76 THE THEORY OF IONS 



precursor of gluten-fibrin. The latter being coagu- 

 lated forms gluten, from which again phyto-albu- 

 mose (gliadin or mucedin) can be separated, leaving 

 the insoluble gluten-fibrin. Aleuron consists of an 

 accumulation of such globulins and albumoses about 

 a crystal or crystals of double phosphate of lime and 

 magnesia ; it is in fact a mixture of homologous 

 proteins, beginning with hetero-albumose and ending 

 with globulins and albumin. An aleuron granule 

 may probably be correctly considered a very coarse 

 representation of the finer proteid molecule of 

 animal structures. 



The proteins of animal structures are derived from 

 those of vegetable origin. Being consumed, they are 

 broken down by digestion, that is, they are depoly- 

 merised and transformed from colloids to crystal- 

 loids. Having entered the organism such crystal- 

 loid substances are again polymerised to form col- 

 loids such as the globulins and albumins of the blood 

 and tissues. 



Proteid-like substances have been prepared syn- 

 thetically by Curtius, Fischer, Siegfried, and others. 

 They have succeeded in linking together two or more 

 amino-acids ; e.g. glycyl-glycyl and glycyl-alanin 

 anhydride, which are dipeptides ; also polypeptides, 

 containing three or four glycin molecules linked to- 

 gether, have been formed. They are esters, but give 

 the biuret reaction, and are considered to be the 

 beginning of a proteid synthesis. Proteoses and 

 peptones have not yet been formed ; they are prob- 

 ably mixtures of various proteins. 



The instability of the molecules of living proteids 

 or biogens, as they are called by Verworn, is due to 



