PROTEINS 151 
Protein Group.—Con. whose true composition is in 
great part not yet clear. They 
contain C, H, O and N in 
fairly large amounts and usu- 
ally some S andoftenP. 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 only 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 probably 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 (Albumens) are 
usually easily coagulable by 
heat and by salts of Cu, Hg, 
Ag, ete. By hydrolysis with 
certain enzymes these com- 
pounds are broken down into 
