FORMATION OF HIPPURIC ACID. 721 



As the thorough investigations of WIECHOWSKI teach, the synthesis 

 of hippuric acid does not stand in any direct relation to the extent of 

 protein metabolism; it varies, on the contrary, with the duration of 

 circulation of benzoic acid and the quantity of glycocoll present in 

 the body. The amount of the latter in intermediary metabolism is so 

 great that in rabbits, on the administration of benzoic acid, more than 

 one-half of the total urine nitrogen may exist as glycocoll. MAGNUS- 

 LEVY l found in rabbits and sheep up to 27.8 per cent of the total nitro- 

 gen as hippuric-acid nitrogen, and both investigators have found so much 

 hippuric-acid nitrogen that it could not be accounted for by the glycocoll 

 preformed from the proteins, which amounts to about 4-5 per cent of 

 the total nitrogen of the protein of the food and body. 



In carnivora (dog) and man the conditions are different, according 

 to BBUGSCH and R. HIRSCH, FEIGIN and BRUGSCH, as in these cases there 

 is no more glycocoll available for hippuric acid formation than is split 

 off from the proteins en hydrolysis. According to the investigations of 

 LEWINSKI 2 this does not seem to be correct, at least not for man. After 

 abundant introduction of benzoic acid in man about 34 per cent of the 

 total nitrogen may be excreted as hippuric acid and in a recent investiga- 

 tion he was able to obtain 50.5 grams pure crystalline hippuric acid 

 from the 24-hour urine of a man after feeding sodium benzoate. 



The abundant production of hippuric acid in herbivora induced ABDER- 

 HALDEN, GIGON and STRAUSS to investigate the comparative supply of 

 certain amino-acids in carnivora and herbivora, and they found in cats, 

 rabbits and hens that the percentage quantity of glycocoll split off from 

 the entire organism (with the exception of the intestinal contents and 

 fat and feathers) by hydrolysis was the same, namely 2.33 to 3.34 per 

 cent of the proteins. In order to account for the large quantity of 

 glycocoll which can be eliminated as hippuric acid, we must admit of a 

 formation of glycoccll. That this occurs in animals fed with benzoic 

 acid has been recently proved by ABDERHALDEN and HIRSCH by very 

 conclusive experiments. It can be assumed that the benzoic acid com- 

 bines with higher amino-acids and that the hippuric acid is formed from 

 this combination. The investigations of MAGNUS-LEVY to prove this 

 assumption, where he used benzoylated higher amino-acids, have not 



Hupfer, Zeitschr. f. physiol. Chem., 37. See also Wiener, " Die Harnsaure," Ergeb- 

 nisse der Physiol., 1, Abt. 1. 



1 Wiechowski, Hofmeister's Beitrage, 7 (literature); A. Mangus-Levy, Munch, 

 med. Wochenschr., 1905; Ringer, Journ. of biol. Chem., 10; Epstein and Bookman, 

 ibid., 10. 



2 Brugsch and Hirsch, Zeitschr. f. exp. Path. u. Therap., 3; Brugsch, Maly's 

 Jahresber., 37, 621, and Bioch. Centralbl., 8, 336; Feigin, Maly's Jahresber., 36, 

 631; Lewinski, Arch. f. exp. Path. u. Pharm., 58 and 61. 



