14 THE SMALL GRAINS 



phosphate of lime and magnesia, and sometimes one or 

 more calcium oxalate crystals; while frequently crystal- 

 line proteins are also present. The latter give the 

 property of swelling up quickly on the addition of water. 

 Chemically, the aleurone grains consist chiefly of three 

 proteins : (1) peptones, insoluble in water (not even 

 precipitated by boiling) ; (2) globulins, insoluble in water, 

 but soluble in 10 per cent or saturated solution of sodium 

 chloride; and (3) albuminates, insoluble in water or the 

 sodium chloride solution, but soluble in alkali. The crys- 

 talline proteins consist either of globulins or albu- 

 minates. 



Gluten of wheat does not exist as such in the dry kernel, 

 but is formed by the addition of water to the proteins, 

 gliadin and glutenin, found in the outer part of the 

 endosperm. 



