!74 LOUIS BAUMAN 



COOH). This compound is converted into creatin when fed or injected 

 into animals (Czemicki ; Jaffe, 1906; Dorner; Bauman and Hines). 



Van Hoogenhuyzo and Verploegh (a) (1905) failed to observe an 

 crease in creatinin excretion after the ingestion of proteins relatively rk 

 in arginin. Myers and Fine (1905) report that the concentration 

 muscle creatin does not appear to be markedly influenced by the feedii 

 of proteins having a high or low content of arginin. Jaffe (/) (1906) di< 

 not observe an increase in creatinin excretion after the injection of arginii 

 into rabbits. Bauman and Marker also failed to note an increase 

 muscle creatin when arginin was circulated through dog muscle. 



Thompson (a) (1917) administered arginin to ducks, dogs and rabbit 

 and observed an increase in the elimination of creatin or creatinin and oi 

 the creatin content of the muscle. Inouye observed that arginin was coi 

 verted into creatin when perfused through the liver of cats. In grown 

 pigs the nature of the protein in the diet determines whether or not 

 creatin appears in the urine (McCollum and Steenbock). Denis (/) 

 (1917) has shown that the creatin excretion in hyperthyroidism may 

 much increased by the addition of protein to the diet. In children thf 

 creatin of the urine varies with the amount of protein in. the diet (Denis 

 and Kramer). Creatinuria in women follows the ingestion of lar 

 amounts of protein (Denis and Minot (a)). 



Kiesser observed an increase in. muscle creatin and in the creatinin 

 excretion of rabbits after the injection of cholin and betain. 



Harding and Young found that arginin was without effect on the 

 creatin excretion of growing dogs but that a variation in the cystin con- 

 tent of the diet was followed by a similar variation in the creatin 

 elimination. 



Most recently Wishart observed an increase in muscle creatin follow- 

 ing the injection of guanidin salts into cats, dogs and frogs. The as- 

 sumption is that guanidin is detoxicated by conversion into creatin. 



In the foregoing experiments the factor of creatin destruction by the 

 tissues must not be overlooked. Creatin . may be synthesized from a 

 precursor but subsequently destroyed. 



Creatin Metabolism 



Muscle. Before discussing this subject it may be well to remind the 

 reader that the experimental results obtained by different investigators are 

 often conflicting and therefore hard to reconcile with one another. 



Considerable evidence seems to show that creatin is a product of muscle 

 metabolism. Its preponderance in muscle suggests that it results from 

 metabolic processes peculiar to this tissue (Pekelharing). Muscle creatin 

 increases with an increase in muscle tonus and conversely paralyzed muscle 



