NUTRITIVE VALUES. 45 



not kept in equilibrium. This was demonstrated by an experiment 

 conducted by the author on himself, and also on dogs. Mancini* 

 has fed large amounts of gelatin and little proteid and claims that 

 gelatin has a proteid sparing action. Murlin^ has replaced two- 

 thirds of the proteid nitrogen by gelatin in the case of both dogs and 

 men reduced to a starvation level and finds the equilibrium is not 

 changed by this substitution. Gelatin and its cleavage products have 

 been studied by Chittenden and Solley e and Levene * among others. 



A valuable contribution to the literature on the subject of the nutri- 

 tive value of gelatin by Murlin 6 has recently appeared. The review 

 of the literature here given is in part taken from this article. The 

 experiments performed by this author were made on dogs and the 

 fasting requirement of nitrogen was used as a working basis. Murlin 

 states that the power of the organism to utilize gelatin as a proteid 

 substitute depends to some extent on the proteid condition of the 

 body at the beginning of the experiment, as well as upon the loss of 

 proteid during its progress. 



In the experiments with dogs as high as 58 per cent of gelatin nitro- 

 gen was substituted for proteid nitrogen, the amount varying with the 

 diet. In the case of man, if two-thirds of the potential energy were 

 in the form of carbohydrates it was found to be possible to supply 63 

 per cent of the total nitrogen in the form of gelatin nitrogen for a 

 period of two days and maintain a daily retention of nitrogen of 0.71 

 gram. 



Exact knowledge of the nutritive value of gelatin had its beginning 

 in the researches of Carl Voit/ published in 1872. As early as 1860 

 Voit and Bischoffs' had established experimentally the truth first 

 perceived by Donders, A that gelatin reduces the proteid requirements 

 of the body; but they were of the opinion at this time that it could 

 perform all the work of proteids and replace them entirely in the diet. 

 After Voit 1 had shown that a part only of the nitrogenous excreta 

 is derived from the proteids of the body tissue, a portion coming from 

 the "circulating" proteids, he again investigated the extent to which 

 gelatin could be substituted for proteid, and reached the following 

 conclusions : 



Gelatin exercises its sparing power on the proteids both with large and with small 

 quantities of proteid (meat) fed at the same time, and with small quantities in much 



"Arch. d. Farmacol. sperim., 1906, 5: 309, 337. 



&Proc. Soc. Exper. Biol, and Med., 1904, 2 :38. 



cj. Physiol., 1891, 12 .2%. 



dZts. physiol. Chem., 1904, 41:8. 



«Amer. J. Physiol., 1907, ^9:287. 



/Zts. Biol., 1872,5:297. 



y Die Gesetze der Ernahrung des Fleischfressers, Leipzig, 1860. 



h Die Nahrungsstoffe, Crefeld, 1853. 



*Zts. Biol., 1869, 5:329. 



