NUCLEIC ACIDS 155 



from the other (guanine), and dog's liver from neither. The results are 

 shown in the following diagrams which are abbreviations of the one on 

 page 1-3S. The' absence of a ferment is indicated by a dotted line. 



ox liver pi^s liver rabbits liver clod's liver 



_LJ _J JJ _LJ 



2. The purine ferments do not appear in an organ simultaneously, 

 but are formed successively as embryonic development proceeds ; so that 

 the distribution depends not only upon the particular tissue and the species, 

 but to a considerable extent upon the age of the animal. None of the 

 purine ferments can be demonstrated in the aqueous liver extract of a 

 pig embryo less than 00 mm. in length. As the embryo increases in length 

 from 90 mm. to 200 mm., adenase makes its appearance, but xanthine 

 oxidase appears only after the birth of the animal. (Jones and Austrian 

 1907.) 



3. The distribution of the purine ferments in. the organs of man is 

 very characteristic. Adenase is not present in any human tissue. Guanase 

 is irregularly distributed, being present in the kidney, liver and lung but 

 absent from the spleen and pancreas. (Jones and Austrian (&).) It is 

 significant that human urine contains adcnine, but not guanine. Xanthine 

 oxidase is profusely present in the human liver but is confined to the one 

 organ. (^Miller and Jones; Winteruitz and Jones.) 



Uricase is not present in the liver, nor in any other organ either of 

 children or adults, nor is allantoine present in human urine, except a trace 

 of the substance that is ingested with the food. It seems curious that 

 man should have lost so useful a function as ability to destroy uric acid. 



4. Uricase may be regarded as a liver ferment since it is probably 

 present in the livers of all the lower animals except the ape (ox, dog, pig, 

 sheep, rabbit, guinea pig, horse, rat, opossum, monkey), and except for 

 an occasional occurrence in the spleen (ox), the ferment is found only 

 in the liver. Its location makes it very effective, so that allantoine is 

 far more abundant than uric acid in the urine of the lower animals. This 

 appears in the analyses of the urine of seventeen animals, twelve of which 

 were made by Hunter and his associates. They calculate a factor for 

 each animal species called the "uricolytic index," which is directly pro- 

 portional to the allantoine, and inversely proportional to the uric acid. 

 The following table, adapted from that of Hunter and Givens (c)(1914), 

 shows the great preponderance of the allantoine over the uric acid in the 

 urine of the lower animals, in contrast to the urine of man and the ape. 



