CHEMICAL BASIS OF THE ANIMAL BODY. 901 



Alloxan. Mesoxalic, Urea. 



C 4 N 2 H 2 4 -f 2H 2 - C 2 H 2 5 4- CN 2 H 4 ; 



and by the action of chlorine uric acid can be split up directly into a molecule of 

 mesoxalic acid and two molecules of urea : 



Uric acid. Mesoxalic acid. Urea. 



C 5 H 4 N 4 3 + Cl, + 4H 2 = C 3 H 2 5 + 2CN 2 H 4 OC + 2HCL 



By oxidation with alkalies, uric acid is converted into allantoin and carbonic 



acid, 



Uric acid. Allantoin. 



C 5 H 4 N 4 3 + H 2 4- = C 4 H 6 N 4 3 + C0 2 ; 



and allantoin, by hydration, becomes allanturic or lantanuric acid and urea, 

 Allantoin. Urea. Allanturic acid. 



C 4 H 6 N 4 3 + H 2 - CH 4 N 2 + C S H 4 N 8 0. 



Now allanturic acid is a compound urea, with a residue of glyoxylic acid. By 

 other oxidations of uric acid, parabanic acid (oxalyl-urea), oxaluric acid (which is 

 hydrated parabanic acid), and dialuric acid (tartrpnyl-urea) are obtained. In fact, 

 all these decompositions of a molecule of uric acid lead to the production of urea 

 and of a carbon acid of some kind or other. The relation of uric acid to urea, as 

 illustrated by the above reactions, is brought very prominently into view by the 

 synthesis of uric acid which has recently been performed. ' It is obtained by simply 

 fusing together glycocine (amido-acetic acid) and urea at a temperature of 200- 

 230 C. The converse formation of glycocine from uric acid with the simultaneous 

 production of ammonia and carbonic anhydride has been known for some time. 

 Since in this latter reaction the ammonia and carbonic anhydride are in the propor- 

 tions in which they would be obtained from cyanic or cyanuric acid, uric acid has 

 been regarded as built up from residues of cyanuric acid and glycin, just as hippuric 

 acid is formed from glycin and benzoic acid. It was also at one time supposed that 

 uric acid might be regarded as tartronyl cyanamide. 



N(CN) 2 

 H 2 



If the existence of some cyanogen residue is thus assumed in the molecule of 

 uric acid, then it must be supposed that before urea can be obtained from it a 

 molecular change takes place by which a portion at least of the nitrogen of the uric 

 acid is converted into the same condition as the rest of the nitrogen, viz., into the 

 amide state. 



If this be so, since the metabolism of the animals in which uric acid replaces 

 urea cannot be supposed to be fundamentally different from that of the urea-pro- 

 ducing animals, we may infer that the antecedent of both uric acid and urea in the 

 regressive metabolism of proteids is, as we suggested above, a body containing some 

 at least of its nitrogen in the form of cyanogen. 2 



Kreatin. C 4 H 9 N 3 2 . 



Occurs as a constant constituent of the juices of muscles, though possibly it 

 may be formed during the process of extraction by the hydration of kreatinin. 

 Kreatin is not a normal constituent of urine, but it is said to occur in traces in 

 several fluids of the body. When found in urine its presence is probably due to 

 the conversion of kreatinin, a constant constituent of urine, into kreatin during 

 its extraction, since Dessaignes 3 has shown that the more rapidly the separation is 

 -effected, the less is the quantity of kreatin obtained, and the greater the amount of 

 kreatinin. 



In the anhydrous form it is white and opaque, but crystallizes with one molecule 

 of water in colorless, transparent rhombic prisms [Fig. 241, a]. It possesses a some- 



1 Horbaczewski ; Ber. d. Deutseh. Chem. Gesell., Jahrg. 1882, S. 2678. 



2 See v. Knieriem, Zeitschr. f. Biol., Bd. xiii. (1877), S. 36. Schroder, Zeitschr. f. physiol. Chem., 

 Bd. ii. (1878), S. 228. 



3 Jahrb. Pharm. (3), Bd. xxxii. S. 41. 



