogs, found that one-frith of the protein nitrogen 

 could be readily replaced by gelatin nitrogen, while in an experiment upon 



1 Arch, des scienc. biol. de St. Petersbourg, 4; Salaskin, Zeitschr. f. physiol. Chern., 

 25; Nencki and Zaleski, Arch. f. exp. Path. u. Pharm., 37. 



2 Voit, 1. c., 123; Panum and Oerum. Nord. Med. Arkiv., 11. 



3 Pfliiger's Arch., 58. 



