PROTEINS 151 



Protein Grouv. — Con, whose true composition is in 



great part not yet clear. They 

 contain C, H, and N in 

 fairly large amounts and usu- 

 ally some S and often P. They 

 may also have in combination 

 certain metallic bases, but 

 this is not proved. They are 

 probably built up of combined 

 chains of amino-acids. Pos- 

 sibly hydrocyanic acid is one 

 of the steps, for it is abundant 

 in many plants when protein- 

 synthesis is active. Possibly 

 carbohydrates also are of 

 importance in the framework 

 of the molecule. The molecule 

 is very large and in the more 

 complex forms dialysis does 

 not occur or oi\\y feebly, but 

 in forms like peptones it 

 readily takes place. The high- 

 er forms lead to the Proto- 

 plasms which are chemically 

 to be regarded as very com- 

 plex protein compounds in 

 which probabl}' various metal- 

 lic bases are combined and 

 which perhaps have one or 

 more carbohydrate nuclei in 

 the molecule. They are very 

 labile compounds, easily de- 

 stroyed by external influences 

 of varied nature. The proto- 

 plasm and higher protein 

 compounds {Albinucns) are 

 usually easily coagulable by 

 heat and by"^salts of Cu, Hg, 

 Ag, etc. By hydrolysis with 

 certain enzymes these com- 

 pounds are broken down into 



