URIC kCID Wl> 'I'll I PDBIN] B0D1 



From an examination of the structural formulas, it will be Been thai 

 they are more or less related to purine (having one of the urea radicles 

 omitted), although it can scarcely be doubted thai thi eparate 



constituents of the oucleic acid group in the animal body, and are nol 

 derived from purine. They are primary products. 



The Chemical Nature of the Substances in Which Purine and 

 Pyrimidine Bases Exist in the Animal Body.- Tn general it may be said 

 thai the amino purines adenine and guanine together with the 

 pyrimidine bases thymine and cytosine — occur combined with phos- 

 phoric acid and a carbohydrate in the various nucleic acids, each of which 

 is again combined with some simple protein to form nuclcin. t lie essen- 

 tial constituent of the chromatin of the nucleus. One of the oxypuri 

 hypoxanthine, may also exist eombined with phosphoric ; s < - i * 1 i rbo- 



hydrate to form a substance presenl in muscle and known as inosinic 

 acid. The general scheme of construction of a nucleic acid of animal 

 origin is illustrated in the following formula suggested by Levene and 

 Jacobs: 89 



According to this formula nucleic acid may be considered i »m- 



pound of polyphosphoric acid, containing carbohydrate groups, which 

 Berve to link the phosphoric acid molecules to tl purine or pyrimi- 



dine. Tn nucleic acids of animal origin, such as the example 

 above, the carbohydrate is a hexos . contains 6 C-al . whei 



