PLATE a 
A. —Com’seedlings 6 weeks old grown in quartz sand mixed at the rate of 3 tons 
per acre with alkaline salts from washings of the Courtland greensand. 
B. —Corn seedlings 6 weeks old grown in quartz sand mixed with the heavy metals 
obtained from the Courtland greensand, but free from lime, at the rate of a tons per 
acre.^ * 
