MUSCULAR TISSUE 343 



creatine of ingested meat is transformed into creatinine and excreted 

 in the urine has been proven untenable through the researches of Folin, 

 Klercker, and Wolf and Shaffer. It is now known that under normal 

 conditions the ingestion of creatine in no way influences the excretion 

 of creatinine. In the case of Eck fistula dogs, however, London and 

 Bolyarski 1 found ingested creatine to increase the output of creatinine 

 in the urine. This finding is of importance as throwing light upon the 

 role of the liver in creatine and creatinine metabolism. In this con- 

 nection it is important to note that there is no normal excretion of 

 endogenous (see page 378) creatine, a statement proven by the fact that 

 if no creatine be ingested none will be excreted. Folin 2 has shown that 

 the main bulk of ingested creatine is retained in the body, unless the diet 

 contains a large amount of protein material. In fasting the urine 

 contains considerable creatine, i.e., 120 mg. or more per day. Under 

 certain pathological conditions, e.g., fevers, the urine may contain 

 endogenous creatine which is probably derived from the catabolism 

 of muscular tissue, as Benedict, Mellanby, and Shaffer have suggested. 

 Benedict and Osterberg 3 believe we may have a high creatine elimina- 

 tion which has no relation to the catabolism of muscle. 



McCrudden 4 reports creatine in the urine in cases of infantilism 

 achondroplasia and cretinism the amount present being increased 

 when the carbohydrate ingestion was increased. 



It has been stated that creatine does not occur in non-striated 

 muscle. It has, however, been found in the non-striated muscles of 

 the lamprey the lowest form of vertebrates. 5 



Amberg and Morrill, 6 Sedgwick, 7 Rose 8 and Folin 9 have shown that 

 creatine is a normal constituent of the urine of infants and children 

 (10-15 mg. per day). Folin explains this phenomenon on the basis of 

 the relatively high protein intake, whereas Rose believes it is due to a 

 peculiar carbohydrate metabolism. 



Besides being a normal constituent of muscle, xanthine has been 

 found in the brain, spleen, pancreas, thymus, kidneys, testicles, liver, 

 and in the urine. It may be obtained in crystalline form (Fig. in, 

 p. 344), but ordinarily it is amorphous. Xanthine is easily soluble in 

 alkalis, less soluble in water and dilute acids, and entirely insoluble in 

 alcohol and ether. 



Condon and Bolyarskii: ZeU, phys. chem., 62, 465, 1909. 



2 Folin: Hammarsten Festschrift y p. 15. 



3 Benedict and Osterberg: Jour. Biol. Chem., 18, 195, 1914. 



4 Me Crudden: Jour. Expt. Med., 15, 457, 1912. 



6 Mellanby: Jour, of Physiol., 36, 472, 1908. Wilson: Jour. Biol. Chem., 18, 17. 1914. 

 Amberg and Morrill: Jour. Biol. Chem., 3, 311, 1907. 



7 Sedgwick: Jour. Am. Med. Ass'n, 55, 1178, 1910. 



8 Rose: Jour. Biol. Chem., 10, 265, 1911. 



9 Folin: Ibid., n, 253, 1912. 



