194 BACTERIOLOGICAL AND ENZYME CHEMISTRY 



Mono-amino acids ; 

 Hydroxy-amino acids ; 

 Di-amino acids ; 

 Amino-dicarboxylic acids ; 

 Sulphur derivatives ; 

 Purin bases ; 

 Ptomaines ; 

 Carbohydrates. 



In addition, simple substances such as sulphuretted hydro- 

 gen, carbonic acid, ammonia, sundry fatty and other acids, 

 etc., are produced. 



Mono-amino Acids 



The following are the chief mono-ammo acids : 

 1. Glycocoll or ammo-acetic acid. This is the simplest 

 member of the mono-amino acids ; it is frequently termed 

 glycin for the sake of convenience in describing its numerous 

 derivatives among the polypeptides. Glycocoll is related, 

 to what is believed to be the mother substance of sJcatol, 

 a substance occurring in excreta, the unpleasant smell of 

 which is largely due to it. Skatol can be recognised in 

 concentrated fresh sewage by the pink colour which is obtained 

 on warming with strong sulphuric acid. It has been shown 

 to be /3-methyl-indol, the relation of the two bodies skatol 

 and indol beirg given by the following formulae : 



