128 CREATIN AND CREATININ 



(acidosis) and that of creatinin 23 is readily appreciable, the 

 former process involving a drain upon the fat deposit, the 

 latter upon the tissue proteins. 



Muscle as the Source of Creatin. In harmony with the 

 hypothesis of consumption of tissue protein in the construc- 

 tion of creatin may be offered the observation, made long 

 ago in the laboratory of Hoppe-Seyler, and recently con- 

 firmed, 24 that in conditions of inanition the muscles are rich 

 in creatin. 



That muscle may be the source of creatin may be directly 

 inferred from the large amount of this substance contained 

 in it. Marked increase of the creatin-creatinin content 

 ensues in isolated frog's muscle upon nervous stimulation 25 ; 

 and the excised functionating mammalian heart in Ringer's 

 solution may discharge considerable quantities of creatin 

 and creatinin into the surrounding fluid. 26 From recent 

 studies of Pekelharing and his pupils the impression is given 

 that tonic contracture of a muscle is more favorable than 

 the short contraction of ordinary muscular action to induce 

 a high degree of cleavage production of creatin. 27 With the 

 work of Gottlieb and his associates, the results of which are 

 in consonance with this view, and those of Seemann (cf . Vol. 

 I of this series, p. 148, Chemistry of the Tissues) before us, 

 we may well assume as a working hypothesis (in spite of the 

 negative results of Mellanby) that creatin can be produced 

 by cleavage from a colloid precursor in muscle tissue not 

 only by vital but also under certain circumstances by post 



23 E. P. Cathcart and M. R. Taylor, 1. c. 



**B. Demant, Zeitschr. f. physiol. Chem., 8, 388, 1879; L. B. Mendel (Yale 

 Univ.), Jour, of Biol. Chem., 10, 255, 1911. 



* T. Graham-Brown and E. P. Cathcart, Jour, of Physiol., 57, XIV, 1908. 



38 S. Weber (Minkowski's Clinic, Greifswald), Arch. f. exper. Pathol., 58, 

 93, 1907. 



27 C. J. C. Van Hoogenhuyze and H. Verploegh, Zeitschr. f. physiol. Chem., 

 46, 415, 1905; C. J. C. Van Hoogenhuyze, Jahresber. f. Tierchem., 39, 445, 1909; 

 C. A. Pekelharing and C. J. C. Van Hoogenhuyze, ibid., 64, 262, 1910; C. A. 

 Pekelharing, ibid., 75, 207, 1911. 



