PLATE i 
A. —Longitudinal section through a node of a normal stalk. Most of the bundles 
were functioning, as is indicated by their staining with methylene blue. Very few 
bundles tested for iron and aluminum in zone B. 
B. —Longitudinal section through a node of a diseased stalk. Very few of the 
bundles were functioning. The inactive bundles contained large accumulations of 
iron (red) and aluminum in the zone B region. This is characteristic of stalks showing 
symptoms of rootrots. 
(824) 
