SPECIAL ARTICLES OF DIET. 



879 



of 500 grms. of meat. On removing 100 grms. of this from the diet, and 

 replacing it by 200 grms. of gelatin, there was a gain of nitrogen to the 

 body representing the putting on of 44 grms. of flesh, whereas when the 

 100 grms. of meat was replaced by 200 grms. of fat, or by 250 grms. of 

 starch, there was a loss of nitrogen representing a loss of flesh to the 

 amount respectively of 50 and 39 grms. 



The following experiments of Voit on a dog are also instructive. 

 The numbers represent grammes : 



That it cannot wholly replace proteid is shown by the fact that 

 even when very large quantities are given either alone or in combination 

 with fat and carbohydrate, an excess of nitrogen appears in the excreta 

 in other words, there is still a loss of flesh from the body. 1 To a 

 certain extent gelatin will act as a fat-sparer, i.e., when given along 

 with proteid, it may prevent the oxidation of body fat, but its activity in 

 this respect is far below that of either fats or carbohydrates. 2 Even 

 the collagenous tissues can apparently not be formed from gelatin 

 ingested, since this wholly appears (as urea, etc.) in the excreta ; these 

 tissues must therefore be formed, like all others, from proteid food. 3 

 Gelatin is also not assimilated if injected into the blood or under the 

 skin ; it appears at once in the urine. 4 



Nucleins and nucleo-proteids, as well as lecithins, are found in all 

 forms of mixed diet ; and although nuclein is not digested by the gastric 

 juice, nor, according to Bokay, 5 by artificial pancreatic juice, there are 

 reasons for believing that a part at least of the nuclein of the food is 

 absorbed and converted in the body into other substances. It is found, 

 for example, that the ingestion of foodstuffs containing much nuclein 

 causes a marked increase of uric acid in the urine, 6 and, as we shall 

 show later on, there is strong reason to believe that the iron necessary 

 for the formation of haemoglobin is derived from some forms of nuclein. 



1 For the evidence of this, see C. Voit, op. tit., S. 122. 



2 C. Voit, op. cit., S. 126. 



3 An interesting historical account of the question of gelatin as an article of diet is 

 given by Voit (op. cit., S. 395). 



4 Cl. Bernard and Barreswil, Journ. de pharm. et chim., Paris, 1844, Se>. 3, tome v. 

 p. 425. 



5 Ztsckr. f. physiol. Chem., Strassburg, 1877, Bd. i. S. 157. 



6 Horbaczewski, Sitzungsb. d. k. Akad. d. IVissensch.^ien, 1891, Bd. c. Abth. 3, S. 78. 



