182 THE PROTEIN SUBSTANCES. 



HN CO 

 For example, uric acid, OC C NH\ , is 2, 6, 8-trioxypurine, adenine, 



VJ^ ^ i-NXlv 



HN C NIK 



HC C NHv , is 6-aminopurine, and heteroxanthine, OC 

 II II >H | || \ 



N C W HN C N^ C 



7-methyl-2, 6-dioxypurine, etc. 



The starting-point used by FISCHER for the synthetical preparation of the 

 purine bases was 2, 6, 8-trichlorpurine, which is obtained, with 8-oxy-2, 6-dichlor- 

 purine as an intermediary product, from potassium urate and phosphorus oxychlo- 

 ride. 



The purine bodies or alloxuric bodies found in the animal body or its 

 excreta are as follows: Uric acid, xanthine, heteroxanthine, 1-methylxan- 

 thine, paraxanthine, guanine, epiyuanine, hypoxanthine, episarkine, adenine 

 (and carnine?). The bodies theobromine, theophylline, and caffeine, occur- 

 ring in the vegetable kingdom, stand in close relation to this group. 



The composition of the purine bodies most important from a physio- 

 logical standpoint is as follows: 



Uric acid, C 5 H 4 N 4 O 3 2, 6, 8-trioxypurine 



Xanthine, C 5 H 4 N 4 O 2 2, 6-dioxypurine 



1-methylxanthine, C 6 H 6 N 4 1-methyl 



Heteroxanthine, C 6 H 6 N 4 O 2 7 " 



Theophylline, C 7 H 8 N 4 O 2 1, 3-dimethyl 



Paraxanthine, C 7 H 8 N 4 O 2 1, 7- " 



Theobromine, C 7 H 8 N 4 O 2 3, 7- " 



Caffeine, C 8 H 10 N 4 O 2 1, 3, 7-trimethyl 



Hypoxanthine, C 5 H 4 N 4 6-oxypurme 



Guanine, C 5 H 5 N 5 2-amino " " 



Epiguanine, C 6 H 7 N 5 7-methyl " 



Adenine, C 5 H 5 N 5 6-aminopurine 



Episarkine, C 4 H 8 N 4 O 3 (?) 



Carnine, C 7 H 8 N,O 3 



After SALOMON 1 had shown the occurrence of xanthine bodies in 

 young cells, the importance of the purine bases as decomposition prod- 

 ucts of cell nuclei and of nucleins was shown by the pioneering researches 

 of KOSSEL, who discovered adenine and theophylline. In those tissues 

 in which, as in the glands, the cells have kept their original state, the 

 purine bases are not found free, but in combination with other atomic 

 groups (nucleic acids). In such tissues, on the contrary, as in muscles, 

 which are poor in cell nuclei, the purine bases are found in the free state. 

 Since the purine bases, as suggested by KOSSEL, stand in close relation- 

 ship to the cell nucleus, it is easy to understand why the quantity of 

 these bodies is so greatly increased when large quantities of nucleated 



1 Sitzungsber. d. Bot. Verein der Provinz Brandenburg, 1880. 



