558 THE URINE. [CH. xxxvu. 



hardly formed at all, its place being taken by ammonia and lactic 

 acid. It is therefore probable that ammonia and lactic acid are 

 normally synthesised in the liver to form uric acid. 



The chief conditions which lead to an increase of uric acid are : 



1. Increase of meat diet and diminution of oxidation processes, 

 such dfc occur in people with sedentary habits. 



2. Pathological conditions allied to gout. 



3. Increase of white corpuscles in the blood, especially in the 

 disease known as leucocythcemia. This latter fact is of great 

 interest, as leucocytes contain large quantities of nuclein. Nuclein 

 yields nitrogenous (purine) bases (adenine, hypoxanthine, &c.), 

 which are closely related to uric acid. 



The close relationship of the purine bases to uric acid has been clearly 

 demonstrated by the work of Emil Fischer, for they are all derivatives of the 

 substance called jwrine. The names and formulae of these substances are as 

 follows : 



Purine C 5 H 4 N 4 



I Hypoxanthine (monoxy-purine) . . . C 5 H 4 N 4 O 



Xan thine (dioxy-purine) .... C 5 H 4 N 4 O 2 



Purme bases | Adenine (ammo-purine) C 5 H 4 N 4 .NH 



vCiuanine (amino-oxy purine) .... C 5 H 4 N 4 O.XH 



Uric acid (trioxy-purine) C 5 H 4 N 4 O 3 



Leaving aside other possible ways in which uric acid is undoubtedly formed 

 in the organism, we have here a way in which uric acid may arise by oxida- 

 tion from the nuclein bases and thus ultimately from the nuclei of cells. 

 Certain forms of diet increase uric acid formation by leading to an increase 

 of leucocytes and consequently increase in the metabolism of their nuclei ; 

 some investigators think, however, that the increase is chiefly due to nuclein 

 in the food. The question is not yet settled. 



Hippuric Acid. 



Hippuric Acid (C 9 H 9 N0 3 ), combined with bases to form 

 hippurates, is present in small quantities in human urine, but in 

 large quantities in the urine of herbivora. This is due to the 

 food of herbivora containing substances belonging to the aromatic 

 group the benzoic acid series. If benzoic acid is given to a 

 man, it unites with glycocine with the elimination of a molecule 

 of water, and is excreted as hippuric acid 



CH 2 .NH 2 CH 2 NH.CO.C 6 H 5 

 C 6 H 5 .COOH+ | =--; +H 2 



COOH COOH 



[Benzoic acid] [Glycocine] [Hippuric acid] [Water]. 



This is a well-marked instance of svnthesis carried out in the 



