THE URINE. 351 



mesoxalyl urea or ALLOXAN, are obtained, C 5 H 4 N 4 3 + -f H 2 = 

 , C 4 H 2 N 2 4 -+- (NH 2 ) 2 00. On warming with nitric acid, uric acid 

 yields alloxan, carbon dioxide, and oxalyl urea or PARABANIC ACID, 

 C 3 H 2 N 2 3 . By the addition of water the parabanic acid passes into 

 OXALURIC ACID, CaHJ^O^ , traces of which are found in the urine 

 and which easily split into oxalic acid and urea. 



Uric acid occurs most abundantly in the urine of birds and of 

 scaly amphibians, in which animals the greater part of the nitrogen 

 of the urine appears in this form. Uric acid occurs frequently in 

 the urine of carnivorous mammalia, but is sometimes absent; in 

 urine of herbivora it is habitually present, though only as traces; in 

 human urine it occurs in greater but still small and variable 

 amounts. Traces of uric acid are also found in several organs and 

 tissues, as in the spleen, lungs, heart, pancreas, liver (especially in 

 birds), and in the brain. It habitually occurs in the blood of birds 

 (MEISSNER). Traces have been found in human blood under 

 normal conditions (ABELES), but especially in gout (GARROD). 

 Uric acid also occurs in large quantities in "chalk-stones," certain 

 urinary calculi, and in guano. It has also been detected in the 

 urine of insects and certain snails. 



The amount of uric acid eliminated with the human urine is 

 subject to considerable variation, but amounts on an average to 

 0.7 grm. during 24 hours on a mixed diet. On a vegetable diet 

 the amount is smaller, and on an abundant meat diet it may rise to 

 2 grms. and over. The relationship of the uric acid to the urea on 

 a mixed diet is on an average 1 : 50-1 : 70. In new-born infants and 

 in the first days of life the elimination of uric acid is increased 

 (MARES), and the relation between the uric acid and urea is about 

 1 : 13-14. After taking glycerin the amount of uric acid is in- 

 creased (HORBACZEWSKI and KANERA), while it is not increased by 

 sodium acrylate (HORBACZEWSKI). 



Uric acid when introduced into the organism of a dog is in great 

 part converted into urea, and as urea is also formed by the action 

 of oxidizing agents on uric acid outside of the body, uric acid has 

 been often considered as a step towards the formation of urea in 

 the organism. Such a view is not, however, well founded, and the 

 statement that an incomplete supply of oxygen and diminished 

 oxidation cause an increased formation of uric acid has not been 



