CHEMICAL COMPOSITION OF THE HUMAN BODY 47 



Allantoin is found in the allantoic fluid and in the urine of 

 newly born mammals. On oxidation it yields urea and oxalic 

 acid: C 4 H 6 N 4 8 + O + 2H 2 O = 2 CO(NH 2 ) 2 + C 2 O 4 H 2 . 



Uric acid can be formed synthetically: 



(a) By melting urea and glycocoll together: 



3 CO(NH 2 ) 2 + NH 2 .CH 2 COOH = C 5 H 4 N 4 O 3 + 3 NH 3 + 2 H 2 O. 



(b) From urea and trichlorlactamide : 

 2CO(NH 2 ) 2 -hC 3 Cl 3 2 H 2 NH 2 =C 5 H 4 Np 3 +ClNH,+H 2 0+2HCl. 



Presence and formation of uric acid in the animal bQdy. 

 Uric acid is found in small quantities in the urine, also in 

 the blood and the organs of the mammals. It is the chief 

 constituent of the urine of birds and reptiles. It is formed, 

 like urea, from the decomposed proteids. In the liver of 

 birds, uric acid appears to be formed synthetically from 

 lactic acid and ammonia salts. If the liver of a bird be 

 extirpated, the urine contains lactic acid and ammonia salts 

 instead of uric acid. Urea and amido acids given to birds 

 is excreted in the form of uric acid. Whether in mammals 

 uric acid is also formed synthetically is not known. 



Uric acid is closely related to the nuclein bases ; by reduc- 

 tion it can be changed to xanthin and hypoxanthin (see 

 below). Hence it is formed in the animal body probably 

 by the splitting up and oxidation of the nucleins. 



It is supposed that the uric acid is especially formed from the 

 nucleins of the nuclei of the decomposed leucocytes. This is 

 based upon the facts that large increase and greater destruction 

 of leucocytes in the blood (leukaemia) is accompanied by greater 

 excretion of uric acid, and that by heating the pulp of spleen or a 

 boiled aqueous extract of spleen with blood, uric acid is formed. 

 In this, however, the oxidizing power of the blood is necessary. 



The excretion of uric acid is increased by food rich in 

 nucleins. Uric acid introduced into the body of a mammal 

 is, for the greater part, excreted as urea. 



4. Nuclein or xanthin bases. These are: 



(a) Guanin, C 5 H 5 N 5 O. 



(b) Xanthin, C 5 H 4 N 4 O 2 . 



