CORN OR MAIZE 95 



promptly, or in the current cross, give a yellow color to the 

 endosperm of the cross-pollinated grains of a white variety 

 (see Par. 90) . Since the hull in this case is transparent, 

 the yellow endosperm shows through and the grain appears 

 yellow. 



On the other hand, the red color sometimes appearing 

 in dent varieties is due, not to a colored endosperm, but to 

 red color in the hull. Hence the red in the hull obscures 

 whatever color there might be in the endosperm (for ex- 

 ample, yellow), and determines the color of the grain. But 

 the pollen does not in the current cross affect the hull, 

 so that impregnation of white grains by pollen from red 

 varieties does not, like the use of yellow pollen, show a few 

 months after fertilization, but must wait to show the red 

 color of the male parent in the next generation. 



The color that is responsible for the blue, purple, or lead- 

 colored appearance of certain kinds of sweet and soft 

 corns, which are different races from ordinary or dent corn, 

 is located in the outer part of the endosperm, or just be- 

 neath the hull. The color, being in the endosperm, is sub- 

 ject to double fertilization, and hence to the immediate 

 display of the color of the pollen-bearing parent. A lead- 

 colored corn planted near a white may immediately cause 

 colored grains to appear on white ears all over the field. 



LABORATORY EXERCISES 

 Roots. 



(1) Plant 10 grains of corn 1 inch deep and other similar lots at 

 depths of 1, 2, 4, and 5 inches below the surface, either in a box 

 of soil or in the garden or field : 



(a) Record the number of days after planting before each 

 plant appears. 



