AMIDES IN METABOLISM OF VEGETARIANS 67 



upon the ground of actual scientific investigation). Of 

 course every soluble protein preparation has in the end a cer- 

 tain ' ' nutritional value ' ' ; whether the ' ' nutritional value' ' in 

 any individual case hears any direct proportion to the price 

 charged for the preparation is a matter which may here be 

 gladly omitted. Unfortunately, however, as far as odor and 

 flavor are concerned, the applicability of the cleavage prod- 

 ucts of protein is far from what one would wish; and 

 moreover, perhaps because of amines present, a variety of 

 collateral effects are likely to appear and for the present de- 

 tract from the therapeutic appreciation of these substances. 



After what has been said above, the possibility of various 

 nitrogenous substances serving as partial substitutes for 

 protein in nutrition may be readily understood. A number 

 of investigations bearing upon this point, concerning the 

 nutritive value of leucin, various albumoses, peptones, pro- 

 tamines, etc., have been published. 55 It may at least be seen 

 that such preparations may serve to conserve protein and 

 that their value as more or less complete substitutes for pro- 

 tein must primarily depend upon just what and how many of 

 the metabolically essential structural units of the protein 

 molecule are missing from their atomic grouping. 



Relation of Amides in Metabolism of Vegetarians; Pro- 

 tein Synthesis from Ammonium Salts. Although the above 

 questions, at least in a fundamental way, seem fairly solved, 

 this certainly cannot be said of another matter, the relation of 

 the amides and aminoacids in metabolism. Because of the 

 wide distribution of aminoacids and amides in plants and 

 owing to the fact that the determination of the value of the 

 various foodstuffs (as turnips, molasses, etc.) is of very great 



66 A. Ellinger (Physiol. Instit., Munich), Zeitschr. f. Biol., 33, 201, 1896; 

 L. Blum ( Hofmeister's Lab.), Inaug. Diss., Strassburg, 1901; V. Henriquez 

 and C. Hansen, Zeitschr. f. physiol. Chem., 48, 383, 1906; 49, 113, 1906; P. 

 Kona and W. Miiller, ibid., 50, 263, 1906; J. R. Murlin, Amer. Journ. of 

 Physiol., 20, 234, 1907-08; cf. therein literature appended. 



