132 CREATIN AND CREATININ 



creatin. A whole series of examples may be appealed to to 

 show that the living body actually is engaged in bringing 

 about such a process of methylation. Metabolically from 

 telluric or selenic acid, as Franz Hofmeister noted, 37 tel- 

 lurium methide or selenium methide can be formed; from. 



pyridin, , according to His, 38 may be produced 



HC <LJ CH 



CH 

 HC /\ CH 



methylpyridylammonium hydroxide, HctlcH; from di- 



N 



CH 3 OH 

 f" 1 TT 



ethylsulphide, 'Ns, according to Neuberg and Grosser, 39 



Ca H 6 ' 



OfTT \ 

 S/ } It is 

 \)H/ 



rather difficult to appreciate precisely why, therefore, we 

 should deny the possibility of methylation of guanidinace- 

 tic acid in metabolism. Even the negative or varying results 

 of experiments intended to influence the elimination of crea- 

 tin and creatinin in the urine and the amount of creatin in 

 the muscles by administration of guanidin acetic acid or of 

 proteins rich in arginin 40 prove but little. It is a well 

 known fact that attempts are not always successful to re- 

 produce at will the processes which accompany protein 

 decomposition in the living body by experimental introduc- 

 tion of their decomposition products. 



87 F. Hofmeister, Arch. f. exper. Pathol., S3, 198, 1894. 



88 W. His, Arch. f. exper. Pathol., 22, 253, 1887. 



39 C. Neuberg and Grosser, 2. Tagung d. deutsch. physiol. Gesel., Cen- 

 tralbl. f. Physiol., 19, 316, 1905. 



40 W. Czernecki ( S'alkowski's Lab.), Zeitschr. f. physiol. Chem., 44, 294, 

 1905; M. Jaffe, ibid., 48, 430, 1906; G. Dorner (Jaffe's Lab.), ibid., 52, 225, 

 1907; O. af Klercker, Hofmeister's Beitr., 8, 59, 1906; E. Mellanby, 1. c. 



