PLATE 9 



A. Barley grown in container with wax seals at 6-inch intervals. 



B. Same with upper portion of container removed. 



C. Wax seal at depth of 2 feet (left) showing the penetration of the seal by roots and 



their abundance under field conditions. Fertilized soil at 2.5 feet depth rilled 

 with copiously branched roots. 

 T>. Arrangement of containers in greenhouse experiment, 1920-21. 



