78 THE SIMPLER NATURAL BASES 



normally very constant, by 10-15 per cent, in the case of choline, and 

 by 6-3-11-3 per cent, in the case of betaine. Riesser considers that 

 these two substances are partially demethylated and then condense 

 with urea, according to the following equations : 



/NH 2 



/NH 2 /OH / 



CO/ + (CH 3 ) 3 |N/ - C : NH +2 CH,OH 



^NHj ^CH, . CH 2 OH Mt r , CH, . CH a OH 



CH 3 



/NH 2 /OH / * 



CO/ 4. rCH \ N/ = C : NH +2 CH,OH 



^ u \ + l^ M Ji : w \ \ 



N NH 2 N CH,.COOH \N.CH 8 .COOH 



CH, 



The two methyl groups would be eliminated as methyl alcohol ; the 

 condensation product from choline would undergo oxidation to 

 creatine. Riesser also administered sarcosine and urea by the mouth 

 and subcutaneously, and in half of the experiments obtained evidence 

 of creatine formation, which would occur as follows : 



CO/ + NH.CHj.COOH = C: NH + H,O. 



NH 2 i u \ST.CH,.COOH 



"3 I 



CH 3 



B. Glycocyamine and Glycocyamidine. 



Although these bases do not occur naturally they may be briefly 

 referred to on account of their relationship to creatine and creatinine 

 respectively, from which they differ by having one methyl group less ; 

 glycocyamine is guanidino-acetic acid and glycocyamidine is the cor- 

 responding anhydride. 



Glycocyamine was first obtained by Strecker, in 1861, by the 

 addition of cyanamide to glycine. Nencki and Sieber [1878] heated 

 glycine with guanidine carbonate at 140, and Korndorfer [1905] 

 found that heating in the water bath was sufficient and more convenient. 

 H. Ramsay [1908] has described a convenient synthesis of glycocy- 

 amine, in which monochloracetic acid is heated with a concentrated 

 aqueous solution of free guanidine (5 mols.) to 60 for two hours. 



The physiological interest of glycocyamine and its anhydride chiefly 

 depends on their supposed methylation in the organism to form creatine 

 and creatinine. The question was first studied by Czernecki [1905] 

 whose results were indecisive or negative; later Jaff6 [1906] found 

 (by Neubauer's method) that 4-5-14-3 per cent, of the glycocyamine, 



