PLATE 3 
A. —The nodal tissues can be classified into two zones, zone A, the growing region, 
and zone B, the vascular plate region. Iron and aluminum compounds concentrate 
in certain tissues in zone B. 
B. —Copper sulphate in N/ioo concentration caused injuries to the tissues in both 
zone A and zone B when injected into the plants. Copper, aluminum, and iron 
salts produce similar effects upon these tissues in different intensities. 
