URTNE 121 



1. Increase of meat diet and diminution of oxidation processes, 

 such as occur in people with sedentary habits. 



2. Increase of white corpuscles in the blood, especially in the 

 disease known as leucocj-thaemia. This latter fact is of great interest, 

 as leucocytes contain large quantities of nuclein. Nuclein jields 

 nitrogenous bases which are closely related to uric acid. 



Purine Substances. — The bases just alluded to are sometimes 

 called the xanthine bases, because xanthine is a prominent member 

 of the group. Sometimes they are termed the nuclein bases, because 

 of their origin from nuclein. Another name they have received is 

 the alloxuric bases, because they contain in combination two radicles, 

 one of alloxan, and the other of urea. Emil Fischer's recent work, 

 however, has shown that they are to be rather regarded as deriva- 

 tives of a substance he has named purine ; hence the name by which 

 they are generally called now, the purine bases. The empirical 

 formulae for purine, the purine bases, and uric acid are as follows : — 

 Purine . . C5H4N4 



Hypoxanthine . C5H4N4O Monoxypurine ^ 



Xanthine . . C5H4N4O2 Dioxypurine [ Purine 



Adenine . . C5H4N4.NH Amino-purine 1 bases 

 Guanine . . C5H4N4O.NH Amino-oxypurinej 

 Uric acid . . C5H4N4O3 Trioxy-purine 



There are a vast number of purine derivatives, but only a few of 

 them have at present any physiological importance. Others in addition 

 to those already enumerated are theophylHne (dimethyl-xanthine), 

 theobromine (also a dimethyl-xanthine), caffeine (trimethyl-xanthine) ; 

 these are of interest, as they occur in tea, cocoa, and coflfee. A few 

 words more may be added in respect to those in our list. 



Purine itself has never been discovered in the body. It has the 

 following structural formula : 



N = C-H 



! I 



H-C C— NH. 



II II >C-H 



N- C-N ^ 



The purine nucleus is depicted in the next formula, and its atoms 

 have been empirically numbered as shown for convenience of 

 description : — 



I I 



\8r 



'N 





