231 THE URINE. 



too small. We must hence assume that some other substance enters 

 into the reaction. This substance, however, is as yet unknown, but 

 we may imagine that one portion of ammonium lactate is first trans- 

 formed into ammonium carbonate, and that the uric acid is then 

 formed through the union of this with another molecule of lactic 

 acid. Horbaczewski, indeed, has shown that artificially uric acid 

 may be formed from lactic acid, ammonia, and carbon dioxide, by 

 heating trichloro-lactic amide together with urea. The reactioii 

 which takes place may be represented by the equation : 



2CO(NH 2 ) 2 + C 3 C1 3 2 H 2 .NH 2 = NH 4 C1 + 2HC1 + H 2 O + C 5 H 4 N 4 O 3 - 

 Trichloro-lactic Uric acid, 



amide. 



On the other hand, it is possible that uric acid may result through 

 the union of glycocoll and urea, and artificially this synthesis can 

 indeed be effected. We have seen, moreover, that on hydrolytic 

 decomposition uric acid yields ammonia, carbon dioxide, and gly- 

 cocoll. In this case the resulting reaction could be expressed by 

 the equation : 



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



While the greater portion of the uric acid is thus formed syn- 

 thetically in the liver of birds and reptiles, a variable but much 

 smaller amount results directly from the xanthin bases through a 

 process of oxidation. 



These are in part derived from disintegrating cells of the body, 

 and are to a certain extent also referable to the ingested food. In 

 man and most mammals this is indeed the only source of the uric 

 acid, and through the researches of Horbaczewski we now know 

 that the nuclear uric acid, as we may term it, is formed together 

 with the xanthin bases in all organs of the body, and is most 

 abundantly produced in those which are especially rich in nuclei, 

 such as the spleen and the lymph-glands. The very interesting 

 observation was further made that larger amounts of uric acid could 

 be obtained from these parts when the blood used in the transfu- 

 sion experiments contained much oxygen, while with venous blood 

 xanthin bases only were produced. In the amphibia and fish, in 

 which the oxidation-processes are especially slugpYh, we accordingly 

 find xanthin bases, but little or no uric acid. The interesting ques- 

 tion now suggests itself, Why is it that in mammals uric acid appears 

 in the urine at all in view of the fact that uric acid which is intro- 

 duced into the stomach is eliminated as urea? A final answer to 

 this question cannot be given, but there is reason to suppose that the 

 uric acid is here first carried to the liver, and is probably oxidized 

 to urea by the oxidizing ferments of this organ. We find, as a 

 matter of fact, that an increased elimination of uric acid result? at 

 once when the blood of the portal vein is prevented from flowing 

 through the liver by establishing a so-called Eck fistula between 

 this and the inferior cava, and when the hepatic artery is at the 



