CREATINE. 547 



tors consider creatine as a step in the formation of urea in the organism. 

 On boiling with acids, creatine is easily converted, with the elimination 

 of water, into the corresponding anhydride, creatinine, C 4 H 7 N 3 O, which 

 is retransformed into creatine by the action of alkali. 



The question as to the relation of creatine to creatinine within the 

 animal body is disputed, and is intimately related to the question as 

 to the role of the creatinine in protein metabolism. As this question 

 is best discussed in connection with creatinine and its elimination in 

 the urine (Chapter XV), we will here only discuss the direct relation of 

 creatine to the muscles and its metabolism. 



Of special interest in this regard, besides the relation between creatine 

 and muscle work which will be discussed below, is the question as to 

 the occurrence of free or combined creatine in the muscle. URANO by 

 the aid of dialysis experiments has shown the probability that the crea- 

 tine does not exist free in the muscle, but as a labile, non-dialyzable 

 combination. Nevertheless GOTTLIEB and STANGASSINGER claim by 

 various researches to have shown in the autolysis of muscles and other 

 organs that creatine is first formed and then first changed into creatinine 

 by special bodies of an enzymotic nature, and then destroyed. SEEM ANN l 

 indeed claims, by an autolysis of three months' duration, to have obtained 

 two to three times as much creatinine directly from the muscle and after 

 the addition of creatinine-free-gelatin four times as much, which is an 

 argument against the enzymotic destruction of creatinine in autolysis, and 

 he admits of the formation of creatine (or creatinine) from protein. 

 The autolytic experiments of ROTHMANN also indicate the formation of 

 creatine from a preliminary body, and the recent experiments of VAN 

 HOOGENHUYZE and VERPLOEGH make the enzymotic transformation 

 of creatine and creatinine probable. MELLANBY positively denies the 

 re-formation of creatine as well as its destruction in autolysis entirely 

 free from bacteria. It is hard to draw positive conclusions from exper- 

 iments with autolysis. The transfusion experiments of GOTTLIEB and 

 STANGASSINGER 2 with the kidneys and livers of dogs not only point to 

 the ability of these organs to decompose creatine, but also for a re-for- 

 mation of creatine in the liver. Further investigations are still very 

 necessary. 



Opinions are not unanimous in regard to the organ where creatine 

 is formed. From recent investigations it is concluded that the liver 

 plays an important part therein. Other organs, especially the muscles, 



1 Urano, Hofmeister's Beitrage, 9; Gottlieb and Stangassinger, Zeitschr. f. physiol. 

 Chem., 52 (and 55); Stangassinger, ibid., 55; Seemann, Zeitschr. f. Biol., 49; Roth- 

 mann, Zeitschr. f. physiol. Chem., 57; v. Hoogenhuyze and Verploegh, ibid., 57; 

 Mellanby, Journ. of Physiol., 36. 



2 Zeitschr. f. physiol. Chem., 55. 



