176 INTERMEDIATE METABOLISM 



general. In these animals it is the most abundant nitro- 

 genous substance in the urine, urea being present only to 

 a shght extent. When the hver is short-circuited by an 

 Eck fistula the amount of uric acid excreted falls consider- 

 ably, its place being taken both in the blood and in the 

 urine by ammonium lactate. When an extract of avian 

 hver is digested with ammonium lactate, uric acid is formed. 

 In the bird, then, the liver synthesises uric acid, taking 

 the three-carbon-atom chain from ammonium lactate. 



Gout 



Our ignorance of the cause of gout arises largely out 

 of the uncertainty which exists as to the form in which 

 uric acid and its salts occur in the blood. Fresh blood 

 contains more uric acid after boiling with acids than 

 before. This suggests that some of the urates exist in 

 combination. 



It is said that the sodium salts exist in two forms, 

 the lactam form, or a-urate— 



NH— CO 



I I 



I I 



CO C— NH 



I It 

 NH— C— NH 



^CO 



which is soluble but unstable, being readily converted into 

 the lactim form, or /3-urate — 



N COH 



I I 



COH C— NH. 



I II >co 



N C-NH^ 



which is less soluble. It has been suggested that the 

 formation of gouty deposits is due to the conversion of 

 the soluble a- into the insoluble y5- form. 



