36 BULLETIN 137, U. S. DEPARTMENT OF AGRICULTURE. 



like compound, is black. The pigments may occur in the hulls, the 

 pericarp, the aleurone layer, and occasionally in the starch endo- 

 sperm. The resulting colors of the grain are quite complicated. 

 White denotes the absence of all pigment; a heavy deposit of the 

 melaninlike compound in the hulls results in black; a light deposit, 

 brown. Anthocyanin in the hulls results in a light violet-red. In 

 naked forms the melaninlike compound in the pericarp results in a 

 black kernel ; anthocyanin produces a violet one. The acid condition 

 of anthocyanin in the pericarp superimposed upon the alkaline con- 

 dition in the aleurone layer gives the eifect of a purple color, while 

 a blue aleurone beneath a colorless pericarp is blue-gray. White hulls 

 over a blue aleurone cause the grain to appear bluish or bluish gray. 

 Black hulls over a blue aleurone give, of course, a black appearance. 

 The anthocyanin is always violet in the hulls and in the pericarp, 

 showing that these tissues are in an acid condition, and always blue 

 in the aleurone layer, showing an alkaline condition. The occurrence 

 of anthocyanin in the pericarp of hull-less barleys is more significant 

 than its production in the aleurone layer. 



