PLATE a 
A. —Base of a normal stalk of yellow dent grown in a well-fertilized soil. 
The basal tissues are free from discolorations and nrngi. The soil showed no avail¬ 
able aluminum salts when tested. 
B. —Stalk of yellow dent in which there are large accumulations of aluminum 
and iron compounds. The roots are rotted and the basal tissues invaded by fungi 
and bacteria. This plant was taken from a soil notably deficient in available phos¬ 
phate but containing available iron and aluminum salts. 
27135—23 - 5 
