592 LINDSTROM, GENETICAL RESEARCH WITH MAIZE 
In this diagram the pericarp (seed-coat) which surrounds the grain 
consists of serveral layers of cells. In the dry, mature grain these cells 

Fig. 1. Diagram of the cross-section of a grain of maize. 
are somewhat distintegrated. It is to be emphasized that this epider- 
mal tissue is of maternal origin. It is not endosperm tissue. These cells 
carry the red or colorless pericarp color mentioned previously. Because 
this tissue is maternal all the grains on the ear are either red, brown, or 
colorless. 
The true endosperm begins with the aleurone cells, a single, distinct 
layer of cells below the pericarp (and the remains of the nucellus). The 
aleurone layer may be considered as the epidermis of the endosperm 
tissue. It carries the purple or red color. The endosperm starch cells 
carry the yellow or colorless white condition. 
Aleurone color. — The inheritance of the anthocyanin pigment in the 
aleurone layer is dependant on five basic factors, (East 1912; Emerson 
1918). For the development of any color whatsoever, the three domi- 
nant factors A, C and R must be present. For red color factor pris es- 
sential, while for purple color Pr is necessary. The fifth pair of aleurone 
