188 



BREEDING CROP PLANTS 



to a single factor. For example, the color in cob and pericarp 

 is often correlated in inheritance. Emerson (1911) has found a 

 case in which the factor for color in the cob behaves as an allelo- 

 morph of the factor for color in the pericarp. In the illustration 

 given in Table XL Ri represents the factor for cob color and Rz 

 the factor for pericarp color. 



TABLE XL. SUMMARY OF A CROSS IN WHICH A FACTOR FOR COB COLOR 

 BEHAVED AS AN ALLELOMORPH OF A FACTOR FOR COLOR OF PERICARP 



East and Hayes (1911) have given a case of a cross between 

 two reddish blush pericarp colors which developed only under 

 light conditions, which gave a 15 : 1 ratio in F 2 . This indicates 

 two separately inherited factors. 



There are numerous expressions of colors. Hayes (1917) ob- 

 tained four pericarp colors which bred comparatively true when 

 self -fertilized. These were called solid red, in which the pericarp 

 was uniformly red; variegated, in which the color was in deep 

 red stripes of various sizes; pattern, in which the color was also 

 in stripes but was much lighter in intensity; colorless, lacking 

 color in the pericarp. The factors for red, variegated, pattern 

 and colorless appeared to form a series of multiple allelomorphs. 

 The cross between pattern and variegated gave an increase in 

 bud sports in F\, i.e., ears which produced two sorts of pericarp 

 color sharply differentiated ; while in F 2 a few solid red ears were 

 obtained and many striped ears. This was presented as an 

 instance in heterozygous material in which a change in a charac- 

 ter occurred. Without attempting an explanation it was pointed 

 out that no such change occurred in six generations of selection 

 in self-fertilized families of the red, striped, or pattern lines. 

 Emerson (1914a, 1917) has studied the inheritance of these 

 anthocyan colors for several years. To explain the production 

 of solid red in variegated races, he supposes a change or mutation 



