THE KREATINS. 107 



Guanin, as has been shown, under the same conditions yields 

 guanidin and parabanic acid, which further illustrates the close 

 relationship between the two classes. 



For a consideration of the methods employed in the isolation of 

 uric acid and its quantitative estimation, the reader is referred to the 

 chapter on the Urine. 



THE KREATINS. 



The kreatins, or kreatinic leucomains, as they are also termed by 

 Gautier, are basic substances which are closely related to the 

 nucleinic bases and to the ureids, which have just been considered. 

 They comprise kreatin, kreatinin, crusokreatinin, xanthokreatinin, 

 amphikreatinin, and two similar substances of doubtful composition. 

 Kreatin, moreover, is related to arginin, and can be produced syntheti- 

 cally through the union of cyanamide and methyl-glycocoll, as arginin 

 results from cyanamide and ornithin. While arginin, however, can 

 be obtained artificially from albuminous material, kreatin has thus 

 far not been isolated in this manner. Its formation from cyanamide 

 and methyl-glycocoll is represented by the equation : 



/NH 2 

 N = C NH 2 + NH(CH 3 ) CH 2 COOH = NH : C< 



X N(CH 3 ) CH 2 COOH 

 Cyanamide. Methyl-glycocoll. Kreatin. 



It can thus be viewed as methyl-guanidin acetic acid. It is thus 

 a homologue of glycocyamin, which results through the union of 

 cyanamide and glycocoll : 



/NH 2 /NH 2 



N==C NH 2 + CH/ = NH : C< 



' -COOH \NH CH 2 COOH 



Cyanamide. Glycocoll. Glucocyamin, 



On dehydration kreatin loses one molecule of water and is trans- 

 formed into kreatinin, which may thus be regarded as the anhydride 

 of kreatin : 



/NH ^H CO 



NH : <X = NH : C( -f H 2 O 



\N(CH 3 ) CH 2 COOH X N(CH 3 ) CH 2 



On oxidation with mercuric oxide kreatin gives rise to the forma- 

 tion of the oxalate of methyl-guanidin or methyl-uramin, which in 

 turn results from guanidin, and this from guanin. 



2C 4 H 9 N 3 2 + 50 = (C 2 H 7 N 3 ) 2 .C 2 H 2 4 + 2CO 2 + H 2 O 

 Kreatiii. Methyi-guanidin 



oxalate. 



On decomposition with baryta-water kreatin yields urea, methyl- 

 glycocoll, and a small amount of hydantoic acid. Kreatinin is 

 similarly transformed into methyl-hydantoin, which is then likewise 

 decomposed into urea and methyl-glycocoll, thus demonstrating 



